X-Git-Url: http://git.meshlink.io/?p=meshlink;a=blobdiff_plain;f=src%2Fmeshlink.c;h=9f3b6ecd2094a89c92e68c0e9e62537b55a04518;hp=1b4492d63742d3cc87594b3813b0d72f976ed62d;hb=b70b090a28ff4cbdce29a3ad030f7d51ce9079b2;hpb=fa05f996c5500c056a36c1d43e33a407f876643c

diff --git a/src/meshlink.c b/src/meshlink.c
index 1b4492d6..9f3b6ecd 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -37,6 +37,7 @@
 #include "ed25519/sha512.h"
 #include "discovery.h"
 #include "devtools.h"
+#include "graph.h"
 
 #ifndef MSG_NOSIGNAL
 #define MSG_NOSIGNAL 0
@@ -164,7 +165,7 @@ static int socket_in_netns(int domain, int type, int protocol, int netns) {
 // Find out what local address a socket would use if we connect to the given address.
 // We do this using connect() on a UDP socket, so the kernel has to resolve the address
 // of both endpoints, but this will actually not send any UDP packet.
-static bool getlocaladdr(char *destaddr, struct sockaddr *sn, socklen_t *sl, int netns) {
+static bool getlocaladdr(char *destaddr, sockaddr_t *sa, socklen_t *salen, int netns) {
 	struct addrinfo *rai = NULL;
 	const struct addrinfo hint = {
 		.ai_family = AF_UNSPEC,
@@ -191,7 +192,7 @@ static bool getlocaladdr(char *destaddr, struct sockaddr *sn, socklen_t *sl, int
 
 	freeaddrinfo(rai);
 
-	if(getsockname(sock, sn, sl)) {
+	if(getsockname(sock, &sa->sa, salen)) {
 		closesocket(sock);
 		return false;
 	}
@@ -201,14 +202,14 @@ static bool getlocaladdr(char *destaddr, struct sockaddr *sn, socklen_t *sl, int
 }
 
 static bool getlocaladdrname(char *destaddr, char *host, socklen_t hostlen, int netns) {
-	struct sockaddr_storage sn;
-	socklen_t sl = sizeof(sn);
+	sockaddr_t sa;
+	socklen_t salen = sizeof(sa);
 
-	if(!getlocaladdr(destaddr, (struct sockaddr *)&sn, &sl, netns)) {
+	if(!getlocaladdr(destaddr, &sa, &salen, netns)) {
 		return false;
 	}
 
-	if(getnameinfo((struct sockaddr *)&sn, sl, host, hostlen, NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)) {
+	if(getnameinfo(&sa.sa, salen, host, hostlen, NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)) {
 		return false;
 	}
 
@@ -220,12 +221,42 @@ 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 = str2addrinfo(host, port ? port : "80", SOCK_STREAM);
 	char line[256];
+	char *hostname = NULL;
 
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 		if(family != AF_UNSPEC && aip->ai_family != family) {
@@ -244,7 +275,9 @@ 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) {
@@ -286,6 +319,21 @@ char *meshlink_get_external_address_for_family(meshlink_handle_t *mesh, int fami
 	return hostname;
 }
 
+static bool is_localaddr(sockaddr_t *sa) {
+	switch(sa->sa.sa_family) {
+	case AF_INET:
+		return *(uint8_t *)(&sa->in.sin_addr.s_addr) == 127;
+
+	case AF_INET6: {
+		uint16_t first = sa->in6.sin6_addr.s6_addr[0] << 8 | sa->in6.sin6_addr.s6_addr[1];
+		return first == 0 || (first & 0xffc0) == 0xfe80;
+	}
+
+	default:
+		return false;
+	}
+}
+
 char *meshlink_get_local_address_for_family(meshlink_handle_t *mesh, int family) {
 	(void)mesh;
 
@@ -299,6 +347,34 @@ char *meshlink_get_local_address_for_family(meshlink_handle_t *mesh, int family)
 		success = getlocaladdrname("2606:2800:220:1:248:1893:25c8:1946", localaddr, sizeof(localaddr), mesh->netns);
 	}
 
+#ifdef HAVE_GETIFADDRS
+
+	if(!success) {
+		struct ifaddrs *ifa = NULL;
+		getifaddrs(&ifa);
+
+		for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
+			sockaddr_t *sa = (sockaddr_t *)ifap->ifa_addr;
+
+			if(sa->sa.sa_family != family) {
+				continue;
+			}
+
+			if(is_localaddr(sa)) {
+				continue;
+			}
+
+			if(!getnameinfo(&sa->sa, SALEN(sa->sa), localaddr, sizeof(localaddr), NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)) {
+				success = true;
+				break;
+			}
+		}
+
+		freeifaddrs(ifa);
+	}
+
+#endif
+
 	if(!success) {
 		meshlink_errno = MESHLINK_ENETWORK;
 		return NULL;
@@ -333,7 +409,7 @@ void remove_duplicate_hostnames(char *host[], char *port[], int n) {
 			break;
 		}
 
-		if(found) {
+		if(found || !is_valid_hostname(host[i])) {
 			free(host[i]);
 			free(port[i]);
 			host[i] = NULL;
@@ -345,10 +421,15 @@ 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;
 	}
@@ -357,112 +438,132 @@ 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);
 
-	if(!(flags & MESHLINK_INVITE_NUMERIC)) {
-		for(int i = 0; i < 4; i++) {
-			if(!hostname[i]) {
-				continue;
-			}
+	// Resolve the hostnames
+	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);
+		// 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;
-			}
+		if(err || !ai_in) {
+			continue;
+		}
 
-			// Convert it to a hostname
-			char resolved_host[NI_MAXHOST];
-			char resolved_port[NI_MAXSERV];
-			err = getnameinfo(ai_in->ai_addr, ai_in->ai_addrlen, resolved_host, sizeof resolved_host, resolved_port, sizeof resolved_port, NI_NUMERICSERV);
+		// 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);
+		}
 
-			if(err) {
-				freeaddrinfo(ai_in);
-				continue;
-			}
+		if(flags & MESHLINK_INVITE_NUMERIC) {
+			// We don't need to do any further conversion
+			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);
+		// 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 || !ai_out) {
-				freeaddrinfo(ai_in);
-				continue;
-			}
+		if(err || !is_valid_hostname(resolved_host)) {
+			freeaddrinfo(ai_in);
+			continue;
+		}
 
-			// Check if it's still the same sockaddr
-			if(ai_in->ai_addrlen != ai_out->ai_addrlen || memcmp(ai_in->ai_addr, ai_out->ai_addr, ai_in->ai_addrlen)) {
-				freeaddrinfo(ai_in);
-				freeaddrinfo(ai_out);
-				continue;
-			}
+		// Convert the hostname back to a sockaddr
+		hint.ai_family = ai_in->ai_family;
+		err = getaddrinfo(resolved_host, resolved_port, &hint, &ai_out);
 
-			// Yes: replace the hostname with the resolved one
-			free(hostname[i]);
-			hostname[i] = xstrdup(resolved_host);
+		if(err || !ai_out) {
+			freeaddrinfo(ai_in);
+			continue;
+		}
 
+		// Check if it's still the same sockaddr
+		if(ai_in->ai_addrlen != ai_out->ai_addrlen || memcmp(ai_in->ai_addr, ai_out->ai_addr, ai_in->ai_addrlen)) {
 			freeaddrinfo(ai_in);
 			freeaddrinfo(ai_out);
+			continue;
 		}
+
+		// Yes: replace the hostname with the resolved one
+		free(hostname[i]);
+		hostname[i] = xstrdup(resolved_host);
+
+		freeaddrinfo(ai_in);
+		freeaddrinfo(ai_out);
 	}
 
 	// Remove duplicates again, since IPv4 and IPv6 addresses might map to the same hostname
-	remove_duplicate_hostnames(hostname, port, 4);
+	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;
 		}
 
-		// Ensure we have the same addresses in our own host config file.
-		char *tmphostport;
-		xasprintf(&tmphostport, "%s %s", hostname[i], port[i]);
-		/// TODO: FIX
-		//config_add_string(&mesh->config, "Address", tmphostport);
-		free(tmphostport);
-
 		// Append the address to the hostport string
 		char *newhostport;
 		xasprintf(&newhostport, (strchr(hostname[i], ':') ? "%s%s[%s]:%s" : "%s%s%s:%s"), hostport ? hostport : "", hostport ? "," : "", hostname[i], port[i]);
@@ -476,7 +577,7 @@ 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,
@@ -492,33 +593,47 @@ 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;
 }
 
 int check_port(meshlink_handle_t *mesh) {
 	for(int i = 0; i < 1000; i++) {
-		int port = 0x1000 + (rand() & 0x7fff);
+		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;
@@ -530,7 +645,56 @@ int check_port(meshlink_handle_t *mesh) {
 	return 0;
 }
 
-static bool finalize_join(meshlink_handle_t *mesh, const void *buf, uint16_t len) {
+static bool write_main_config_files(meshlink_handle_t *mesh) {
+	if(!mesh->confbase) {
+		return true;
+	}
+
+	uint8_t buf[4096];
+
+	/* Write the main config file */
+	packmsg_output_t out = {buf, sizeof buf};
+
+	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
+	packmsg_add_str(&out, mesh->name);
+	packmsg_add_bin(&out, ecdsa_get_private_key(mesh->private_key), 96);
+	packmsg_add_bin(&out, ecdsa_get_private_key(mesh->invitation_key), 96);
+	packmsg_add_uint16(&out, atoi(mesh->myport));
+
+	if(!packmsg_output_ok(&out)) {
+		return false;
+	}
+
+	config_t config = {buf, packmsg_output_size(&out, buf)};
+
+	if(!main_config_write(mesh, "current", &config, mesh->config_key)) {
+		return false;
+	}
+
+	/* Write our own host config file */
+	if(!node_write_config(mesh, mesh->self)) {
+		return false;
+	}
+
+	return true;
+}
+
+typedef struct {
+	meshlink_handle_t *mesh;
+	int sock;
+	char cookie[18 + 32];
+	char hash[18];
+	bool success;
+	sptps_t sptps;
+	char *data;
+	size_t thedatalen;
+	size_t blen;
+	char line[4096];
+	char buffer[4096];
+} join_state_t;
+
+static bool finalize_join(join_state_t *state, const void *buf, uint16_t len) {
+	meshlink_handle_t *mesh = state->mesh;
 	packmsg_input_t in = {buf, len};
 	uint32_t version = packmsg_get_uint32(&in);
 
@@ -541,7 +705,7 @@ static bool finalize_join(meshlink_handle_t *mesh, const void *buf, uint16_t len
 
 	char *name = packmsg_get_str_dup(&in);
 	packmsg_skip_element(&in); /* submesh */
-	int32_t devclass = packmsg_get_int32(&in);
+	dev_class_t devclass = packmsg_get_int32(&in);
 	uint32_t count = packmsg_get_array(&in);
 
 	if(!name) {
@@ -551,53 +715,33 @@ static bool finalize_join(meshlink_handle_t *mesh, const void *buf, uint16_t len
 
 	if(!check_id(name)) {
 		logger(mesh, MESHLINK_DEBUG, "Invalid Name found in invitation: %s!\n", name);
+		free(name);
 		return false;
 	}
 
 	if(!count) {
 		logger(mesh, MESHLINK_ERROR, "Incomplete invitation file!\n");
+		free(name);
 		return false;
 	}
 
-	// Initialize configuration directory
-	if(!config_init(mesh)) {
-		return false;
-	}
-
-	// Write main config file
-	uint8_t outbuf[4096];
-	packmsg_output_t out = {outbuf, sizeof(outbuf)};
-	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
-	packmsg_add_str(&out, name);
-	packmsg_add_bin(&out, ecdsa_get_private_key(mesh->private_key), 96);
-	packmsg_add_uint16(&out, atoi(mesh->myport));
-
-	config_t config = {outbuf, packmsg_output_size(&out, outbuf)};
+	free(mesh->name);
+	free(mesh->self->name);
+	mesh->name = name;
+	mesh->self->name = xstrdup(name);
+	mesh->self->devclass = devclass == DEV_CLASS_UNKNOWN ? mesh->devclass : devclass;
 
-	if(!main_config_write(mesh, &config)) {
+	// Initialize configuration directory
+	if(!config_init(mesh, "current")) {
 		return false;
 	}
 
-	// Write our own host config file
-	out.ptr = outbuf;
-	out.len = sizeof(outbuf);
-	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
-	packmsg_add_str(&out, name);
-	packmsg_add_str(&out, CORE_MESH);
-	packmsg_add_int32(&out, devclass);
-	packmsg_add_bool(&out, false);
-	packmsg_add_bin(&out, ecdsa_get_public_key(mesh->private_key), 32);
-	packmsg_add_str(&out, ""); // TODO: copy existing canonical address, in case it was added before meshlink_join().
-	packmsg_add_array(&out, 0);
-
-	config.len = packmsg_output_size(&out, outbuf);
-
-	if(!config_write(mesh, name, &config)) {
+	if(!write_main_config_files(mesh)) {
 		return false;
 	}
 
 	// Write host config files
-	while(count--) {
+	for(uint32_t i = 0; i < count; i++) {
 		const void *data;
 		uint32_t len = packmsg_get_bin_raw(&in, &data);
 
@@ -608,57 +752,85 @@ static bool finalize_join(meshlink_handle_t *mesh, const void *buf, uint16_t len
 
 		packmsg_input_t in2 = {data, len};
 		uint32_t version = packmsg_get_uint32(&in2);
+		char *name = packmsg_get_str_dup(&in2);
 
-		if(version != MESHLINK_CONFIG_VERSION) {
-			logger(mesh, MESHLINK_ERROR, "Invalid host config file in invitation file!\n");
-			return false;
+		if(!packmsg_input_ok(&in2) || version != MESHLINK_CONFIG_VERSION || !check_id(name)) {
+			free(name);
+			packmsg_input_invalidate(&in);
+			break;
 		}
 
-		char *host = packmsg_get_str_dup(&in2);
-
-		if(!check_id(host)) {
-			logger(mesh, MESHLINK_ERROR, "Invalid node name in invitation file!\n");
-			free(host);
-			return false;
+		if(!check_id(name)) {
+			free(name);
+			break;
 		}
 
-		if(!strcmp(host, name)) {
+		if(!strcmp(name, mesh->name)) {
 			logger(mesh, MESHLINK_DEBUG, "Secondary chunk would overwrite our own host config file.\n");
-			free(host);
+			free(name);
+			meshlink_errno = MESHLINK_EPEER;
 			return false;
 		}
 
+		node_t *n = new_node();
+		n->name = name;
+
 		config_t config = {data, len};
-		config_write(mesh, host, &config);
 
-		node_t *n = new_node();
-		n->name = host;
-		node_read_full(mesh, n);
-		n->devclass = mesh->devclass;
+		if(!node_read_from_config(mesh, n, &config)) {
+			free_node(n);
+			logger(mesh, MESHLINK_ERROR, "Invalid host config file in invitation file!\n");
+			meshlink_errno = MESHLINK_EPEER;
+			return false;
+		}
+
+		if(i == 0) {
+			/* The first host config file is of the inviter itself;
+			 * remember the address we are currently using for the invitation connection.
+			 */
+			sockaddr_t sa;
+			socklen_t salen = sizeof(sa);
+
+			if(getpeername(state->sock, &sa.sa, &salen) == 0) {
+				node_add_recent_address(mesh, n, &sa);
+			}
+		}
+
+		/* Clear the reachability times, since we ourself have never seen these nodes yet */
+		n->last_reachable = 0;
+		n->last_unreachable = 0;
+
+		if(!node_write_config(mesh, n)) {
+			free_node(n);
+			return false;
+		}
+
 		node_add(mesh, n);
 	}
 
-	sptps_send_record(&(mesh->sptps), 1, ecdsa_get_public_key(mesh->private_key), 32);
+	/* Ensure the configuration directory metadata is on disk */
+	if(!config_sync(mesh, "current") || !sync_path(mesh->confbase)) {
+		return false;
+	}
+
+	if(!mesh->inviter_commits_first) {
+		devtool_set_inviter_commits_first(false);
+	}
 
-	free(mesh->name);
-	free(mesh->self->name);
-	mesh->name = xstrdup(name);
-	mesh->self->name = xstrdup(name);
+	sptps_send_record(&state->sptps, 1, ecdsa_get_public_key(mesh->private_key), 32);
 
 	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;
+	join_state_t *state = handle;
 	const char *ptr = data;
 
 	while(len) {
-		int result = send(mesh->sock, ptr, len, 0);
+		int result = send(state->sock, ptr, len, 0);
 
 		if(result == -1 && errno == EINTR) {
 			continue;
@@ -674,37 +846,57 @@ static bool invitation_send(void *handle, uint8_t type, const void *data, size_t
 }
 
 static bool invitation_receive(void *handle, uint8_t type, const void *msg, uint16_t len) {
-	meshlink_handle_t *mesh = handle;
+	join_state_t *state = handle;
+	meshlink_handle_t *mesh = state->mesh;
+
+	if(mesh->inviter_commits_first) {
+		switch(type) {
+		case SPTPS_HANDSHAKE:
+			return sptps_send_record(&state->sptps, 2, state->cookie, 18 + 32);
 
-	switch(type) {
-	case SPTPS_HANDSHAKE:
-		return sptps_send_record(&(mesh->sptps), 0, mesh->cookie, sizeof(mesh)->cookie);
+		case 1:
+			break;
 
-	case 0:
-		return finalize_join(mesh, msg, len);
+		case 0:
+			if(!finalize_join(state, msg, len)) {
+				return false;
+			}
 
-	case 1:
-		logger(mesh, MESHLINK_DEBUG, "Invitation succesfully accepted.\n");
-		shutdown(mesh->sock, SHUT_RDWR);
-		mesh->success = true;
-		break;
+			logger(mesh, MESHLINK_DEBUG, "Invitation successfully accepted.\n");
+			shutdown(state->sock, SHUT_RDWR);
+			state->success = true;
+			break;
 
-	default:
-		return false;
+		default:
+			return false;
+		}
+	} else {
+		switch(type) {
+		case SPTPS_HANDSHAKE:
+			return sptps_send_record(&state->sptps, 0, state->cookie, 18);
+
+		case 0:
+			return finalize_join(state, msg, len);
+
+		case 1:
+			logger(mesh, MESHLINK_DEBUG, "Invitation successfully accepted.\n");
+			shutdown(state->sock, SHUT_RDWR);
+			state->success = true;
+			break;
+
+		default:
+			return false;
+		}
 	}
 
 	return true;
 }
 
-static bool recvline(meshlink_handle_t *mesh, size_t len) {
+static bool recvline(join_state_t *state) {
 	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);
+	while(!(newline = memchr(state->buffer, '\n', state->blen))) {
+		int result = recv(state->sock, state->buffer + state->blen, sizeof(state)->buffer - state->blen, 0);
 
 		if(result == -1 && errno == EINTR) {
 			continue;
@@ -712,24 +904,25 @@ static bool recvline(meshlink_handle_t *mesh, size_t len) {
 			return false;
 		}
 
-		mesh->blen += result;
+		state->blen += result;
 	}
 
-	if((size_t)(newline - mesh->buffer) >= len) {
+	if((size_t)(newline - state->buffer) >= sizeof(state->line)) {
 		return false;
 	}
 
-	len = newline - mesh->buffer;
+	size_t len = newline - state->buffer;
 
-	memcpy(mesh->line, mesh->buffer, len);
-	mesh->line[len] = 0;
-	memmove(mesh->buffer, newline + 1, mesh->blen - len - 1);
-	mesh->blen -= len + 1;
+	memcpy(state->line, state->buffer, len);
+	state->line[len] = 0;
+	memmove(state->buffer, newline + 1, state->blen - len - 1);
+	state->blen -= len + 1;
 
 	return true;
 }
+
 static bool sendline(int fd, char *format, ...) {
-	static char buffer[4096];
+	char buffer[4096];
 	char *p = buffer;
 	int blen = 0;
 	va_list ap;
@@ -774,6 +967,7 @@ static const char *errstr[] = {
 	[MESHLINK_EPEER] = "Error communicating with peer",
 	[MESHLINK_ENOTSUP] = "Operation not supported",
 	[MESHLINK_EBUSY] = "MeshLink instance already in use",
+	[MESHLINK_EBLACKLISTED] = "Node is blacklisted",
 };
 
 const char *meshlink_strerror(meshlink_errno_t err) {
@@ -823,47 +1017,42 @@ static struct timeval idle(event_loop_t *loop, void *data) {
 
 // Get our local address(es) by simulating connecting to an Internet host.
 static void add_local_addresses(meshlink_handle_t *mesh) {
-	struct sockaddr_storage sn;
-	socklen_t sl = sizeof(sn);
+	sockaddr_t sa;
+	sa.storage.ss_family = AF_UNKNOWN;
+	socklen_t salen = sizeof(sa);
 
 	// IPv4 example.org
 
-	if(getlocaladdr("93.184.216.34", (struct sockaddr *)&sn, &sl, mesh->netns)) {
-		((struct sockaddr_in *)&sn)->sin_port = ntohs(atoi(mesh->myport));
-		meshlink_hint_address(mesh, (meshlink_node_t *)mesh->self, (struct sockaddr *)&sn);
+	if(getlocaladdr("93.184.216.34", &sa, &salen, mesh->netns)) {
+		sa.in.sin_port = ntohs(atoi(mesh->myport));
+		node_add_recent_address(mesh, mesh->self, &sa);
 	}
 
 	// IPv6 example.org
 
-	sl = sizeof(sn);
+	salen = sizeof(sa);
 
-	if(getlocaladdr("2606:2800:220:1:248:1893:25c8:1946", (struct sockaddr *)&sn, &sl, mesh->netns)) {
-		((struct sockaddr_in6 *)&sn)->sin6_port = ntohs(atoi(mesh->myport));
-		meshlink_hint_address(mesh, (meshlink_node_t *)mesh->self, (struct sockaddr *)&sn);
+	if(getlocaladdr("2606:2800:220:1:248:1893:25c8:1946", &sa, &salen, mesh->netns)) {
+		sa.in6.sin6_port = ntohs(atoi(mesh->myport));
+		node_add_recent_address(mesh, mesh->self, &sa);
 	}
 }
 
-#if 0
-static bool meshlink_write_config(meshlink_handle_t *mesh) {
-	uint8_t buf[1024];
-	packmsg_output_t out = {buf, sizeof buf};
-	packmsg_add_str(&out, mesh->name);
-	packmsg_add_uint32(&out, mesh->devclass);
-	packmsg_add_uint16(&out, mesh->port);
-	packmsg_add_bin(&out, ecdsa, sizeof(ecdsa));
-	uint32_t len = packmsg_output_size(&out, buf);
+static bool meshlink_setup(meshlink_handle_t *mesh) {
+	if(!config_destroy(mesh->confbase, "new")) {
+		logger(mesh, MESHLINK_ERROR, "Could not delete configuration in %s/new: %s\n", mesh->confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
 
-	if(!len) {
-		logger(mesh, MESHLINK_DEBUG, "Could not create configuration data\n",);
-		meshlink_errno = MESHLINK_EINTERNAL;
+	if(!config_destroy(mesh->confbase, "old")) {
+		logger(mesh, MESHLINK_ERROR, "Could not delete configuration in %s/old: %s\n", mesh->confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
 		return false;
 	}
-}
-#endif
 
-static bool meshlink_setup(meshlink_handle_t *mesh) {
-	if(!config_init(mesh)) {
-		logger(mesh, MESHLINK_ERROR, "Could not set up configuration in %s: %s\n", mesh->confbase, strerror(errno));
+	if(!config_init(mesh, "current")) {
+		logger(mesh, MESHLINK_ERROR, "Could not set up configuration in %s/current: %s\n", mesh->confbase, strerror(errno));
 		meshlink_errno = MESHLINK_ESTORAGE;
 		return false;
 	}
@@ -884,37 +1073,16 @@ static bool meshlink_setup(meshlink_handle_t *mesh) {
 	mesh->self->name = xstrdup(mesh->name);
 	mesh->self->devclass = mesh->devclass;
 	mesh->self->ecdsa = ecdsa_set_public_key(ecdsa_get_public_key(mesh->private_key));
+	mesh->self->session_id = mesh->session_id;
 
-	// Write the main config file
-	uint8_t buf[4096];
-	packmsg_output_t out = {buf, sizeof(buf)};
-
-	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
-	packmsg_add_str(&out, mesh->name);
-	packmsg_add_bin(&out, ecdsa_get_private_key(mesh->private_key), 96);
-	packmsg_add_bin(&out, ecdsa_get_private_key(mesh->invitation_key), 96);
-	packmsg_add_uint16(&out, atoi(mesh->myport));
-
-	config_t config = {buf, packmsg_output_size(&out, buf)};
-
-	if(!main_config_write(mesh, &config)) {
+	if(!write_main_config_files(mesh)) {
+		logger(mesh, MESHLINK_ERROR, "Could not write main config files into %s/current: %s\n", mesh->confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
 		return false;
 	}
 
-	// Write our own host config file
-	out.ptr = buf;
-	out.len = sizeof(buf);
-	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
-	packmsg_add_str(&out, mesh->name);
-	packmsg_add_int32(&out, mesh->devclass);
-	packmsg_add_bool(&out, false);
-	packmsg_add_bin(&out, ecdsa_get_public_key(mesh->private_key), 32);
-	packmsg_add_str(&out, ""); // TODO: copy existing canonical address, in case it was added before meshlink_join().
-	packmsg_add_array(&out, 0);
-
-	config.len = packmsg_output_size(&out, buf);
-
-	if(!config_write(mesh, mesh->name, &config)) {
+	/* Ensure the configuration directory metadata is on disk */
+	if(!config_sync(mesh, "current")) {
 		return false;
 	}
 
@@ -922,16 +1090,9 @@ static bool meshlink_setup(meshlink_handle_t *mesh) {
 }
 
 static bool meshlink_read_config(meshlink_handle_t *mesh) {
-	// Open the configuration file and lock it
-	if(!main_config_lock(mesh)) {
-		logger(NULL, MESHLINK_ERROR, "Cannot lock main config file\n");
-		meshlink_errno = MESHLINK_ESTORAGE;
-		return false;
-	}
-
 	config_t config;
 
-	if(!main_config_read(mesh, &config)) {
+	if(!main_config_read(mesh, "current", &config, mesh->config_key)) {
 		logger(NULL, MESHLINK_ERROR, "Could not read main configuration file!");
 		return false;
 	}
@@ -978,9 +1139,11 @@ static bool meshlink_read_config(meshlink_handle_t *mesh) {
 	mesh->self = new_node();
 	mesh->self->name = xstrdup(name);
 	mesh->self->devclass = mesh->devclass;
+	mesh->self->session_id = mesh->session_id;
 
 	if(!node_read_public_key(mesh, mesh->self)) {
 		logger(NULL, MESHLINK_ERROR, "Could not read our host configuration file!");
+		meshlink_errno = MESHLINK_ESTORAGE;
 		free_node(mesh->self);
 		mesh->self = NULL;
 		return false;
@@ -1024,16 +1187,17 @@ meshlink_open_params_t *meshlink_open_params_init(const char *confbase, const ch
 
 	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;
-		}
-	}
-
-	if((int)devclass < 0 || devclass > _DEV_CLASS_MAX) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	};
+
+	if(!check_id(name)) {
+		logger(NULL, MESHLINK_ERROR, "Invalid name given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
+	if(devclass < 0 || devclass >= DEV_CLASS_COUNT) {
 		logger(NULL, MESHLINK_ERROR, "Invalid devclass given!\n");
 		meshlink_errno = MESHLINK_EINVAL;
 		return NULL;
@@ -1079,6 +1243,76 @@ bool meshlink_open_params_set_storage_key(meshlink_open_params_t *params, const
 	return true;
 }
 
+bool meshlink_encrypted_key_rotate(meshlink_handle_t *mesh, const void *new_key, size_t new_keylen) {
+	if(!mesh || !new_key || !new_keylen) {
+		logger(mesh, MESHLINK_ERROR, "Invalid arguments given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	// Create hash for the new key
+	void *new_config_key;
+	new_config_key = xmalloc(CHACHA_POLY1305_KEYLEN);
+
+	if(!prf(new_key, new_keylen, "MeshLink configuration key", 26, new_config_key, CHACHA_POLY1305_KEYLEN)) {
+		logger(mesh, MESHLINK_ERROR, "Error creating new configuration key!\n");
+		meshlink_errno = MESHLINK_EINTERNAL;
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	// Copy contents of the "current" confbase sub-directory to "new" confbase sub-directory with the new key
+
+	if(!config_copy(mesh, "current", mesh->config_key, "new", new_config_key)) {
+		logger(mesh, MESHLINK_ERROR, "Could not set up configuration in %s/old: %s\n", mesh->confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	devtool_keyrotate_probe(1);
+
+	// Rename confbase/current/ to confbase/old
+
+	if(!config_rename(mesh, "current", "old")) {
+		logger(mesh, MESHLINK_ERROR, "Cannot rename %s/current to %s/old\n", mesh->confbase, mesh->confbase);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	devtool_keyrotate_probe(2);
+
+	// Rename confbase/new/ to confbase/current
+
+	if(!config_rename(mesh, "new", "current")) {
+		logger(mesh, MESHLINK_ERROR, "Cannot rename %s/new to %s/current\n", mesh->confbase, mesh->confbase);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	devtool_keyrotate_probe(3);
+
+	// Cleanup the "old" confbase sub-directory
+
+	if(!config_destroy(mesh->confbase, "old")) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	// Change the mesh handle key with new key
+
+	free(mesh->config_key);
+	mesh->config_key = new_config_key;
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
 void meshlink_open_params_free(meshlink_open_params_t *params) {
 	if(!params) {
 		meshlink_errno = MESHLINK_EINVAL;
@@ -1092,7 +1326,21 @@ void meshlink_open_params_free(meshlink_open_params_t *params) {
 	free(params);
 }
 
+/// Device class traits
+static const dev_class_traits_t default_class_traits[DEV_CLASS_COUNT] = {
+	{ .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 10000, .edge_weight = 1 }, // DEV_CLASS_BACKBONE
+	{ .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 100, .edge_weight = 3 },   // DEV_CLASS_STATIONARY
+	{ .pingtimeout = 5, .pinginterval = 60, .min_connects = 3, .max_connects = 3, .edge_weight = 6 },     // DEV_CLASS_PORTABLE
+	{ .pingtimeout = 5, .pinginterval = 60, .min_connects = 1, .max_connects = 1, .edge_weight = 9 },     // DEV_CLASS_UNKNOWN
+};
+
 meshlink_handle_t *meshlink_open(const char *confbase, const char *name, const char *appname, dev_class_t devclass) {
+	if(!confbase || !*confbase) {
+		logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
 	/* Create a temporary struct on the stack, to avoid allocating and freeing one. */
 	meshlink_open_params_t params;
 	memset(&params, 0, sizeof(params));
@@ -1107,8 +1355,15 @@ meshlink_handle_t *meshlink_open(const char *confbase, const char *name, const c
 }
 
 meshlink_handle_t *meshlink_open_encrypted(const char *confbase, const char *name, const char *appname, dev_class_t devclass, const void *key, size_t keylen) {
+	if(!confbase || !*confbase) {
+		logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
 	/* Create a temporary struct on the stack, to avoid allocating and freeing one. */
-	meshlink_open_params_t params = {NULL};
+	meshlink_open_params_t params;
+	memset(&params, 0, sizeof(params));
 
 	params.confbase = (char *)confbase;
 	params.name = (char *)name;
@@ -1123,18 +1378,25 @@ meshlink_handle_t *meshlink_open_encrypted(const char *confbase, const char *nam
 	return meshlink_open_ex(&params);
 }
 
+meshlink_handle_t *meshlink_open_ephemeral(const char *name, const char *appname, dev_class_t devclass) {
+	/* Create a temporary struct on the stack, to avoid allocating and freeing one. */
+	meshlink_open_params_t params;
+	memset(&params, 0, sizeof(params));
+
+	params.name = (char *)name;
+	params.appname = (char *)appname;
+	params.devclass = devclass;
+	params.netns = -1;
+
+	return meshlink_open_ex(&params);
+}
+
 meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	// Validate arguments provided by the application
 	bool usingname = false;
 
 	logger(NULL, MESHLINK_DEBUG, "meshlink_open called\n");
 
-	if(!params->confbase || !*params->confbase) {
-		logger(NULL, MESHLINK_ERROR, "No confbase given!\n");
-		meshlink_errno = MESHLINK_EINVAL;
-		return NULL;
-	}
-
 	if(!params->appname || !*params->appname) {
 		logger(NULL, MESHLINK_ERROR, "No appname given!\n");
 		meshlink_errno = MESHLINK_EINVAL;
@@ -1161,7 +1423,7 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 		}
 	}
 
-	if((int)params->devclass < 0 || params->devclass > _DEV_CLASS_MAX) {
+	if(params->devclass < 0 || params->devclass >= DEV_CLASS_COUNT) {
 		logger(NULL, MESHLINK_ERROR, "Invalid devclass given!\n");
 		meshlink_errno = MESHLINK_EINVAL;
 		return NULL;
@@ -1174,13 +1436,27 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	}
 
 	meshlink_handle_t *mesh = xzalloc(sizeof(meshlink_handle_t));
-	mesh->confbase = xstrdup(params->confbase);
+
+	if(params->confbase) {
+		mesh->confbase = xstrdup(params->confbase);
+	}
+
 	mesh->appname = xstrdup(params->appname);
 	mesh->devclass = params->devclass;
 	mesh->discovery = true;
 	mesh->invitation_timeout = 604800; // 1 week
 	mesh->netns = params->netns;
 	mesh->submeshes = NULL;
+	mesh->log_cb = global_log_cb;
+	mesh->log_level = global_log_level;
+
+	randomize(&mesh->prng_state, sizeof(mesh->prng_state));
+
+	do {
+		randomize(&mesh->session_id, sizeof(mesh->session_id));
+	} while(mesh->session_id == 0);
+
+	memcpy(mesh->dev_class_traits, default_class_traits, sizeof(default_class_traits));
 
 	if(usingname) {
 		mesh->name = xstrdup(params->name);
@@ -1192,6 +1468,7 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 
 		if(!prf(params->key, params->keylen, "MeshLink configuration key", 26, mesh->config_key, CHACHA_POLY1305_KEYLEN)) {
 			logger(NULL, MESHLINK_ERROR, "Error creating configuration key!\n");
+			meshlink_close(mesh);
 			meshlink_errno = MESHLINK_EINTERNAL;
 			return NULL;
 		}
@@ -1201,7 +1478,7 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	pthread_mutexattr_t attr;
 	pthread_mutexattr_init(&attr);
 	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
-	pthread_mutex_init(&(mesh->mesh_mutex), &attr);
+	pthread_mutex_init(&mesh->mutex, &attr);
 
 	mesh->threadstarted = false;
 	event_loop_init(&mesh->loop);
@@ -1209,9 +1486,15 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 
 	meshlink_queue_init(&mesh->outpacketqueue);
 
+	// Atomically lock the configuration directory.
+	if(!main_config_lock(mesh)) {
+		meshlink_close(mesh);
+		return NULL;
+	}
+
 	// If no configuration exists yet, create it.
 
-	if(!main_config_exists(mesh)) {
+	if(!meshlink_confbase_exists(mesh)) {
 		if(!meshlink_setup(mesh)) {
 			logger(NULL, MESHLINK_ERROR, "Cannot create initial configuration\n");
 			meshlink_close(mesh);
@@ -1261,7 +1544,11 @@ meshlink_handle_t *meshlink_open_ex(const meshlink_open_params_t *params) {
 	}
 
 	add_local_addresses(mesh);
-	node_write_config(mesh, mesh->self);
+
+	if(!node_write_config(mesh, mesh->self)) {
+		logger(NULL, MESHLINK_ERROR, "Cannot update configuration\n");
+		return NULL;
+	}
 
 	idle_set(&mesh->loop, idle, mesh);
 
@@ -1285,11 +1572,11 @@ meshlink_submesh_t *meshlink_submesh_open(meshlink_handle_t  *mesh, const char *
 	}
 
 	//lock mesh->nodes
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	s = (meshlink_submesh_t *)create_submesh(mesh, submesh);
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return s;
 }
@@ -1301,28 +1588,46 @@ static void *meshlink_main_loop(void *arg) {
 #ifdef HAVE_SETNS
 
 		if(setns(mesh->netns, CLONE_NEWNET) != 0) {
+			pthread_cond_signal(&mesh->cond);
 			return NULL;
 		}
 
 #else
+		pthread_cond_signal(&mesh->cond);
 		return NULL;
 #endif // HAVE_SETNS
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+#if HAVE_CATTA
+
+	if(mesh->discovery) {
+		discovery_start(mesh);
+	}
+
+#endif
+
+	pthread_mutex_lock(&mesh->mutex);
 
 	logger(mesh, MESHLINK_DEBUG, "Starting main_loop...\n");
+	pthread_cond_broadcast(&mesh->cond);
 	main_loop(mesh);
 	logger(mesh, MESHLINK_DEBUG, "main_loop returned.\n");
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
+
+#if HAVE_CATTA
+
+	// Stop discovery
+	if(mesh->discovery) {
+		discovery_stop(mesh);
+	}
+
+#endif
+
 	return NULL;
 }
 
 bool meshlink_start(meshlink_handle_t *mesh) {
-	assert(mesh->self);
-	assert(mesh->private_key);
-
 	if(!mesh) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
@@ -1330,11 +1635,16 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 
 	logger(mesh, MESHLINK_DEBUG, "meshlink_start called\n");
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	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));
 
 	if(mesh->threadstarted) {
 		logger(mesh, MESHLINK_DEBUG, "thread was already running\n");
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return true;
 	}
 
@@ -1344,15 +1654,13 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 		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));
+		pthread_mutex_unlock(&mesh->mutex);
 		return false;
 	}
 
@@ -1367,25 +1675,17 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 		memset(&mesh->thread, 0, sizeof(mesh)->thread);
 		meshlink_errno = MESHLINK_EINTERNAL;
 		event_loop_stop(&mesh->loop);
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return false;
 	}
 
+	pthread_cond_wait(&mesh->cond, &mesh->mutex);
 	mesh->threadstarted = true;
 
-#if HAVE_CATTA
-
-	if(mesh->discovery) {
-		discovery_start(mesh);
-	}
-
-#endif
-
-	assert(mesh->self->ecdsa);
-	assert(!memcmp((uint8_t *)mesh->self->ecdsa + 64, (uint8_t *)mesh->private_key + 64, 32));
-
+	// Ensure we are considered reachable
+	graph(mesh);
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 	return true;
 }
 
@@ -1395,25 +1695,16 @@ void meshlink_stop(meshlink_handle_t *mesh) {
 		return;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	logger(mesh, MESHLINK_DEBUG, "meshlink_stop called\n");
 
-#if HAVE_CATTA
-
-	// Stop discovery
-	if(mesh->discovery) {
-		discovery_stop(mesh);
-	}
-
-#endif
-
 	// 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);
+		socklen_t salen = sizeof(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));
@@ -1427,9 +1718,9 @@ void meshlink_stop(meshlink_handle_t *mesh) {
 
 	if(mesh->threadstarted) {
 		// Wait for the main thread to finish
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		pthread_join(mesh->thread, NULL);
-		pthread_mutex_lock(&(mesh->mesh_mutex));
+		pthread_mutex_lock(&mesh->mutex);
 
 		mesh->threadstarted = false;
 	}
@@ -1446,11 +1737,25 @@ void meshlink_stop(meshlink_handle_t *mesh) {
 
 	exit_outgoings(mesh);
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	// Ensure we are considered unreachable
+	if(mesh->nodes) {
+		graph(mesh);
+	}
+
+	// Try to write out any changed node config files, ignore errors at this point.
+	if(mesh->nodes) {
+		for splay_each(node_t, n, mesh->nodes) {
+			if(n->status.dirty) {
+				n->status.dirty = !node_write_config(mesh, n);
+			}
+		}
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_close(meshlink_handle_t *mesh) {
-	if(!mesh || !mesh->confbase) {
+	if(!mesh) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return;
 	}
@@ -1459,7 +1764,7 @@ void meshlink_close(meshlink_handle_t *mesh) {
 	meshlink_stop(mesh);
 
 	// lock is not released after this
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	// Close and free all resources used.
 
@@ -1483,13 +1788,28 @@ void meshlink_close(meshlink_handle_t *mesh) {
 		close(mesh->netns);
 	}
 
+	for(vpn_packet_t *packet; (packet = meshlink_queue_pop(&mesh->outpacketqueue));) {
+		free(packet);
+	}
+
+	meshlink_queue_exit(&mesh->outpacketqueue);
+
 	free(mesh->name);
 	free(mesh->appname);
 	free(mesh->confbase);
-	pthread_mutex_destroy(&(mesh->mesh_mutex));
+	free(mesh->config_key);
+	free(mesh->external_address_url);
+	ecdsa_free(mesh->private_key);
+
+	if(mesh->invitation_addresses) {
+		list_delete_list(mesh->invitation_addresses);
+	}
 
 	main_config_unlock(mesh);
 
+	pthread_mutex_unlock(&mesh->mutex);
+	pthread_mutex_destroy(&mesh->mutex);
+
 	memset(mesh, 0, sizeof(*mesh));
 
 	free(mesh);
@@ -1501,7 +1821,61 @@ bool meshlink_destroy(const char *confbase) {
 		return false;
 	}
 
-	return config_destroy(confbase);
+	/* Exit early if the confbase directory itself doesn't exist */
+	if(access(confbase, F_OK) && errno == ENOENT) {
+		return true;
+	}
+
+	/* Take the lock the same way meshlink_open() would. */
+	char lockfilename[PATH_MAX];
+	snprintf(lockfilename, sizeof(lockfilename), "%s" SLASH "meshlink.lock", confbase);
+
+	FILE *lockfile = fopen(lockfilename, "w+");
+
+	if(!lockfile) {
+		logger(NULL, MESHLINK_ERROR, "Could not open lock file %s: %s", lockfilename, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+#ifdef FD_CLOEXEC
+	fcntl(fileno(lockfile), F_SETFD, FD_CLOEXEC);
+#endif
+
+#ifdef HAVE_MINGW
+	// TODO: use _locking()?
+#else
+
+	if(flock(fileno(lockfile), LOCK_EX | LOCK_NB) != 0) {
+		logger(NULL, MESHLINK_ERROR, "Configuration directory %s still in use\n", lockfilename);
+		fclose(lockfile);
+		meshlink_errno = MESHLINK_EBUSY;
+		return false;
+	}
+
+#endif
+
+	if(!config_destroy(confbase, "current") || !config_destroy(confbase, "new") || !config_destroy(confbase, "old")) {
+		logger(NULL, MESHLINK_ERROR, "Cannot remove sub-directories in %s: %s\n", confbase, strerror(errno));
+		return false;
+	}
+
+	if(unlink(lockfilename)) {
+		logger(NULL, MESHLINK_ERROR, "Cannot remove lock file %s: %s\n", lockfilename, strerror(errno));
+		fclose(lockfile);
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	fclose(lockfile);
+
+	if(!sync_path(confbase)) {
+		logger(NULL, MESHLINK_ERROR, "Cannot sync directory %s: %s\n", confbase, strerror(errno));
+		meshlink_errno = MESHLINK_ESTORAGE;
+		return false;
+	}
+
+	return true;
 }
 
 void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb) {
@@ -1510,9 +1884,9 @@ void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb)
 		return;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	mesh->receive_cb = cb;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_set_connection_try_cb(meshlink_handle_t *mesh, meshlink_connection_try_cb_t cb) {
@@ -1521,9 +1895,9 @@ void meshlink_set_connection_try_cb(meshlink_handle_t *mesh, meshlink_connection
 		return;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	mesh->connection_try_cb = cb;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb) {
@@ -1532,9 +1906,20 @@ void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_c
 		return;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	mesh->node_status_cb = cb;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+void meshlink_set_node_pmtu_cb(meshlink_handle_t *mesh, meshlink_node_pmtu_cb_t cb) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	mesh->node_pmtu_cb = cb;
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_set_node_duplicate_cb(meshlink_handle_t *mesh, meshlink_node_duplicate_cb_t cb) {
@@ -1543,23 +1928,34 @@ void meshlink_set_node_duplicate_cb(meshlink_handle_t *mesh, meshlink_node_dupli
 		return;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	mesh->node_duplicate_cb = cb;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb) {
 	if(mesh) {
-		pthread_mutex_lock(&(mesh->mesh_mutex));
+		pthread_mutex_lock(&mesh->mutex);
 		mesh->log_cb = cb;
 		mesh->log_level = cb ? level : 0;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 	} else {
 		global_log_cb = cb;
 		global_log_level = cb ? level : 0;
 	}
 }
 
+void meshlink_set_error_cb(struct meshlink_handle *mesh, meshlink_error_cb_t cb) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	mesh->error_cb = cb;
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
 bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, size_t len) {
 	meshlink_packethdr_t *hdr;
 
@@ -1582,6 +1978,7 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 
 	if(n->status.blacklisted) {
 		logger(mesh, MESHLINK_ERROR, "Node %s blacklisted, dropping packet\n", n->name);
+		meshlink_errno = MESHLINK_EBLACKLISTED;
 		return false;
 	}
 
@@ -1614,13 +2011,14 @@ bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const
 	}
 
 	// Notify event loop
-	signal_trigger(&(mesh->loop), &(mesh->datafromapp));
+	signal_trigger(&mesh->loop, &mesh->datafromapp);
 
 	return true;
 }
 
-void meshlink_send_from_queue(event_loop_t *loop, meshlink_handle_t *mesh) {
+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) {
@@ -1630,6 +2028,8 @@ void meshlink_send_from_queue(event_loop_t *loop, meshlink_handle_t *mesh) {
 	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) {
@@ -1638,19 +2038,19 @@ ssize_t meshlink_get_pmtu(meshlink_handle_t *mesh, meshlink_node_t *destination)
 		return -1;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	node_t *n = (node_t *)destination;
 
 	if(!n->status.reachable) {
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return 0;
 
 	} else if(n->mtuprobes > 30 && n->minmtu) {
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return n->minmtu;
 	} else {
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return MTU;
 	}
 }
@@ -1661,13 +2061,13 @@ char *meshlink_get_fingerprint(meshlink_handle_t *mesh, meshlink_node_t *node) {
 		return NULL;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	node_t *n = (node_t *)node;
 
 	if(!node_read_public_key(mesh, n) || !n->ecdsa) {
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return false;
 	}
 
@@ -1677,7 +2077,7 @@ char *meshlink_get_fingerprint(meshlink_handle_t *mesh, meshlink_node_t *node) {
 		meshlink_errno = MESHLINK_EINTERNAL;
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 	return fingerprint;
 }
 
@@ -1696,12 +2096,17 @@ meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name) {
 		return NULL;
 	}
 
-	meshlink_node_t *node = NULL;
+	node_t *n = NULL;
+
+	pthread_mutex_lock(&mesh->mutex);
+	n = lookup_node(mesh, (char *)name); // TODO: make lookup_node() use const
+	pthread_mutex_unlock(&mesh->mutex);
+
+	if(!n) {
+		meshlink_errno = MESHLINK_ENOENT;
+	}
 
-	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;
+	return (meshlink_node_t *)n;
 }
 
 meshlink_submesh_t *meshlink_get_submesh(meshlink_handle_t *mesh, const char *name) {
@@ -1712,9 +2117,14 @@ meshlink_submesh_t *meshlink_get_submesh(meshlink_handle_t *mesh, const char *na
 
 	meshlink_submesh_t *submesh = NULL;
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 	submesh = (meshlink_submesh_t *)lookup_submesh(mesh, name);
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
+
+	if(!submesh) {
+		meshlink_errno = MESHLINK_ENOENT;
+	}
+
 	return submesh;
 }
 
@@ -1727,7 +2137,7 @@ meshlink_node_t **meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_
 	meshlink_node_t **result;
 
 	//lock mesh->nodes
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	*nmemb = mesh->nodes->count;
 	result = realloc(nodes, *nmemb * sizeof(*nodes));
@@ -1744,7 +2154,7 @@ meshlink_node_t **meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_
 		meshlink_errno = MESHLINK_ENOMEM;
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return result;
 }
@@ -1752,19 +2162,19 @@ meshlink_node_t **meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_
 static meshlink_node_t **meshlink_get_all_nodes_by_condition(meshlink_handle_t *mesh, const void *condition, meshlink_node_t **nodes, size_t *nmemb, search_node_by_condition_t search_node) {
 	meshlink_node_t **result;
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	*nmemb = 0;
 
 	for splay_each(node_t, n, mesh->nodes) {
-		if(true == search_node(n, condition)) {
-			*nmemb = *nmemb + 1;
+		if(search_node(n, condition)) {
+			++*nmemb;
 		}
 	}
 
 	if(*nmemb == 0) {
 		free(nodes);
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
@@ -1774,7 +2184,7 @@ static meshlink_node_t **meshlink_get_all_nodes_by_condition(meshlink_handle_t *
 		meshlink_node_t **p = result;
 
 		for splay_each(node_t, n, mesh->nodes) {
-			if(true == search_node(n, condition)) {
+			if(search_node(n, condition)) {
 				*p++ = (meshlink_node_t *)n;
 			}
 		}
@@ -1784,7 +2194,7 @@ static meshlink_node_t **meshlink_get_all_nodes_by_condition(meshlink_handle_t *
 		meshlink_errno = MESHLINK_ENOMEM;
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return result;
 }
@@ -1792,7 +2202,7 @@ static meshlink_node_t **meshlink_get_all_nodes_by_condition(meshlink_handle_t *
 static bool search_node_by_dev_class(const node_t *node, const void *condition) {
 	dev_class_t *devclass = (dev_class_t *)condition;
 
-	if(*devclass == node->devclass) {
+	if(*devclass == (dev_class_t)node->devclass) {
 		return true;
 	}
 
@@ -1807,8 +2217,33 @@ static bool search_node_by_submesh(const node_t *node, const void *condition) {
 	return false;
 }
 
+struct time_range {
+	time_t start;
+	time_t end;
+};
+
+static bool search_node_by_last_reachable(const node_t *node, const void *condition) {
+	const struct time_range *range = condition;
+	time_t start = node->last_reachable;
+	time_t end = node->last_unreachable;
+
+	if(end < start) {
+		end = time(NULL);
+
+		if(end < start) {
+			start = end;
+		}
+	}
+
+	if(range->end >= range->start) {
+		return start <= range->end && end >= range->start;
+	} else {
+		return start > range->start || end < range->end;
+	}
+}
+
 meshlink_node_t **meshlink_get_all_nodes_by_dev_class(meshlink_handle_t *mesh, dev_class_t devclass, meshlink_node_t **nodes, size_t *nmemb) {
-	if(!mesh || ((int)devclass < 0) || (devclass > _DEV_CLASS_MAX) || !nmemb) {
+	if(!mesh || devclass < 0 || devclass >= DEV_CLASS_COUNT || !nmemb) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return NULL;
 	}
@@ -1825,6 +2260,17 @@ meshlink_node_t **meshlink_get_all_nodes_by_submesh(meshlink_handle_t *mesh, mes
 	return meshlink_get_all_nodes_by_condition(mesh, submesh, nodes, nmemb, search_node_by_submesh);
 }
 
+meshlink_node_t **meshlink_get_all_nodes_by_last_reachable(meshlink_handle_t *mesh, time_t start, time_t end, meshlink_node_t **nodes, size_t *nmemb) {
+	if(!mesh || !nmemb) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
+	struct time_range range = {start, end};
+
+	return meshlink_get_all_nodes_by_condition(mesh, &range, nodes, nmemb, search_node_by_last_reachable);
+}
+
 dev_class_t meshlink_get_node_dev_class(meshlink_handle_t *mesh, meshlink_node_t *node) {
 	if(!mesh || !node) {
 		meshlink_errno = MESHLINK_EINVAL;
@@ -1833,11 +2279,11 @@ dev_class_t meshlink_get_node_dev_class(meshlink_handle_t *mesh, meshlink_node_t
 
 	dev_class_t devclass;
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	devclass = ((node_t *)node)->devclass;
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return devclass;
 }
@@ -1857,6 +2303,31 @@ meshlink_submesh_t *meshlink_get_node_submesh(meshlink_handle_t *mesh, meshlink_
 	return s;
 }
 
+bool meshlink_get_node_reachability(struct meshlink_handle *mesh, struct meshlink_node *node, time_t *last_reachable, time_t *last_unreachable) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return NULL;
+	}
+
+	node_t *n = (node_t *)node;
+	bool reachable;
+
+	pthread_mutex_lock(&mesh->mutex);
+	reachable = n->status.reachable && !n->status.blacklisted;
+
+	if(last_reachable) {
+		*last_reachable = n->last_reachable;
+	}
+
+	if(last_unreachable) {
+		*last_unreachable = n->last_unreachable;
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return reachable;
+}
+
 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;
@@ -1868,21 +2339,21 @@ bool meshlink_sign(meshlink_handle_t *mesh, const void *data, size_t len, void *
 		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	if(!ecdsa_sign(mesh->private_key, data, len, signature)) {
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return false;
 	}
 
 	*siglen = MESHLINK_SIGLEN;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 	return true;
 }
 
 bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len, const void *signature, size_t siglen) {
-	if(!mesh || !data || !len || !signature) {
+	if(!mesh || !source || !data || !len || !signature) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
 	}
@@ -1892,7 +2363,7 @@ bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const voi
 		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	bool rval = false;
 
@@ -1905,12 +2376,12 @@ bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const voi
 		rval = ecdsa_verify(((struct node_t *)source)->ecdsa, data, len, signature);
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 	return rval;
 }
 
 static bool refresh_invitation_key(meshlink_handle_t *mesh) {
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	size_t count = invitation_purge_old(mesh, time(NULL) - mesh->invitation_timeout);
 
@@ -1918,7 +2389,7 @@ static bool refresh_invitation_key(meshlink_handle_t *mesh) {
 		// TODO: Update invitation key if necessary?
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return mesh->invitation_key;
 }
@@ -1949,35 +2420,93 @@ bool meshlink_set_canonical_address(meshlink_handle_t *mesh, meshlink_node_t *no
 		canonical_address = xstrdup(address);
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	node_t *n = (node_t *)node;
 	free(n->canonical_address);
 	n->canonical_address = canonical_address;
-	n->status.dirty = true;
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	if(!node_write_config(mesh, n)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
 
-	return true;
-}
+	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);
+	return config_sync(mesh, "current");
 }
 
-bool meshlink_add_external_address(meshlink_handle_t *mesh) {
-	if(!mesh) {
+bool meshlink_add_invitation_address(struct meshlink_handle *mesh, const char *address, const char *port) {
+	if(!mesh || !address) {
 		meshlink_errno = MESHLINK_EINVAL;
 		return false;
 	}
 
-	char *address = meshlink_get_external_address(mesh);
-
+	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);
+}
+
+bool meshlink_add_external_address(meshlink_handle_t *mesh) {
+	if(!mesh) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	char *address = meshlink_get_external_address(mesh);
+
 	if(!address) {
 		return false;
 	}
 
-	bool rval = meshlink_add_address(mesh, address);
+	bool rval = meshlink_set_canonical_address(mesh, (meshlink_node_t *)mesh->self, address, NULL);
 	free(address);
 
 	return rval;
@@ -1994,7 +2523,13 @@ int meshlink_get_port(meshlink_handle_t *mesh) {
 		return -1;
 	}
 
-	return atoi(mesh->myport);
+	int port;
+
+	pthread_mutex_lock(&mesh->mutex);
+	port = atoi(mesh->myport);
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return port;
 }
 
 bool meshlink_set_port(meshlink_handle_t *mesh, int port) {
@@ -2007,7 +2542,7 @@ 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;
 	}
@@ -2016,25 +2551,48 @@ bool meshlink_set_port(meshlink_handle_t *mesh, int port) {
 
 	bool rval = false;
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	if(mesh->threadstarted) {
 		meshlink_errno = MESHLINK_EINVAL;
 		goto done;
 	}
 
+	free(mesh->myport);
+	xasprintf(&mesh->myport, "%d", port);
+
+	/* Close down the network. This also deletes mesh->self. */
 	close_network_connections(mesh);
 
-	// TODO: write meshlink.conf again
+	/* Recreate mesh->self. */
+	mesh->self = new_node();
+	mesh->self->name = xstrdup(mesh->name);
+	mesh->self->devclass = mesh->devclass;
+	mesh->self->session_id = mesh->session_id;
+	xasprintf(&mesh->myport, "%d", port);
 
-	if(!setup_network(mesh)) {
+	if(!node_read_public_key(mesh, mesh->self)) {
+		logger(NULL, MESHLINK_ERROR, "Could not read our host configuration file!");
+		meshlink_errno = MESHLINK_ESTORAGE;
+		free_node(mesh->self);
+		mesh->self = NULL;
+		goto done;
+	} else if(!setup_network(mesh)) {
 		meshlink_errno = MESHLINK_ENETWORK;
-	} else {
-		rval = true;
+		goto done;
 	}
 
+	/* Rebuild our own list of recent addresses */
+	memset(mesh->self->recent, 0, sizeof(mesh->self->recent));
+	add_local_addresses(mesh);
+
+	/* Write meshlink.conf with the updated port number */
+	write_main_config_files(mesh);
+
+	rval = config_sync(mesh, "current");
+
 done:
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 
 	return rval && meshlink_get_port(mesh) == port;
 }
@@ -2063,29 +2621,29 @@ char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, c
 		s = (meshlink_submesh_t *)mesh->self->submesh;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	// Check validity of the new node's name
 	if(!check_id(name)) {
-		logger(mesh, MESHLINK_DEBUG, "Invalid name for node.\n");
+		logger(mesh, MESHLINK_ERROR, "Invalid name for node.\n");
 		meshlink_errno = MESHLINK_EINVAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
 	// Ensure no host configuration file with that name exists
-	if(config_exists(mesh, name)) {
-		logger(mesh, MESHLINK_DEBUG, "A host config file for %s already exists!\n", name);
+	if(config_exists(mesh, "current", name)) {
+		logger(mesh, MESHLINK_ERROR, "A host config file for %s already exists!\n", name);
 		meshlink_errno = MESHLINK_EEXIST;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
 	// Ensure no other nodes know about this name
-	if(meshlink_get_node(mesh, name)) {
-		logger(mesh, MESHLINK_DEBUG, "A node with name %s is already known!\n", name);
+	if(lookup_node(mesh, name)) {
+		logger(mesh, MESHLINK_ERROR, "A node with name %s is already known!\n", name);
 		meshlink_errno = MESHLINK_EEXIST;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
@@ -2093,18 +2651,27 @@ char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, c
 	char *address = get_my_hostname(mesh, flags);
 
 	if(!address) {
-		logger(mesh, MESHLINK_DEBUG, "No Address known for ourselves!\n");
+		logger(mesh, MESHLINK_ERROR, "No Address known for ourselves!\n");
 		meshlink_errno = MESHLINK_ERESOLV;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
 	if(!refresh_invitation_key(mesh)) {
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
+	// If we changed our own host config file, write it out now
+	if(mesh->self->status.dirty) {
+		if(!node_write_config(mesh, mesh->self)) {
+			logger(mesh, MESHLINK_ERROR, "Could not write our own host config file!\n");
+			pthread_mutex_unlock(&mesh->mutex);
+			return NULL;
+		}
+	}
+
 	char hash[64];
 
 	// Create a hash of the key.
@@ -2137,11 +2704,15 @@ char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, c
 	packmsg_add_str(&inv, s ? s->name : CORE_MESH);
 	packmsg_add_int32(&inv, DEV_CLASS_UNKNOWN); /* TODO: allow this to be set by inviter? */
 
-	/* TODO: Add several host config files to bootstrap connections */
-	config_t configs[5] = {NULL};
+	/* TODO: Add several host config files to bootstrap connections.
+	 * Note: make sure we only add config files of nodes that are in the core mesh or the same submesh,
+	 * and are not blacklisted.
+	 */
+	config_t configs[5];
+	memset(configs, 0, sizeof(configs));
 	int count = 0;
 
-	if(config_read(mesh, mesh->self->name, &configs[count])) {
+	if(config_read(mesh, "current", mesh->self->name, &configs[count], mesh->config_key)) {
 		count++;
 	}
 
@@ -2155,10 +2726,10 @@ char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, c
 
 	config_t config = {outbuf, packmsg_output_size(&inv, outbuf)};
 
-	if(!invitation_write(mesh, cookiehash, &config)) {
+	if(!invitation_write(mesh, "current", cookiehash, &config, mesh->config_key)) {
 		logger(mesh, MESHLINK_DEBUG, "Could not create invitation file %s: %s\n", cookiehash, strerror(errno));
 		meshlink_errno = MESHLINK_ESTORAGE;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
@@ -2167,7 +2738,7 @@ char *meshlink_invite_ex(meshlink_handle_t *mesh, meshlink_submesh_t *submesh, c
 	xasprintf(&url, "%s/%s%s", address, hash, cookie);
 	free(address);
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
 	return url;
 }
 
@@ -2181,18 +2752,33 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	join_state_t state = {
+		.mesh = mesh,
+		.sock = -1,
+	};
+
+	ecdsa_t *key = NULL;
+	ecdsa_t *hiskey = NULL;
+
+	//TODO: think of a better name for this variable, or of a different way to tokenize the invitation URL.
+	char copy[strlen(invitation) + 1];
+
+	pthread_mutex_lock(&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");
+		logger(mesh, MESHLINK_ERROR, "Cannot join while started\n");
 		meshlink_errno = MESHLINK_EINVAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
+	}
+
+	// Refuse to join a mesh if we are already part of one. We are part of one if we know at least one other node.
+	if(mesh->nodes->count > 1) {
+		logger(mesh, MESHLINK_ERROR, "Already part of an existing mesh\n");
+		meshlink_errno = MESHLINK_EINVAL;
+		goto exit;
 	}
 
-	//TODO: think of a better name for this variable, or of a different way to tokenize the invitation URL.
-	char copy[strlen(invitation) + 1];
 	strcpy(copy, invitation);
 
 	// Split the invitation URL into a list of hostname/port tuples, a key hash and a cookie.
@@ -2212,22 +2798,24 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 	char *address = copy;
 	char *port = NULL;
 
-	if(!b64decode(slash, mesh->hash, 18) || !b64decode(slash + 24, mesh->cookie, 18)) {
+	if(!b64decode(slash, state.hash, 18) || !b64decode(slash + 24, state.cookie, 18)) {
 		goto invalid;
 	}
 
+	if(mesh->inviter_commits_first) {
+		memcpy(state.cookie + 18, ecdsa_get_public_key(mesh->private_key), 32);
+	}
+
 	// Generate a throw-away key for the invitation.
-	ecdsa_t *key = ecdsa_generate();
+	key = ecdsa_generate();
 
 	if(!key) {
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
 	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.
@@ -2267,23 +2855,25 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 
 		if(ai) {
 			for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
-				mesh->sock = socket_in_netns(aip->ai_family, aip->ai_socktype, aip->ai_protocol, mesh->netns);
+				state.sock = socket_in_netns(aip->ai_family, aip->ai_socktype, aip->ai_protocol, mesh->netns);
 
-				if(mesh->sock == -1) {
+				if(state.sock == -1) {
 					logger(mesh, MESHLINK_DEBUG, "Could not open socket: %s\n", strerror(errno));
 					meshlink_errno = MESHLINK_ENETWORK;
 					continue;
 				}
 
-				set_timeout(mesh->sock, 5000);
+				set_timeout(state.sock, 5000);
 
-				if(connect(mesh->sock, aip->ai_addr, aip->ai_addrlen)) {
+				if(connect(state.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;
+					closesocket(state.sock);
+					state.sock = -1;
 					continue;
 				}
+
+				break;
 			}
 
 			freeaddrinfo(ai);
@@ -2291,30 +2881,27 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 			meshlink_errno = MESHLINK_ERESOLV;
 		}
 
-		if(mesh->sock != -1 || !comma) {
+		if(state.sock != -1 || !comma) {
 			break;
 		}
 
 		address = comma;
 	}
 
-	if(mesh->sock == -1) {
-		pthread_mutex_unlock(&mesh->mesh_mutex);
-		return false;
+	if(state.sock == -1) {
+		goto exit;
 	}
 
 	logger(mesh, MESHLINK_DEBUG, "Connected to %s port %s...\n", address, port);
 
 	// Tell him we have an invitation, and give him our throw-away key.
 
-	mesh->blen = 0;
+	state.blen = 0;
 
-	if(!sendline(mesh->sock, "0 ?%s %d.%d %s", b64key, PROT_MAJOR, 1, mesh->appname)) {
+	if(!sendline(state.sock, "0 ?%s %d.%d %s", b64key, PROT_MAJOR, PROT_MINOR, mesh->appname)) {
 		logger(mesh, MESHLINK_DEBUG, "Error sending request to %s port %s: %s\n", address, port, strerror(errno));
-		closesocket(mesh->sock);
 		meshlink_errno = MESHLINK_ENETWORK;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
 	free(b64key);
@@ -2322,58 +2909,51 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 	char hisname[4096] = "";
 	int code, hismajor, hisminor = 0;
 
-	if(!recvline(mesh, sizeof(mesh)->line) || sscanf(mesh->line, "%d %s %d.%d", &code, hisname, &hismajor, &hisminor) < 3 || code != 0 || hismajor != PROT_MAJOR || !check_id(hisname) || !recvline(mesh, sizeof(mesh)->line) || !rstrip(mesh->line) || sscanf(mesh->line, "%d ", &code) != 1 || code != ACK || strlen(mesh->line) < 3) {
+	if(!recvline(&state) || sscanf(state.line, "%d %s %d.%d", &code, hisname, &hismajor, &hisminor) < 3 || code != 0 || hismajor != PROT_MAJOR || !check_id(hisname) || !recvline(&state) || !rstrip(state.line) || sscanf(state.line, "%d ", &code) != 1 || code != ACK || strlen(state.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;
+		goto exit;
 	}
 
 	// Check if the hash of the key he gave us matches the hash in the URL.
-	char *fingerprint = mesh->line + 2;
+	char *fingerprint = state.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);
+		logger(mesh, MESHLINK_DEBUG, "Could not create hash\n%s\n", state.line + 2);
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
-	if(memcmp(hishash, mesh->hash, 18)) {
-		logger(mesh, MESHLINK_DEBUG, "Peer has an invalid key!\n%s\n", mesh->line + 2);
+	if(memcmp(hishash, state.hash, 18)) {
+		logger(mesh, MESHLINK_DEBUG, "Peer has an invalid key!\n%s\n", state.line + 2);
 		meshlink_errno = MESHLINK_EPEER;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
-
+		goto exit;
 	}
 
-	ecdsa_t *hiskey = ecdsa_set_base64_public_key(fingerprint);
+	hiskey = ecdsa_set_base64_public_key(fingerprint);
 
 	if(!hiskey) {
 		meshlink_errno = MESHLINK_EINTERNAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
 	// 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)) {
+	if(!sptps_start(&state.sptps, &state, 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;
+		goto exit;
 	}
 
 	// Feed rest of input buffer to SPTPS
-	if(!sptps_receive_data(&mesh->sptps, mesh->buffer, mesh->blen)) {
+	if(!sptps_receive_data(&state.sptps, state.buffer, state.blen)) {
 		meshlink_errno = MESHLINK_EPEER;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
-	int len;
+	ssize_t len;
+	logger(mesh, MESHLINK_DEBUG, "Starting invitation recv loop: %d %zu\n", state.sock, sizeof(state.line));
 
-	while((len = recv(mesh->sock, mesh->line, sizeof(mesh)->line, 0))) {
+	while((len = recv(state.sock, state.line, sizeof(state.line), 0))) {
 		if(len < 0) {
 			if(errno == EINTR) {
 				continue;
@@ -2381,36 +2961,42 @@ bool meshlink_join(meshlink_handle_t *mesh, const char *invitation) {
 
 			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;
+			goto exit;
 		}
 
-		if(!sptps_receive_data(&mesh->sptps, mesh->line, len)) {
+		if(!sptps_receive_data(&state.sptps, state.line, len)) {
 			meshlink_errno = MESHLINK_EPEER;
-			pthread_mutex_unlock(&(mesh->mesh_mutex));
-			return false;
+			goto exit;
 		}
 	}
 
-	sptps_stop(&mesh->sptps);
-	ecdsa_free(hiskey);
-	ecdsa_free(key);
-	closesocket(mesh->sock);
-
-	if(!mesh->success) {
+	if(!state.success) {
 		logger(mesh, MESHLINK_DEBUG, "Connection closed by peer, invitation cancelled.\n");
 		meshlink_errno = MESHLINK_EPEER;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return false;
+		goto exit;
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	sptps_stop(&state.sptps);
+	ecdsa_free(hiskey);
+	ecdsa_free(key);
+	closesocket(state.sock);
+
+	pthread_mutex_unlock(&mesh->mutex);
 	return true;
 
 invalid:
 	logger(mesh, MESHLINK_DEBUG, "Invalid invitation URL\n");
 	meshlink_errno = MESHLINK_EINVAL;
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+exit:
+	sptps_stop(&state.sptps);
+	ecdsa_free(hiskey);
+	ecdsa_free(key);
+
+	if(state.sock != -1) {
+		closesocket(state.sock);
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
 	return false;
 }
 
@@ -2420,38 +3006,67 @@ char *meshlink_export(meshlink_handle_t *mesh) {
 		return NULL;
 	}
 
-	config_t config;
+	// Create a config file on the fly.
+
+	uint8_t buf[4096];
+	packmsg_output_t out = {buf, sizeof(buf)};
+	packmsg_add_uint32(&out, MESHLINK_CONFIG_VERSION);
+	packmsg_add_str(&out, mesh->name);
+	packmsg_add_str(&out, CORE_MESH);
+
+	pthread_mutex_lock(&mesh->mutex);
 
-	// Get our config file
+	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 : "");
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	uint32_t count = 0;
 
-	if(!config_read(mesh, mesh->self->name, &config)) {
-		meshlink_errno = MESHLINK_ESTORAGE;
-		pthread_mutex_unlock(&mesh->mesh_mutex);
-		return NULL;
+	for(uint32_t i = 0; i < MAX_RECENT; i++) {
+		if(mesh->self->recent[i].sa.sa_family) {
+			count++;
+		} else {
+			break;
+		}
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	packmsg_add_array(&out, count);
 
-	// Prepare a base64-encoded packmsg array containing our config file
+	for(uint32_t i = 0; i < count; i++) {
+		packmsg_add_sockaddr(&out, &mesh->self->recent[i]);
+	}
 
-	uint8_t *buf = xmalloc(((config.len + 4) * 4) / 3 + 4);
-	packmsg_output_t out = {buf, config.len + 4};
-	packmsg_add_array(&out, 1);
-	packmsg_add_bin(&out, config.buf, config.len);
-	config_free(&config);
+	packmsg_add_int64(&out, 0);
+	packmsg_add_int64(&out, 0);
+
+	pthread_mutex_unlock(&mesh->mutex);
 
 	if(!packmsg_output_ok(&out)) {
 		logger(mesh, MESHLINK_DEBUG, "Error creating export data\n");
 		meshlink_errno = MESHLINK_EINTERNAL;
-		free(buf);
 		return NULL;
 	}
 
-	b64encode_urlsafe(buf, (char *)buf, packmsg_output_size(&out, buf));
+	// Prepare a base64-encoded packmsg array containing our config file
+
+	uint32_t len = packmsg_output_size(&out, buf);
+	uint32_t len2 = ((len + 4) * 4) / 3 + 4;
+	uint8_t *buf2 = xmalloc(len2);
+	packmsg_output_t out2 = {buf2, len2};
+	packmsg_add_array(&out2, 1);
+	packmsg_add_bin(&out2, buf, packmsg_output_size(&out, buf));
+
+	if(!packmsg_output_ok(&out2)) {
+		logger(mesh, MESHLINK_DEBUG, "Error creating export data\n");
+		meshlink_errno = MESHLINK_EINTERNAL;
+		free(buf2);
+		return NULL;
+	}
+
+	b64encode_urlsafe(buf2, (char *)buf2, packmsg_output_size(&out2, buf2));
 
-	return (char *)buf;
+	return (char *)buf2;
 }
 
 bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
@@ -2479,7 +3094,7 @@ bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
 		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
 	while(count--) {
 		const void *data;
@@ -2495,7 +3110,7 @@ bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
 
 		if(!packmsg_input_ok(&in2) || version != MESHLINK_CONFIG_VERSION || !check_id(name)) {
 			free(name);
-			packmsg_input_invalidate(&in2);
+			packmsg_input_invalidate(&in);
 			break;
 		}
 
@@ -2507,60 +3122,37 @@ bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
 		node_t *n = lookup_node(mesh, name);
 
 		if(n) {
-			free(name);
 			logger(mesh, MESHLINK_DEBUG, "Node %s already exists, not importing\n", name);
+			free(name);
 			continue;
 		}
 
 		n = new_node();
 		n->name = name;
-		char *submesh_name = packmsg_get_str_dup(&in2);
-
-		if(submesh_name) {
-			if(!strcmp(submesh_name, CORE_MESH)) {
-				n->submesh = NULL;
-			} else {
-				n->submesh = lookup_or_create_submesh(mesh, submesh_name);
-
-				if(!n->submesh) {
-					packmsg_input_invalidate(&in2);
-				}
-			}
-
-			free(submesh_name);
-		}
 
-		n->devclass = packmsg_get_int32(&in2);
-		n->status.blacklisted = packmsg_get_bool(&in2);
-		const void *key;
-		uint32_t keylen = packmsg_get_bin_raw(&in2, &key);
-
-		if(keylen == 32) {
-			n->ecdsa = ecdsa_set_public_key(key);
-		}
-
-		n->canonical_address = packmsg_get_str_dup(&in2);
-		uint32_t count = packmsg_get_array(&in2);
+		config_t config = {data, len};
 
-		if(count > 5) {
-			count = 5;
+		if(!node_read_from_config(mesh, n, &config)) {
+			free_node(n);
+			packmsg_input_invalidate(&in);
+			break;
 		}
 
-		for(uint32_t i = 0; i < count; i++) {
-			n->recent[i] = packmsg_get_sockaddr(&in2);
-		}
+		/* Clear the reachability times, since we ourself have never seen these nodes yet */
+		n->last_reachable = 0;
+		n->last_unreachable = 0;
 
-		if(!packmsg_done(&in2) || keylen != 32) {
-			packmsg_input_invalidate(&in2);
+		if(!node_write_config(mesh, n)) {
 			free_node(n);
-		} else {
-			config_t config = {data, len};
-			config_write(mesh, n->name, &config);
-			node_add(mesh, n);
+			return false;
 		}
+
+		node_add(mesh, n);
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	pthread_mutex_unlock(&mesh->mutex);
+
+	free(buf);
 
 	if(!packmsg_done(&in)) {
 		logger(mesh, MESHLINK_ERROR, "Invalid data\n");
@@ -2568,41 +3160,33 @@ bool meshlink_import(meshlink_handle_t *mesh, const char *data) {
 		return false;
 	}
 
-	return true;
-}
-
-void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
-	if(!mesh || !node) {
-		meshlink_errno = MESHLINK_EINVAL;
-		return;
+	if(!config_sync(mesh, "current")) {
+		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
-
-	node_t *n;
-	n = (node_t *)node;
+	return true;
+}
 
+static bool blacklist(meshlink_handle_t *mesh, node_t *n) {
 	if(n == mesh->self) {
-		logger(mesh, MESHLINK_ERROR, "%s blacklisting itself?\n", node->name);
+		logger(mesh, MESHLINK_ERROR, "%s blacklisting itself?\n", n->name);
 		meshlink_errno = MESHLINK_EINVAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return;
+		return false;
 	}
 
 	if(n->status.blacklisted) {
-		logger(mesh, MESHLINK_DEBUG, "Node %s already blacklisted\n", node->name);
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return;
+		logger(mesh, MESHLINK_DEBUG, "Node %s already blacklisted\n", n->name);
+		return true;
 	}
 
 	n->status.blacklisted = true;
-	n->status.dirty = true;
-	logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", node->name);
 
-	//Immediately terminate any connections we have with the blacklisted node
+	/* Immediately shut down any connections we have with the blacklisted node.
+	 * We can't call terminate_connection(), because we might be called from a callback function.
+	 */
 	for list_each(connection_t, c, mesh->connections) {
 		if(c->node == n) {
-			terminate_connection(mesh, c, c->status.active);
+			shutdown(c->socket, SHUT_RDWR);
 		}
 	}
 
@@ -2615,111 +3199,319 @@ void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
 	n->status.udp_confirmed = false;
 
 	if(n->status.reachable) {
-		update_node_status(mesh, n);
+		n->last_unreachable = mesh->loop.now.tv_sec;
 	}
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
+	/* Graph updates will suppress status updates for blacklisted nodes, so we need to
+	 * manually call the status callback if necessary.
+	 */
+	if(n->status.reachable && mesh->node_status_cb) {
+		mesh->node_status_cb(mesh, (meshlink_node_t *)n, false);
+	}
+
+	return node_write_config(mesh, n) && config_sync(mesh, "current");
 }
 
-void meshlink_whitelist(meshlink_handle_t *mesh, meshlink_node_t *node) {
+bool meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node) {
 	if(!mesh || !node) {
 		meshlink_errno = MESHLINK_EINVAL;
-		return;
+		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
-	node_t *n = (node_t *)node;
-
-	if(!n->status.blacklisted) {
-		logger(mesh, MESHLINK_DEBUG, "Node %s was already whitelisted\n", node->name);
-		meshlink_errno = MESHLINK_EINVAL;
-		pthread_mutex_unlock(&(mesh->mesh_mutex));
-		return;
+	if(!blacklist(mesh, (node_t *)node)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
 	}
 
-	n->status.blacklisted = false;
-	n->status.dirty = true;
-
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
-	return;
-}
+	pthread_mutex_unlock(&mesh->mutex);
 
-void meshlink_set_default_blacklist(meshlink_handle_t *mesh, bool blacklist) {
-	mesh->default_blacklist = blacklist;
+	logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", node->name);
+	return true;
 }
 
-/* Hint that a hostname may be found at an address
- * See header file for detailed comment.
- */
-void meshlink_hint_address(meshlink_handle_t *mesh, meshlink_node_t *node, const struct sockaddr *addr) {
-	if(!mesh || !node || !addr) {
-		meshlink_errno = EINVAL;
-		return;
+bool meshlink_blacklist_by_name(meshlink_handle_t *mesh, const char *name) {
+	if(!mesh || !name) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
 	}
 
-	pthread_mutex_lock(&(mesh->mesh_mutex));
+	pthread_mutex_lock(&mesh->mutex);
 
-	node_t *n = (node_t *)node;
-	memmove(n->recent + 1, n->recent, 4 * sizeof(*n->recent));
-	memcpy(n->recent, addr, SALEN(*addr));
-	n->status.dirty = true;
+	node_t *n = lookup_node(mesh, (char *)name);
 
-	pthread_mutex_unlock(&(mesh->mesh_mutex));
-	// @TODO do we want to fire off a connection attempt right away?
-}
+	if(!n) {
+		n = new_node();
+		n->name = xstrdup(name);
+		node_add(mesh, n);
+	}
 
-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;
+	if(!blacklist(mesh, (node_t *)n)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	logger(mesh, MESHLINK_DEBUG, "Blacklisted %s.\n", name);
+	return true;
 }
 
-static ssize_t channel_recv(struct utcp_connection *connection, const void *data, size_t len) {
-	meshlink_channel_t *channel = connection->priv;
+static bool whitelist(meshlink_handle_t *mesh, node_t *n) {
+	if(n == mesh->self) {
+		logger(mesh, MESHLINK_ERROR, "%s whitelisting itself?\n", n->name);
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
 
-	if(!channel) {
-		abort();
+	if(!n->status.blacklisted) {
+		logger(mesh, MESHLINK_DEBUG, "Node %s was already whitelisted\n", n->name);
+		return true;
 	}
 
-	node_t *n = channel->node;
-	meshlink_handle_t *mesh = n->mesh;
+	n->status.blacklisted = false;
 
-	if(n->status.destroyed) {
-		meshlink_channel_close(mesh, channel);
-	} else if(channel->receive_cb) {
-		channel->receive_cb(mesh, channel, data, len);
+	if(n->status.reachable) {
+		n->last_reachable = mesh->loop.now.tv_sec;
+		update_node_status(mesh, n);
 	}
 
-	return len;
+	return node_write_config(mesh, n) && config_sync(mesh, "current");
 }
 
-static void channel_accept(struct utcp_connection *utcp_connection, uint16_t port) {
-	node_t *n = utcp_connection->utcp->priv;
-
-	if(!n) {
-		abort();
+bool meshlink_whitelist(meshlink_handle_t *mesh, meshlink_node_t *node) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
 	}
 
-	meshlink_handle_t *mesh = n->mesh;
+	pthread_mutex_lock(&mesh->mutex);
 
-	if(!mesh->channel_accept_cb) {
-		return;
+	if(!whitelist(mesh, (node_t *)node)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
 	}
 
-	meshlink_channel_t *channel = xzalloc(sizeof(*channel));
-	channel->node = n;
-	channel->c = utcp_connection;
+	pthread_mutex_unlock(&mesh->mutex);
 
-	if(mesh->channel_accept_cb(mesh, channel, port, NULL, 0)) {
-		utcp_accept(utcp_connection, channel_recv, channel);
-	} else {
-		free(channel);
-	}
+	logger(mesh, MESHLINK_DEBUG, "Whitelisted %s.\n", node->name);
+	return true;
 }
 
-static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
+bool meshlink_whitelist_by_name(meshlink_handle_t *mesh, const char *name) {
+	if(!mesh || !name) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	node_t *n = lookup_node(mesh, (char *)name);
+
+	if(!n) {
+		n = new_node();
+		n->name = xstrdup(name);
+		node_add(mesh, n);
+	}
+
+	if(!whitelist(mesh, (node_t *)n)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	logger(mesh, MESHLINK_DEBUG, "Whitelisted %s.\n", name);
+	return true;
+}
+
+void meshlink_set_default_blacklist(meshlink_handle_t *mesh, bool blacklist) {
+	mesh->default_blacklist = blacklist;
+}
+
+bool meshlink_forget_node(meshlink_handle_t *mesh, meshlink_node_t *node) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	node_t *n = (node_t *)node;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Check that the node is not reachable */
+	if(n->status.reachable || n->connection) {
+		pthread_mutex_unlock(&mesh->mutex);
+		logger(mesh, MESHLINK_WARNING, "Could not forget %s: still reachable", n->name);
+		return false;
+	}
+
+	/* Check that we don't have any active UTCP connections */
+	if(n->utcp && utcp_is_active(n->utcp)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		logger(mesh, MESHLINK_WARNING, "Could not forget %s: active UTCP connections", n->name);
+		return false;
+	}
+
+	/* Check that we have no active connections to this node */
+	for list_each(connection_t, c, mesh->connections) {
+		if(c->node == n) {
+			pthread_mutex_unlock(&mesh->mutex);
+			logger(mesh, MESHLINK_WARNING, "Could not forget %s: active connection", n->name);
+			return false;
+		}
+	}
+
+	/* Remove any pending outgoings to this node */
+	if(mesh->outgoings) {
+		for list_each(outgoing_t, outgoing, mesh->outgoings) {
+			if(outgoing->node == n) {
+				list_delete_node(mesh->outgoings, node);
+			}
+		}
+	}
+
+	/* Delete the config file for this node */
+	if(!config_delete(mesh, "current", n->name)) {
+		pthread_mutex_unlock(&mesh->mutex);
+		return false;
+	}
+
+	/* Delete the node struct and any remaining edges referencing this node */
+	node_del(mesh, n);
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return config_sync(mesh, "current");
+}
+
+/* Hint that a hostname may be found at an address
+ * See header file for detailed comment.
+ */
+void meshlink_hint_address(meshlink_handle_t *mesh, meshlink_node_t *node, const struct sockaddr *addr) {
+	if(!mesh || !node || !addr) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	node_t *n = (node_t *)node;
+
+	if(node_add_recent_address(mesh, n, (sockaddr_t *)addr)) {
+		if(!node_write_config(mesh, n)) {
+			logger(mesh, MESHLINK_DEBUG, "Could not update %s\n", n->name);
+		}
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+	// @TODO do we want to fire off a connection attempt right away?
+}
+
+static bool channel_pre_accept(struct utcp *utcp, uint16_t port) {
+	(void)port;
+	node_t *n = utcp->priv;
+	meshlink_handle_t *mesh = n->mesh;
+	return mesh->channel_accept_cb;
+}
+
+static void aio_signal(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_aio_buffer_t *aio) {
+	if(aio->data) {
+		if(aio->cb.buffer) {
+			aio->cb.buffer(mesh, channel, aio->data, aio->len, aio->priv);
+		}
+	} else {
+		if(aio->cb.fd) {
+			aio->cb.fd(mesh, channel, aio->fd, aio->done, aio->priv);
+		}
+	}
+}
+
+static ssize_t channel_recv(struct utcp_connection *connection, const void *data, size_t len) {
+	meshlink_channel_t *channel = connection->priv;
+
+	if(!channel) {
+		abort();
+	}
+
+	node_t *n = channel->node;
+	meshlink_handle_t *mesh = n->mesh;
+
+	if(n->status.destroyed) {
+		meshlink_channel_close(mesh, channel);
+		return len;
+	}
+
+	const char *p = data;
+	size_t left = len;
+
+	while(channel->aio_receive) {
+		meshlink_aio_buffer_t *aio = channel->aio_receive;
+		size_t todo = aio->len - aio->done;
+
+		if(todo > left) {
+			todo = left;
+		}
+
+		if(aio->data) {
+			memcpy((char *)aio->data + aio->done, p, todo);
+		} else {
+			ssize_t result = write(aio->fd, p, todo);
+
+			if(result > 0) {
+				todo = result;
+			}
+		}
+
+		aio->done += todo;
+
+		if(aio->done == aio->len) {
+			channel->aio_receive = aio->next;
+			aio_signal(mesh, channel, aio);
+			free(aio);
+		}
+
+		p += todo;
+		left -= todo;
+
+		if(!left && len) {
+			return len;
+		}
+	}
+
+	if(channel->receive_cb) {
+		channel->receive_cb(mesh, channel, p, left);
+	}
+
+	return len;
+}
+
+static void channel_accept(struct utcp_connection *utcp_connection, uint16_t port) {
+	node_t *n = utcp_connection->utcp->priv;
+
+	if(!n) {
+		abort();
+	}
+
+	meshlink_handle_t *mesh = n->mesh;
+
+	if(!mesh->channel_accept_cb) {
+		return;
+	}
+
+	meshlink_channel_t *channel = xzalloc(sizeof(*channel));
+	channel->node = n;
+	channel->c = utcp_connection;
+
+	if(mesh->channel_accept_cb(mesh, channel, port, NULL, 0)) {
+		utcp_accept(utcp_connection, channel_recv, channel);
+	} else {
+		free(channel);
+	}
+}
+
+static ssize_t channel_send(struct utcp *utcp, const void *data, size_t len) {
 	node_t *n = utcp->priv;
 
 	if(n->status.destroyed) {
@@ -2759,16 +3551,69 @@ 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;
+		ssize_t sent;
 
-	if(channel->poll_cb) {
-		channel->poll_cb(mesh, channel, len);
+		if(len > left) {
+			len = left;
+		}
+
+		if(aio->data) {
+			sent = utcp_send(connection, (char *)aio->data + aio->done, len);
+		} else {
+			char buf[65536];
+			size_t todo = utcp_get_sndbuf_free(connection);
+
+			if(todo > left) {
+				todo = left;
+			}
+
+			if(todo > sizeof(buf)) {
+				todo = sizeof(buf);
+			}
+
+			ssize_t result = read(aio->fd, buf, todo);
+
+			if(result > 0) {
+				sent = utcp_send(connection, buf, result);
+			} else {
+				sent = result;
+			}
+		}
+
+		if(sent >= 0) {
+			aio->done += sent;
+		}
+
+		/* If the buffer is now completely sent, call the callback and dispose of it. */
+		if(aio->done >= aio->len) {
+			channel->aio_send = aio->next;
+			aio_signal(mesh, channel, aio);
+			free(aio);
+		}
+	} else {
+		if(channel->poll_cb) {
+			channel->poll_cb(mesh, channel, len);
+		} else {
+			utcp_set_poll_cb(connection, NULL);
+		}
 	}
 }
 
 void meshlink_set_channel_poll_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_poll_cb_t cb) {
-	(void)mesh;
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
 	channel->poll_cb = cb;
-	utcp_set_poll_cb(channel->c, cb ? channel_poll : NULL);
+	utcp_set_poll_cb(channel->c, (cb || channel->aio_send) ? channel_poll : NULL);
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb) {
@@ -2777,7 +3622,7 @@ void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_ac
 		return;
 	}
 
-	pthread_mutex_lock(&mesh->mesh_mutex);
+	pthread_mutex_lock(&mesh->mutex);
 	mesh->channel_accept_cb = cb;
 	mesh->receive_cb = channel_receive;
 
@@ -2787,11 +3632,37 @@ void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_ac
 		}
 	}
 
-	pthread_mutex_unlock(&mesh->mesh_mutex);
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+void meshlink_set_channel_sndbuf(meshlink_handle_t *mesh, meshlink_channel_t *channel, size_t size) {
+	(void)mesh;
+
+	if(!channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	utcp_set_sndbuf(channel->c, size);
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+void meshlink_set_channel_rcvbuf(meshlink_handle_t *mesh, meshlink_channel_t *channel, size_t size) {
+	(void)mesh;
+
+	if(!channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	utcp_set_rcvbuf(channel->c, size);
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_node_t *node, uint16_t port, meshlink_channel_receive_cb_t cb, const void *data, size_t len, uint32_t flags) {
-	if(data || len) {
+	if(data && len) {
 		abort();        // TODO: handle non-NULL data
 	}
 
@@ -2800,6 +3671,8 @@ meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_n
 		return NULL;
 	}
 
+	pthread_mutex_lock(&mesh->mutex);
+
 	node_t *n = (node_t *)node;
 
 	if(!n->utcp) {
@@ -2808,20 +3681,30 @@ meshlink_channel_t *meshlink_channel_open_ex(meshlink_handle_t *mesh, meshlink_n
 
 		if(!n->utcp) {
 			meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
+			pthread_mutex_unlock(&mesh->mutex);
 			return NULL;
 		}
 	}
 
 	if(n->status.blacklisted) {
 		logger(mesh, MESHLINK_ERROR, "Cannot open a channel with blacklisted node\n");
+		meshlink_errno = MESHLINK_EBLACKLISTED;
+		pthread_mutex_unlock(&mesh->mutex);
 		return NULL;
 	}
 
 	meshlink_channel_t *channel = xzalloc(sizeof(*channel));
 	channel->node = n;
 	channel->receive_cb = cb;
+
+	if(data && !len) {
+		channel->priv = (void *)data;
+	}
+
 	channel->c = utcp_connect_ex(n->utcp, port, channel_recv, channel, flags);
 
+	pthread_mutex_unlock(&mesh->mutex);
+
 	if(!channel->c) {
 		meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
 		free(channel);
@@ -2841,7 +3724,9 @@ void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *chan
 		return;
 	}
 
+	pthread_mutex_lock(&mesh->mutex);
 	utcp_shutdown(channel->c, direction);
+	pthread_mutex_unlock(&mesh->mutex);
 }
 
 void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
@@ -2850,7 +3735,25 @@ void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel
 		return;
 	}
 
+	pthread_mutex_lock(&mesh->mutex);
+
 	utcp_close(channel->c);
+
+	/* Clean up any outstanding AIO buffers. */
+	for(meshlink_aio_buffer_t *aio = channel->aio_send, *next; aio; aio = next) {
+		next = aio->next;
+		aio_signal(mesh, channel, aio);
+		free(aio);
+	}
+
+	for(meshlink_aio_buffer_t *aio = channel->aio_receive, *next; aio; aio = next) {
+		next = aio->next;
+		aio_signal(mesh, channel, aio);
+		free(aio);
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
+
 	free(channel);
 }
 
@@ -2874,9 +3777,18 @@ ssize_t meshlink_channel_send(meshlink_handle_t *mesh, meshlink_channel_t *chann
 	// Then, preferably 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);
+	ssize_t retval;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Disallow direct calls to utcp_send() while we still have AIO active. */
+	if(channel->aio_send) {
+		retval = 0;
+	} else {
+		retval = utcp_send(channel->c, data, len);
+	}
+
+	pthread_mutex_unlock(&mesh->mutex);
 
 	if(retval < 0) {
 		meshlink_errno = MESHLINK_ENETWORK;
@@ -2885,6 +3797,146 @@ ssize_t meshlink_channel_send(meshlink_handle_t *mesh, meshlink_channel_t *chann
 	return retval;
 }
 
+bool meshlink_channel_aio_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len, meshlink_aio_cb_t cb, void *priv) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	if(!len || !data) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
+	aio->data = data;
+	aio->len = len;
+	aio->cb.buffer = cb;
+	aio->priv = priv;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Append the AIO buffer descriptor to the end of the chain */
+	meshlink_aio_buffer_t **p = &channel->aio_send;
+
+	while(*p) {
+		p = &(*p)->next;
+	}
+
+	*p = aio;
+
+	/* Ensure the poll callback is set, and call it right now to push data if possible */
+	utcp_set_poll_cb(channel->c, channel_poll);
+	channel_poll(channel->c, len);
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
+bool meshlink_channel_aio_fd_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, int fd, size_t len, meshlink_aio_fd_cb_t cb, void *priv) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	if(!len || fd == -1) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
+	aio->fd = fd;
+	aio->len = len;
+	aio->cb.fd = cb;
+	aio->priv = priv;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Append the AIO buffer descriptor to the end of the chain */
+	meshlink_aio_buffer_t **p = &channel->aio_send;
+
+	while(*p) {
+		p = &(*p)->next;
+	}
+
+	*p = aio;
+
+	/* Ensure the poll callback is set, and call it right now to push data if possible */
+	utcp_set_poll_cb(channel->c, channel_poll);
+	channel_poll(channel->c, len);
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
+bool meshlink_channel_aio_receive(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len, meshlink_aio_cb_t cb, void *priv) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	if(!len || !data) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
+	aio->data = data;
+	aio->len = len;
+	aio->cb.buffer = cb;
+	aio->priv = priv;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Append the AIO buffer descriptor to the end of the chain */
+	meshlink_aio_buffer_t **p = &channel->aio_receive;
+
+	while(*p) {
+		p = &(*p)->next;
+	}
+
+	*p = aio;
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
+bool meshlink_channel_aio_fd_receive(meshlink_handle_t *mesh, meshlink_channel_t *channel, int fd, size_t len, meshlink_aio_fd_cb_t cb, void *priv) {
+	if(!mesh || !channel) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	if(!len || fd == -1) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return false;
+	}
+
+	meshlink_aio_buffer_t *aio = xzalloc(sizeof(*aio));
+	aio->fd = fd;
+	aio->len = len;
+	aio->cb.fd = cb;
+	aio->priv = priv;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	/* Append the AIO buffer descriptor to the end of the chain */
+	meshlink_aio_buffer_t **p = &channel->aio_receive;
+
+	while(*p) {
+		p = &(*p)->next;
+	}
+
+	*p = aio;
+
+	pthread_mutex_unlock(&mesh->mutex);
+
+	return true;
+}
+
 uint32_t meshlink_channel_get_flags(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
 	if(!mesh || !channel) {
 		meshlink_errno = MESHLINK_EINVAL;
@@ -2912,6 +3964,25 @@ size_t meshlink_channel_get_recvq(meshlink_handle_t *mesh, meshlink_channel_t *c
 	return utcp_get_recvq(channel->c);
 }
 
+void meshlink_set_node_channel_timeout(meshlink_handle_t *mesh, meshlink_node_t *node, int timeout) {
+	if(!mesh || !node) {
+		meshlink_errno = MESHLINK_EINVAL;
+		return;
+	}
+
+	node_t *n = (node_t *)node;
+
+	pthread_mutex_lock(&mesh->mutex);
+
+	if(!n->utcp) {
+		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+	}
+
+	utcp_set_user_timeout(n->utcp, timeout);
+
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
 void update_node_status(meshlink_handle_t *mesh, node_t *n) {
 	if(n->status.reachable && mesh->channel_accept_cb && !n->utcp) {
 		n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
@@ -2920,6 +3991,16 @@ void update_node_status(meshlink_handle_t *mesh, node_t *n) {
 	if(mesh->node_status_cb) {
 		mesh->node_status_cb(mesh, (meshlink_node_t *)n, n->status.reachable && !n->status.blacklisted);
 	}
+
+	if(mesh->node_pmtu_cb) {
+		mesh->node_pmtu_cb(mesh, (meshlink_node_t *)n, n->minmtu);
+	}
+}
+
+void update_node_pmtu(meshlink_handle_t *mesh, node_t *n) {
+	if(mesh->node_pmtu_cb && !n->status.blacklisted) {
+		mesh->node_pmtu_cb(mesh, (meshlink_node_t *)n, n->minmtu);
+	}
 }
 
 void handle_duplicate_node(meshlink_handle_t *mesh, node_t *n) {
@@ -2939,7 +4020,7 @@ void meshlink_enable_discovery(meshlink_handle_t *mesh, bool enable) {
 		return;
 	}
 
-	pthread_mutex_lock(&mesh->mesh_mutex);
+	pthread_mutex_lock(&mesh->mutex);
 
 	if(mesh->discovery == enable) {
 		goto end;
@@ -2956,7 +4037,7 @@ void meshlink_enable_discovery(meshlink_handle_t *mesh, bool enable) {
 	mesh->discovery = enable;
 
 end:
-	pthread_mutex_unlock(&mesh->mesh_mutex);
+	pthread_mutex_unlock(&mesh->mutex);
 #else
 	(void)mesh;
 	(void)enable;
@@ -2964,21 +4045,96 @@ end:
 #endif
 }
 
+void meshlink_set_dev_class_timeouts(meshlink_handle_t *mesh, dev_class_t devclass, int pinginterval, int pingtimeout) {
+	if(!mesh || devclass < 0 || devclass >= DEV_CLASS_COUNT) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	if(pinginterval < 1 || pingtimeout < 1 || pingtimeout > pinginterval) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	mesh->dev_class_traits[devclass].pinginterval = pinginterval;
+	mesh->dev_class_traits[devclass].pingtimeout = pingtimeout;
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+void meshlink_set_dev_class_fast_retry_period(meshlink_handle_t *mesh, dev_class_t devclass, int fast_retry_period) {
+	if(!mesh || devclass < 0 || devclass >= DEV_CLASS_COUNT) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	if(fast_retry_period < 0) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	mesh->dev_class_traits[devclass].fast_retry_period = fast_retry_period;
+	pthread_mutex_unlock(&mesh->mutex);
+}
+
+extern void meshlink_set_inviter_commits_first(struct meshlink_handle *mesh, bool inviter_commits_first) {
+	if(!mesh) {
+		meshlink_errno = EINVAL;
+		return;
+	}
+
+	pthread_mutex_lock(&mesh->mutex);
+	mesh->inviter_commits_first = inviter_commits_first;
+	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 handle_network_change(meshlink_handle_t *mesh, bool online) {
+	(void)online;
+
+	if(!mesh->connections || !mesh->loop.running) {
+		return;
+	}
+
+	retry(mesh);
+}
+
+void call_error_cb(meshlink_handle_t *mesh, meshlink_errno_t meshlink_errno) {
+	// We should only call the callback function if we are in the background thread.
+	if(!mesh->error_cb) {
+		return;
+	}
+
+	if(!mesh->threadstarted) {
+		return;
+	}
+
+	if(mesh->thread == pthread_self()) {
+		mesh->error_cb(mesh, meshlink_errno);
+	}
+}
+
 static void __attribute__((constructor)) meshlink_init(void) {
 	crypto_init();
-	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
-};