Add meshlink_get_all_nodes_by_last_reachable().

[meshlink] / src / meshlink.c

/*
    meshlink.c -- Implementation of the MeshLink API.
    Copyright (C) 2014-2018 Guus Sliepen <guus@meshlink.io>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "system.h"
#include <pthread.h>

#include "crypto.h"
#include "ecdsagen.h"
#include "logger.h"
#include "meshlink_internal.h"
#include "netutl.h"
#include "node.h"
#include "submesh.h"
#include "packmsg.h"
#include "prf.h"
#include "protocol.h"
#include "route.h"
#include "sockaddr.h"
#include "utils.h"
#include "xalloc.h"
#include "ed25519/sha512.h"
#include "discovery.h"
#include "devtools.h"

#ifndef MSG_NOSIGNAL
#define MSG_NOSIGNAL 0
#endif
__thread meshlink_errno_t meshlink_errno;
meshlink_log_cb_t global_log_cb;
meshlink_log_level_t global_log_level;

typedef bool (*search_node_by_condition_t)(const node_t *, const void *);

static int rstrip(char *value) {
        int len = strlen(value);

        while(len && strchr("\t\r\n ", value[len - 1])) {
                value[--len] = 0;
        }

        return len;
}

static void get_canonical_address(node_t *n, char **hostname, char **port) {
        if(!n->canonical_address) {
                return;
        }

        *hostname = xstrdup(n->canonical_address);
        char *space = strchr(*hostname, ' ');

        if(space) {
                *space++ = 0;
                *port = xstrdup(space);
        }
}

static bool is_valid_hostname(const char *hostname) {
        if(!*hostname) {
                return false;
        }

        for(const char *p = hostname; *p; p++) {
                if(!(isalnum(*p) || *p == '-' || *p == '.' || *p == ':')) {
                        return false;
                }
        }

        return true;
}

static bool is_valid_port(const char *port) {
        if(!*port) {
                return false;
        }

        if(isdigit(*port)) {
                char *end;
                unsigned long int result = strtoul(port, &end, 10);
                return result && result < 65536 && !*end;
        }

        for(const char *p = port; *p; p++) {
                if(!(isalnum(*p) || *p == '-')) {
                        return false;
                }
        }

        return true;
}

static void set_timeout(int sock, int timeout) {
#ifdef _WIN32
        DWORD tv = timeout;
#else
        struct timeval tv;
        tv.tv_sec = timeout / 1000;
        tv.tv_usec = (timeout - tv.tv_sec * 1000) * 1000;
#endif
        setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
        setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
}

struct socket_in_netns_params {
        int domain;
        int type;
        int protocol;
        int netns;
        int fd;
};

#ifdef HAVE_SETNS
static void *socket_in_netns_thread(void *arg) {
        struct socket_in_netns_params *params = arg;

        if(setns(params->netns, CLONE_NEWNET) == -1) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        params->fd = socket(params->domain, params->type, params->protocol);

        return NULL;
}
#endif // HAVE_SETNS

static int socket_in_netns(int domain, int type, int protocol, int netns) {
        if(netns == -1) {
                return socket(domain, type, protocol);
        }

#ifdef HAVE_SETNS
        struct socket_in_netns_params params = {domain, type, protocol, netns, -1};

        pthread_t thr;

        if(pthread_create(&thr, NULL, socket_in_netns_thread, &params) == 0) {
                pthread_join(thr, NULL);
        }

        return params.fd;
#else
        return -1;
#endif // HAVE_SETNS

}

// Find out what local address a socket would use if we connect to the given address.
// We do this using connect() on a UDP socket, so the kernel has to resolve the address
// of both endpoints, but this will actually not send any UDP packet.
static bool getlocaladdr(char *destaddr, struct sockaddr *sn, socklen_t *sl, int netns) {
        struct addrinfo *rai = NULL;
        const struct addrinfo hint = {
                .ai_family = AF_UNSPEC,
                .ai_socktype = SOCK_DGRAM,
                .ai_protocol = IPPROTO_UDP,
        };

        if(getaddrinfo(destaddr, "80", &hint, &rai) || !rai) {
                return false;
        }

        int sock = socket_in_netns(rai->ai_family, rai->ai_socktype, rai->ai_protocol, netns);

        if(sock == -1) {
                freeaddrinfo(rai);
                return false;
        }

        if(connect(sock, rai->ai_addr, rai->ai_addrlen) && !sockwouldblock(errno)) {
                closesocket(sock);
                freeaddrinfo(rai);
                return false;
        }

        freeaddrinfo(rai);

        if(getsockname(sock, sn, sl)) {
                closesocket(sock);
                return false;
        }

        closesocket(sock);
        return true;
}

static bool getlocaladdrname(char *destaddr, char *host, socklen_t hostlen, int netns) {
        struct sockaddr_storage sn;
        socklen_t sl = sizeof(sn);

        if(!getlocaladdr(destaddr, (struct sockaddr *)&sn, &sl, netns)) {
                return false;
        }

        if(getnameinfo((struct sockaddr *)&sn, sl, host, hostlen, NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)) {
                return false;
        }

        return true;
}

char *meshlink_get_external_address(meshlink_handle_t *mesh) {
        return meshlink_get_external_address_for_family(mesh, AF_UNSPEC);
}

char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int family) {
        char *hostname = NULL;

        logger(mesh, MESHLINK_DEBUG, "Trying to discover externally visible hostname...\n");
        struct addrinfo *ai = str2addrinfo("meshlink.io", "80", SOCK_STREAM);
        static const char request[] = "GET http://www.meshlink.io/host.cgi HTTP/1.0\r\n\r\n";
        char line[256];

        for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
                if(family != AF_UNSPEC && aip->ai_family != family) {
                        continue;
                }

                int s = socket_in_netns(aip->ai_family, aip->ai_socktype, aip->ai_protocol, mesh->netns);

                if(s >= 0) {
                        set_timeout(s, 5000);

                        if(connect(s, aip->ai_addr, aip->ai_addrlen)) {
                                closesocket(s);
                                s = -1;
                        }
                }

                if(s >= 0) {
                        send(s, request, sizeof(request) - 1, 0);
                        int len = recv(s, line, sizeof(line) - 1, MSG_WAITALL);

                        if(len > 0) {
                                line[len] = 0;

                                if(line[len - 1] == '\n') {
                                        line[--len] = 0;
                                }

                                char *p = strrchr(line, '\n');

                                if(p && p[1]) {
                                        hostname = xstrdup(p + 1);
                                }
                        }

                        closesocket(s);

                        if(hostname) {
                                break;
                        }
                }
        }

        if(ai) {
                freeaddrinfo(ai);
        }

        // Check that the hostname is reasonable
        if(hostname && !is_valid_hostname(hostname)) {
                free(hostname);
                hostname = NULL;
        }

        if(!hostname) {
                meshlink_errno = MESHLINK_ERESOLV;
        }

        return hostname;
}

char *meshlink_get_local_address_for_family(meshlink_handle_t *mesh, int family) {
        (void)mesh;

        // Determine address of the local interface used for outgoing connections.
        char localaddr[NI_MAXHOST];
        bool success = false;

        if(family == AF_INET) {
                success = getlocaladdrname("93.184.216.34", localaddr, sizeof(localaddr), mesh->netns);
        } else if(family == AF_INET6) {
                success = getlocaladdrname("2606:2800:220:1:248:1893:25c8:1946", localaddr, sizeof(localaddr), mesh->netns);
        }

        if(!success) {
                meshlink_errno = MESHLINK_ENETWORK;
                return NULL;
        }

        return xstrdup(localaddr);
}

void remove_duplicate_hostnames(char *host[], char *port[], int n) {
        for(int i = 0; i < n; i++) {
                if(!host[i]) {
                        continue;
                }

                // Ignore duplicate hostnames
                bool found = false;

                for(int j = 0; j < i; j++) {
                        if(!host[j]) {
                                continue;
                        }

                        if(strcmp(host[i], host[j])) {
                                continue;
                        }

                        if(strcmp(port[i], port[j])) {
                                continue;
                        }

                        found = true;
                        break;
                }

                if(found || !is_valid_hostname(host[i])) {
                        free(host[i]);
                        free(port[i]);
                        host[i] = NULL;
                        port[i] = NULL;
                        continue;
                }
        }
}

// This gets the hostname part for use in invitation URLs
static char *get_my_hostname(meshlink_handle_t *mesh, uint32_t flags) {
        char *hostname[4] = {NULL};
        char *port[4] = {NULL};
        char *hostport = NULL;

        if(!(flags & (MESHLINK_INVITE_LOCAL | MESHLINK_INVITE_PUBLIC))) {
                flags |= MESHLINK_INVITE_LOCAL | MESHLINK_INVITE_PUBLIC;
        }

        if(!(flags & (MESHLINK_INVITE_IPV4 | MESHLINK_INVITE_IPV6))) {
                flags |= MESHLINK_INVITE_IPV4 | MESHLINK_INVITE_IPV6;
        }

        // Add local addresses if requested
        if(flags & MESHLINK_INVITE_LOCAL) {
                if(flags & MESHLINK_INVITE_IPV4) {
                        hostname[0] = meshlink_get_local_address_for_family(mesh, AF_INET);
                }

                if(flags & MESHLINK_INVITE_IPV6) {
                        hostname[1] = meshlink_get_local_address_for_family(mesh, AF_INET6);
                }
        }

        // Add public/canonical addresses if requested
        if(flags & MESHLINK_INVITE_PUBLIC) {
                // Try the CanonicalAddress first
                get_canonical_address(mesh->self, &hostname[2], &port[2]);

                if(!hostname[2]) {
                        if(flags & MESHLINK_INVITE_IPV4) {
                                hostname[2] = meshlink_get_external_address_for_family(mesh, AF_INET);
                        }

                        if(flags & MESHLINK_INVITE_IPV6) {
                                hostname[3] = meshlink_get_external_address_for_family(mesh, AF_INET6);
                        }
                }
        }

        for(int i = 0; i < 4; i++) {
                // Ensure we always have a port number
                if(hostname[i] && !port[i]) {
                        port[i] = xstrdup(mesh->myport);
                }
        }

        remove_duplicate_hostnames(hostname, port, 4);

        if(!(flags & MESHLINK_INVITE_NUMERIC)) {
                for(int i = 0; i < 4; i++) {
                        if(!hostname[i]) {
                                continue;
                        }

                        // Convert what we have to a sockaddr
                        struct addrinfo *ai_in, *ai_out;
                        struct addrinfo hint = {
                                .ai_family = AF_UNSPEC,
                                .ai_flags = AI_NUMERICSERV,
                                .ai_socktype = SOCK_STREAM,
                        };
                        int err = getaddrinfo(hostname[i], port[i], &hint, &ai_in);

                        if(err || !ai_in) {
                                continue;
                        }

                        // Convert it to a hostname
                        char resolved_host[NI_MAXHOST];
                        char resolved_port[NI_MAXSERV];
                        err = getnameinfo(ai_in->ai_addr, ai_in->ai_addrlen, resolved_host, sizeof resolved_host, resolved_port, sizeof resolved_port, NI_NUMERICSERV);

                        if(err || !is_valid_hostname(resolved_host)) {
                                freeaddrinfo(ai_in);
                                continue;
                        }

                        // Convert the hostname back to a sockaddr
                        hint.ai_family = ai_in->ai_family;
                        err = getaddrinfo(resolved_host, resolved_port, &hint, &ai_out);

                        if(err || !ai_out) {
                                freeaddrinfo(ai_in);
                                continue;
                        }

                        // Check if it's still the same sockaddr
                        if(ai_in->ai_addrlen != ai_out->ai_addrlen || memcmp(ai_in->ai_addr, ai_out->ai_addr, ai_in->ai_addrlen)) {
                                freeaddrinfo(ai_in);
                                freeaddrinfo(ai_out);
                                continue;
                        }

                        // Yes: replace the hostname with the resolved one
                        free(hostname[i]);
                        hostname[i] = xstrdup(resolved_host);

                        freeaddrinfo(ai_in);
                        freeaddrinfo(ai_out);
                }
        }

        // Remove duplicates again, since IPv4 and IPv6 addresses might map to the same hostname
        remove_duplicate_hostnames(hostname, port, 4);

        // Concatenate all unique address to the hostport string
        for(int i = 0; i < 4; i++) {
                if(!hostname[i]) {
                        continue;
                }

                // Ensure we have the same addresses in our own host config file.
                char *tmphostport;
                xasprintf(&tmphostport, "%s %s", hostname[i], port[i]);
                /// TODO: FIX
                //config_add_string(&mesh->config, "Address", tmphostport);
                free(tmphostport);

                // Append the address to the hostport string
                char *newhostport;
                xasprintf(&newhostport, (strchr(hostname[i], ':') ? "%s%s[%s]:%s" : "%s%s%s:%s"), hostport ? hostport : "", hostport ? "," : "", hostname[i], port[i]);
                free(hostport);
                hostport = newhostport;

                free(hostname[i]);
                free(port[i]);
        }

        return hostport;
}

static bool try_bind(int port) {
        struct addrinfo *ai = NULL;
        struct addrinfo hint = {
                .ai_flags = AI_PASSIVE,
                .ai_family = AF_UNSPEC,
                .ai_socktype = SOCK_STREAM,
                .ai_protocol = IPPROTO_TCP,
        };

        char portstr[16];
        snprintf(portstr, sizeof(portstr), "%d", port);

        if(getaddrinfo(NULL, portstr, &hint, &ai) || !ai) {
                return false;
        }

        //while(ai) {
        for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
                int fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);

                if(!fd) {
                        freeaddrinfo(ai);
                        return false;
                }

                int result = bind(fd, aip->ai_addr, aip->ai_addrlen);
                closesocket(fd);

                if(result) {
                        freeaddrinfo(ai);
                        return false;
                }
        }

        freeaddrinfo(ai);
        return true;
}

static int check_port(meshlink_handle_t *mesh) {
        for(int i = 0; i < 1000; i++) {
                int port = 0x1000 + prng(mesh, 0x8000);

                if(try_bind(port)) {
                        free(mesh->myport);
                        xasprintf(&mesh->myport, "%d", port);
                        return port;
                }
        }

        meshlink_errno = MESHLINK_ENETWORK;
        logger(mesh, MESHLINK_DEBUG, "Could not find any available network port.\n");
        return 0;
}

static bool write_main_config_files(meshlink_handle_t *mesh) {
        if(!mesh->confbase) {
                return true;
        }

        uint8_t buf[4096];

        /* Write the main config file */
        packmsg_output_t out = {buf, sizeof buf};

        packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
        packmsg_add_str(&out, mesh->name);
        packmsg_add_bin(&out, ecdsa_get_private_key(mesh->private_key), 96);
        packmsg_add_bin(&out, ecdsa_get_private_key(mesh->invitation_key), 96);
        packmsg_add_uint16(&out, atoi(mesh->myport));

        if(!packmsg_output_ok(&out)) {
                return false;
        }

        config_t config = {buf, packmsg_output_size(&out, buf)};

        if(!main_config_write(mesh, "current", &config, mesh->config_key)) {
                return false;
        }

        /* Write our own host config file */
        if(!node_write_config(mesh, mesh->self)) {
                return false;
        }

        return true;
}

static bool finalize_join(meshlink_handle_t *mesh, const void *buf, uint16_t len) {
        packmsg_input_t in = {buf, len};
        uint32_t version = packmsg_get_uint32(&in);

        if(version != MESHLINK_INVITATION_VERSION) {
                logger(mesh, MESHLINK_ERROR, "Invalid invitation version!\n");
                return false;
        }

        char *name = packmsg_get_str_dup(&in);
        packmsg_skip_element(&in); /* submesh */
        dev_class_t devclass = packmsg_get_int32(&in);
        uint32_t count = packmsg_get_array(&in);

        if(!name) {
                logger(mesh, MESHLINK_DEBUG, "No Name found in invitation!\n");
                return false;
        }

        if(!check_id(name)) {
                logger(mesh, MESHLINK_DEBUG, "Invalid Name found in invitation: %s!\n", name);
                free(name);
                return false;
        }

        if(!count) {
                logger(mesh, MESHLINK_ERROR, "Incomplete invitation file!\n");
                free(name);
                return false;
        }

        free(mesh->name);
        free(mesh->self->name);
        mesh->name = name;
        mesh->self->name = xstrdup(name);
        mesh->self->devclass = devclass == DEV_CLASS_UNKNOWN ? mesh->devclass : devclass;

        // Initialize configuration directory
        if(!config_init(mesh, "current")) {
                return false;
        }

        if(!write_main_config_files(mesh)) {
                return false;
        }

        // Write host config files
        while(count--) {
                const void *data;
                uint32_t len = packmsg_get_bin_raw(&in, &data);

                if(!len) {
                        logger(mesh, MESHLINK_ERROR, "Incomplete invitation file!\n");
                        return false;
                }

                packmsg_input_t in2 = {data, len};
                uint32_t version = packmsg_get_uint32(&in2);
                char *name = packmsg_get_str_dup(&in2);

                if(!packmsg_input_ok(&in2) || version != MESHLINK_CONFIG_VERSION || !check_id(name)) {
                        free(name);
                        packmsg_input_invalidate(&in);
                        break;
                }

                if(!check_id(name)) {
                        free(name);
                        break;
                }

                if(!strcmp(name, mesh->name)) {
                        logger(mesh, MESHLINK_DEBUG, "Secondary chunk would overwrite our own host config file.\n");
                        free(name);
                        meshlink_errno = MESHLINK_EPEER;
                        return false;
                }

                node_t *n = new_node();
                n->name = name;

                config_t config = {data, len};

                if(!node_read_from_config(mesh, n, &config)) {
                        free_node(n);
                        logger(mesh, MESHLINK_ERROR, "Invalid host config file in invitation file!\n");
                        meshlink_errno = MESHLINK_EPEER;
                        return false;
                }

                node_add(mesh, n);

                if(!config_write(mesh, "current", n->name, &config, mesh->config_key)) {
                        return false;
                }
        }

        /* Ensure the configuration directory metadata is on disk */
        if(!config_sync(mesh, "current") || !sync_path(mesh->confbase)) {
                return false;
        }

        sptps_send_record(&mesh->sptps, 1, ecdsa_get_public_key(mesh->private_key), 32);

        logger(mesh, MESHLINK_DEBUG, "Configuration stored in: %s\n", mesh->confbase);

        return true;
}

static bool invitation_send(void *handle, uint8_t type, const void *data, size_t len) {
        (void)type;
        meshlink_handle_t *mesh = handle;
        const char *ptr = data;

        while(len) {
                int result = send(mesh->sock, ptr, len, 0);

                if(result == -1 && errno == EINTR) {
                        continue;
                } else if(result <= 0) {
                        return false;
                }

                ptr += result;
                len -= result;
        }

        return true;
}

static bool invitation_receive(void *handle, uint8_t type, const void *msg, uint16_t len) {
        meshlink_handle_t *mesh = handle;

        switch(type) {
        case SPTPS_HANDSHAKE:
                return sptps_send_record(&mesh->sptps, 0, mesh->cookie, sizeof(mesh)->cookie);

        case 0:
                return finalize_join(mesh, msg, len);

        case 1:
                logger(mesh, MESHLINK_DEBUG, "Invitation succesfully accepted.\n");
                shutdown(mesh->sock, SHUT_RDWR);
                mesh->success = true;
                break;

        default:
                return false;
        }

        return true;
}

static bool recvline(meshlink_handle_t *mesh, size_t len) {
        char *newline = NULL;

        if(!mesh->sock) {
                abort();
        }

        while(!(newline = memchr(mesh->buffer, '\n', mesh->blen))) {
                int result = recv(mesh->sock, mesh->buffer + mesh->blen, sizeof(mesh)->buffer - mesh->blen, 0);

                if(result == -1 && errno == EINTR) {
                        continue;
                } else if(result <= 0) {
                        return false;
                }

                mesh->blen += result;
        }

        if((size_t)(newline - mesh->buffer) >= len) {
                return false;
        }

        len = newline - mesh->buffer;

        memcpy(mesh->line, mesh->buffer, len);
        mesh->line[len] = 0;
        memmove(mesh->buffer, newline + 1, mesh->blen - len - 1);
        mesh->blen -= len + 1;

        return true;
}

static bool sendline(int fd, char *format, ...) {
        char buffer[4096];
        char *p = buffer;
        int blen = 0;
        va_list ap;

        va_start(ap, format);
        blen = vsnprintf(buffer, sizeof(buffer), format, ap);
        va_end(ap);

        if(blen < 1 || (size_t)blen >= sizeof(buffer)) {
                return false;
        }

        buffer[blen] = '\n';
        blen++;

        while(blen) {
                int result = send(fd, p, blen, MSG_NOSIGNAL);

                if(result == -1 && errno == EINTR) {
                        continue;
                } else if(result <= 0) {
                        return false;
                }

                p += result;
                blen -= result;
        }

        return true;
}

static const char *errstr[] = {
        [MESHLINK_OK] = "No error",
        [MESHLINK_EINVAL] = "Invalid argument",
        [MESHLINK_ENOMEM] = "Out of memory",
        [MESHLINK_ENOENT] = "No such node",
        [MESHLINK_EEXIST] = "Node already exists",
        [MESHLINK_EINTERNAL] = "Internal error",
        [MESHLINK_ERESOLV] = "Could not resolve hostname",
        [MESHLINK_ESTORAGE] = "Storage error",
        [MESHLINK_ENETWORK] = "Network error",
        [MESHLINK_EPEER] = "Error communicating with peer",
        [MESHLINK_ENOTSUP] = "Operation not supported",
        [MESHLINK_EBUSY] = "MeshLink instance already in use",
        [MESHLINK_EBLACKLISTED] = "Node is blacklisted",
};

const char *meshlink_strerror(meshlink_errno_t err) {
        if((int)err < 0 || err >= sizeof(errstr) / sizeof(*errstr)) {
                return "Invalid error code";
        }

        return errstr[err];
}

static bool ecdsa_keygen(meshlink_handle_t *mesh) {
        logger(mesh, MESHLINK_DEBUG, "Generating ECDSA keypairs:\n");

        mesh->private_key = ecdsa_generate();
        mesh->invitation_key = ecdsa_generate();

        if(!mesh->private_key || !mesh->invitation_key) {
                logger(mesh, MESHLINK_DEBUG, "Error during key generation!\n");
                meshlink_errno = MESHLINK_EINTERNAL;
                return false;
        }

        logger(mesh, MESHLINK_DEBUG, "Done.\n");

        return true;
}

static struct timeval idle(event_loop_t *loop, void *data) {
        (void)loop;
        meshlink_handle_t *mesh = data;
        struct timeval t, tmin = {3600, 0};

        for splay_each(node_t, n, mesh->nodes) {
                if(!n->utcp) {
                        continue;
                }

                t = utcp_timeout(n->utcp);

                if(timercmp(&t, &tmin, <)) {
                        tmin = t;
                }
        }

        return tmin;
}

// Get our local address(es) by simulating connecting to an Internet host.
static void add_local_addresses(meshlink_handle_t *mesh) {
        struct sockaddr_storage sn;
        sn.ss_family = AF_UNKNOWN;
        socklen_t sl = sizeof(sn);

        // IPv4 example.org

        if(getlocaladdr("93.184.216.34", (struct sockaddr *)&sn, &sl, mesh->netns)) {
                ((struct sockaddr_in *)&sn)->sin_port = ntohs(atoi(mesh->myport));
                meshlink_hint_address(mesh, (meshlink_node_t *)mesh->self, (struct sockaddr *)&sn);
        }

        // IPv6 example.org

        sl = sizeof(sn);

        if(getlocaladdr("2606:2800:220:1:248:1893:25c8:1946", (struct sockaddr *)&sn, &sl, mesh->netns)) {
                ((struct sockaddr_in6 *)&sn)->sin6_port = ntohs(atoi(mesh->myport));
                meshlink_hint_address(mesh, (meshlink_node_t *)mesh->self, (struct sockaddr *)&sn);
        }
}

static bool meshlink_setup(meshlink_handle_t *mesh) {
        if(!config_init(mesh, "current")) {
                logger(mesh, MESHLINK_ERROR, "Could not set up configuration in %s/current: %s\n", mesh->confbase, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                return false;
        }

        if(!ecdsa_keygen(mesh)) {
                meshlink_errno = MESHLINK_EINTERNAL;
                return false;
        }

        if(check_port(mesh) == 0) {
                meshlink_errno = MESHLINK_ENETWORK;
                return false;
        }

        /* Create a node for ourself */

        mesh->self = new_node();
        mesh->self->name = xstrdup(mesh->name);
        mesh->self->devclass = mesh->devclass;
        mesh->self->ecdsa = ecdsa_set_public_key(ecdsa_get_public_key(mesh->private_key));
        mesh->self->session_id = mesh->session_id;

        if(!write_main_config_files(mesh)) {
                logger(mesh, MESHLINK_ERROR, "Could not write main config files into %s/current: %s\n", mesh->confbase, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                return false;
        }

        /* Ensure the configuration directory metadata is on disk */
        if(!config_sync(mesh, "current")) {
                return false;
        }

        return true;
}

static bool meshlink_read_config(meshlink_handle_t *mesh) {
        config_t config;

        if(!main_config_read(mesh, "current", &config, mesh->config_key)) {
                logger(NULL, MESHLINK_ERROR, "Could not read main configuration file!");
                return false;
        }

        packmsg_input_t in = {config.buf, config.len};
        const void *private_key;
        const void *invitation_key;

        uint32_t version = packmsg_get_uint32(&in);
        char *name = packmsg_get_str_dup(&in);
        uint32_t private_key_len = packmsg_get_bin_raw(&in, &private_key);
        uint32_t invitation_key_len = packmsg_get_bin_raw(&in, &invitation_key);
        uint16_t myport = packmsg_get_uint16(&in);

        if(!packmsg_done(&in) || version != MESHLINK_CONFIG_VERSION || private_key_len != 96 || invitation_key_len != 96) {
                logger(NULL, MESHLINK_ERROR, "Error parsing main configuration file!");
                free(name);
                config_free(&config);
                return false;
        }

#if 0

        // TODO: check this?
        if(mesh->name && strcmp(mesh->name, name)) {
                logger(NULL, MESHLINK_ERROR, "Configuration is for a different name (%s)!", name);
                meshlink_errno = MESHLINK_ESTORAGE;
                free(name);
                config_free(&config);
                return false;
        }

#endif

        free(mesh->name);
        mesh->name = name;
        xasprintf(&mesh->myport, "%u", myport);
        mesh->private_key = ecdsa_set_private_key(private_key);
        mesh->invitation_key = ecdsa_set_private_key(invitation_key);
        config_free(&config);

        /* Create a node for ourself and read our host configuration file */

        mesh->self = new_node();
        mesh->self->name = xstrdup(name);
        mesh->self->devclass = mesh->devclass;
        mesh->self->session_id = mesh->session_id;

        if(!node_read_public_key(mesh, mesh->self)) {
                logger(NULL, MESHLINK_ERROR, "Could not read our host configuration file!");
                meshlink_errno = MESHLINK_ESTORAGE;
                free_node(mesh->self);
                mesh->self = NULL;
                return false;
        }

        return true;
}

#ifdef HAVE_SETNS
static void *setup_network_in_netns_thread(void *arg) {
        meshlink_handle_t *mesh = arg;

        if(setns(mesh->netns, CLONE_NEWNET) != 0) {
                return NULL;
        }

        bool success = setup_network(mesh);
        add_local_addresses(mesh);
        return success ? arg : NULL;
}
#endif // HAVE_SETNS

meshlink_open_params_t *meshlink_open_params_init(const char *confbase, const char *name, const char *appname, dev_class_t devclass) {
        if(!confbase || !*confbase) {
                logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(!appname || !*appname) {
                logger(NULL, MESHLINK_ERROR, "No appname given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(strchr(appname, ' ')) {
                logger(NULL, MESHLINK_ERROR, "Invalid appname given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(!name || !*name) {
                logger(NULL, MESHLINK_ERROR, "No name given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        };

        if(!check_id(name)) {
                logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(devclass < 0 || devclass >= DEV_CLASS_COUNT) {
                logger(NULL, MESHLINK_ERROR, "Invalid devclass given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        meshlink_open_params_t *params = xzalloc(sizeof * params);

        params->confbase = xstrdup(confbase);
        params->name = xstrdup(name);
        params->appname = xstrdup(appname);
        params->devclass = devclass;
        params->netns = -1;

        return params;
}

bool meshlink_open_params_set_netns(meshlink_open_params_t *params, int netns) {
        if(!params) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        params->netns = netns;

        return true;
}

bool meshlink_open_params_set_storage_key(meshlink_open_params_t *params, const void *key, size_t keylen) {
        if(!params) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if((!key && keylen) || (key && !keylen)) {
                logger(NULL, MESHLINK_ERROR, "Invalid key length!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        params->key = key;
        params->keylen = keylen;

        return true;
}

bool meshlink_encrypted_key_rotate(meshlink_handle_t *mesh, const void *new_key, size_t new_keylen) {
        if(!mesh || !new_key || !new_keylen) {
                logger(mesh, MESHLINK_ERROR, "Invalid arguments given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        // Create hash for the new key
        void *new_config_key;
        new_config_key = xmalloc(CHACHA_POLY1305_KEYLEN);

        if(!prf(new_key, new_keylen, "MeshLink configuration key", 26, new_config_key, CHACHA_POLY1305_KEYLEN)) {
                logger(mesh, MESHLINK_ERROR, "Error creating new configuration key!\n");
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Copy contents of the "current" confbase sub-directory to "new" confbase sub-directory with the new key

        if(!config_copy(mesh, "current", mesh->config_key, "new", new_config_key)) {
                logger(mesh, MESHLINK_ERROR, "Could not set up configuration in %s/old: %s\n", mesh->confbase, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        devtool_keyrotate_probe(1);

        // Rename confbase/current/ to confbase/old

        if(!config_rename(mesh, "current", "old")) {
                logger(mesh, MESHLINK_ERROR, "Cannot rename %s/current to %s/old\n", mesh->confbase, mesh->confbase);
                meshlink_errno = MESHLINK_ESTORAGE;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        devtool_keyrotate_probe(2);

        // Rename confbase/new/ to confbase/current

        if(!config_rename(mesh, "new", "current")) {
                logger(mesh, MESHLINK_ERROR, "Cannot rename %s/new to %s/current\n", mesh->confbase, mesh->confbase);
                meshlink_errno = MESHLINK_ESTORAGE;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        devtool_keyrotate_probe(3);

        // Cleanup the "old" confbase sub-directory

        if(!config_destroy(mesh->confbase, "old")) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Change the mesh handle key with new key

        free(mesh->config_key);
        mesh->config_key = new_config_key;

        pthread_mutex_unlock(&mesh->mutex);

        return true;
}

void meshlink_open_params_free(meshlink_open_params_t *params) {
        if(!params) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        free(params->confbase);
        free(params->name);
        free(params->appname);

        free(params);
}

/// Device class traits
static const dev_class_traits_t default_class_traits[DEV_CLASS_COUNT] = {
        { .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 10000, .edge_weight = 1 }, // DEV_CLASS_BACKBONE
        { .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 100, .edge_weight = 3 },   // DEV_CLASS_STATIONARY
        { .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 3, .edge_weight = 6 },     // DEV_CLASS_PORTABLE
        { .pingtimeout = 5, .pinginterval = 60, .min_connects = 1, .max_connects = 1, .edge_weight = 9 },     // DEV_CLASS_UNKNOWN
};

meshlink_handle_t *meshlink_open(const char *confbase, const char *name, const char *appname, dev_class_t devclass) {
        if(!confbase || !*confbase) {
                logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        /* Create a temporary struct on the stack, to avoid allocating and freeing one. */
        meshlink_open_params_t params;
        memset(&params, 0, sizeof(params));

        params.confbase = (char *)confbase;
        params.name = (char *)name;
        params.appname = (char *)appname;
        params.devclass = devclass;
        params.netns = -1;

        return meshlink_open_ex(&params);
}

meshlink_handle_t *meshlink_open_encrypted(const char *confbase, const char *name, const char *appname, dev_class_t devclass, const void *key, size_t keylen) {
        if(!confbase || !*confbase) {
                logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        /* Create a temporary struct on the stack, to avoid allocating and freeing one. */
        meshlink_open_params_t params;
        memset(&params, 0, sizeof(params));

        params.confbase = (char *)confbase;
        params.name = (char *)name;
        params.appname = (char *)appname;
        params.devclass = devclass;
        params.netns = -1;

        if(!meshlink_open_params_set_storage_key(&params, key, keylen)) {
                return false;
        }

        return meshlink_open_ex(&params);
}

meshlink_handle_t *meshlink_open_ephemeral(const char *name, const char *appname, dev_class_t devclass) {
        /* Create a temporary struct on the stack, to avoid allocating and freeing one. */
        meshlink_open_params_t params;
        memset(&params, 0, sizeof(params));

        params.name = (char *)name;
        params.appname = (char *)appname;
        params.devclass = devclass;
        params.netns = -1;

        return meshlink_open_ex(&params);
}

meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
        // Validate arguments provided by the application
        bool usingname = false;

        logger(NULL, MESHLINK_DEBUG, "meshlink_open called\n");

        if(!params->appname || !*params->appname) {
                logger(NULL, MESHLINK_ERROR, "No appname given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(strchr(params->appname, ' ')) {
                logger(NULL, MESHLINK_ERROR, "Invalid appname given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(!params->name || !*params->name) {
                logger(NULL, MESHLINK_ERROR, "No name given!\n");
                //return NULL;
        } else { //check name only if there is a name != NULL

                if(!check_id(params->name)) {
                        logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
                        meshlink_errno = MESHLINK_EINVAL;
                        return NULL;
                } else {
                        usingname = true;
                }
        }

        if(params->devclass < 0 || params->devclass >= DEV_CLASS_COUNT) {
                logger(NULL, MESHLINK_ERROR, "Invalid devclass given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if((params->key && !params->keylen) || (!params->key && params->keylen)) {
                logger(NULL, MESHLINK_ERROR, "Invalid key length!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        meshlink_handle_t *mesh = xzalloc(sizeof(meshlink_handle_t));

        if(params->confbase) {
                mesh->confbase = xstrdup(params->confbase);
        }

        mesh->appname = xstrdup(params->appname);
        mesh->devclass = params->devclass;
        mesh->discovery = true;
        mesh->invitation_timeout = 604800; // 1 week
        mesh->netns = params->netns;
        mesh->submeshes = NULL;
        mesh->log_cb = global_log_cb;
        mesh->log_level = global_log_level;

        randomize(&mesh->prng_state, sizeof(mesh->prng_state));

        do {
                randomize(&mesh->session_id, sizeof(mesh->session_id));
        } while(mesh->session_id == 0);

        memcpy(mesh->dev_class_traits, default_class_traits, sizeof(default_class_traits));

        if(usingname) {
                mesh->name = xstrdup(params->name);
        }

        // Hash the key
        if(params->key) {
                mesh->config_key = xmalloc(CHACHA_POLY1305_KEYLEN);

                if(!prf(params->key, params->keylen, "MeshLink configuration key", 26, mesh->config_key, CHACHA_POLY1305_KEYLEN)) {
                        logger(NULL, MESHLINK_ERROR, "Error creating configuration key!\n");
                        meshlink_close(mesh);
                        meshlink_errno = MESHLINK_EINTERNAL;
                        return NULL;
                }
        }

        // initialize mutex
        pthread_mutexattr_t attr;
        pthread_mutexattr_init(&attr);
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
        pthread_mutex_init(&mesh->mutex, &attr);

        mesh->threadstarted = false;
        event_loop_init(&mesh->loop);
        mesh->loop.data = mesh;

        meshlink_queue_init(&mesh->outpacketqueue);

        // Atomically lock the configuration directory.
        if(!main_config_lock(mesh)) {
                meshlink_close(mesh);
                return NULL;
        }

        // If no configuration exists yet, create it.

        if(!meshlink_confbase_exists(mesh)) {
                if(!meshlink_setup(mesh)) {
                        logger(NULL, MESHLINK_ERROR, "Cannot create initial configuration\n");
                        meshlink_close(mesh);
                        return NULL;
                }
        } else {
                if(!meshlink_read_config(mesh)) {
                        logger(NULL, MESHLINK_ERROR, "Cannot read main configuration\n");
                        meshlink_close(mesh);
                        return NULL;
                }
        }

#ifdef HAVE_MINGW
        struct WSAData wsa_state;
        WSAStartup(MAKEWORD(2, 2), &wsa_state);
#endif

        // Setup up everything
        // TODO: we should not open listening sockets yet

        bool success = false;

        if(mesh->netns != -1) {
#ifdef HAVE_SETNS
                pthread_t thr;

                if(pthread_create(&thr, NULL, setup_network_in_netns_thread, mesh) == 0) {
                        void *retval = NULL;
                        success = pthread_join(thr, &retval) == 0 && retval;
                }

#else
                meshlink_errno = MESHLINK_EINTERNAL;
                return NULL;

#endif // HAVE_SETNS
        } else {
                success = setup_network(mesh);
                add_local_addresses(mesh);
        }

        if(!success) {
                meshlink_close(mesh);
                meshlink_errno = MESHLINK_ENETWORK;
                return NULL;
        }

        add_local_addresses(mesh);

        if(!node_write_config(mesh, mesh->self)) {
                logger(NULL, MESHLINK_ERROR, "Cannot update configuration\n");
                return NULL;
        }

        idle_set(&mesh->loop, idle, mesh);

        logger(NULL, MESHLINK_DEBUG, "meshlink_open returning\n");
        return mesh;
}

meshlink_submesh_t *meshlink_submesh_open(meshlink_handle_t  *mesh, const char *submesh) {
        meshlink_submesh_t *s = NULL;

        if(!mesh) {
                logger(NULL, MESHLINK_ERROR, "No mesh handle given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(!submesh || !*submesh) {
                logger(NULL, MESHLINK_ERROR, "No submesh name given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        //lock mesh->nodes
        pthread_mutex_lock(&mesh->mutex);

        s = (meshlink_submesh_t *)create_submesh(mesh, submesh);

        pthread_mutex_unlock(&mesh->mutex);

        return s;
}

static void *meshlink_main_loop(void *arg) {
        meshlink_handle_t *mesh = arg;

        if(mesh->netns != -1) {
#ifdef HAVE_SETNS

                if(setns(mesh->netns, CLONE_NEWNET) != 0) {
                        pthread_cond_signal(&mesh->cond);
                        return NULL;
                }

#else
                pthread_cond_signal(&mesh->cond);
                return NULL;
#endif // HAVE_SETNS
        }

#if HAVE_CATTA

        if(mesh->discovery) {
                discovery_start(mesh);
        }

#endif

        pthread_mutex_lock(&mesh->mutex);

        logger(mesh, MESHLINK_DEBUG, "Starting main_loop...\n");
        pthread_cond_broadcast(&mesh->cond);
        main_loop(mesh);
        logger(mesh, MESHLINK_DEBUG, "main_loop returned.\n");

        pthread_mutex_unlock(&mesh->mutex);

#if HAVE_CATTA

        // Stop discovery
        if(mesh->discovery) {
                discovery_stop(mesh);
        }

#endif

        return NULL;
}

bool meshlink_start(meshlink_handle_t *mesh) {
        assert(mesh->self);
        assert(mesh->private_key);

        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        logger(mesh, MESHLINK_DEBUG, "meshlink_start called\n");

        pthread_mutex_lock(&mesh->mutex);

        assert(mesh->self->ecdsa);
        assert(!memcmp((uint8_t *)mesh->self->ecdsa + 64, (uint8_t *)mesh->private_key + 64, 32));

        if(mesh->threadstarted) {
                logger(mesh, MESHLINK_DEBUG, "thread was already running\n");
                pthread_mutex_unlock(&mesh->mutex);
                return true;
        }

        if(mesh->listen_socket[0].tcp.fd < 0) {
                logger(mesh, MESHLINK_ERROR, "Listening socket not open\n");
                meshlink_errno = MESHLINK_ENETWORK;
                return false;
        }

        mesh->thedatalen = 0;

        // TODO: open listening sockets first

        //Check that a valid name is set
        if(!mesh->name) {
                logger(mesh, MESHLINK_DEBUG, "No name given!\n");
                meshlink_errno = MESHLINK_EINVAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        init_outgoings(mesh);

        // Start the main thread

        event_loop_start(&mesh->loop);

        if(pthread_create(&mesh->thread, NULL, meshlink_main_loop, mesh) != 0) {
                logger(mesh, MESHLINK_DEBUG, "Could not start thread: %s\n", strerror(errno));
                memset(&mesh->thread, 0, sizeof(mesh)->thread);
                meshlink_errno = MESHLINK_EINTERNAL;
                event_loop_stop(&mesh->loop);
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_cond_wait(&mesh->cond, &mesh->mutex);
        mesh->threadstarted = true;
        mesh->self->last_reachable = time(NULL);
        mesh->self->status.dirty = true;

        pthread_mutex_unlock(&mesh->mutex);
        return true;
}

void meshlink_stop(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        logger(mesh, MESHLINK_DEBUG, "meshlink_stop called\n");

        if(mesh->self) {
                mesh->self->last_unreachable = time(NULL);
                mesh->self->status.dirty = true;
        }

        // Shut down the main thread
        event_loop_stop(&mesh->loop);

        // Send ourselves a UDP packet to kick the event loop
        for(int i = 0; i < mesh->listen_sockets; i++) {
                sockaddr_t sa;
                socklen_t salen = sizeof(sa.sa);

                if(getsockname(mesh->listen_socket[i].udp.fd, &sa.sa, &salen) == -1) {
                        logger(mesh, MESHLINK_ERROR, "System call `%s' failed: %s", "getsockname", sockstrerror(sockerrno));
                        continue;
                }

                if(sendto(mesh->listen_socket[i].udp.fd, "", 1, MSG_NOSIGNAL, &sa.sa, salen) == -1) {
                        logger(mesh, MESHLINK_ERROR, "Could not send a UDP packet to ourself: %s", sockstrerror(sockerrno));
                }
        }

        if(mesh->threadstarted) {
                // Wait for the main thread to finish
                pthread_mutex_unlock(&mesh->mutex);
                pthread_join(mesh->thread, NULL);
                pthread_mutex_lock(&mesh->mutex);

                mesh->threadstarted = false;
        }

        // Close all metaconnections
        if(mesh->connections) {
                for(list_node_t *node = mesh->connections->head, *next; node; node = next) {
                        next = node->next;
                        connection_t *c = node->data;
                        c->outgoing = NULL;
                        terminate_connection(mesh, c, false);
                }
        }

        exit_outgoings(mesh);

        // Try to write out any changed node config files, ignore errors at this point.
        if(mesh->nodes) {
                for splay_each(node_t, n, mesh->nodes) {
                        if(n->status.dirty) {
                                n->status.dirty = !node_write_config(mesh, n);
                        }
                }
        }

        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_close(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        // stop can be called even if mesh has not been started
        meshlink_stop(mesh);

        // lock is not released after this
        pthread_mutex_lock(&mesh->mutex);

        // Close and free all resources used.

        close_network_connections(mesh);

        logger(mesh, MESHLINK_INFO, "Terminating");

        event_loop_exit(&mesh->loop);

#ifdef HAVE_MINGW

        if(mesh->confbase) {
                WSACleanup();
        }

#endif

        ecdsa_free(mesh->invitation_key);

        if(mesh->netns != -1) {
                close(mesh->netns);
        }

        for(vpn_packet_t *packet; (packet = meshlink_queue_pop(&mesh->outpacketqueue));) {
                free(packet);
        }

        meshlink_queue_exit(&mesh->outpacketqueue);

        free(mesh->name);
        free(mesh->appname);
        free(mesh->confbase);
        free(mesh->config_key);
        ecdsa_free(mesh->private_key);

        main_config_unlock(mesh);

        pthread_mutex_unlock(&mesh->mutex);
        pthread_mutex_destroy(&mesh->mutex);

        memset(mesh, 0, sizeof(*mesh));

        free(mesh);
}

bool meshlink_destroy(const char *confbase) {
        if(!confbase) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        /* Exit early if the confbase directory itself doesn't exist */
        if(access(confbase, F_OK) && errno == ENOENT) {
                return true;
        }

        /* Take the lock the same way meshlink_open() would. */
        char lockfilename[PATH_MAX];
        snprintf(lockfilename, sizeof(lockfilename), "%s" SLASH "meshlink.lock", confbase);

        FILE *lockfile = fopen(lockfilename, "w+");

        if(!lockfile) {
                logger(NULL, MESHLINK_ERROR, "Could not open lock file %s: %s", lockfilename, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                return false;
        }

#ifdef FD_CLOEXEC
        fcntl(fileno(lockfile), F_SETFD, FD_CLOEXEC);
#endif

#ifdef HAVE_MINGW
        // TODO: use _locking()?
#else

        if(flock(fileno(lockfile), LOCK_EX | LOCK_NB) != 0) {
                logger(NULL, MESHLINK_ERROR, "Configuration directory %s still in use\n", lockfilename);
                fclose(lockfile);
                meshlink_errno = MESHLINK_EBUSY;
                return false;
        }

#endif

        if(!config_destroy(confbase, "current") || !config_destroy(confbase, "new") || !config_destroy(confbase, "old")) {
                logger(NULL, MESHLINK_ERROR, "Cannot remove sub-directories in %s: %s\n", confbase, strerror(errno));
                return false;
        }

        if(unlink(lockfilename)) {
                logger(NULL, MESHLINK_ERROR, "Cannot remove lock file %s: %s\n", lockfilename, strerror(errno));
                fclose(lockfile);
                meshlink_errno = MESHLINK_ESTORAGE;
                return false;
        }

        fclose(lockfile);

        /* TODO: do we need to remove confbase? Potential race condition? */
        if(!sync_path(confbase)) {
                logger(NULL, MESHLINK_ERROR, "Cannot sync directory %s: %s\n", confbase, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                return false;
        }

        return true;
}

void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->receive_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_connection_try_cb(meshlink_handle_t *mesh, meshlink_connection_try_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->connection_try_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->node_status_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_node_pmtu_cb(meshlink_handle_t *mesh, meshlink_node_pmtu_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->node_pmtu_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_node_duplicate_cb(meshlink_handle_t *mesh, meshlink_node_duplicate_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->node_duplicate_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb) {
        if(mesh) {
                pthread_mutex_lock(&mesh->mutex);
                mesh->log_cb = cb;
                mesh->log_level = cb ? level : 0;
                pthread_mutex_unlock(&mesh->mutex);
        } else {
                global_log_cb = cb;
                global_log_level = cb ? level : 0;
        }
}

void meshlink_set_error_cb(struct meshlink_handle *mesh, meshlink_error_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->error_cb = cb;
        pthread_mutex_unlock(&mesh->mutex);
}

bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len) {
        meshlink_packethdr_t *hdr;

        // Validate arguments
        if(!mesh || !destination || len >= MAXSIZE - sizeof(*hdr)) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!len) {
                return true;
        }

        if(!data) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        node_t *n = (node_t *)destination;

        if(n->status.blacklisted) {
                logger(mesh, MESHLINK_ERROR, "Node %s blacklisted, dropping packet\n", n->name);
                meshlink_errno = MESHLINK_EBLACKLISTED;
                return false;
        }

        // Prepare the packet
        vpn_packet_t *packet = malloc(sizeof(*packet));

        if(!packet) {
                meshlink_errno = MESHLINK_ENOMEM;
                return false;
        }

        packet->probe = false;
        packet->tcp = false;
        packet->len = len + sizeof(*hdr);

        hdr = (meshlink_packethdr_t *)packet->data;
        memset(hdr, 0, sizeof(*hdr));
        // leave the last byte as 0 to make sure strings are always
        // null-terminated if they are longer than the buffer
        strncpy((char *)hdr->destination, destination->name, (sizeof(hdr)->destination) - 1);
        strncpy((char *)hdr->source, mesh->self->name, (sizeof(hdr)->source) - 1);

        memcpy(packet->data + sizeof(*hdr), data, len);

        // Queue it
        if(!meshlink_queue_push(&mesh->outpacketqueue, packet)) {
                free(packet);
                meshlink_errno = MESHLINK_ENOMEM;
                return false;
        }

        // Notify event loop
        signal_trigger(&mesh->loop, &mesh->datafromapp);

        return true;
}

void meshlink_send_from_queue(event_loop_t *loop, void *data) {
        (void)loop;
        meshlink_handle_t *mesh = data;
        vpn_packet_t *packet = meshlink_queue_pop(&mesh->outpacketqueue);

        if(!packet) {
                return;
        }

        mesh->self->in_packets++;
        mesh->self->in_bytes += packet->len;
        route(mesh, mesh->self, packet);

        free(packet);
}

ssize_t meshlink_get_pmtu(meshlink_handle_t *mesh, meshlink_node_t *destination) {
        if(!mesh || !destination) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = (node_t *)destination;

        if(!n->status.reachable) {
                pthread_mutex_unlock(&mesh->mutex);
                return 0;

        } else if(n->mtuprobes > 30 && n->minmtu) {
                pthread_mutex_unlock(&mesh->mutex);
                return n->minmtu;
        } else {
                pthread_mutex_unlock(&mesh->mutex);
                return MTU;
        }
}

char *meshlink_get_fingerprint(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = (node_t *)node;

        if(!node_read_public_key(mesh, n) || !n->ecdsa) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        char *fingerprint = ecdsa_get_base64_public_key(n->ecdsa);

        if(!fingerprint) {
                meshlink_errno = MESHLINK_EINTERNAL;
        }

        pthread_mutex_unlock(&mesh->mutex);
        return fingerprint;
}

meshlink_node_t *meshlink_get_self(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        return (meshlink_node_t *)mesh->self;
}

meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name) {
        if(!mesh || !name) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        node_t *n = NULL;

        pthread_mutex_lock(&mesh->mutex);
        n = lookup_node(mesh, (char *)name); // TODO: make lookup_node() use const
        pthread_mutex_unlock(&mesh->mutex);

        if(!n) {
                meshlink_errno = MESHLINK_ENOENT;
        }

        return (meshlink_node_t *)n;
}

meshlink_submesh_t *meshlink_get_submesh(meshlink_handle_t *mesh, const char *name) {
        if(!mesh || !name) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        meshlink_submesh_t *submesh = NULL;

        pthread_mutex_lock(&mesh->mutex);
        submesh = (meshlink_submesh_t *)lookup_submesh(mesh, name);
        pthread_mutex_unlock(&mesh->mutex);

        if(!submesh) {
                meshlink_errno = MESHLINK_ENOENT;
        }

        return submesh;
}

meshlink_node_t **meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t *nmemb) {
        if(!mesh || !nmemb || (*nmemb && !nodes)) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        meshlink_node_t **result;

        //lock mesh->nodes
        pthread_mutex_lock(&mesh->mutex);

        *nmemb = mesh->nodes->count;
        result = realloc(nodes, *nmemb * sizeof(*nodes));

        if(result) {
                meshlink_node_t **p = result;

                for splay_each(node_t, n, mesh->nodes) {
                        *p++ = (meshlink_node_t *)n;
                }
        } else {
                *nmemb = 0;
                free(nodes);
                meshlink_errno = MESHLINK_ENOMEM;
        }

        pthread_mutex_unlock(&mesh->mutex);

        return result;
}

static meshlink_node_t **meshlink_get_all_nodes_by_condition(meshlink_handle_t *mesh, const void *condition, meshlink_node_t **nodes, size_t *nmemb, search_node_by_condition_t search_node) {
        meshlink_node_t **result;

        pthread_mutex_lock(&mesh->mutex);

        *nmemb = 0;

        for splay_each(node_t, n, mesh->nodes) {
                if(search_node(n, condition)) {
                        ++*nmemb;
                }
        }

        if(*nmemb == 0) {
                free(nodes);
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        result = realloc(nodes, *nmemb * sizeof(*nodes));

        if(result) {
                meshlink_node_t **p = result;

                for splay_each(node_t, n, mesh->nodes) {
                        if(search_node(n, condition)) {
                                *p++ = (meshlink_node_t *)n;
                        }
                }
        } else {
                *nmemb = 0;
                free(nodes);
                meshlink_errno = MESHLINK_ENOMEM;
        }

        pthread_mutex_unlock(&mesh->mutex);

        return result;
}

static bool search_node_by_dev_class(const node_t *node, const void *condition) {
        dev_class_t *devclass = (dev_class_t *)condition;

        if(*devclass == (dev_class_t)node->devclass) {
                return true;
        }

        return false;
}

static bool search_node_by_submesh(const node_t *node, const void *condition) {
        if(condition == node->submesh) {
                return true;
        }

        return false;
}

struct time_range {
        time_t start;
        time_t end;
};

static bool search_node_by_last_reachable(const node_t *node, const void *condition) {
        const struct time_range *range = condition;
        time_t start = node->last_reachable;
        time_t end = node->last_unreachable;

        if(end < start) {
                end = time(NULL);

                if(end < start) {
                        start = end;
                }
        }

        if(range->end >= range->start) {
                return start <= range->end && end >= range->start;
        } else {
                return start > range->start || end < range->end;
        }
}

meshlink_node_t **meshlink_get_all_nodes_by_dev_class(meshlink_handle_t *mesh, dev_class_t devclass, meshlink_node_t **nodes, size_t *nmemb) {
        if(!mesh || devclass < 0 || devclass >= DEV_CLASS_COUNT || !nmemb) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        return meshlink_get_all_nodes_by_condition(mesh, &devclass, nodes, nmemb, search_node_by_dev_class);
}

meshlink_node_t **meshlink_get_all_nodes_by_submesh(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, meshlink_node_t **nodes, size_t *nmemb) {
        if(!mesh || !submesh || !nmemb) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        return meshlink_get_all_nodes_by_condition(mesh, submesh, nodes, nmemb, search_node_by_submesh);
}

meshlink_node_t **meshlink_get_all_nodes_by_last_reachable(meshlink_handle_t *mesh, time_t start, time_t end, meshlink_node_t **nodes, size_t *nmemb) {
        if(!mesh || !nmemb) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        struct time_range range = {start, end};

        return meshlink_get_all_nodes_by_condition(mesh, &range, nodes, nmemb, search_node_by_last_reachable);
}

dev_class_t meshlink_get_node_dev_class(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        dev_class_t devclass;

        pthread_mutex_lock(&mesh->mutex);

        devclass = ((node_t *)node)->devclass;

        pthread_mutex_unlock(&mesh->mutex);

        return devclass;
}

meshlink_submesh_t *meshlink_get_node_submesh(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        node_t *n = (node_t *)node;

        meshlink_submesh_t *s;

        s = (meshlink_submesh_t *)n->submesh;

        return s;
}

bool meshlink_sign(meshlink_handle_t *mesh, const void *data, size_t len, void *signature, size_t *siglen) {
        if(!mesh || !data || !len || !signature || !siglen) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(*siglen < MESHLINK_SIGLEN) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        if(!ecdsa_sign(mesh->private_key, data, len, signature)) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        *siglen = MESHLINK_SIGLEN;
        pthread_mutex_unlock(&mesh->mutex);
        return true;
}

bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len, const void *signature, size_t siglen) {
        if(!mesh || !data || !len || !signature) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(siglen != MESHLINK_SIGLEN) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        bool rval = false;

        struct node_t *n = (struct node_t *)source;

        if(!node_read_public_key(mesh, n)) {
                meshlink_errno = MESHLINK_EINTERNAL;
                rval = false;
        } else {
                rval = ecdsa_verify(((struct node_t *)source)->ecdsa, data, len, signature);
        }

        pthread_mutex_unlock(&mesh->mutex);
        return rval;
}

static bool refresh_invitation_key(meshlink_handle_t *mesh) {
        pthread_mutex_lock(&mesh->mutex);

        size_t count = invitation_purge_old(mesh, time(NULL) - mesh->invitation_timeout);

        if(!count) {
                // TODO: Update invitation key if necessary?
        }

        pthread_mutex_unlock(&mesh->mutex);

        return mesh->invitation_key;
}

bool meshlink_set_canonical_address(meshlink_handle_t *mesh, meshlink_node_t *node, const char *address, const char *port) {
        if(!mesh || !node || !address) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!is_valid_hostname(address)) {
                logger(mesh, MESHLINK_DEBUG, "Invalid character in address: %s\n", address);
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(port && !is_valid_port(port)) {
                logger(mesh, MESHLINK_DEBUG, "Invalid character in port: %s\n", address);
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        char *canonical_address;

        if(port) {
                xasprintf(&canonical_address, "%s %s", address, port);
        } else {
                canonical_address = xstrdup(address);
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = (node_t *)node;
        free(n->canonical_address);
        n->canonical_address = canonical_address;

        if(!node_write_config(mesh, n)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);

        return config_sync(mesh, "current");
}

bool meshlink_add_address(meshlink_handle_t *mesh, const char *address) {
        return meshlink_set_canonical_address(mesh, (meshlink_node_t *)mesh->self, address, NULL);
}

bool meshlink_add_external_address(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        char *address = meshlink_get_external_address(mesh);

        if(!address) {
                return false;
        }

        bool rval = meshlink_add_address(mesh, address);
        free(address);

        return rval;
}

int meshlink_get_port(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        if(!mesh->myport) {
                meshlink_errno = MESHLINK_EINTERNAL;
                return -1;
        }

        int port;

        pthread_mutex_lock(&mesh->mutex);
        port = atoi(mesh->myport);
        pthread_mutex_unlock(&mesh->mutex);

        return port;
}

bool meshlink_set_port(meshlink_handle_t *mesh, int port) {
        if(!mesh || port < 0 || port >= 65536 || mesh->threadstarted) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(mesh->myport && port == atoi(mesh->myport)) {
                return true;
        }

        if(!try_bind(port)) {
                meshlink_errno = MESHLINK_ENETWORK;
                return false;
        }

        devtool_trybind_probe();

        bool rval = false;

        pthread_mutex_lock(&mesh->mutex);

        if(mesh->threadstarted) {
                meshlink_errno = MESHLINK_EINVAL;
                goto done;
        }

        free(mesh->myport);
        xasprintf(&mesh->myport, "%d", port);

        /* Close down the network. This also deletes mesh->self. */
        close_network_connections(mesh);

        /* Recreate mesh->self. */
        mesh->self = new_node();
        mesh->self->name = xstrdup(mesh->name);
        mesh->self->devclass = mesh->devclass;
        mesh->self->session_id = mesh->session_id;
        xasprintf(&mesh->myport, "%d", port);

        if(!node_read_public_key(mesh, mesh->self)) {
                logger(NULL, MESHLINK_ERROR, "Could not read our host configuration file!");
                meshlink_errno = MESHLINK_ESTORAGE;
                free_node(mesh->self);
                mesh->self = NULL;
                goto done;
        } else if(!setup_network(mesh)) {
                meshlink_errno = MESHLINK_ENETWORK;
                goto done;
        }

        /* Rebuild our own list of recent addresses */
        memset(mesh->self->recent, 0, sizeof(mesh->self->recent));
        add_local_addresses(mesh);

        /* Write meshlink.conf with the updated port number */
        write_main_config_files(mesh);

        rval = config_sync(mesh, "current");

done:
        pthread_mutex_unlock(&mesh->mutex);

        return rval && meshlink_get_port(mesh) == port;
}

void meshlink_set_invitation_timeout(meshlink_handle_t *mesh, int timeout) {
        mesh->invitation_timeout = timeout;
}

char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, const char *name, uint32_t flags) {
        meshlink_submesh_t *s = NULL;

        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        if(submesh) {
                s = (meshlink_submesh_t *)lookup_submesh(mesh, submesh->name);

                if(s != submesh) {
                        logger(mesh, MESHLINK_DEBUG, "Invalid SubMesh Handle.\n");
                        meshlink_errno = MESHLINK_EINVAL;
                        return NULL;
                }
        } else {
                s = (meshlink_submesh_t *)mesh->self->submesh;
        }

        pthread_mutex_lock(&mesh->mutex);

        // Check validity of the new node's name
        if(!check_id(name)) {
                logger(mesh, MESHLINK_DEBUG, "Invalid name for node.\n");
                meshlink_errno = MESHLINK_EINVAL;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        // Ensure no host configuration file with that name exists
        if(config_exists(mesh, "current", name)) {
                logger(mesh, MESHLINK_DEBUG, "A host config file for %s already exists!\n", name);
                meshlink_errno = MESHLINK_EEXIST;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        // Ensure no other nodes know about this name
        if(meshlink_get_node(mesh, name)) {
                logger(mesh, MESHLINK_DEBUG, "A node with name %s is already known!\n", name);
                meshlink_errno = MESHLINK_EEXIST;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        // Get the local address
        char *address = get_my_hostname(mesh, flags);

        if(!address) {
                logger(mesh, MESHLINK_DEBUG, "No Address known for ourselves!\n");
                meshlink_errno = MESHLINK_ERESOLV;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        if(!refresh_invitation_key(mesh)) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        char hash[64];

        // Create a hash of the key.
        char *fingerprint = ecdsa_get_base64_public_key(mesh->invitation_key);
        sha512(fingerprint, strlen(fingerprint), hash);
        b64encode_urlsafe(hash, hash, 18);

        // Create a random cookie for this invitation.
        char cookie[25];
        randomize(cookie, 18);

        // Create a filename that doesn't reveal the cookie itself
        char buf[18 + strlen(fingerprint)];
        char cookiehash[64];
        memcpy(buf, cookie, 18);
        memcpy(buf + 18, fingerprint, sizeof(buf) - 18);
        sha512(buf, sizeof(buf), cookiehash);
        b64encode_urlsafe(cookiehash, cookiehash, 18);

        b64encode_urlsafe(cookie, cookie, 18);

        free(fingerprint);

        /* Construct the invitation file */
        uint8_t outbuf[4096];
        packmsg_output_t inv = {outbuf, sizeof(outbuf)};

        packmsg_add_uint32(&inv, MESHLINK_INVITATION_VERSION);
        packmsg_add_str(&inv, name);
        packmsg_add_str(&inv, s ? s->name : CORE_MESH);
        packmsg_add_int32(&inv, DEV_CLASS_UNKNOWN); /* TODO: allow this to be set by inviter? */

        /* TODO: Add several host config files to bootstrap connections.
         * Note: make sure we only add config files of nodes that are in the core mesh or the same submesh,
         * and are not blacklisted.
         */
        config_t configs[5];
        memset(configs, 0, sizeof(configs));
        int count = 0;

        if(config_read(mesh, "current", mesh->self->name, &configs[count], mesh->config_key)) {
                count++;
        }

        /* Append host config files to the invitation file */
        packmsg_add_array(&inv, count);

        for(int i = 0; i < count; i++) {
                packmsg_add_bin(&inv, configs[i].buf, configs[i].len);
                config_free(&configs[i]);
        }

        config_t config = {outbuf, packmsg_output_size(&inv, outbuf)};

        if(!invitation_write(mesh, "current", cookiehash, &config, mesh->config_key)) {
                logger(mesh, MESHLINK_DEBUG, "Could not create invitation file %s: %s\n", cookiehash, strerror(errno));
                meshlink_errno = MESHLINK_ESTORAGE;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        // Create an URL from the local address, key hash and cookie
        char *url;
        xasprintf(&url, "%s/%s%s", address, hash, cookie);
        free(address);

        pthread_mutex_unlock(&mesh->mutex);
        return url;
}

char *meshlink_invite(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, const char *name) {
        return meshlink_invite_ex(mesh, submesh, name, 0);
}

bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
        if(!mesh || !invitation) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        //Before doing meshlink_join make sure we are not connected to another mesh
        if(mesh->threadstarted) {
                logger(mesh, MESHLINK_ERROR, "Cannot join while started\n");
                meshlink_errno = MESHLINK_EINVAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Refuse to join a mesh if we are already part of one. We are part of one if we know at least one other node.
        if(mesh->nodes->count > 1) {
                logger(mesh, MESHLINK_ERROR, "Already part of an existing mesh\n");
                meshlink_errno = MESHLINK_EINVAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        //TODO: think of a better name for this variable, or of a different way to tokenize the invitation URL.
        char copy[strlen(invitation) + 1];
        strcpy(copy, invitation);

        // Split the invitation URL into a list of hostname/port tuples, a key hash and a cookie.

        char *slash = strchr(copy, '/');

        if(!slash) {
                goto invalid;
        }

        *slash++ = 0;

        if(strlen(slash) != 48) {
                goto invalid;
        }

        char *address = copy;
        char *port = NULL;

        if(!b64decode(slash, mesh->hash, 18) || !b64decode(slash + 24, mesh->cookie, 18)) {
                goto invalid;
        }

        // Generate a throw-away key for the invitation.
        ecdsa_t *key = ecdsa_generate();

        if(!key) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        char *b64key = ecdsa_get_base64_public_key(key);
        char *comma;
        mesh->sock = -1;

        while(address && *address) {
                // We allow commas in the address part to support multiple addresses in one invitation URL.
                comma = strchr(address, ',');

                if(comma) {
                        *comma++ = 0;
                }

                // Split of the port
                port = strrchr(address, ':');

                if(!port) {
                        goto invalid;
                }

                *port++ = 0;

                // IPv6 address are enclosed in brackets, per RFC 3986
                if(*address == '[') {
                        address++;
                        char *bracket = strchr(address, ']');

                        if(!bracket) {
                                goto invalid;
                        }

                        *bracket++ = 0;

                        if(*bracket) {
                                goto invalid;
                        }
                }

                // Connect to the meshlink daemon mentioned in the URL.
                struct addrinfo *ai = str2addrinfo(address, port, SOCK_STREAM);

                if(ai) {
                        for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
                                mesh->sock = socket_in_netns(aip->ai_family, aip->ai_socktype, aip->ai_protocol, mesh->netns);

                                if(mesh->sock == -1) {
                                        logger(mesh, MESHLINK_DEBUG, "Could not open socket: %s\n", strerror(errno));
                                        meshlink_errno = MESHLINK_ENETWORK;
                                        continue;
                                }

                                set_timeout(mesh->sock, 5000);

                                if(connect(mesh->sock, aip->ai_addr, aip->ai_addrlen)) {
                                        logger(mesh, MESHLINK_DEBUG, "Could not connect to %s port %s: %s\n", address, port, strerror(errno));
                                        meshlink_errno = MESHLINK_ENETWORK;
                                        closesocket(mesh->sock);
                                        mesh->sock = -1;
                                        continue;
                                }
                        }

                        freeaddrinfo(ai);
                } else {
                        meshlink_errno = MESHLINK_ERESOLV;
                }

                if(mesh->sock != -1 || !comma) {
                        break;
                }

                address = comma;
        }

        if(mesh->sock == -1) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        logger(mesh, MESHLINK_DEBUG, "Connected to %s port %s...\n", address, port);

        // Tell him we have an invitation, and give him our throw-away key.

        mesh->blen = 0;

        if(!sendline(mesh->sock, "0 ?%s %d.%d %s", b64key, PROT_MAJOR, PROT_MINOR, mesh->appname)) {
                logger(mesh, MESHLINK_DEBUG, "Error sending request to %s port %s: %s\n", address, port, strerror(errno));
                closesocket(mesh->sock);
                meshlink_errno = MESHLINK_ENETWORK;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        free(b64key);

        char hisname[4096] = "";
        int code, hismajor, hisminor = 0;

        if(!recvline(mesh, sizeof(mesh)->line) || sscanf(mesh->line, "%d %s %d.%d", &code, hisname, &hismajor, &hisminor) < 3 || code != 0 || hismajor != PROT_MAJOR || !check_id(hisname) || !recvline(mesh, sizeof(mesh)->line) || !rstrip(mesh->line) || sscanf(mesh->line, "%d ", &code) != 1 || code != ACK || strlen(mesh->line) < 3) {
                logger(mesh, MESHLINK_DEBUG, "Cannot read greeting from peer\n");
                closesocket(mesh->sock);
                meshlink_errno = MESHLINK_ENETWORK;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Check if the hash of the key he gave us matches the hash in the URL.
        char *fingerprint = mesh->line + 2;
        char hishash[64];

        if(sha512(fingerprint, strlen(fingerprint), hishash)) {
                logger(mesh, MESHLINK_DEBUG, "Could not create hash\n%s\n", mesh->line + 2);
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        if(memcmp(hishash, mesh->hash, 18)) {
                logger(mesh, MESHLINK_DEBUG, "Peer has an invalid key!\n%s\n", mesh->line + 2);
                meshlink_errno = MESHLINK_EPEER;
                pthread_mutex_unlock(&mesh->mutex);
                return false;

        }

        ecdsa_t *hiskey = ecdsa_set_base64_public_key(fingerprint);

        if(!hiskey) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Start an SPTPS session
        if(!sptps_start(&mesh->sptps, mesh, true, false, key, hiskey, meshlink_invitation_label, sizeof(meshlink_invitation_label), invitation_send, invitation_receive)) {
                meshlink_errno = MESHLINK_EINTERNAL;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        // Feed rest of input buffer to SPTPS
        if(!sptps_receive_data(&mesh->sptps, mesh->buffer, mesh->blen)) {
                meshlink_errno = MESHLINK_EPEER;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        int len;

        while((len = recv(mesh->sock, mesh->line, sizeof(mesh)->line, 0))) {
                if(len < 0) {
                        if(errno == EINTR) {
                                continue;
                        }

                        logger(mesh, MESHLINK_DEBUG, "Error reading data from %s port %s: %s\n", address, port, strerror(errno));
                        meshlink_errno = MESHLINK_ENETWORK;
                        pthread_mutex_unlock(&mesh->mutex);
                        return false;
                }

                if(!sptps_receive_data(&mesh->sptps, mesh->line, len)) {
                        meshlink_errno = MESHLINK_EPEER;
                        pthread_mutex_unlock(&mesh->mutex);
                        return false;
                }
        }

        sptps_stop(&mesh->sptps);
        ecdsa_free(hiskey);
        ecdsa_free(key);
        closesocket(mesh->sock);

        if(!mesh->success) {
                logger(mesh, MESHLINK_DEBUG, "Connection closed by peer, invitation cancelled.\n");
                meshlink_errno = MESHLINK_EPEER;
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);
        return true;

invalid:
        logger(mesh, MESHLINK_DEBUG, "Invalid invitation URL\n");
        meshlink_errno = MESHLINK_EINVAL;
        pthread_mutex_unlock(&mesh->mutex);
        return false;
}

char *meshlink_export(meshlink_handle_t *mesh) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        // Create a config file on the fly.

        uint8_t buf[4096];
        packmsg_output_t out = {buf, sizeof(buf)};
        packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
        packmsg_add_str(&out, mesh->name);
        packmsg_add_str(&out, CORE_MESH);

        pthread_mutex_lock(&mesh->mutex);

        packmsg_add_int32(&out, mesh->self->devclass);
        packmsg_add_bool(&out, mesh->self->status.blacklisted);
        packmsg_add_bin(&out, ecdsa_get_public_key(mesh->private_key), 32);
        packmsg_add_str(&out, mesh->self->canonical_address ? mesh->self->canonical_address : "");

        uint32_t count = 0;

        for(uint32_t i = 0; i < MAX_RECENT; i++) {
                if(mesh->self->recent[i].sa.sa_family) {
                        count++;
                } else {
                        break;
                }
        }

        packmsg_add_array(&out, count);

        for(uint32_t i = 0; i < count; i++) {
                packmsg_add_sockaddr(&out, &mesh->self->recent[i]);
        }

        packmsg_add_int64(&out, 0);
        packmsg_add_int64(&out, 0);

        pthread_mutex_unlock(&mesh->mutex);

        if(!packmsg_output_ok(&out)) {
                logger(mesh, MESHLINK_DEBUG, "Error creating export data\n");
                meshlink_errno = MESHLINK_EINTERNAL;
                return NULL;
        }

        // Prepare a base64-encoded packmsg array containing our config file

        uint32_t len = packmsg_output_size(&out, buf);
        uint32_t len2 = ((len + 4) * 4) / 3 + 4;
        uint8_t *buf2 = xmalloc(len2);
        packmsg_output_t out2 = {buf2, len2};
        packmsg_add_array(&out2, 1);
        packmsg_add_bin(&out2, buf, packmsg_output_size(&out, buf));

        if(!packmsg_output_ok(&out2)) {
                logger(mesh, MESHLINK_DEBUG, "Error creating export data\n");
                meshlink_errno = MESHLINK_EINTERNAL;
                free(buf2);
                return NULL;
        }

        b64encode_urlsafe(buf2, (char *)buf2, packmsg_output_size(&out2, buf2));

        return (char *)buf2;
}

bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
        if(!mesh || !data) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        size_t datalen = strlen(data);
        uint8_t *buf = xmalloc(datalen);
        int buflen = b64decode(data, buf, datalen);

        if(!buflen) {
                logger(mesh, MESHLINK_DEBUG, "Invalid data\n");
                meshlink_errno = MESHLINK_EPEER;
                return false;
        }

        packmsg_input_t in = {buf, buflen};
        uint32_t count = packmsg_get_array(&in);

        if(!count) {
                logger(mesh, MESHLINK_DEBUG, "Invalid data\n");
                meshlink_errno = MESHLINK_EPEER;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        while(count--) {
                const void *data;
                uint32_t len = packmsg_get_bin_raw(&in, &data);

                if(!len) {
                        break;
                }

                packmsg_input_t in2 = {data, len};
                uint32_t version = packmsg_get_uint32(&in2);
                char *name = packmsg_get_str_dup(&in2);

                if(!packmsg_input_ok(&in2) || version != MESHLINK_CONFIG_VERSION || !check_id(name)) {
                        free(name);
                        packmsg_input_invalidate(&in);
                        break;
                }

                if(!check_id(name)) {
                        free(name);
                        break;
                }

                node_t *n = lookup_node(mesh, name);

                if(n) {
                        logger(mesh, MESHLINK_DEBUG, "Node %s already exists, not importing\n", name);
                        free(name);
                        continue;
                }

                n = new_node();
                n->name = name;

                config_t config = {data, len};

                if(!node_read_from_config(mesh, n, &config)) {
                        free_node(n);
                        packmsg_input_invalidate(&in);
                        break;
                }

                if(!config_write(mesh, "current", n->name, &config, mesh->config_key)) {
                        free_node(n);
                        return false;
                }

                node_add(mesh, n);
        }

        pthread_mutex_unlock(&mesh->mutex);

        free(buf);

        if(!packmsg_done(&in)) {
                logger(mesh, MESHLINK_ERROR, "Invalid data\n");
                meshlink_errno = MESHLINK_EPEER;
                return false;
        }

        if(!config_sync(mesh, "current")) {
                return false;
        }

        return true;
}

static bool blacklist(meshlink_handle_t *mesh, node_t *n) {
        if(n == mesh->self) {
                logger(mesh, MESHLINK_ERROR, "%s blacklisting itself?\n", n->name);
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(n->status.blacklisted) {
                logger(mesh, MESHLINK_DEBUG, "Node %s already blacklisted\n", n->name);
                return true;
        }

        n->status.blacklisted = true;

        /* Immediately shut down any connections we have with the blacklisted node.
         * We can't call terminate_connection(), because we might be called from a callback function.
         */
        for list_each(connection_t, c, mesh->connections) {
                if(c->node == n) {
                        shutdown(c->socket, SHUT_RDWR);
                }
        }

        utcp_abort_all_connections(n->utcp);

        n->mtu = 0;
        n->minmtu = 0;
        n->maxmtu = MTU;
        n->mtuprobes = 0;
        n->status.udp_confirmed = false;

        /* Graph updates will suppress status updates for blacklisted nodes, so we need to
         * manually call the status callback if necessary.
         */
        if(n->status.reachable && mesh->node_status_cb) {
                mesh->node_status_cb(mesh, (meshlink_node_t *)n, false);
        }

        return node_write_config(mesh, n) && config_sync(mesh, "current");
}

bool meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        if(!blacklist(mesh, (node_t *)node)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);

        logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", node->name);
        return true;
}

bool meshlink_blacklist_by_name(meshlink_handle_t *mesh, const char *name) {
        if(!mesh || !name) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = lookup_node(mesh, (char *)name);

        if(!n) {
                n = new_node();
                n->name = xstrdup(name);
                node_add(mesh, n);
        }

        if(!blacklist(mesh, (node_t *)n)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);

        logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", name);
        return true;
}

static bool whitelist(meshlink_handle_t *mesh, node_t *n) {
        if(n == mesh->self) {
                logger(mesh, MESHLINK_ERROR, "%s whitelisting itself?\n", n->name);
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!n->status.blacklisted) {
                logger(mesh, MESHLINK_DEBUG, "Node %s was already whitelisted\n", n->name);
                return true;
        }

        n->status.blacklisted = false;

        if(n->status.reachable) {
                update_node_status(mesh, n);
        }

        return node_write_config(mesh, n) && config_sync(mesh, "current");
}

bool meshlink_whitelist(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        if(!whitelist(mesh, (node_t *)node)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);

        logger(mesh, MESHLINK_DEBUG, "Whitelisted %s.\n", node->name);
        return true;
}

bool meshlink_whitelist_by_name(meshlink_handle_t *mesh, const char *name) {
        if(!mesh || !name) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = lookup_node(mesh, (char *)name);

        if(!n) {
                n = new_node();
                n->name = xstrdup(name);
                node_add(mesh, n);
        }

        if(!whitelist(mesh, (node_t *)n)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        pthread_mutex_unlock(&mesh->mutex);

        logger(mesh, MESHLINK_DEBUG, "Whitelisted %s.\n", name);
        return true;
}

void meshlink_set_default_blacklist(meshlink_handle_t *mesh, bool blacklist) {
        mesh->default_blacklist = blacklist;
}

bool meshlink_forget_node(meshlink_handle_t *mesh, meshlink_node_t *node) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        node_t *n = (node_t *)node;

        pthread_mutex_lock(&mesh->mutex);

        /* Check that the node is not reachable */
        if(n->status.reachable || n->connection) {
                pthread_mutex_unlock(&mesh->mutex);
                logger(mesh, MESHLINK_WARNING, "Could not forget %s: still reachable", n->name);
                return false;
        }

        /* Check that we don't have any active UTCP connections */
        if(n->utcp && utcp_is_active(n->utcp)) {
                pthread_mutex_unlock(&mesh->mutex);
                logger(mesh, MESHLINK_WARNING, "Could not forget %s: active UTCP connections", n->name);
                return false;
        }

        /* Check that we have no active connections to this node */
        for list_each(connection_t, c, mesh->connections) {
                if(c->node == n) {
                        pthread_mutex_unlock(&mesh->mutex);
                        logger(mesh, MESHLINK_WARNING, "Could not forget %s: active connection", n->name);
                        return false;
                }
        }

        /* Remove any pending outgoings to this node */
        if(mesh->outgoings) {
                for list_each(outgoing_t, outgoing, mesh->outgoings) {
                        if(outgoing->node == n) {
                                list_delete_node(mesh->outgoings, node);
                        }
                }
        }

        /* Delete the config file for this node */
        if(!config_delete(mesh, "current", n->name)) {
                pthread_mutex_unlock(&mesh->mutex);
                return false;
        }

        /* Delete the node struct and any remaining edges referencing this node */
        node_del(mesh, n);

        pthread_mutex_unlock(&mesh->mutex);

        return config_sync(mesh, "current");
}

/* Hint that a hostname may be found at an address
 * See header file for detailed comment.
 */
void meshlink_hint_address(meshlink_handle_t *mesh, meshlink_node_t *node, const struct sockaddr *addr) {
        if(!mesh || !node || !addr) {
                meshlink_errno = EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = (node_t *)node;
        memmove(n->recent + 1, n->recent, (MAX_RECENT - 1) * sizeof(*n->recent));
        memcpy(n->recent, addr, SALEN(*addr));

        if(!node_write_config(mesh, n)) {
                logger(mesh, MESHLINK_DEBUG, "Could not update %s\n", n->name);
        }

        pthread_mutex_unlock(&mesh->mutex);
        // @TODO do we want to fire off a connection attempt right away?
}

static bool channel_pre_accept(struct utcp *utcp, uint16_t port) {
        (void)port;
        node_t *n = utcp->priv;
        meshlink_handle_t *mesh = n->mesh;
        return mesh->channel_accept_cb;
}

static void aio_signal(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_aio_buffer_t *aio) {
        if(aio->data) {
                if(aio->cb.buffer) {
                        aio->cb.buffer(mesh, channel, aio->data, aio->len, aio->priv);
                }
        } else {
                if(aio->cb.fd) {
                        aio->cb.fd(mesh, channel, aio->fd, aio->done, aio->priv);
                }
        }
}

static ssize_t channel_recv(struct utcp_connection *connection, const void *data, size_t len) {
        meshlink_channel_t *channel = connection->priv;

        if(!channel) {
                abort();
        }

        node_t *n = channel->node;
        meshlink_handle_t *mesh = n->mesh;

        if(n->status.destroyed) {
                meshlink_channel_close(mesh, channel);
                return len;
        }

        const char *p = data;
        size_t left = len;

        while(channel->aio_receive) {
                meshlink_aio_buffer_t *aio = channel->aio_receive;
                size_t todo = aio->len - aio->done;

                if(todo > left) {
                        todo = left;
                }

                if(aio->data) {
                        memcpy((char *)aio->data + aio->done, p, todo);
                } else {
                        ssize_t result = write(aio->fd, p, todo);

                        if(result > 0) {
                                todo = result;
                        }
                }

                aio->done += todo;

                if(aio->done == aio->len) {
                        channel->aio_receive = aio->next;
                        aio_signal(mesh, channel, aio);
                        free(aio);
                }

                p += todo;
                left -= todo;

                if(!left && len) {
                        return len;
                }
        }

        if(channel->receive_cb) {
                channel->receive_cb(mesh, channel, p, left);
        }

        return len;
}

static void channel_accept(struct utcp_connection *utcp_connection, uint16_t port) {
        node_t *n = utcp_connection->utcp->priv;

        if(!n) {
                abort();
        }

        meshlink_handle_t *mesh = n->mesh;

        if(!mesh->channel_accept_cb) {
                return;
        }

        meshlink_channel_t *channel = xzalloc(sizeof(*channel));
        channel->node = n;
        channel->c = utcp_connection;

        if(mesh->channel_accept_cb(mesh, channel, port, NULL, 0)) {
                utcp_accept(utcp_connection, channel_recv, channel);
        } else {
                free(channel);
        }
}

static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
        node_t *n = utcp->priv;

        if(n->status.destroyed) {
                return -1;
        }

        meshlink_handle_t *mesh = n->mesh;
        return meshlink_send(mesh, (meshlink_node_t *)n, data, len) ? (ssize_t)len : -1;
}

void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_receive_cb_t cb) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        channel->receive_cb = cb;
}

static void channel_receive(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len) {
        (void)mesh;
        node_t *n = (node_t *)source;

        if(!n->utcp) {
                abort();
        }

        utcp_recv(n->utcp, data, len);
}

static void channel_poll(struct utcp_connection *connection, size_t len) {
        meshlink_channel_t *channel = connection->priv;

        if(!channel) {
                abort();
        }

        node_t *n = channel->node;
        meshlink_handle_t *mesh = n->mesh;
        meshlink_aio_buffer_t *aio = channel->aio_send;

        if(aio) {
                /* We at least one AIO buffer. Send as much as possible form the first buffer. */
                size_t left = aio->len - aio->done;
                ssize_t sent;

                if(len > left) {
                        len = left;
                }

                if(aio->data) {
                        sent = utcp_send(connection, (char *)aio->data + aio->done, len);
                } else {
                        char buf[65536];
                        size_t todo = utcp_get_sndbuf_free(connection);

                        if(todo > left) {
                                todo = left;
                        }

                        if(todo > sizeof(buf)) {
                                todo = sizeof(buf);
                        }

                        ssize_t result = read(aio->fd, buf, todo);

                        if(result > 0) {
                                sent = utcp_send(connection, buf, result);
                        } else {
                                sent = result;
                        }
                }

                if(sent >= 0) {
                        aio->done += sent;
                }

                /* If the buffer is now completely sent, call the callback and dispose of it. */
                if(aio->done >= aio->len) {
                        channel->aio_send = aio->next;
                        aio_signal(mesh, channel, aio);
                        free(aio);
                }
        } else {
                if(channel->poll_cb) {
                        channel->poll_cb(mesh, channel, len);
                } else {
                        utcp_set_poll_cb(connection, NULL);
                }
        }
}

void meshlink_set_channel_poll_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_poll_cb_t cb) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        channel->poll_cb = cb;
        utcp_set_poll_cb(channel->c, (cb || channel->aio_send) ? channel_poll : NULL);
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb) {
        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->channel_accept_cb = cb;
        mesh->receive_cb = channel_receive;

        for splay_each(node_t, n, mesh->nodes) {
                if(!n->utcp && n != mesh->self) {
                        n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
                }
        }

        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_channel_sndbuf(meshlink_handle_t *mesh, meshlink_channel_t *channel, size_t size) {
        (void)mesh;

        if(!channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        utcp_set_sndbuf(channel->c, size);
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_set_channel_rcvbuf(meshlink_handle_t *mesh, meshlink_channel_t *channel, size_t size) {
        (void)mesh;

        if(!channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        utcp_set_rcvbuf(channel->c, size);
        pthread_mutex_unlock(&mesh->mutex);
}

meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_node_t *node, uint16_t port, meshlink_channel_receive_cb_t cb, const void *data, size_t len, uint32_t flags) {
        if(data && len) {
                abort();        // TODO: handle non-NULL data
        }

        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return NULL;
        }

        pthread_mutex_lock(&mesh->mutex);

        node_t *n = (node_t *)node;

        if(!n->utcp) {
                n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
                mesh->receive_cb = channel_receive;

                if(!n->utcp) {
                        meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
                        pthread_mutex_unlock(&mesh->mutex);
                        return NULL;
                }
        }

        if(n->status.blacklisted) {
                logger(mesh, MESHLINK_ERROR, "Cannot open a channel with blacklisted node\n");
                meshlink_errno = MESHLINK_EBLACKLISTED;
                pthread_mutex_unlock(&mesh->mutex);
                return NULL;
        }

        meshlink_channel_t *channel = xzalloc(sizeof(*channel));
        channel->node = n;
        channel->receive_cb = cb;

        if(data && !len) {
                channel->priv = (void *)data;
        }

        channel->c = utcp_connect_ex(n->utcp, port, channel_recv, channel, flags);

        pthread_mutex_unlock(&mesh->mutex);

        if(!channel->c) {
                meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
                free(channel);
                return NULL;
        }

        return channel;
}

meshlink_channel_t *meshlink_channel_open(meshlink_handle_t *mesh, meshlink_node_t *node, uint16_t port, meshlink_channel_receive_cb_t cb, const void *data, size_t len) {
        return meshlink_channel_open_ex(mesh, node, port, cb, data, len, MESHLINK_CHANNEL_TCP);
}

void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *channel, int direction) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        utcp_shutdown(channel->c, direction);
        pthread_mutex_unlock(&mesh->mutex);
}

void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);

        utcp_close(channel->c);

        /* Clean up any outstanding AIO buffers. */
        for(meshlink_aio_buffer_t *aio = channel->aio_send, *next; aio; aio = next) {
                next = aio->next;
                aio_signal(mesh, channel, aio);
                free(aio);
        }

        for(meshlink_aio_buffer_t *aio = channel->aio_receive, *next; aio; aio = next) {
                next = aio->next;
                aio_signal(mesh, channel, aio);
                free(aio);
        }

        pthread_mutex_unlock(&mesh->mutex);

        free(channel);
}

ssize_t meshlink_channel_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        if(!len) {
                return 0;
        }

        if(!data) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        // TODO: more finegrained locking.
        // Ideally we want to put the data into the UTCP connection's send buffer.
        // Then, preferably only if there is room in the receiver window,
        // kick the meshlink thread to go send packets.

        ssize_t retval;

        pthread_mutex_lock(&mesh->mutex);

        /* Disallow direct calls to utcp_send() while we still have AIO active. */
        if(channel->aio_send) {
                retval = 0;
        } else {
                retval = utcp_send(channel->c, data, len);
        }

        pthread_mutex_unlock(&mesh->mutex);

        if(retval < 0) {
                meshlink_errno = MESHLINK_ENETWORK;
        }

        return retval;
}

bool meshlink_channel_aio_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len, meshlink_aio_cb_t cb, void *priv) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!len || !data) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
        aio->data = data;
        aio->len = len;
        aio->cb.buffer = cb;
        aio->priv = priv;

        pthread_mutex_lock(&mesh->mutex);

        /* Append the AIO buffer descriptor to the end of the chain */
        meshlink_aio_buffer_t **p = &channel->aio_send;

        while(*p) {
                p = &(*p)->next;
        }

        *p = aio;

        /* Ensure the poll callback is set, and call it right now to push data if possible */
        utcp_set_poll_cb(channel->c, channel_poll);
        channel_poll(channel->c, len);

        pthread_mutex_unlock(&mesh->mutex);

        return true;
}

bool meshlink_channel_aio_fd_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, int fd, size_t len, meshlink_aio_fd_cb_t cb, void *priv) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!len || fd == -1) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
        aio->fd = fd;
        aio->len = len;
        aio->cb.fd = cb;
        aio->priv = priv;

        pthread_mutex_lock(&mesh->mutex);

        /* Append the AIO buffer descriptor to the end of the chain */
        meshlink_aio_buffer_t **p = &channel->aio_send;

        while(*p) {
                p = &(*p)->next;
        }

        *p = aio;

        /* Ensure the poll callback is set, and call it right now to push data if possible */
        utcp_set_poll_cb(channel->c, channel_poll);
        channel_poll(channel->c, len);

        pthread_mutex_unlock(&mesh->mutex);

        return true;
}

bool meshlink_channel_aio_receive(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len, meshlink_aio_cb_t cb, void *priv) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!len || !data) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
        aio->data = data;
        aio->len = len;
        aio->cb.buffer = cb;
        aio->priv = priv;

        pthread_mutex_lock(&mesh->mutex);

        /* Append the AIO buffer descriptor to the end of the chain */
        meshlink_aio_buffer_t **p = &channel->aio_receive;

        while(*p) {
                p = &(*p)->next;
        }

        *p = aio;

        pthread_mutex_unlock(&mesh->mutex);

        return true;
}

bool meshlink_channel_aio_fd_receive(meshlink_handle_t *mesh, meshlink_channel_t *channel, int fd, size_t len, meshlink_aio_fd_cb_t cb, void *priv) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        if(!len || fd == -1) {
                meshlink_errno = MESHLINK_EINVAL;
                return false;
        }

        meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
        aio->fd = fd;
        aio->len = len;
        aio->cb.fd = cb;
        aio->priv = priv;

        pthread_mutex_lock(&mesh->mutex);

        /* Append the AIO buffer descriptor to the end of the chain */
        meshlink_aio_buffer_t **p = &channel->aio_receive;

        while(*p) {
                p = &(*p)->next;
        }

        *p = aio;

        pthread_mutex_unlock(&mesh->mutex);

        return true;
}

uint32_t meshlink_channel_get_flags(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        return channel->c->flags;
}

size_t meshlink_channel_get_sendq(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        return utcp_get_sendq(channel->c);
}

size_t meshlink_channel_get_recvq(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
        if(!mesh || !channel) {
                meshlink_errno = MESHLINK_EINVAL;
                return -1;
        }

        return utcp_get_recvq(channel->c);
}

void meshlink_set_node_channel_timeout(meshlink_handle_t *mesh, meshlink_node_t *node, int timeout) {
        if(!mesh || !node) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        node_t *n = (node_t *)node;

        pthread_mutex_lock(&mesh->mutex);

        if(!n->utcp) {
                n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
        }

        utcp_set_user_timeout(n->utcp, timeout);

        pthread_mutex_unlock(&mesh->mutex);
}

void update_node_status(meshlink_handle_t *mesh, node_t *n) {
        if(n->status.reachable && mesh->channel_accept_cb && !n->utcp) {
                n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
        }

        if(mesh->node_status_cb) {
                mesh->node_status_cb(mesh, (meshlink_node_t *)n, n->status.reachable && !n->status.blacklisted);
        }

        if(mesh->node_pmtu_cb) {
                mesh->node_pmtu_cb(mesh, (meshlink_node_t *)n, n->minmtu);
        }
}

void update_node_pmtu(meshlink_handle_t *mesh, node_t *n) {
        if(mesh->node_pmtu_cb && !n->status.blacklisted) {
                mesh->node_pmtu_cb(mesh, (meshlink_node_t *)n, n->minmtu);
        }
}

void handle_duplicate_node(meshlink_handle_t *mesh, node_t *n) {
        if(!mesh->node_duplicate_cb || n->status.duplicate) {
                return;
        }

        n->status.duplicate = true;
        mesh->node_duplicate_cb(mesh, (meshlink_node_t *)n);
}

void meshlink_enable_discovery(meshlink_handle_t *mesh, bool enable) {
#if HAVE_CATTA

        if(!mesh) {
                meshlink_errno = MESHLINK_EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);

        if(mesh->discovery == enable) {
                goto end;
        }

        if(mesh->threadstarted) {
                if(enable) {
                        discovery_start(mesh);
                } else {
                        discovery_stop(mesh);
                }
        }

        mesh->discovery = enable;

end:
        pthread_mutex_unlock(&mesh->mutex);
#else
        (void)mesh;
        (void)enable;
        meshlink_errno = MESHLINK_ENOTSUP;
#endif
}

void meshlink_set_dev_class_timeouts(meshlink_handle_t *mesh, dev_class_t devclass, int pinginterval, int pingtimeout) {
        if(!mesh || devclass < 0 || devclass >= DEV_CLASS_COUNT) {
                meshlink_errno = EINVAL;
                return;
        }

        if(pinginterval < 1 || pingtimeout < 1 || pingtimeout > pinginterval) {
                meshlink_errno = EINVAL;
                return;
        }

        pthread_mutex_lock(&mesh->mutex);
        mesh->dev_class_traits[devclass].pinginterval = pinginterval;
        mesh->dev_class_traits[devclass].pingtimeout = pingtimeout;
        pthread_mutex_unlock(&mesh->mutex);
}

void handle_network_change(meshlink_handle_t *mesh, bool online) {
        (void)online;

        if(!mesh->connections || !mesh->loop.running) {
                return;
        }

        retry(mesh);
}

void call_error_cb(meshlink_handle_t *mesh, meshlink_errno_t meshlink_errno) {
        // We should only call the callback function if we are in the background thread.
        if(!mesh->error_cb) {
                return;
        }

        if(!mesh->threadstarted) {
                return;
        }

        if(mesh->thread == pthread_self()) {
                mesh->error_cb(mesh, meshlink_errno);
        }
}


static void __attribute__((constructor)) meshlink_init(void) {
        crypto_init();
}

static void __attribute__((destructor)) meshlink_exit(void) {
        crypto_exit();
}