X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fmeshlink.c;h=c25e08c5c72a25da131ed0c11cc32dcba239744a;hb=4a839c62c32ae4933b24215e3fb25cdb159fcd4e;hp=b566498551940ba8299d68b31599d736b0b8c717;hpb=a42b1de9411a578f6af6fc0e9fe04b5781a0bd60;p=meshlink

diff --git a/src/meshlink.c b/src/meshlink.c
index b5664985..9a0e914a 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -1,6 +1,6 @@
 /*
     meshlink.c -- Implementation of the MeshLink API.
-    Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
+    Copyright (C) 2014, 2017 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
@@ -16,357 +16,2677 @@
     with this program; if not, write to the Free Software Foundation, Inc.,
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
+#define VAR_SERVER 1    /* Should be in meshlink.conf */
+#define VAR_HOST 2      /* Can be in host config file */
+#define VAR_MULTIPLE 4  /* Multiple statements allowed */
+#define VAR_OBSOLETE 8  /* Should not be used anymore */
+#define VAR_SAFE 16     /* Variable is safe when accepting invitations */
+#define MAX_ADDRESS_LENGTH 45 /* Max length of an (IPv6) address */
+#define MAX_PORT_LENGTH 5 /* 0-65535 */
+typedef struct {
+	const char *name;
+	int type;
+} var_t;
 
 #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 "protocol.h"
 #include "route.h"
+#include "sockaddr.h"
+#include "utils.h"
 #include "xalloc.h"
+#include "ed25519/sha512.h"
+#include "discovery.h"
 
-meshlink_handle_t *mesh;
+#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;
+
+//TODO: this can go away completely
+const var_t variables[] = {
+	/* Server configuration */
+	{"ConnectTo", VAR_SERVER | VAR_MULTIPLE | VAR_SAFE},
+	{"Name", VAR_SERVER},
+	/* Host configuration */
+	{"CanonicalAddress", VAR_HOST},
+	{"Address", VAR_HOST | VAR_MULTIPLE},
+	{"ECDSAPublicKey", VAR_HOST},
+	{"Port", VAR_HOST},
+	{NULL, 0}
+};
+
+static bool fcopy(FILE *out, const char *filename) {
+	FILE *in = fopen(filename, "r");
+
+	if(!in) {
+		logger(NULL, MESHLINK_ERROR, "Could not open %s: %s\n", filename, strerror(errno));
+		return false;
+	}
+
+	char buf[1024];
+	size_t len;
+
+	while((len = fread(buf, 1, sizeof(buf), in))) {
+		fwrite(buf, len, 1, out);
+	}
+
+	fclose(in);
+	return true;
+}
+
+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 scan_for_hostname(const char *filename, char **hostname, char **port) {
+	char line[4096];
+	bool canonical = false;
+
+	if(!filename || (*hostname && *port)) {
+		return;
+	}
+
+	FILE *f = fopen(filename, "r");
+
+	if(!f) {
+		return;
+	}
+
+	while(fgets(line, sizeof(line), f)) {
+		if(!rstrip(line)) {
+			continue;
+		}
+
+		char *p = line, *q;
+		p += strcspn(p, "\t =");
+
+		if(!*p) {
+			continue;
+		}
+
+		q = p + strspn(p, "\t ");
+
+		if(*q == '=') {
+			q += 1 + strspn(q + 1, "\t ");
+		}
+
+		// q is now pointing to the hostname
+		*p = 0;
+		p = q + strcspn(q, "\t ");
+
+		if(*p) {
+			*p++ = 0;
+		}
+
+		p += strspn(p, "\t ");
+		p[strcspn(p, "\t ")] = 0;
+		// p is now pointing to the port, if present
+
+		if(!*port && !strcasecmp(line, "Port")) {
+			*port = xstrdup(q);
+		} else if(!canonical && !*hostname && !strcasecmp(line, "Address")) {
+			// Check that the hostname is a symbolic name (it's not a numeric IPv4 or IPv6 address)
+			if(!q[strspn(q, "0123456789.")] || strchr(q, ':')) {
+				continue;
+			}
+
+			*hostname = xstrdup(q);
+
+			if(*p) {
+				free(*port);
+				*port = xstrdup(p);
+			}
+		} else if(!strcasecmp(line, "CanonicalAddress")) {
+			*hostname = xstrdup(q);
+			canonical = true;
+
+			if(*p) {
+				free(*port);
+				*port = xstrdup(p);
+			}
+		}
+
+		if(canonical && *hostname && *port) {
+			break;
+		}
+	}
+
+	fclose(f);
+}
+
+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));
+}
+
+// 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 getlocaladdrname(char *destaddr, char *host, socklen_t hostlen) {
+	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(rai->ai_family, rai->ai_socktype, rai->ai_protocol);
+
+	if(sock == -1) {
+		freeaddrinfo(rai);
+		return false;
+	}
+
+	if(connect(sock, rai->ai_addr, rai->ai_addrlen) && !sockwouldblock(errno)) {
+		freeaddrinfo(rai);
+		return false;
+	}
+
+	freeaddrinfo(rai);
+
+	struct sockaddr_storage sn;
+	socklen_t sl = sizeof(sn);
+
+	if(getsockname(sock, (struct sockaddr *)&sn, &sl)) {
+		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(aip->ai_family, aip->ai_socktype, aip->ai_protocol);
+
+		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 there is no hostname, determine the address used for an outgoing connection.
+	if(!hostname) {
+		char localaddr[NI_MAXHOST];
+		bool success = false;
+
+		if(family == AF_INET) {
+			success = getlocaladdrname("93.184.216.34", localaddr, sizeof(localaddr));
+		} else if(family == AF_INET6) {
+			success = getlocaladdrname("2606:2800:220:1:248:1893:25c8:1946", localaddr, sizeof(localaddr));
+		}
+
+		if(success) {
+			hostname = xstrdup(localaddr);
+		}
+	}
+
+	if(!hostname) {
+		meshlink_errno = MESHLINK_ERESOLV;
+	}
+
+	return hostname;
+}
+
+// This gets the hostname part for use in invitation URLs
+static char *get_my_hostname(meshlink_handle_t *mesh) {
+	char *hostname[2] = {NULL};
+	char *port = NULL;
+	char *hostport = NULL;
+	char *name = mesh->self->name;
+	char filename[PATH_MAX] = "";
+
+	// Use first Address statement in own host config file
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+	scan_for_hostname(filename, &hostname[0], &port);
+
+	if(hostname[0]) {
+		goto done;
+	}
+
+	hostname[0] = meshlink_get_external_address_for_family(mesh, AF_INET);
+	hostname[1] = meshlink_get_external_address_for_family(mesh, AF_INET6);
+
+	if(!hostname[0] && !hostname[1]) {
+		return NULL;
+	}
+
+	if(hostname[0] && hostname[1] && !strcmp(hostname[0], hostname[1])) {
+		free(hostname[1]);
+		hostname[1] = NULL;
+	}
+
+	port = xstrdup(mesh->myport);
+
+	for(int i = 0; i < 2; i++) {
+		if(hostname[i]) {
+			char *tmphostport;
+			xasprintf(&tmphostport, "%s %s", hostname[i], port);
+			append_config_file(mesh, mesh->self->name, "Address", tmphostport);
+			free(tmphostport);
+		}
+	}
+
+done:
+
+	for(int i = 0; i < 2; i++) {
+		if(!hostname[i]) {
+			continue;
+		}
+
+		char *newhostport;
+		xasprintf(&newhostport, (strchr(hostname[i], ':') ? "%s%s[%s]" : "%s%s%s"), hostport ? hostport : "", hostport ? "," : "", hostname[i]);
+		free(hostname[i]);
+		free(hostport);
+		hostport = newhostport;
+	}
+
+	if(port) {
+		char *newhostport;
+		xasprintf(&newhostport, "%s:%s", hostport, port);
+		free(port);
+		free(hostport);
+		hostport = newhostport;
+	}
+
+	return hostport;
+}
+
+static char *get_line(const char **data) {
+	if(!data || !*data) {
+		return NULL;
+	}
+
+	if(! **data) {
+		*data = NULL;
+		return NULL;
+	}
+
+	static char line[1024];
+	const char *end = strchr(*data, '\n');
+	size_t len = end ? (size_t)(end - *data) : strlen(*data);
+
+	if(len >= sizeof(line)) {
+		logger(NULL, MESHLINK_ERROR, "Maximum line length exceeded!\n");
+		return NULL;
+	}
+
+	if(len && !isprint(**data)) {
+		abort();
+	}
+
+	memcpy(line, *data, len);
+	line[len] = 0;
+
+	if(end) {
+		*data = end + 1;
+	} else {
+		*data = NULL;
+	}
+
+	return line;
+}
+
+static char *get_value(const char *data, const char *var) {
+	char *line = get_line(&data);
+
+	if(!line) {
+		return NULL;
+	}
+
+	char *sep = line + strcspn(line, " \t=");
+	char *val = sep + strspn(sep, " \t");
+
+	if(*val == '=') {
+		val += 1 + strspn(val + 1, " \t");
+	}
+
+	*sep = 0;
+
+	if(strcasecmp(line, var)) {
+		return NULL;
+	}
+
+	return val;
+}
+
+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) {
+		int fd = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);
+
+		if(!fd) {
+			freeaddrinfo(ai);
+			return false;
+		}
+
+		int result = bind(fd, ai->ai_addr, ai->ai_addrlen);
+		closesocket(fd);
+
+		if(result) {
+			freeaddrinfo(ai);
+			return false;
+		}
+
+		ai = ai->ai_next;
+	}
+
+	freeaddrinfo(ai);
+	return true;
+}
+
+int check_port(meshlink_handle_t *mesh) {
+	for(int i = 0; i < 1000; i++) {
+		int port = 0x1000 + (rand() & 0x7fff);
+
+		if(try_bind(port)) {
+			char filename[PATH_MAX];
+			snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->name);
+			FILE *f = fopen(filename, "a");
+
+			if(!f) {
+				meshlink_errno = MESHLINK_ESTORAGE;
+				logger(mesh, MESHLINK_DEBUG, "Could not store Port.\n");
+				return 0;
+			}
+
+			fprintf(f, "Port = %d\n", port);
+			fclose(f);
+			return port;
+		}
+	}
+
+	meshlink_errno = MESHLINK_ENETWORK;
+	logger(mesh, MESHLINK_DEBUG, "Could not find any available network port.\n");
+	return 0;
+}
+
+static void deltree(const char *dirname) {
+	DIR *d = opendir(dirname);
+
+	if(d) {
+		struct dirent *ent;
+
+		while((ent = readdir(d))) {
+			if(ent->d_name[0] == '.') {
+				continue;
+			}
+
+			char filename[PATH_MAX];
+			snprintf(filename, sizeof(filename), "%s" SLASH "%s", dirname, ent->d_name);
+
+			if(unlink(filename)) {
+				deltree(filename);
+			}
+		}
+
+		closedir(d);
+	}
+
+	rmdir(dirname);
+}
+
+static bool finalize_join(meshlink_handle_t *mesh) {
+	char *name = xstrdup(get_value(mesh->data, "Name"));
+
+	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);
+		return false;
+	}
+
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "meshlink.conf", mesh->confbase);
+
+	FILE *f = fopen(filename, "w");
+
+	if(!f) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create file %s: %s\n", filename, strerror(errno));
+		return false;
+	}
+
+	fprintf(f, "Name = %s\n", name);
+
+	// Wipe all old host config files and invitations
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts", mesh->confbase);
+	deltree(filename);
+
+	if(mkdir(filename, 0777) && errno != EEXIST) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", filename, strerror(errno));
+		return false;
+	}
+
+	snprintf(filename, sizeof(filename), "%s" SLASH "invitations", mesh->confbase);
+	deltree(filename);
+
+	// Create a new host config file for ourself
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+	FILE *fh = fopen(filename, "w");
+
+	if(!fh) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create file %s: %s\n", filename, strerror(errno));
+		fclose(f);
+		return false;
+	}
+
+	// Filter first chunk on approved keywords, split between meshlink.conf and hosts/Name
+	// Other chunks go unfiltered to their respective host config files
+	const char *p = mesh->data;
+	char *l, *value;
+
+	while((l = get_line(&p))) {
+		// Ignore comments
+		if(*l == '#') {
+			continue;
+		}
+
+		// Split line into variable and value
+		int len = strcspn(l, "\t =");
+		value = l + len;
+		value += strspn(value, "\t ");
+
+		if(*value == '=') {
+			value++;
+			value += strspn(value, "\t ");
+		}
+
+		l[len] = 0;
+
+		// Is it a Name?
+		if(!strcasecmp(l, "Name"))
+			if(strcmp(value, name)) {
+				break;
+			} else {
+				continue;
+			} else if(!strcasecmp(l, "NetName")) {
+			continue;
+		}
+
+		// Check the list of known variables
+		bool found = false;
+		int i;
+
+		for(i = 0; variables[i].name; i++) {
+			if(strcasecmp(l, variables[i].name)) {
+				continue;
+			}
+
+			found = true;
+			break;
+		}
+
+		// Ignore unknown and unsafe variables
+		if(!found) {
+			logger(mesh, MESHLINK_DEBUG, "Ignoring unknown variable '%s' in invitation.\n", l);
+			continue;
+		} else if(!(variables[i].type & VAR_SAFE)) {
+			logger(mesh, MESHLINK_DEBUG, "Ignoring unsafe variable '%s' in invitation.\n", l);
+			continue;
+		}
+
+		// Copy the safe variable to the right config file
+		fprintf(variables[i].type & VAR_HOST ? fh : f, "%s = %s\n", l, value);
+	}
+
+	fclose(f);
+
+	while(l && !strcasecmp(l, "Name")) {
+		if(!check_id(value)) {
+			logger(mesh, MESHLINK_DEBUG, "Invalid Name found in invitation.\n");
+			return false;
+		}
+
+		if(!strcmp(value, name)) {
+			logger(mesh, MESHLINK_DEBUG, "Secondary chunk would overwrite our own host config file.\n");
+			return false;
+		}
+
+		snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, value);
+		f = fopen(filename, "w");
+
+		if(!f) {
+			logger(mesh, MESHLINK_DEBUG, "Could not create file %s: %s\n", filename, strerror(errno));
+			return false;
+		}
+
+		while((l = get_line(&p))) {
+			if(!strcmp(l, "#---------------------------------------------------------------#")) {
+				continue;
+			}
+
+			int len = strcspn(l, "\t =");
+
+			if(len == 4 && !strncasecmp(l, "Name", 4)) {
+				value = l + len;
+				value += strspn(value, "\t ");
+
+				if(*value == '=') {
+					value++;
+					value += strspn(value, "\t ");
+				}
+
+				l[len] = 0;
+				break;
+			}
+
+			fputs(l, f);
+			fputc('\n', f);
+		}
+
+		fclose(f);
+	}
+
+	char *b64key = ecdsa_get_base64_public_key(mesh->self->connection->ecdsa);
+
+	if(!b64key) {
+		fclose(fh);
+		return false;
+	}
+
+	fprintf(fh, "ECDSAPublicKey = %s\n", b64key);
+	fprintf(fh, "Port = %s\n", mesh->myport);
+
+	fclose(fh);
+
+	sptps_send_record(&(mesh->sptps), 1, b64key, strlen(b64key));
+	free(b64key);
+
+	free(mesh->name);
+	free(mesh->self->name);
+	free(mesh->self->connection->name);
+	mesh->name = xstrdup(name);
+	mesh->self->name = xstrdup(name);
+	mesh->self->connection->name = name;
+
+	logger(mesh, MESHLINK_DEBUG, "Configuration stored in: %s\n", mesh->confbase);
+
+	load_all_nodes(mesh);
+
+	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:
+		mesh->data = xrealloc(mesh->data, mesh->thedatalen + len + 1);
+		memcpy(mesh->data + mesh->thedatalen, msg, len);
+		mesh->thedatalen += len;
+		mesh->data[mesh->thedatalen] = 0;
+		break;
+
+	case 1:
+		mesh->thedatalen = 0;
+		return finalize_join(mesh);
+
+	case 2:
+		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, ...) {
+	static 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",
+};
+
+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) {
+	ecdsa_t *key;
+	FILE *f;
+	char pubname[PATH_MAX], privname[PATH_MAX];
+
+	logger(mesh, MESHLINK_DEBUG, "Generating ECDSA keypair:\n");
+
+	if(!(key = ecdsa_generate())) {
+		logger(mesh, MESHLINK_DEBUG, "Error during key generation!\n");
+		meshlink_errno = MESHLINK_EINTERNAL;
+		return false;
+	} else {
+		logger(mesh, MESHLINK_DEBUG, "Done.\n");
+	}
+
+	if(snprintf(privname, sizeof(privname), "%s" SLASH "ecdsa_key.priv", mesh->confbase) >= PATH_MAX) {
+		logger(mesh, MESHLINK_DEBUG, "Filename too long: %s" SLASH "ecdsa_key.priv\n", mesh->confbase);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	f = fopen(privname, "wb");
+
+	if(!f) {
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+#ifdef HAVE_FCHMOD
+	fchmod(fileno(f), 0600);
+#endif
+
+	if(!ecdsa_write_pem_private_key(key, f)) {
+		logger(mesh, MESHLINK_DEBUG, "Error writing private key!\n");
+		ecdsa_free(key);
+		fclose(f);
+		meshlink_errno = MESHLINK_EINTERNAL;
+		return false;
+	}
+
+	fclose(f);
+
+	snprintf(pubname, sizeof(pubname), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->name);
+	f = fopen(pubname, "a");
+
+	if(!f) {
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	char *pubkey = ecdsa_get_base64_public_key(key);
+	fprintf(f, "ECDSAPublicKey = %s\n", pubkey);
+	free(pubkey);
+
+	fclose(f);
+	ecdsa_free(key);
+
+	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) {
+	char host[NI_MAXHOST];
+	char entry[MAX_STRING_SIZE];
+
+	// IPv4 example.org
+
+	if(getlocaladdrname("93.184.216.34", host, sizeof(host))) {
+		snprintf(entry, sizeof(entry), "%s %s", host, mesh->myport);
+		append_config_file(mesh, mesh->name, "Address", entry);
+	}
+
+	// IPv6 example.org
+
+	if(getlocaladdrname("2606:2800:220:1:248:1893:25c8:1946", host, sizeof(host))) {
+		snprintf(entry, sizeof(entry), "%s %s", host, mesh->myport);
+		append_config_file(mesh, mesh->name, "Address", entry);
+	}
+}
+
+static bool meshlink_setup(meshlink_handle_t *mesh) {
+	if(mkdir(mesh->confbase, 0777) && errno != EEXIST) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", mesh->confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts", mesh->confbase);
+
+	if(mkdir(filename, 0777) && errno != EEXIST) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	snprintf(filename, sizeof(filename), "%s" SLASH "meshlink.conf", mesh->confbase);
+
+	if(!access(filename, F_OK)) {
+		logger(mesh, MESHLINK_DEBUG, "Configuration file %s already exists!\n", filename);
+		meshlink_errno = MESHLINK_EEXIST;
+		return false;
+	}
+
+	FILE *f = fopen(filename, "w");
+
+	if(!f) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create file %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	fprintf(f, "Name = %s\n", mesh->name);
+	fclose(f);
+
+	if(!ecdsa_keygen(mesh)) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		unlink(filename);
+		return false;
+	}
+
+	if(check_port(mesh) == 0) {
+		meshlink_errno = MESHLINK_ENETWORK;
+		unlink(filename);
+		return false;
+	}
+
+	return true;
+}
+
+meshlink_handle_t *meshlink_open(const char *confbase, const char *name, const char *appname, dev_class_t devclass) {
+	// Validate arguments provided by the application
+	bool usingname = false;
+
+	logger(NULL, MESHLINK_DEBUG, "meshlink_open called\n");
+
+	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(!name || !*name) {
+		logger(NULL, MESHLINK_ERROR, "No name given!\n");
+		//return NULL;
+	} else { //check name only if there is a name != NULL
+
+		if(!check_id(name)) {
+			logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
+			meshlink_errno = MESHLINK_EINVAL;
+			return NULL;
+		} else {
+			usingname = true;
+		}
+	}
+
+	if((int)devclass < 0 || devclass > _DEV_CLASS_MAX) {
+		logger(NULL, MESHLINK_ERROR, "Invalid devclass given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
+	meshlink_handle_t *mesh = xzalloc(sizeof(meshlink_handle_t));
+	mesh->confbase = xstrdup(confbase);
+	mesh->appname = xstrdup(appname);
+	mesh->devclass = devclass;
+	mesh->discovery = true;
+	mesh->invitation_timeout = 604800; // 1 week
+
+	if(usingname) {
+		mesh->name = xstrdup(name);
+	}
+
+	// initialize mutex
+	pthread_mutexattr_t attr;
+	pthread_mutexattr_init(&attr);
+	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+	pthread_mutex_init(&(mesh->mesh_mutex), &attr);
+
+	mesh->threadstarted = false;
+	event_loop_init(&mesh->loop);
+	mesh->loop.data = mesh;
+
+	meshlink_queue_init(&mesh->outpacketqueue);
+
+	// Check whether meshlink.conf already exists
+
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "meshlink.conf", confbase);
+
+	if(access(filename, R_OK)) {
+		if(errno == ENOENT) {
+			// If not, create it
+			if(!meshlink_setup(mesh)) {
+				// meshlink_errno is set by meshlink_setup()
+				return NULL;
+			}
+		} else {
+			logger(NULL, MESHLINK_ERROR, "Cannot not read from %s: %s\n", filename, strerror(errno));
+			meshlink_close(mesh);
+			meshlink_errno = MESHLINK_ESTORAGE;
+			return NULL;
+		}
+	}
+
+	// Read the configuration
+
+	init_configuration(&mesh->config);
+
+	if(!read_server_config(mesh)) {
+		meshlink_close(mesh);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		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
+
+	if(!setup_network(mesh)) {
+		meshlink_close(mesh);
+		meshlink_errno = MESHLINK_ENETWORK;
+		return NULL;
+	}
+
+	add_local_addresses(mesh);
+
+	idle_set(&mesh->loop, idle, mesh);
+
+	logger(NULL, MESHLINK_DEBUG, "meshlink_open returning\n");
+	return mesh;
+}
+
+static void *meshlink_main_loop(void *arg) {
+	meshlink_handle_t *mesh = arg;
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	try_outgoing_connections(mesh);
+
+	logger(mesh, MESHLINK_DEBUG, "Starting main_loop...\n");
+	main_loop(mesh);
+	logger(mesh, MESHLINK_DEBUG, "main_loop returned.\n");
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return NULL;
+}
+
+bool meshlink_start(meshlink_handle_t *mesh) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	logger(mesh, MESHLINK_DEBUG, "meshlink_start called\n");
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	if(mesh->threadstarted) {
+		logger(mesh, MESHLINK_DEBUG, "thread was already running\n");
+		pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+		return false;
+	}
+
+	// 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->mesh_mutex));
+		return false;
+	}
+
+	mesh->threadstarted = true;
+
+	if(mesh->discovery) {
+		discovery_start(mesh);
+	}
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return true;
+}
+
+void meshlink_stop(meshlink_handle_t *mesh) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+	logger(mesh, MESHLINK_DEBUG, "meshlink_stop called\n");
+
+	// Stop discovery
+	if(mesh->discovery) {
+		discovery_stop(mesh);
+	}
+
+	// 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->mesh_mutex));
+		pthread_join(mesh->thread, NULL);
+		pthread_mutex_lock(&(mesh->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);
+		}
+	}
+
+	if(mesh->outgoings) {
+		list_delete_list(mesh->outgoings);
+		mesh->outgoings = NULL;
+	}
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+}
+
+void meshlink_close(meshlink_handle_t *mesh) {
+	if(!mesh || !mesh->confbase) {
+		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->mesh_mutex));
+
+	// Close and free all resources used.
+
+	close_network_connections(mesh);
+
+	logger(mesh, MESHLINK_INFO, "Terminating");
+
+	exit_configuration(&mesh->config);
+	event_loop_exit(&mesh->loop);
+
+#ifdef HAVE_MINGW
+
+	if(mesh->confbase) {
+		WSACleanup();
+	}
+
+#endif
+
+	ecdsa_free(mesh->invitation_key);
+
+	free(mesh->name);
+	free(mesh->appname);
+	free(mesh->confbase);
+	pthread_mutex_destroy(&(mesh->mesh_mutex));
+
+	memset(mesh, 0, sizeof(*mesh));
+
+	free(mesh);
+}
+
+bool meshlink_destroy(const char *confbase) {
+	if(!confbase) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "meshlink.conf", confbase);
+
+	if(unlink(filename)) {
+		if(errno == ENOENT) {
+			meshlink_errno = MESHLINK_ENOENT;
+			return false;
+		} else {
+			logger(NULL, MESHLINK_ERROR, "Cannot delete %s: %s\n", filename, strerror(errno));
+			meshlink_errno = MESHLINK_ESTORAGE;
+			return false;
+		}
+	}
+
+	deltree(confbase);
+
+	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->mesh_mutex));
+	mesh->receive_cb = cb;
+	pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+	mesh->node_status_cb = cb;
+	pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+		mesh->log_cb = cb;
+		mesh->log_level = cb ? level : 0;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+	} else {
+		global_log_cb = cb;
+		global_log_level = cb ? level : 0;
+	}
+}
+
+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;
+	}
+
+	// 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, meshlink_handle_t *mesh) {
+	(void)loop;
+	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);
+}
+
+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->mesh_mutex));
+
+	node_t *n = (node_t *)destination;
+
+	if(!n->status.reachable) {
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return 0;
+
+	} else if(n->mtuprobes > 30 && n->minmtu) {
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return n->minmtu;
+	} else {
+		pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+
+	node_t *n = (node_t *)node;
+
+	if(!node_read_ecdsa_public_key(mesh, n) || !n->ecdsa) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
+
+	char *fingerprint = ecdsa_get_base64_public_key(n->ecdsa);
+
+	if(!fingerprint) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+	}
+
+	pthread_mutex_unlock(&(mesh->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;
+	}
+
+	meshlink_node_t *node = NULL;
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+	node = (meshlink_node_t *)lookup_node(mesh, (char *)name); // TODO: make lookup_node() use const
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return node;
+}
+
+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->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->mesh_mutex));
+
+	return result;
+}
+
+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->mesh_mutex));
+
+	if(!ecdsa_sign(mesh->self->connection->ecdsa, data, len, signature)) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
+
+	*siglen = MESHLINK_SIGLEN;
+	pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+
+	bool rval = false;
+
+	struct node_t *n = (struct node_t *)source;
+	node_read_ecdsa_public_key(mesh, n);
+
+	if(!n->ecdsa) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		rval = false;
+	} else {
+		rval = ecdsa_verify(((struct node_t *)source)->ecdsa, data, len, signature);
+	}
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return rval;
+}
+
+static bool refresh_invitation_key(meshlink_handle_t *mesh) {
+	char filename[PATH_MAX];
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	snprintf(filename, sizeof(filename), "%s" SLASH "invitations", mesh->confbase);
+
+	if(mkdir(filename, 0700) && errno != EEXIST) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create directory %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
+
+	// Count the number of valid invitations, clean up old ones
+	DIR *dir = opendir(filename);
+
+	if(!dir) {
+		logger(mesh, MESHLINK_DEBUG, "Could not read directory %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
+
+	errno = 0;
+	int count = 0;
+	struct dirent *ent;
+	time_t deadline = time(NULL) - 604800; // 1 week in the past
+
+	while((ent = readdir(dir))) {
+		if(strlen(ent->d_name) != 24) {
+			continue;
+		}
+
+		char invname[PATH_MAX];
+		struct stat st;
+
+		if(snprintf(invname, sizeof(invname), "%s" SLASH "%s", filename, ent->d_name) >= PATH_MAX) {
+			logger(mesh, MESHLINK_DEBUG, "Filename too long: %s" SLASH "%s", filename, ent->d_name);
+			continue;
+		}
+
+		if(!stat(invname, &st)) {
+			if(mesh->invitation_key && deadline < st.st_mtime) {
+				count++;
+			} else {
+				unlink(invname);
+			}
+		} else {
+			logger(mesh, MESHLINK_DEBUG, "Could not stat %s: %s\n", invname, strerror(errno));
+			errno = 0;
+		}
+	}
+
+	if(errno) {
+		logger(mesh, MESHLINK_DEBUG, "Error while reading directory %s: %s\n", filename, strerror(errno));
+		closedir(dir);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
+
+	closedir(dir);
+
+	snprintf(filename, sizeof(filename), "%s" SLASH "invitations" SLASH "ecdsa_key.priv", mesh->confbase);
+
+	// Remove the key if there are no outstanding invitations.
+	if(!count) {
+		unlink(filename);
+
+		if(mesh->invitation_key) {
+			ecdsa_free(mesh->invitation_key);
+			mesh->invitation_key = NULL;
+		}
+	}
+
+	if(mesh->invitation_key) {
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return true;
+	}
+
+	// Create a new key if necessary.
+	FILE *f = fopen(filename, "rb");
+
+	if(!f) {
+		if(errno != ENOENT) {
+			logger(mesh, MESHLINK_DEBUG, "Could not read %s: %s\n", filename, strerror(errno));
+			meshlink_errno = MESHLINK_ESTORAGE;
+			pthread_mutex_unlock(&(mesh->mesh_mutex));
+			return false;
+		}
+
+		mesh->invitation_key = ecdsa_generate();
+
+		if(!mesh->invitation_key) {
+			logger(mesh, MESHLINK_DEBUG, "Could not generate a new key!\n");
+			meshlink_errno = MESHLINK_EINTERNAL;
+			pthread_mutex_unlock(&(mesh->mesh_mutex));
+			return false;
+		}
+
+		f = fopen(filename, "wb");
+
+		if(!f) {
+			logger(mesh, MESHLINK_DEBUG, "Could not write %s: %s\n", filename, strerror(errno));
+			meshlink_errno = MESHLINK_ESTORAGE;
+			pthread_mutex_unlock(&(mesh->mesh_mutex));
+			return false;
+		}
+
+		chmod(filename, 0600);
+		ecdsa_write_pem_private_key(mesh->invitation_key, f);
+		fclose(f);
+	} else {
+		mesh->invitation_key = ecdsa_read_pem_private_key(f);
+		fclose(f);
+
+		if(!mesh->invitation_key) {
+			logger(mesh, MESHLINK_DEBUG, "Could not read private key from %s\n", filename);
+			meshlink_errno = MESHLINK_ESTORAGE;
+		}
+	}
+
+	pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+	bool rval = modify_config_file(mesh, node->name, "CanonicalAddress", canonical_address, 1);
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+
+	free(canonical_address);
+	return rval;
+}
+
+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 = false;
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+	rval = append_config_file(mesh, mesh->self->name, "Address", address);
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+
+	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;
+	}
+
+	return atoi(mesh->myport);
+}
+
+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;
+	}
+
+	bool rval = false;
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	if(mesh->threadstarted) {
+		meshlink_errno = MESHLINK_EINVAL;
+		goto done;
+	}
+
+	close_network_connections(mesh);
+	exit_configuration(&mesh->config);
+
+	char portstr[10];
+	snprintf(portstr, sizeof(portstr), "%d", port);
+	portstr[sizeof(portstr) - 1] = 0;
+
+	modify_config_file(mesh, mesh->name, "Port", portstr, true);
+
+	init_configuration(&mesh->config);
+
+	if(!read_server_config(mesh)) {
+		meshlink_errno = MESHLINK_ESTORAGE;
+	} else if(!setup_network(mesh)) {
+		meshlink_errno = MESHLINK_ENETWORK;
+	} else {
+		rval = true;
+	}
+
+done:
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+
+	return rval;
+}
+
+void meshlink_set_invitation_timeout(meshlink_handle_t *mesh, int timeout) {
+	mesh->invitation_timeout = timeout;
+}
+
+char *meshlink_invite(meshlink_handle_t *mesh, const char *name) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
+	pthread_mutex_lock(&(mesh->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->mesh_mutex));
+		return NULL;
+	}
+
+	// Ensure no host configuration file with that name exists
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+
+	if(!access(filename, F_OK)) {
+		logger(mesh, MESHLINK_DEBUG, "A host config file for %s already exists!\n", name);
+		meshlink_errno = MESHLINK_EEXIST;
+		pthread_mutex_unlock(&(mesh->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->mesh_mutex));
+		return NULL;
+	}
+
+	// Get the local address
+	char *address = get_my_hostname(mesh);
+
+	if(!address) {
+		logger(mesh, MESHLINK_DEBUG, "No Address known for ourselves!\n");
+		meshlink_errno = MESHLINK_ERESOLV;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return NULL;
+	}
+
+	if(!refresh_invitation_key(mesh)) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		pthread_mutex_unlock(&(mesh->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);
+
+	// Create a file containing the details of the invitation.
+	snprintf(filename, sizeof(filename), "%s" SLASH "invitations" SLASH "%s", mesh->confbase, cookiehash);
+	int ifd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
+
+	if(!ifd) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create invitation file %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return NULL;
+	}
+
+	FILE *f = fdopen(ifd, "w");
+
+	if(!f) {
+		abort();
+	}
+
+	// Fill in the details.
+	fprintf(f, "Name = %s\n", name);
+	fprintf(f, "ConnectTo = %s\n", mesh->self->name);
+
+	// Copy Broadcast and Mode
+	snprintf(filename, sizeof(filename), "%s" SLASH "meshlink.conf", mesh->confbase);
+	FILE *tc = fopen(filename,  "r");
+
+	if(tc) {
+		char buf[1024];
+
+		while(fgets(buf, sizeof(buf), tc)) {
+			if((!strncasecmp(buf, "Mode", 4) && strchr(" \t=", buf[4]))
+			                || (!strncasecmp(buf, "Broadcast", 9) && strchr(" \t=", buf[9]))) {
+				fputs(buf, f);
+
+				// Make sure there is a newline character.
+				if(!strchr(buf, '\n')) {
+					fputc('\n', f);
+				}
+			}
+		}
+
+		fclose(tc);
+	} else {
+		logger(mesh, MESHLINK_DEBUG, "Could not create %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return NULL;
+	}
+
+	fprintf(f, "#---------------------------------------------------------------#\n");
+	fprintf(f, "Name = %s\n", mesh->self->name);
+
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->self->name);
+	fcopy(f, filename);
+	fclose(f);
+
+	// 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->mesh_mutex));
+	return url;
+}
+
+bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
+	if(!mesh || !invitation) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	//Before doing meshlink_join make sure we are not connected to another mesh
+	if(mesh->threadstarted) {
+		logger(mesh, MESHLINK_DEBUG, "Already connected to a mesh\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		pthread_mutex_unlock(&(mesh->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 hostname, port, key hash and cookie.
+
+	char *slash = strchr(copy, '/');
+
+	if(!slash) {
+		goto invalid;
+	}
+
+	*slash++ = 0;
+
+	if(strlen(slash) != 48) {
+		goto invalid;
+	}
+
+	char *address = copy;
+	char *port = strrchr(address, ':');
+
+	if(!port) {
+		goto invalid;
+	}
+
+	*port++ = 0;
+
+	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->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;
+		}
+
+		// IPv6 address are enclosed in brackets, per RFC 3986
+		if(*address == '[') {
+			address++;
+			char *bracket = strchr(address, ']');
+
+			if(!bracket) {
+				goto invalid;
+			}
+
+			*bracket++ = 0;
+
+			if(comma && bracket != comma) {
+				goto invalid;
+			}
+		}
 
-static const char *errstr[] = {
-	[MESHLINK_OK] = "No error",
-	[MESHLINK_ENOMEM] = "Out of memory",
-	[MESHLINK_ENOENT] = "No such node",
-};
+		// Connect to the meshlink daemon mentioned in the URL.
+		struct addrinfo *ai = str2addrinfo(address, port, SOCK_STREAM);
 
-const char *meshlink_strerror(meshlink_errno_t errno) {
-	return errstr[errno];
-}
+		if(ai) {
+			for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
+				mesh->sock = socket(aip->ai_family, aip->ai_socktype, aip->ai_protocol);
 
-// TODO: hack, remove once all global variables are gone.
-static void set_mesh(meshlink_handle_t *localmesh) {
-	mesh = localmesh;
-}
+				if(mesh->sock == -1) {
+					logger(mesh, MESHLINK_DEBUG, "Could not open socket: %s\n", strerror(errno));
+					meshlink_errno = MESHLINK_ENETWORK;
+					continue;
+				}
 
-static bool ecdsa_keygen(meshlink_handle_t *mesh) {
-	ecdsa_t *key;
-	FILE *f;
-	char pubname[PATH_MAX], privname[PATH_MAX];
+				set_timeout(mesh->sock, 5000);
 
-	fprintf(stderr, "Generating ECDSA keypair:\n");
+				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;
+				}
+			}
 
-	if(!(key = ecdsa_generate())) {
-		fprintf(stderr, "Error during key generation!\n");
-		return false;
-	} else
-		fprintf(stderr, "Done.\n");
+			freeaddrinfo(ai);
+		} else {
+			meshlink_errno = MESHLINK_ERESOLV;
+		}
+
+		if(mesh->sock != -1 || !comma) {
+			break;
+		}
 
-	snprintf(privname, sizeof privname, "%s" SLASH "ecdsa_key.priv", mesh->confbase);
-	f = fopen(privname, "w");
+		address = comma;
+	}
 
-	if(!f)
+	if(mesh->sock == -1) {
+		pthread_mutex_unlock(&mesh->mesh_mutex);
 		return false;
+	}
 
-#ifdef HAVE_FCHMOD
-	fchmod(fileno(f), 0600);
-#endif
+	logger(mesh, MESHLINK_DEBUG, "Connected to %s port %s...\n", address, port);
 
-	if(!ecdsa_write_pem_private_key(key, f)) {
-		fprintf(stderr, "Error writing private key!\n");
-		ecdsa_free(key);
-		fclose(f);
+	// Tell him we have an invitation, and give him our throw-away key.
+
+	mesh->blen = 0;
+
+	if(!sendline(mesh->sock, "0 ?%s %d.%d", b64key, PROT_MAJOR, 1)) {
+		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->mesh_mutex));
 		return false;
 	}
 
-	fclose(f);
+	free(b64key);
 
+	char hisname[4096] = "";
+	int code, hismajor, hisminor = 0;
 
-	snprintf(pubname, sizeof pubname, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->name);
-	f = fopen(pubname, "a");
+	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->mesh_mutex));
+		return false;
+	}
 
-	if(!f)
+	// 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->mesh_mutex));
 		return false;
+	}
 
-	char *pubkey = ecdsa_get_base64_public_key(key);
-	fprintf(f, "ECDSAPublicKey = %s\n", pubkey);
-	free(pubkey);
+	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->mesh_mutex));
+		return false;
 
-	fclose(f);
-	ecdsa_free(key);
+	}
 
-	return true;
-}
+	ecdsa_t *hiskey = ecdsa_set_base64_public_key(fingerprint);
 
-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,
-	};
+	if(!hiskey) {
+		meshlink_errno = MESHLINK_EINTERNAL;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
 
-	char portstr[16];
-	snprintf(portstr, sizeof portstr, "%d", port);
+	// 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->mesh_mutex));
+		return false;
+	}
 
-	if(getaddrinfo(NULL, portstr, &hint, &ai) || !ai)
+	// 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->mesh_mutex));
 		return false;
+	}
 
-	while(ai) {
-		int fd = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);
-		if(!fd)
+	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->mesh_mutex));
 			return false;
-		int result = bind(fd, ai->ai_addr, ai->ai_addrlen);
-		closesocket(fd);
-		if(result)
+		}
+
+		if(!sptps_receive_data(&mesh->sptps, mesh->line, len)) {
+			meshlink_errno = MESHLINK_EPEER;
+			pthread_mutex_unlock(&(mesh->mesh_mutex));
 			return false;
-		ai = ai->ai_next;
+		}
+	}
+
+	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->mesh_mutex));
+		return false;
 	}
 
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
 	return true;
+
+invalid:
+	logger(mesh, MESHLINK_DEBUG, "Invalid invitation URL\n");
+	meshlink_errno = MESHLINK_EINVAL;
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return false;
 }
 
-static int check_port(meshlink_handle_t *mesh) {
-	if(try_bind(655))
-		return 655;
+char *meshlink_export(meshlink_handle_t *mesh) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
 
-	fprintf(stderr, "Warning: could not bind to port 655.\n");
+	pthread_mutex_lock(&(mesh->mesh_mutex));
 
-	for(int i = 0; i < 100; i++) {
-		int port = 0x1000 + (rand() & 0x7fff);
-		if(try_bind(port)) {
-			char filename[PATH_MAX];
-			snprintf(filename, sizeof filename, "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->name);
-			FILE *f = fopen(filename, "a");
-			if(!f) {
-				fprintf(stderr, "Please change MeshLink's Port manually.\n");
-				return 0;
-			}
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, mesh->self->name);
+	FILE *f = fopen(filename, "r");
 
-			fprintf(f, "Port = %d\n", port);
-			fclose(f);
-			fprintf(stderr, "MeshLink will instead listen on port %d.\n", port);
-			return port;
-		}
+	if(!f) {
+		logger(mesh, MESHLINK_DEBUG, "Could not open %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return NULL;
 	}
 
-	fprintf(stderr, "Please change MeshLink's Port manually.\n");
-	return 0;
+	fseek(f, 0, SEEK_END);
+	int fsize = ftell(f);
+	rewind(f);
+
+	size_t len = fsize + 9 + strlen(mesh->self->name);
+	char *buf = xmalloc(len);
+	snprintf(buf, len, "Name = %s\n", mesh->self->name);
+
+	if(fread(buf + len - fsize - 1, fsize, 1, f) != 1) {
+		logger(mesh, MESHLINK_DEBUG, "Error reading from %s: %s\n", filename, strerror(errno));
+		fclose(f);
+		free(buf);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return NULL;
+	}
+
+	fclose(f);
+	buf[len - 1] = 0;
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return buf;
 }
 
-static bool meshlink_setup(meshlink_handle_t *mesh) {
-	char meshlink_conf[PATH_MAX];
-	char hosts_dir[PATH_MAX];
+bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
+	if(!mesh || !data) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
 
-	if(mkdir(mesh->confbase, 0777) && errno != EEXIST) {
-		fprintf(stderr, "Could not create directory %s: %s\n", mesh->confbase, strerror(errno));
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	if(strncmp(data, "Name = ", 7)) {
+		logger(mesh, MESHLINK_DEBUG, "Invalid data\n");
+		meshlink_errno = MESHLINK_EPEER;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
 		return false;
 	}
 
-	snprintf(hosts_dir, sizeof hosts_dir, "%s" SLASH "hosts", mesh->confbase);
+	char *end = strchr(data + 7, '\n');
 
-	if(mkdir(hosts_dir, 0777) && errno != EEXIST) {
-		fprintf(stderr, "Could not create directory %s: %s\n", hosts_dir, strerror(errno));
+	if(!end) {
+		logger(mesh, MESHLINK_DEBUG, "Invalid data\n");
+		meshlink_errno = MESHLINK_EPEER;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
 		return false;
 	}
 
-	snprintf(meshlink_conf, sizeof meshlink_conf, "%s" SLASH "meshlink.conf", mesh->confbase);
+	int len = end - (data + 7);
+	char name[len + 1];
+	memcpy(name, data + 7, len);
+	name[len] = 0;
 
-	if(!access(meshlink_conf, F_OK)) {
-		fprintf(stderr, "Configuration file %s already exists!\n", meshlink_conf);
+	if(!check_id(name)) {
+		logger(mesh, MESHLINK_DEBUG, "Invalid Name\n");
+		meshlink_errno = MESHLINK_EPEER;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
 		return false;
 	}
 
-	FILE *f = fopen(meshlink_conf, "w");
-	if(!f) {
-		fprintf(stderr, "Could not create file %s: %s\n", meshlink_conf, strerror(errno));
-		return 1;
+	char filename[PATH_MAX];
+	snprintf(filename, sizeof(filename), "%s" SLASH "hosts" SLASH "%s", mesh->confbase, name);
+
+	if(!access(filename, F_OK)) {
+		logger(mesh, MESHLINK_DEBUG, "File %s already exists, not importing\n", filename);
+		meshlink_errno = MESHLINK_EEXIST;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
 	}
 
-	fprintf(f, "Name = %s\n", mesh->name);
-	fclose(f);
+	if(errno != ENOENT) {
+		logger(mesh, MESHLINK_DEBUG, "Error accessing %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		return false;
+	}
 
-	if(!ecdsa_keygen(mesh))
+	FILE *f = fopen(filename, "w");
+
+	if(!f) {
+		logger(mesh, MESHLINK_DEBUG, "Could not create %s: %s\n", filename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&(mesh->mesh_mutex));
 		return false;
+	}
+
+	fwrite(end + 1, strlen(end + 1), 1, f);
+	fclose(f);
 
-	check_port(mesh);
+	load_all_nodes(mesh);
 
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
 	return true;
 }
 
-meshlink_handle_t *meshlink_open(const char *confbase, const char *name) {
-	// Validate arguments provided by the application
-
-	if(!confbase || !*confbase) {
-		fprintf(stderr, "No confbase given!\n");
-		return NULL;
+void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
 	}
 
-	if(!name || !*name) {
-		fprintf(stderr, "No name given!\n");
-		return NULL;
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	node_t *n;
+	n = (node_t *)node;
+	n->status.blacklisted = true;
+	logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", node->name);
+
+	//Make blacklisting persistent in the config file
+	append_config_file(mesh, n->name, "blacklisted", "yes");
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return;
+}
+
+void meshlink_whitelist(meshlink_handle_t *mesh, meshlink_node_t *node) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
 	}
 
-	if(!check_id(name)) {
-		fprintf(stderr, "Invalid name given!\n");
-		return NULL;
+	pthread_mutex_lock(&(mesh->mesh_mutex));
+
+	node_t *n = (node_t *)node;
+	n->status.blacklisted = false;
+
+	//TODO: remove blacklisted = yes from the config file
+
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	return;
+}
+
+void meshlink_set_default_blacklist(meshlink_handle_t *mesh, bool blacklist) {
+	mesh->default_blacklist = blacklist;
+}
+
+/* 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) {
+		return;
 	}
 
-	meshlink_handle_t *mesh = xzalloc(sizeof *mesh);
-	mesh->confbase = xstrdup(confbase);
-	mesh->name = xstrdup(name);
-	event_loop_init(&mesh->loop);
-	set_mesh(mesh);
+	// Ignore hints about ourself.
+	if((node_t *)node == mesh->self) {
+		return;
+	}
 
-	// TODO: should be set by a function.
-	mesh->debug_level = 5;
+	pthread_mutex_lock(&(mesh->mesh_mutex));
 
-	// Check whether meshlink.conf already exists
+	char *host = NULL, *port = NULL, *str = NULL;
+	sockaddr2str((const sockaddr_t *)addr, &host, &port);
 
-	char filename[PATH_MAX];
-	snprintf(filename, sizeof filename, "%s" SLASH "meshlink.conf", confbase);
+	if(host && port) {
+		xasprintf(&str, "%s %s", host, port);
 
-	if(access(filename, R_OK)) {
-		if(errno == ENOENT) {
-			// If not, create it
-			meshlink_setup(mesh);
+		if((strncmp("fe80", host, 4) != 0) && (strncmp("127.", host, 4) != 0) && (strcmp("localhost", host) != 0)) {
+			modify_config_file(mesh, node->name, "Address", str, 5);
 		} else {
-			fprintf(stderr, "Cannot not read from %s: %s\n", filename, strerror(errno));
-			return meshlink_close(mesh), NULL;
+			logger(mesh, MESHLINK_DEBUG, "Not adding Link Local IPv6 Address to config\n");
 		}
 	}
 
-	// Read the configuration
+	free(str);
+	free(host);
+	free(port);
 
-	init_configuration(&mesh->config);
+	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	// @TODO do we want to fire off a connection attempt right away?
+}
 
-	if(!read_server_config(mesh))
-		return meshlink_close(mesh), NULL;
+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;
+}
 
-	// Setup up everything
-	// TODO: we should not open listening sockets yet
+static ssize_t channel_recv(struct utcp_connection *connection, const void *data, size_t len) {
+	meshlink_channel_t *channel = connection->priv;
+
+	if(!channel) {
+		abort();
+	}
 
-	if(!setup_network(mesh))
-		return meshlink_close(mesh), NULL;
+	node_t *n = channel->node;
+	meshlink_handle_t *mesh = n->mesh;
 
-	return mesh;
+	if(n->status.destroyed) {
+		meshlink_channel_close(mesh, channel);
+	} else if(channel->receive_cb) {
+		channel->receive_cb(mesh, channel, data, len);
+	}
+
+	return len;
 }
 
-void *meshlink_main_loop(void *arg) {
-	meshlink_handle_t *mesh = arg;
+static void channel_accept(struct utcp_connection *utcp_connection, uint16_t port) {
+	node_t *n = utcp_connection->utcp->priv;
 
-	try_outgoing_connections();
+	if(!n) {
+		abort();
+	}
 
-	main_loop();
+	meshlink_handle_t *mesh = n->mesh;
 
-	return NULL;
+	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);
+	}
 }
 
-bool meshlink_start(meshlink_handle_t *mesh) {
-	// TODO: open listening sockets first
+static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
+	node_t *n = utcp->priv;
 
-	// Start the main thread
+	if(n->status.destroyed) {
+		return -1;
+	}
 
-	if(pthread_create(&mesh->thread, NULL, meshlink_main_loop, mesh) != 0) {
-		fprintf(stderr, "Could not start thread: %s\n", strerror(errno));
-		memset(&mesh->thread, 0, sizeof mesh->thread);
-		return false;
+	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;
 	}
 
-	return true;
+	channel->receive_cb = cb;
 }
 
-void meshlink_stop(meshlink_handle_t *mesh) {
-	// TODO: close the listening sockets to signal the main thread to shut down
+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;
 
-	// Wait for the main thread to finish
+	if(!n->utcp) {
+		abort();
+	}
 
-	pthread_join(mesh->thread, NULL);
+	utcp_recv(n->utcp, data, len);
 }
 
-void meshlink_close(meshlink_handle_t *mesh) {
-	// Close and free all resources used.
+static void channel_poll(struct utcp_connection *connection, size_t len) {
+	meshlink_channel_t *channel = connection->priv;
 
-	close_network_connections();
+	if(!channel) {
+		abort();
+	}
 
-	logger(DEBUG_ALWAYS, LOG_NOTICE, "Terminating");
+	node_t *n = channel->node;
+	meshlink_handle_t *mesh = n->mesh;
 
-	exit_configuration(&mesh->config);
-	event_loop_exit(&mesh->loop);
+	if(channel->poll_cb) {
+		channel->poll_cb(mesh, channel, len);
+	}
 }
 
-void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb) {
-	mesh->receive_cb = cb;
+void meshlink_set_channel_poll_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_poll_cb_t cb) {
+	(void)mesh;
+	channel->poll_cb = cb;
+	utcp_set_poll_cb(channel->c, cb ? channel_poll : NULL);
 }
 
-void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb) {
-	mesh->node_status_cb = cb;
-}
+void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
 
-void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb) {
-	mesh->log_cb = cb;
-	mesh->log_level = level;
+	pthread_mutex_lock(&mesh->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->mesh_mutex);
 }
 
-bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, unsigned int len) {
-	vpn_packet_t packet;
-	meshlink_packethdr_t *hdr = (meshlink_packethdr_t *)packet.data;
-	if (sizeof(meshlink_packethdr_t) + len > MAXSIZE) {
-		//log something
-		return false;
+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
 	}
 
-	packet.probe = false;
-	memset(hdr, 0, sizeof *hdr);
-	memcpy(hdr->destination, destination->name, sizeof hdr->destination);
-	memcpy(hdr->source, mesh->self->name, sizeof hdr->source);
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
 
-	packet.len = sizeof *hdr + len;
-	memcpy(packet.data + sizeof *hdr, data, len);
+	node_t *n = (node_t *)node;
 
-        mesh->self->in_packets++;
-        mesh->self->in_bytes += packet.len;
-        route(mesh->self, &packet);
-	return false;
-}
+	if(!n->utcp) {
+		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+		mesh->receive_cb = channel_receive;
 
-meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name) {
-	return (meshlink_node_t *)lookup_node(name);
-	return NULL;
-}
+		if(!n->utcp) {
+			meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
+			return NULL;
+		}
+	}
 
-size_t meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t nmemb) {
-	return 0;
+	meshlink_channel_t *channel = xzalloc(sizeof(*channel));
+	channel->node = n;
+	channel->receive_cb = cb;
+	channel->c = utcp_connect_ex(n->utcp, port, channel_recv, channel, flags);
+
+	if(!channel->c) {
+		meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
+		free(channel);
+		return NULL;
+	}
+
+	return channel;
 }
 
-char *meshlink_sign(meshlink_handle_t *mesh, const char *data, size_t len) {
-	return NULL;
+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);
 }
 
-bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const char *data, size_t len, const char *signature) {
-	return false;
+void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *channel, int direction) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	utcp_shutdown(channel->c, direction);
 }
 
-char *meshlink_invite(meshlink_handle_t *mesh, const char *name) {
-	return NULL;
+void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	utcp_close(channel->c);
+	free(channel);
 }
 
-bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
-	return false;
+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, preferrably only if there is room in the receiver window,
+	// kick the meshlink thread to go send packets.
+
+	pthread_mutex_lock(&mesh->mesh_mutex);
+	ssize_t retval = utcp_send(channel->c, data, len);
+	pthread_mutex_unlock(&mesh->mesh_mutex);
+
+	if(retval < 0) {
+		meshlink_errno = MESHLINK_ENETWORK;
+	}
+
+	return retval;
 }
 
-char *meshlink_export(meshlink_handle_t *mesh) {
-	return NULL;
+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;
 }
 
-bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
-	return false;
+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);
+	}
 }
 
-void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
+void meshlink_enable_discovery(meshlink_handle_t *mesh, bool enable) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->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->mesh_mutex);
 }
 
 static void __attribute__((constructor)) meshlink_init(void) {
 	crypto_init();
+	unsigned int seed;
+	randomize(&seed, sizeof(seed));
+	srand(seed);
 }
 
 static void __attribute__((destructor)) meshlink_exit(void) {
 	crypto_exit();
 }
+
+/// Device class traits
+dev_class_traits_t dev_class_traits[_DEV_CLASS_MAX + 1] = {
+	{ .min_connects = 3, .max_connects = 10000, .edge_weight = 1 }, // DEV_CLASS_BACKBONE
+	{ .min_connects = 3, .max_connects = 100, .edge_weight = 3 },   // DEV_CLASS_STATIONARY
+	{ .min_connects = 3, .max_connects = 3, .edge_weight = 6 },             // DEV_CLASS_PORTABLE
+	{ .min_connects = 1, .max_connects = 1, .edge_weight = 9 },             // DEV_CLASS_UNKNOWN
+};