+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;
+ meshlink_handle_t *mesh = n->mesh;
+ return meshlink_send(mesh, (meshlink_node_t *)n, data, len) ? len : -1;
+}
+
+void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_receive_cb_t cb) {
+ if(!mesh || !channel) {
+ meshlink_errno = MESHLINK_EINVAL;
+ return;
+ }
+
+ channel->receive_cb = cb;
+}
+
+static void channel_receive(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len) {
+ node_t *n = (node_t *)source;
+ if(!n->utcp)
+ abort();
+ utcp_recv(n->utcp, data, len);
+}
+
+static void channel_poll(struct utcp_connection *connection, size_t len) {
+ meshlink_channel_t *channel = connection->priv;
+ if(!channel)
+ abort();
+ node_t *n = channel->node;
+ meshlink_handle_t *mesh = n->mesh;
+ if(channel->poll_cb)
+ channel->poll_cb(mesh, channel, len);
+}
+
+void meshlink_set_channel_poll_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_poll_cb_t cb) {
+ channel->poll_cb = cb;
+ utcp_set_poll_cb(channel->c, cb ? channel_poll : NULL);
+}
+
+void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb) {
+ if(!mesh) {
+ meshlink_errno = MESHLINK_EINVAL;
+ return;
+ }
+
+ pthread_mutex_lock(&mesh->mesh_mutex);
+ mesh->channel_accept_cb = cb;
+ mesh->receive_cb = channel_receive;
+ for splay_each(node_t, n, mesh->nodes) {
+ if(!n->utcp && n != mesh->self)
+ n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+ }
+ pthread_mutex_unlock(&mesh->mesh_mutex);
+}
+
+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(!mesh || !node) {
+ meshlink_errno = MESHLINK_EINVAL;
+ return NULL;
+ }
+
+ node_t *n = (node_t *)node;
+ if(!n->utcp) {
+ n->utcp = utcp_init(channel_accept, channel_pre_accept, channel_send, n);
+ mesh->receive_cb = channel_receive;
+ if(!n->utcp) {
+ meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
+ return NULL;
+ }
+ }
+ meshlink_channel_t *channel = xzalloc(sizeof(*channel));
+ channel->node = n;
+ channel->receive_cb = cb;
+ channel->c = utcp_connect_ex(n->utcp, port, channel_recv, channel, flags);
+ if(!channel->c) {
+ meshlink_errno = errno == ENOMEM ? MESHLINK_ENOMEM : MESHLINK_EINTERNAL;
+ free(channel);
+ return NULL;
+ }
+ return channel;
+}
+
+meshlink_channel_t *meshlink_channel_open(meshlink_handle_t *mesh, meshlink_node_t *node, uint16_t port, meshlink_channel_receive_cb_t cb, const void *data, size_t len) {
+ return meshlink_channel_open_ex(mesh, node, port, cb, data, len, MESHLINK_CHANNEL_TCP);
+}
+
+void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *channel, int direction) {
+ if(!mesh || !channel) {
+ meshlink_errno = MESHLINK_EINVAL;
+ return;
+ }
+
+ utcp_shutdown(channel->c, direction);
+}
+
+void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel) {
+ if(!mesh || !channel) {
+ meshlink_errno = MESHLINK_EINVAL;
+ return;
+ }