X-Git-Url: http://git.meshlink.io/?p=meshlink;a=blobdiff_plain;f=src%2Fmeshlink.c;h=80bcc9704480afc84c2bbffe2203db85d2a93ac3;hp=0354c86dc096d5036d6a2298c28dfd5cfbb4fd9e;hb=f3e15df2c965d014a3281416e502be96170063e8;hpb=4b9b60a5faaa9438ee6c2b4eb67103497ed62a4b

diff --git a/src/meshlink.c b/src/meshlink.c
index 0354c86d..80bcc970 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -20,10 +20,12 @@
 #include "system.h"
 #include <pthread.h>
 
+#include "adns.h"
 #include "crypto.h"
 #include "ecdsagen.h"
 #include "logger.h"
 #include "meshlink_internal.h"
+#include "net.h"
 #include "netutl.h"
 #include "node.h"
 #include "submesh.h"
@@ -171,6 +173,7 @@ static bool getlocaladdr(char *destaddr, sockaddr_t *sa, socklen_t *salen, int n
 		.ai_family = AF_UNSPEC,
 		.ai_socktype = SOCK_DGRAM,
 		.ai_protocol = IPPROTO_UDP,
+		.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV,
 	};
 
 	if(getaddrinfo(destaddr, "80", &hint, &rai) || !rai) {
@@ -221,12 +224,42 @@ char *meshlink_get_external_address(meshlink_handle_t *mesh) {
 }
 
 char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int family) {
-	char *hostname = NULL;
+	const char *url = mesh->external_address_url;
+
+	if(!url) {
+		url = "http://meshlink.io/host.cgi";
+	}
+
+	/* Find the hostname part between the slashes */
+	if(strncmp(url, "http://", 7)) {
+		abort();
+		meshlink_errno = MESHLINK_EINTERNAL;
+		return NULL;
+	}
+
+	const char *begin = url + 7;
+
+	const char *end = strchr(begin, '/');
+
+	if(!end) {
+		end = begin + strlen(begin);
+	}
+
+	/* Make a copy */
+	char host[end - begin + 1];
+	strncpy(host, begin, end - begin);
+	host[end - begin] = 0;
+
+	char *port = strchr(host, ':');
+
+	if(port) {
+		*port++ = 0;
+	}
 
 	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";
+	struct addrinfo *ai = adns_blocking_request(mesh, xstrdup(host), xstrdup(port ? port : "80"), 5);
 	char line[256];
+	char *hostname = NULL;
 
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 		if(family != AF_UNSPEC && aip->ai_family != family) {
@@ -245,7 +278,9 @@ char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int fami
 		}
 
 		if(s >= 0) {
-			send(s, request, sizeof(request) - 1, 0);
+			send(s, "GET ", 4, 0);
+			send(s, url, strlen(url), 0);
+			send(s, " HTTP/1.0\r\n\r\n", 13, 0);
 			int len = recv(s, line, sizeof(line) - 1, MSG_WAITALL);
 
 			if(len > 0) {
@@ -389,10 +424,15 @@ void remove_duplicate_hostnames(char *host[], char *port[], int n) {
 
 // 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};
+	int count = 4 + (mesh->invitation_addresses ? mesh->invitation_addresses->count : 0);
+	int n = 0;
+	char *hostname[count];
+	char *port[count];
 	char *hostport = NULL;
 
+	memset(hostname, 0, sizeof(hostname));
+	memset(port, 0, sizeof(port));
+
 	if(!(flags & (MESHLINK_INVITE_LOCAL | MESHLINK_INVITE_PUBLIC))) {
 		flags |= MESHLINK_INVITE_LOCAL | MESHLINK_INVITE_PUBLIC;
 	}
@@ -401,109 +441,86 @@ static char *get_my_hostname(meshlink_handle_t *mesh, uint32_t flags) {
 		flags |= MESHLINK_INVITE_IPV4 | MESHLINK_INVITE_IPV6;
 	}
 
+	// Add all explicitly set invitation addresses
+	if(mesh->invitation_addresses) {
+		for list_each(char, combo, mesh->invitation_addresses) {
+			hostname[n] = xstrdup(combo);
+			char *slash = strrchr(hostname[n], '/');
+
+			if(slash) {
+				*slash = 0;
+				port[n] = xstrdup(slash + 1);
+			}
+
+			n++;
+		}
+	}
+
 	// 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);
+			hostname[n++] = 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);
+			hostname[n++] = 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]);
+		get_canonical_address(mesh->self, &hostname[n], &port[n]);
 
-		if(!hostname[2]) {
+		if(!hostname[n] && count == 4) {
 			if(flags & MESHLINK_INVITE_IPV4) {
-				hostname[2] = meshlink_get_external_address_for_family(mesh, AF_INET);
+				hostname[n++] = 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);
+				hostname[n++] = meshlink_get_external_address_for_family(mesh, AF_INET6);
 			}
+		} else {
+			n++;
 		}
 	}
 
-	for(int i = 0; i < 4; i++) {
+	for(int i = 0; i < n; i++) {
 		// Ensure we always have a port number
 		if(hostname[i] && !port[i]) {
 			port[i] = xstrdup(mesh->myport);
 		}
 	}
 
-	remove_duplicate_hostnames(hostname, port, 4);
+	remove_duplicate_hostnames(hostname, port, n);
 
 	// Resolve the hostnames
-	for(int i = 0; i < 4; i++) {
+	for(int i = 0; i < n; 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;
-		}
+		struct addrinfo *ai_in = adns_blocking_request(mesh, xstrdup(hostname[i]), xstrdup(port[i]), 5);
 
-		// Remember the address
-		node_add_recent_address(mesh, mesh->self, (sockaddr_t *)ai_in->ai_addr);
-
-		if(flags & MESHLINK_INVITE_NUMERIC) {
-			// We don't need to do any further conversion
-			freeaddrinfo(ai_in);
+		if(!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;
+		// Remember the address(es)
+		for(struct addrinfo *aip = ai_in; aip; aip = aip->ai_next) {
+			node_add_recent_address(mesh, mesh->self, (sockaddr_t *)aip->ai_addr);
 		}
 
-		// 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);
+		continue;
 	}
 
 	// Remove duplicates again, since IPv4 and IPv6 addresses might map to the same hostname
-	remove_duplicate_hostnames(hostname, port, 4);
+	remove_duplicate_hostnames(hostname, port, n);
 
 	// Concatenate all unique address to the hostport string
-	for(int i = 0; i < 4; i++) {
+	for(int i = 0; i < n; i++) {
 		if(!hostname[i]) {
 			continue;
 		}
@@ -521,7 +538,7 @@ static char *get_my_hostname(meshlink_handle_t *mesh, uint32_t flags) {
 	return hostport;
 }
 
-static bool try_bind(int port) {
+static bool try_bind(meshlink_handle_t *mesh, int port) {
 	struct addrinfo *ai = NULL;
 	struct addrinfo hint = {
 		.ai_flags = AI_PASSIVE,
@@ -537,33 +554,47 @@ static bool try_bind(int port) {
 		return false;
 	}
 
-	//while(ai) {
+	bool success = false;
+
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
-		int fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
+		/* Try to bind to TCP. */
 
-		if(!fd) {
-			freeaddrinfo(ai);
-			return false;
+		int tcp_fd = setup_tcp_listen_socket(mesh, aip);
+
+		if(tcp_fd == -1) {
+			if(errno == EADDRINUSE) {
+				/* If this port is in use for any address family, avoid it. */
+				success = false;
+				break;
+			} else {
+				continue;
+			}
 		}
 
-		int result = bind(fd, aip->ai_addr, aip->ai_addrlen);
-		closesocket(fd);
+		/* If TCP worked, then we require that UDP works as well. */
 
-		if(result) {
-			freeaddrinfo(ai);
-			return false;
+		int udp_fd = setup_udp_listen_socket(mesh, aip);
+
+		if(udp_fd == -1) {
+			closesocket(tcp_fd);
+			success = false;
+			break;
 		}
+
+		closesocket(tcp_fd);
+		closesocket(udp_fd);
+		success = true;
 	}
 
 	freeaddrinfo(ai);
-	return true;
+	return success;
 }
 
-static int check_port(meshlink_handle_t *mesh) {
+int check_port(meshlink_handle_t *mesh) {
 	for(int i = 0; i < 1000; i++) {
 		int port = 0x1000 + prng(mesh, 0x8000);
 
-		if(try_bind(port)) {
+		if(try_bind(mesh, port)) {
 			free(mesh->myport);
 			xasprintf(&mesh->myport, "%d", port);
 			return port;
@@ -634,24 +665,28 @@ static bool finalize_join(join_state_t *state, const void *buf, uint16_t len) {
 	}
 
 	char *name = packmsg_get_str_dup(&in);
-	packmsg_skip_element(&in); /* submesh */
+	char *submesh_name = packmsg_get_str_dup(&in);
 	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");
+	if(!name || !check_id(name)) {
+		logger(mesh, MESHLINK_DEBUG, "No valid Name found in invitation!\n");
+		free(name);
+		free(submesh_name);
 		return false;
 	}
 
-	if(!check_id(name)) {
-		logger(mesh, MESHLINK_DEBUG, "Invalid Name found in invitation: %s!\n", name);
+	if(!submesh_name || (strcmp(submesh_name, CORE_MESH) && !check_id(submesh_name))) {
+		logger(mesh, MESHLINK_DEBUG, "No valid Submesh found in invitation!\n");
 		free(name);
+		free(submesh_name);
 		return false;
 	}
 
 	if(!count) {
 		logger(mesh, MESHLINK_ERROR, "Incomplete invitation file!\n");
 		free(name);
+		free(submesh_name);
 		return false;
 	}
 
@@ -659,6 +694,8 @@ static bool finalize_join(join_state_t *state, const void *buf, uint16_t len) {
 	free(mesh->self->name);
 	mesh->name = name;
 	mesh->self->name = xstrdup(name);
+	mesh->self->submesh = strcmp(submesh_name, CORE_MESH) ? lookup_or_create_submesh(mesh, submesh_name) : NULL;
+	free(submesh_name);
 	mesh->self->devclass = devclass == DEV_CLASS_UNKNOWN ? mesh->devclass : devclass;
 
 	// Initialize configuration directory
@@ -925,10 +962,18 @@ static bool ecdsa_keygen(meshlink_handle_t *mesh) {
 	return true;
 }
 
-static struct timeval idle(event_loop_t *loop, void *data) {
+static bool timespec_lt(const struct timespec *a, const struct timespec *b) {
+	if(a->tv_sec == b->tv_sec) {
+		return a->tv_nsec < b->tv_nsec;
+	} else {
+		return a->tv_sec < b->tv_sec;
+	}
+}
+
+static struct timespec idle(event_loop_t *loop, void *data) {
 	(void)loop;
 	meshlink_handle_t *mesh = data;
-	struct timeval t, tmin = {3600, 0};
+	struct timespec t, tmin = {3600, 0};
 
 	for splay_each(node_t, n, mesh->nodes) {
 		if(!n->utcp) {
@@ -937,7 +982,7 @@ static struct timeval idle(event_loop_t *loop, void *data) {
 
 		t = utcp_timeout(n->utcp);
 
-		if(timercmp(&t, &tmin, <)) {
+		if(timespec_lt(&t, &tmin)) {
 			tmin = t;
 		}
 	}
@@ -1044,9 +1089,6 @@ static bool meshlink_read_config(meshlink_handle_t *mesh) {
 		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;
@@ -1055,8 +1097,6 @@ static bool meshlink_read_config(meshlink_handle_t *mesh) {
 		return false;
 	}
 
-#endif
-
 	free(mesh->name);
 	mesh->name = name;
 	xasprintf(&mesh->myport, "%u", myport);
@@ -1091,7 +1131,6 @@ static void *setup_network_in_netns_thread(void *arg) {
 	}
 
 	bool success = setup_network(mesh);
-	add_local_addresses(mesh);
 	return success ? arg : NULL;
 }
 #endif // HAVE_SETNS
@@ -1115,13 +1154,7 @@ meshlink_open_params_t *meshlink_open_params_init(const char *confbase, const ch
 		return NULL;
 	}
 
-	if(!name || !*name) {
-		logger(NULL, MESHLINK_ERROR, "No name given!\n");
-		meshlink_errno = MESHLINK_EINVAL;
-		return NULL;
-	};
-
-	if(!check_id(name)) {
+	if(name && !check_id(name)) {
 		logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
 		meshlink_errno = MESHLINK_EINVAL;
 		return NULL;
@@ -1136,7 +1169,7 @@ meshlink_open_params_t *meshlink_open_params_init(const char *confbase, const ch
 	meshlink_open_params_t *params = xzalloc(sizeof * params);
 
 	params->confbase = xstrdup(confbase);
-	params->name = xstrdup(name);
+	params->name = name ? xstrdup(name) : NULL;
 	params->appname = xstrdup(appname);
 	params->devclass = devclass;
 	params->netns = -1;
@@ -1309,6 +1342,36 @@ meshlink_handle_t *meshlink_open_encrypted(const char *confbase, const char *nam
 }
 
 meshlink_handle_t *meshlink_open_ephemeral(const char *name, const char *appname, dev_class_t devclass) {
+	if(!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(!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(devclass < 0 || devclass >= DEV_CLASS_COUNT) {
+		logger(NULL, MESHLINK_ERROR, "Invalid devclass 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));
@@ -1322,11 +1385,9 @@ meshlink_handle_t *meshlink_open_ephemeral(const char *name, const char *appname
 }
 
 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");
 
+	// Validate arguments provided by the application
 	if(!params->appname || !*params->appname) {
 		logger(NULL, MESHLINK_ERROR, "No appname given!\n");
 		meshlink_errno = MESHLINK_EINVAL;
@@ -1339,18 +1400,10 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 		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->name && !check_id(params->name)) {
+		logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
 	}
 
 	if(params->devclass < 0 || params->devclass >= DEV_CLASS_COUNT) {
@@ -1379,6 +1432,7 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	mesh->submeshes = NULL;
 	mesh->log_cb = global_log_cb;
 	mesh->log_level = global_log_level;
+	mesh->packet = xmalloc(sizeof(vpn_packet_t));
 
 	randomize(&mesh->prng_state, sizeof(mesh->prng_state));
 
@@ -1388,9 +1442,7 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 
 	memcpy(mesh->dev_class_traits, default_class_traits, sizeof(default_class_traits));
 
-	if(usingname) {
-		mesh->name = xstrdup(params->name);
-	}
+	mesh->name = params->name ? xstrdup(params->name) : NULL;
 
 	// Hash the key
 	if(params->key) {
@@ -1425,6 +1477,13 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	// If no configuration exists yet, create it.
 
 	if(!meshlink_confbase_exists(mesh)) {
+		if(!mesh->name) {
+			logger(NULL, MESHLINK_ERROR, "No configuration files found!\n");
+			meshlink_close(mesh);
+			meshlink_errno = MESHLINK_ESTORAGE;
+			return NULL;
+		}
+
 		if(!meshlink_setup(mesh)) {
 			logger(NULL, MESHLINK_ERROR, "Cannot create initial configuration\n");
 			meshlink_close(mesh);
@@ -1464,7 +1523,6 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 #endif // HAVE_SETNS
 	} else {
 		success = setup_network(mesh);
-		add_local_addresses(mesh);
 	}
 
 	if(!success) {
@@ -1558,9 +1616,6 @@ static void *meshlink_main_loop(void *arg) {
 }
 
 bool meshlink_start(meshlink_handle_t *mesh) {
-	assert(mesh->self);
-	assert(mesh->private_key);
-
 	if(!mesh) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
@@ -1570,6 +1625,8 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 
 	pthread_mutex_lock(&mesh->mutex);
 
+	assert(mesh->self);
+	assert(mesh->private_key);
 	assert(mesh->self->ecdsa);
 	assert(!memcmp((uint8_t *)mesh->self->ecdsa + 64, (uint8_t *)mesh->private_key + 64, 32));
 
@@ -1596,6 +1653,7 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 	}
 
 	init_outgoings(mesh);
+	init_adns(mesh);
 
 	// Start the main thread
 
@@ -1666,6 +1724,7 @@ void meshlink_stop(meshlink_handle_t *mesh) {
 		}
 	}
 
+	exit_adns(mesh);
 	exit_outgoings(mesh);
 
 	// Ensure we are considered unreachable
@@ -1729,8 +1788,14 @@ void meshlink_close(meshlink_handle_t *mesh) {
 	free(mesh->appname);
 	free(mesh->confbase);
 	free(mesh->config_key);
+	free(mesh->external_address_url);
+	free(mesh->packet);
 	ecdsa_free(mesh->private_key);
 
+	if(mesh->invitation_addresses) {
+		list_delete_list(mesh->invitation_addresses);
+	}
+
 	main_config_unlock(mesh);
 
 	pthread_mutex_unlock(&mesh->mutex);
@@ -1882,20 +1947,10 @@ void meshlink_set_error_cb(struct meshlink_handle *mesh, meshlink_error_cb_t cb)
 	pthread_mutex_unlock(&mesh->mutex);
 }
 
-bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len) {
+static bool prepare_packet(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len, vpn_packet_t *packet) {
 	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) {
+	if(len > MAXSIZE - sizeof(*hdr)) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
 	}
@@ -1909,13 +1964,6 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 	}
 
 	// 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);
@@ -1924,11 +1972,60 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 	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);
+	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);
 
+	return true;
+}
+
+static bool meshlink_send_immediate(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len) {
+	assert(mesh);
+	assert(destination);
+	assert(data);
+	assert(len);
+
+	// Prepare the packet
+	if(!prepare_packet(mesh, destination, data, len, mesh->packet)) {
+		return false;
+	}
+
+	// Send it immediately
+	route(mesh, mesh->self, mesh->packet);
+
+	return true;
+}
+
+bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len) {
+	// Validate arguments
+	if(!mesh || !destination) {
+		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;
+	}
+
+	if(!prepare_packet(mesh, destination, data, len, packet)) {
+		free(packet);
+		return false;
+	}
+
 	// Queue it
 	if(!meshlink_queue_push(&mesh->outpacketqueue, packet)) {
 		free(packet);
@@ -1936,6 +2033,8 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 		return false;
 	}
 
+	logger(mesh, MESHLINK_DEBUG, "Adding packet of %zu bytes to packet queue", len);
+
 	// Notify event loop
 	signal_trigger(&mesh->loop, &mesh->datafromapp);
 
@@ -1945,17 +2044,16 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 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;
-	}
+	logger(mesh, MESHLINK_DEBUG, "Flushing the packet queue");
 
-	mesh->self->in_packets++;
-	mesh->self->in_bytes += packet->len;
-	route(mesh, mesh->self, packet);
-
-	free(packet);
+	for(vpn_packet_t *packet; (packet = meshlink_queue_pop(&mesh->outpacketqueue));) {
+		logger(mesh, MESHLINK_DEBUG, "Removing packet of %d bytes from packet queue", packet->len);
+		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) {
@@ -2327,13 +2425,20 @@ bool meshlink_set_canonical_address(meshlink_handle_t *mesh, meshlink_node_t *no
 	}
 
 	if(!is_valid_hostname(address)) {
-		logger(mesh, MESHLINK_DEBUG, "Invalid character in address: %s\n", address);
+		logger(mesh, MESHLINK_DEBUG, "Invalid character in address: %s", address);
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
 	}
 
+	if((node_t *)node != mesh->self && !port) {
+		logger(mesh, MESHLINK_DEBUG, "Missing port number!");
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+
+	}
+
 	if(port && !is_valid_port(port)) {
-		logger(mesh, MESHLINK_DEBUG, "Invalid character in port: %s\n", address);
+		logger(mesh, MESHLINK_DEBUG, "Invalid character in port: %s", address);
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
 	}
@@ -2362,6 +2467,60 @@ bool meshlink_set_canonical_address(meshlink_handle_t *mesh, meshlink_node_t *no
 	return config_sync(mesh, "current");
 }
 
+bool meshlink_add_invitation_address(struct meshlink_handle *mesh, const char *address, const char *port) {
+	if(!mesh || !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 *combo;
+
+	if(port) {
+		xasprintf(&combo, "%s/%s", address, port);
+	} else {
+		combo = xstrdup(address);
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	if(!mesh->invitation_addresses) {
+		mesh->invitation_addresses = list_alloc((list_action_t)free);
+	}
+
+	list_insert_tail(mesh->invitation_addresses, combo);
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
+void meshlink_clear_invitation_addresses(struct meshlink_handle *mesh) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	if(mesh->invitation_addresses) {
+		list_delete_list(mesh->invitation_addresses);
+		mesh->invitation_addresses = NULL;
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
 bool meshlink_add_address(meshlink_handle_t *mesh, const char *address) {
 	return meshlink_set_canonical_address(mesh, (meshlink_node_t *)mesh->self, address, NULL);
 }
@@ -2378,7 +2537,7 @@ bool meshlink_add_external_address(meshlink_handle_t *mesh) {
 		return false;
 	}
 
-	bool rval = meshlink_add_address(mesh, address);
+	bool rval = meshlink_set_canonical_address(mesh, (meshlink_node_t *)mesh->self, address, NULL);
 	free(address);
 
 	return rval;
@@ -2414,7 +2573,7 @@ bool meshlink_set_port(meshlink_handle_t *mesh, int port) {
 		return true;
 	}
 
-	if(!try_bind(port)) {
+	if(!try_bind(mesh, port)) {
 		meshlink_errno = MESHLINK_ENETWORK;
 		return false;
 	}
@@ -2723,7 +2882,7 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 		}
 
 		// Connect to the meshlink daemon mentioned in the URL.
-		struct addrinfo *ai = str2addrinfo(address, port, SOCK_STREAM);
+		struct addrinfo *ai = adns_blocking_request(mesh, xstrdup(address), xstrdup(port), 5);
 
 		if(ai) {
 			for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
@@ -2744,6 +2903,8 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 					state.sock = -1;
 					continue;
 				}
+
+				break;
 			}
 
 			freeaddrinfo(ai);
@@ -2889,7 +3050,15 @@ char *meshlink_export(meshlink_handle_t *mesh) {
 	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 : "");
+
+	if(mesh->self->canonical_address && !strchr(mesh->self->canonical_address, ' ')) {
+		char *canonical_address = NULL;
+		xasprintf(&canonical_address, "%s %s", mesh->self->canonical_address, mesh->myport);
+		packmsg_add_str(&out, canonical_address);
+		free(canonical_address);
+	} else {
+		packmsg_add_str(&out, mesh->self->canonical_address ? mesh->self->canonical_address : "");
+	}
 
 	uint32_t count = 0;
 
@@ -3069,7 +3238,7 @@ static bool blacklist(meshlink_handle_t *mesh, node_t *n) {
 	n->status.udp_confirmed = false;
 
 	if(n->status.reachable) {
-		n->last_unreachable = mesh->loop.now.tv_sec;
+		n->last_unreachable = time(NULL);
 	}
 
 	/* Graph updates will suppress status updates for blacklisted nodes, so we need to
@@ -3143,7 +3312,7 @@ static bool whitelist(meshlink_handle_t *mesh, node_t *n) {
 	n->status.blacklisted = false;
 
 	if(n->status.reachable) {
-		n->last_reachable = mesh->loop.now.tv_sec;
+		n->last_reachable = time(NULL);
 		update_node_status(mesh, n);
 	}
 
@@ -3298,6 +3467,15 @@ static void aio_signal(meshlink_handle_t *mesh, meshlink_channel_t *channel, mes
 	}
 }
 
+static void aio_abort(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_aio_buffer_t **aio) {
+	while(*aio) {
+		meshlink_aio_buffer_t *next = (*aio)->next;
+		aio_signal(mesh, channel, *aio);
+		free(*aio);
+		*aio = next;
+	}
+}
+
 static ssize_t channel_recv(struct utcp_connection *connection, const void *data, size_t len) {
 	meshlink_channel_t *channel = connection->priv;
 
@@ -3317,6 +3495,12 @@ static ssize_t channel_recv(struct utcp_connection *connection, const void *data
 	size_t left = len;
 
 	while(channel->aio_receive) {
+		if(!len) {
+			/* This receive callback signalled an error, abort all outstanding AIO buffers. */
+			aio_abort(mesh, channel, &channel->aio_receive);
+			break;
+		}
+
 		meshlink_aio_buffer_t *aio = channel->aio_receive;
 		size_t todo = aio->len - aio->done;
 
@@ -3329,12 +3513,21 @@ static ssize_t channel_recv(struct utcp_connection *connection, const void *data
 		} else {
 			ssize_t result = write(aio->fd, p, todo);
 
-			if(result > 0) {
-				todo = result;
+			if(result <= 0) {
+				/* Writing to fd failed, cancel just this AIO buffer. */
+				logger(mesh, MESHLINK_ERROR, "Writing to AIO fd %d failed: %s", aio->fd, strerror(errno));
+				channel->aio_receive = aio->next;
+				aio_signal(mesh, channel, aio);
+				free(aio);
+				continue;
 			}
+
+			todo = result;
 		}
 
 		aio->done += todo;
+		p += todo;
+		left -= todo;
 
 		if(aio->done == aio->len) {
 			channel->aio_receive = aio->next;
@@ -3342,10 +3535,7 @@ static ssize_t channel_recv(struct utcp_connection *connection, const void *data
 			free(aio);
 		}
 
-		p += todo;
-		left -= todo;
-
-		if(!left && len) {
+		if(!left) {
 			return len;
 		}
 	}
@@ -3381,6 +3571,17 @@ static void channel_accept(struct utcp_connection *utcp_connection, uint16_t por
 	}
 }
 
+static void channel_retransmit(struct utcp_connection *utcp_connection) {
+	node_t *n = utcp_connection->utcp->priv;
+	meshlink_handle_t *mesh = n->mesh;
+
+	if(n->mtuprobes == 31) {
+		timeout_set(&mesh->loop, &n->mtutimeout, &(struct timespec) {
+			0, 0
+		});
+	}
+}
+
 static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
 	node_t *n = utcp->priv;
 
@@ -3389,7 +3590,7 @@ static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
 	}
 
 	meshlink_handle_t *mesh = n->mesh;
-	return meshlink_send(mesh, (meshlink_node_t *)n, data, len) ? (ssize_t)len : -1;
+	return meshlink_send_immediate(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) {
@@ -3421,57 +3622,79 @@ static void channel_poll(struct utcp_connection *connection, size_t len) {
 
 	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;
+	while(channel->aio_send) {
+		if(!len) {
+			/* This poll callback signalled an error, abort all outstanding AIO buffers. */
+			aio_abort(mesh, channel, &channel->aio_send);
+			break;
+		}
+
+		/* We have at least one AIO buffer. Send as much as possible from the buffers. */
+		meshlink_aio_buffer_t *aio = channel->aio_send;
+		size_t todo = aio->len - aio->done;
 		ssize_t sent;
 
-		if(len > left) {
-			len = left;
+		if(todo > len) {
+			todo = len;
 		}
 
 		if(aio->data) {
-			sent = utcp_send(connection, (char *)aio->data + aio->done, len);
+			sent = utcp_send(connection, (char *)aio->data + aio->done, todo);
 		} else {
-			char buf[65536];
-			size_t todo = utcp_get_sndbuf_free(connection);
-
-			if(todo > left) {
-				todo = left;
-			}
-
-			if(todo > sizeof(buf)) {
-				todo = sizeof(buf);
-			}
-
+			char buf[todo];
 			ssize_t result = read(aio->fd, buf, todo);
 
 			if(result > 0) {
-				sent = utcp_send(connection, buf, result);
+				todo = result;
+				sent = utcp_send(connection, buf, todo);
 			} else {
-				sent = result;
+				/* Reading from fd failed, cancel just this AIO buffer. */
+				if(result != 0) {
+					logger(mesh, MESHLINK_ERROR, "Reading from AIO fd %d failed: %s", aio->fd, strerror(errno));
+				}
+
+				channel->aio_send = aio->next;
+				aio_signal(mesh, channel, aio);
+				free(aio);
+				aio = channel->aio_send;
+				continue;
 			}
 		}
 
-		if(sent >= 0) {
-			aio->done += sent;
+		if(sent != (ssize_t)todo) {
+			/* We should never get a partial send at this point */
+			assert(sent < 0);
+
+			/* Sending failed, abort all outstanding AIO buffers and send a poll callback. */
+			aio_abort(mesh, channel, &channel->aio_send);
+			len = 0;
+			break;
 		}
 
-		/* 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);
+		aio->done += sent;
+		len -= sent;
+
+		/* If we didn't finish this buffer, exit early. */
+		if(aio->done < aio->len) {
+			return;
 		}
-	} else {
-		if(channel->poll_cb) {
-			channel->poll_cb(mesh, channel, len);
-		} else {
-			utcp_set_poll_cb(connection, NULL);
+
+		/* Signal completion of this buffer, and go to the next one. */
+		channel->aio_send = aio->next;
+		aio_signal(mesh, channel, aio);
+		free(aio);
+
+		if(!len) {
+			return;
 		}
 	}
+
+	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) {
@@ -3499,6 +3722,8 @@ void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_ac
 	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);
+			utcp_set_mtu(n->utcp, n->mtu - sizeof(meshlink_packethdr_t));
+			utcp_set_retransmit_cb(n->utcp, channel_retransmit);
 		}
 	}
 
@@ -3547,6 +3772,8 @@ meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_n
 
 	if(!n->utcp) {
 		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+		utcp_set_mtu(n->utcp, n->mtu - sizeof(meshlink_packethdr_t));
+		utcp_set_retransmit_cb(n->utcp, channel_retransmit);
 		mesh->receive_cb = channel_receive;
 
 		if(!n->utcp) {
@@ -3610,17 +3837,8 @@ void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel
 	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);
-	}
+	aio_abort(mesh, channel, &channel->aio_send);
+	aio_abort(mesh, channel, &channel->aio_receive);
 
 	pthread_mutex_unlock(&mesh->mutex);
 
@@ -3697,7 +3915,11 @@ bool meshlink_channel_aio_send(meshlink_handle_t *mesh, meshlink_channel_t *chan
 
 	/* 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);
+	size_t todo = MIN(len, utcp_get_rcvbuf_free(channel->c));
+
+	if(todo) {
+		channel_poll(channel->c, todo);
+	}
 
 	pthread_mutex_unlock(&mesh->mutex);
 
@@ -3734,7 +3956,11 @@ bool meshlink_channel_aio_fd_send(meshlink_handle_t *mesh, meshlink_channel_t *c
 
 	/* 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);
+	size_t left = utcp_get_rcvbuf_free(channel->c);
+
+	if(left) {
+		channel_poll(channel->c, left);
+	}
 
 	pthread_mutex_unlock(&mesh->mutex);
 
@@ -3834,6 +4060,15 @@ size_t meshlink_channel_get_recvq(meshlink_handle_t *mesh, meshlink_channel_t *c
 	return utcp_get_recvq(channel->c);
 }
 
+size_t meshlink_channel_get_mss(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return -1;
+	}
+
+	return utcp_get_mss(channel->node->utcp);
+}
+
 void meshlink_set_node_channel_timeout(meshlink_handle_t *mesh, meshlink_node_t *node, int timeout) {
 	if(!mesh || !node) {
 		meshlink_errno = MESHLINK_EINVAL;
@@ -3846,6 +4081,8 @@ void meshlink_set_node_channel_timeout(meshlink_handle_t *mesh, meshlink_node_t
 
 	if(!n->utcp) {
 		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+		utcp_set_mtu(n->utcp, n->mtu - sizeof(meshlink_packethdr_t));
+		utcp_set_retransmit_cb(n->utcp, channel_retransmit);
 	}
 
 	utcp_set_user_timeout(n->utcp, timeout);
@@ -3856,6 +4093,8 @@ void meshlink_set_node_channel_timeout(meshlink_handle_t *mesh, meshlink_node_t
 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);
+		utcp_set_mtu(n->utcp, n->mtu - sizeof(meshlink_packethdr_t));
+		utcp_set_retransmit_cb(n->utcp, channel_retransmit);
 	}
 
 	if(mesh->node_status_cb) {
@@ -3868,6 +4107,8 @@ void update_node_status(meshlink_handle_t *mesh, node_t *n) {
 }
 
 void update_node_pmtu(meshlink_handle_t *mesh, node_t *n) {
+	utcp_set_mtu(n->utcp, (n->minmtu > MINMTU ? n->minmtu : MINMTU) - sizeof(meshlink_packethdr_t));
+
 	if(mesh->node_pmtu_cb && !n->status.blacklisted) {
 		mesh->node_pmtu_cb(mesh, (meshlink_node_t *)n, n->minmtu);
 	}
@@ -3959,6 +4200,32 @@ extern void meshlink_set_inviter_commits_first(struct meshlink_handle *mesh, boo
 	pthread_mutex_unlock(&mesh->mutex);
 }
 
+void meshlink_set_external_address_discovery_url(struct meshlink_handle *mesh, const char *url) {
+	if(!mesh) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	if(url && (strncmp(url, "http://", 7) || strchr(url, ' '))) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	free(mesh->external_address_url);
+	mesh->external_address_url = url ? xstrdup(url) : NULL;
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+void meshlink_set_scheduling_granularity(struct meshlink_handle *mesh, long granularity) {
+	if(!mesh || granularity < 0) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	utcp_set_clock_granularity(granularity);
+}
+
 void handle_network_change(meshlink_handle_t *mesh, bool online) {
 	(void)online;
 
@@ -3986,6 +4253,7 @@ void call_error_cb(meshlink_handle_t *mesh, meshlink_errno_t meshlink_errno) {
 
 static void __attribute__((constructor)) meshlink_init(void) {
 	crypto_init();
+	utcp_set_clock_granularity(10000);
 }
 
 static void __attribute__((destructor)) meshlink_exit(void) {