Use condition variables to wait for threads to finish initializing.

To prevent a race condition when calling meshlink_stop() right after
meshlink_start(), we need to wait for the MeshLink and Catta threads to
finish initializing before we can return from meshlink_start().

diff --git a/src/discovery.c b/src/discovery.c
index 076bddcfd08201db5163636d21f24d604b25cdbd..9064523c9c603222cd2e55bd8736a56c1f712ec5 100644 (file)
--- a/src/discovery.c
+++ b/src/discovery.c
@@ -78,16 +78,12 @@ static void discovery_create_services(meshlink_handle_t *mesh) {
        assert(mesh->catta_servicetype != NULL);
        assert(mesh->self != NULL);
 
-       pthread_mutex_lock(&(mesh->mesh_mutex));
-
        logger(mesh, MESHLINK_DEBUG, "Adding service\n");
 
        /* Ifthis is the first time we're called, let's create a new entry group */
-       if(!mesh->catta_group) {
-               if(!(mesh->catta_group = catta_s_entry_group_new(mesh->catta_server, discovery_entry_group_callback, mesh))) {
-                       logger(mesh, MESHLINK_ERROR, "catta_entry_group_new() failed: %s\n", catta_strerror(catta_server_errno(mesh->catta_server)));
-                       goto fail;
-               }
+       if(!(mesh->catta_group = catta_s_entry_group_new(mesh->catta_server, discovery_entry_group_callback, mesh))) {
+               logger(mesh, MESHLINK_ERROR, "catta_entry_group_new() failed: %s\n", catta_strerror(catta_server_errno(mesh->catta_server)));
+               goto fail;
        }
 
        /* Create txt records */
@@ -131,32 +127,41 @@ static void discovery_server_callback(CattaServer *server, CattaServerState stat
 
        switch(state) {
        case CATTA_SERVER_RUNNING:
-
                /* The serve has startup successfully and registered its host
                 * name on the network, so it's time to create our services */
+               pthread_mutex_lock(&(mesh->mesh_mutex));
+
                if(!mesh->catta_group) {
                        discovery_create_services(mesh);
                }
 
+               pthread_mutex_unlock(&(mesh->mesh_mutex));
+
                break;
 
        case CATTA_SERVER_COLLISION: {
+               /* A host name collision happened. Let's pick a new name for the server */
+               char hostname[17];
+               generate_rand_string(hostname, sizeof(hostname));
+
+               pthread_mutex_lock(&(mesh->mesh_mutex));
+               //
                // asserts
                assert(mesh->catta_server != NULL);
                assert(mesh->catta_poll != NULL);
 
-               /* A host name collision happened. Let's pick a new name for the server */
-               char hostname[17];
-               generate_rand_string(hostname, sizeof(hostname));
                int result = catta_server_set_host_name(mesh->catta_server, hostname);
 
                if(result < 0) {
                        catta_simple_poll_quit(mesh->catta_poll);
                }
+
+               pthread_mutex_unlock(&(mesh->mesh_mutex));
        }
        break;
 
        case CATTA_SERVER_REGISTERING:
+               pthread_mutex_lock(&(mesh->mesh_mutex));
 
                /* Let's drop our registered services. When the server is back
                 * in CATTA_SERVER_RUNNING state we will register them
@@ -166,15 +171,21 @@ static void discovery_server_callback(CattaServer *server, CattaServerState stat
                        mesh->catta_group = NULL;
                }
 
+               pthread_mutex_unlock(&(mesh->mesh_mutex));
+
                break;
 
        case CATTA_SERVER_FAILURE:
+               pthread_mutex_lock(&(mesh->mesh_mutex));
+
                // asserts
                assert(mesh->catta_server != NULL);
                assert(mesh->catta_poll != NULL);
 
                /* Terminate on failure */
                catta_simple_poll_quit(mesh->catta_poll);
+
+               pthread_mutex_unlock(&(mesh->mesh_mutex));
                break;
 
        case CATTA_SERVER_INVALID:
@@ -186,103 +197,87 @@ static void discovery_resolve_callback(CattaSServiceResolver *resolver, CattaIfI
        (void)interface_;
        (void)protocol;
        (void)flags;
-       meshlink_handle_t *mesh = userdata;
+       (void)name;
+       (void)type;
+       (void)domain;
+       (void)host_name;
 
-       // asserts
-       assert(resolver != NULL);
-       assert(mesh != NULL);
-       assert(mesh->catta_server != NULL);
+       meshlink_handle_t *mesh = userdata;
 
-       /* Called whenever a service has been resolved successfully or timed out */
-       switch(event) {
-       case CATTA_RESOLVER_FAILURE:
-               // asserts
-               assert(name != NULL);
-               assert(type != NULL);
-               assert(domain != NULL);
-               break;
+       if(event != CATTA_RESOLVER_FOUND) {
+               catta_s_service_resolver_free(resolver);
+               return;
+       }
 
-       case CATTA_RESOLVER_FOUND: {
-               // asserts
-               assert(name != NULL);
-               assert(type != NULL);
-               assert(domain != NULL);
-               assert(host_name != NULL);
-               assert(address != NULL);
-               assert(txt != NULL);
+       // retrieve fingerprint
+       CattaStringList *node_name_li = catta_string_list_find(txt, MESHLINK_MDNS_NAME_KEY);
+       CattaStringList *node_fp_li = catta_string_list_find(txt, MESHLINK_MDNS_FINGERPRINT_KEY);
 
-               // retrieve fingerprint
-               CattaStringList *node_name_li = catta_string_list_find(txt, MESHLINK_MDNS_NAME_KEY);
-               CattaStringList *node_fp_li = catta_string_list_find(txt, MESHLINK_MDNS_FINGERPRINT_KEY);
+       if(node_name_li != NULL && node_fp_li != NULL) {
+               char *node_name = (char *)catta_string_list_get_text(node_name_li) + strlen(MESHLINK_MDNS_NAME_KEY);
+               char *node_fp = (char *)catta_string_list_get_text(node_fp_li) + strlen(MESHLINK_MDNS_FINGERPRINT_KEY);
 
-               if(node_name_li != NULL && node_fp_li != NULL) {
-                       char *node_name = (char *)catta_string_list_get_text(node_name_li) + strlen(MESHLINK_MDNS_NAME_KEY);
-                       char *node_fp = (char *)catta_string_list_get_text(node_fp_li) + strlen(MESHLINK_MDNS_FINGERPRINT_KEY);
+               if(node_name[0] == '=' && node_fp[0] == '=') {
+                       pthread_mutex_lock(&(mesh->mesh_mutex));
 
-                       if(node_name[0] == '=' && node_fp[0] == '=') {
-                               pthread_mutex_lock(&(mesh->mesh_mutex));
+                       node_name += 1;
+                       node_fp += 1;
 
-                               node_name += 1;
-                               node_fp += 1;
+                       meshlink_node_t *node = meshlink_get_node(mesh, node_name);
 
-                               meshlink_node_t *node = meshlink_get_node(mesh, node_name);
+                       if(node != NULL) {
+                               logger(mesh, MESHLINK_INFO, "Node %s is part of the mesh network.\n", node->name);
 
-                               if(node != NULL) {
-                                       logger(mesh, MESHLINK_INFO, "Node %s is part of the mesh network.\n", node->name);
+                               sockaddr_t naddress;
+                               memset(&naddress, 0, sizeof(naddress));
 
-                                       sockaddr_t naddress;
-                                       memset(&naddress, 0, sizeof(naddress));
+                               switch(address->proto) {
+                               case CATTA_PROTO_INET: {
+                                       naddress.in.sin_family = AF_INET;
+                                       naddress.in.sin_port = htons(port);
+                                       naddress.in.sin_addr.s_addr = address->data.ipv4.address;
+                               }
+                               break;
 
-                                       switch(address->proto) {
-                                       case CATTA_PROTO_INET: {
-                                               naddress.in.sin_family = AF_INET;
-                                               naddress.in.sin_port = htons(port);
-                                               naddress.in.sin_addr.s_addr = address->data.ipv4.address;
-                                       }
-                                       break;
+                               case CATTA_PROTO_INET6: {
+                                       naddress.in6.sin6_family = AF_INET6;
+                                       naddress.in6.sin6_port = htons(port);
+                                       memcpy(naddress.in6.sin6_addr.s6_addr, address->data.ipv6.address, sizeof(naddress.in6.sin6_addr.s6_addr));
+                               }
+                               break;
 
-                                       case CATTA_PROTO_INET6: {
-                                               naddress.in6.sin6_family = AF_INET6;
-                                               naddress.in6.sin6_port = htons(port);
-                                               memcpy(naddress.in6.sin6_addr.s6_addr, address->data.ipv6.address, sizeof(naddress.in6.sin6_addr.s6_addr));
-                                       }
+                               default:
+                                       naddress.unknown.family = AF_UNKNOWN;
                                        break;
+                               }
 
-                                       default:
-                                               naddress.unknown.family = AF_UNKNOWN;
-                                               break;
-                                       }
-
-                                       if(naddress.unknown.family != AF_UNKNOWN) {
-                                               meshlink_hint_address(mesh, (meshlink_node_t *)node, (struct sockaddr *)&naddress);
-
-                                               node_t *n = (node_t *)node;
+                               if(naddress.unknown.family != AF_UNKNOWN) {
+                                       meshlink_hint_address(mesh, (meshlink_node_t *)node, (struct sockaddr *)&naddress);
 
-                                               if(n->connection && n->connection->outgoing) {
-                                                       n->connection->outgoing->timeout = 0;
+                                       node_t *n = (node_t *)node;
 
-                                                       if(n->connection->outgoing->ev.cb) {
-                                                               timeout_set(&mesh->loop, &n->connection->outgoing->ev, &(struct timeval) {
-                                                                       0, 0
-                                                               });
-                                                       }
+                                       if(n->connection && n->connection->outgoing) {
+                                               n->connection->outgoing->timeout = 0;
 
-                                                       n->connection->last_ping_time = 0;
+                                               if(n->connection->outgoing->ev.cb) {
+                                                       timeout_set(&mesh->loop, &n->connection->outgoing->ev, &(struct timeval) {
+                                                               0, 0
+                                                       });
                                                }
 
-                                       } else {
-                                               logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", node->name);
+                                               n->connection->last_ping_time = 0;
                                        }
+
                                } else {
-                                       logger(mesh, MESHLINK_WARNING, "Node %s is not part of the mesh network.\n", node_name);
+                                       logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", node->name);
                                }
-
-                               pthread_mutex_unlock(&(mesh->mesh_mutex));
+                       } else {
+                               logger(mesh, MESHLINK_WARNING, "Node %s is not part of the mesh network.\n", node_name);
                        }
+
+                       pthread_mutex_unlock(&(mesh->mesh_mutex));
                }
        }
-       break;
-       }
 
        catta_s_service_resolver_free(resolver);
 }
@@ -292,20 +287,17 @@ static void discovery_browse_callback(CattaSServiceBrowser *browser, CattaIfInde
        (void)flags;
        meshlink_handle_t *mesh = userdata;
 
-       // asserts
-       assert(mesh != NULL);
-       assert(mesh->catta_server != NULL);
-       assert(mesh->catta_poll != NULL);
-
        /* Called whenever a new services becomes available on the LAN or is removed from the LAN */
        switch(event) {
        case CATTA_BROWSER_FAILURE:
+               pthread_mutex_lock(&mesh->mesh_mutex);
                catta_simple_poll_quit(mesh->catta_poll);
+               pthread_mutex_unlock(&mesh->mesh_mutex);
                break;
 
        case CATTA_BROWSER_NEW:
-               catta_s_service_resolver_new(mesh->catta_server, interface_, protocol, name, type, domain, CATTA_PROTO_UNSPEC, 0, discovery_resolve_callback, mesh);
                pthread_mutex_lock(&mesh->mesh_mutex);
+               catta_s_service_resolver_new(mesh->catta_server, interface_, protocol, name, type, domain, CATTA_PROTO_UNSPEC, 0, discovery_resolve_callback, mesh);
                handle_network_change(mesh, ++mesh->catta_interfaces);
                pthread_mutex_unlock(&mesh->mesh_mutex);
                break;
@@ -405,6 +397,10 @@ static void *discovery_loop(void *userdata) {
                goto fail;
        }
 
+       pthread_mutex_lock(&mesh->discovery_mutex);
+       pthread_cond_broadcast(&mesh->discovery_cond);
+       pthread_mutex_unlock(&mesh->discovery_mutex);
+
        catta_simple_poll_loop(mesh->catta_poll);
 
 fail:
@@ -456,6 +452,10 @@ bool discovery_start(meshlink_handle_t *mesh) {
                return false;
        }
 
+       pthread_mutex_lock(&mesh->discovery_mutex);
+       pthread_cond_wait(&mesh->discovery_cond, &mesh->discovery_mutex);
+       pthread_mutex_unlock(&mesh->discovery_mutex);
+
        mesh->discovery_threadstarted = true;
 
        return true;

diff --git a/src/meshlink.c b/src/meshlink.c
index 7e2e20e5c358b08b4ad7a57789055671cca3d626..20dad9f43caf437d15155931f2d528b3e1a30e42 100644 (file)
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -1382,16 +1382,16 @@ 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) {
@@ -1400,10 +1400,15 @@ static void *meshlink_main_loop(void *arg) {
 
 #endif
 
+       pthread_mutex_lock(&(mesh->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));
+
 #if HAVE_CATTA
 
        // Stop discovery
@@ -1413,7 +1418,6 @@ static void *meshlink_main_loop(void *arg) {
 
 #endif
 
-       pthread_mutex_unlock(&(mesh->mesh_mutex));
        return NULL;
 }
 
@@ -1430,6 +1434,9 @@ bool meshlink_start(meshlink_handle_t *mesh) {
 
        pthread_mutex_lock(&(mesh->mesh_mutex));
 
+       assert(mesh->self->ecdsa);
+       assert(!memcmp((uint8_t *)mesh->self->ecdsa + 64, (uint8_t *)mesh->private_key + 64, 32));
+
        if(mesh->threadstarted) {
                logger(mesh, MESHLINK_DEBUG, "thread was already running\n");
                pthread_mutex_unlock(&(mesh->mesh_mutex));
@@ -1469,12 +1476,9 @@ bool meshlink_start(meshlink_handle_t *mesh) {
                return false;
        }
 
+       pthread_cond_wait(&mesh->cond, &mesh->mesh_mutex);
        mesh->threadstarted = true;
 
-       assert(mesh->self->ecdsa);
-       assert(!memcmp((uint8_t *)mesh->self->ecdsa + 64, (uint8_t *)mesh->private_key + 64, 32));
-
-
        pthread_mutex_unlock(&(mesh->mesh_mutex));
        return true;
 }

diff --git a/src/meshlink_internal.h b/src/meshlink_internal.h
index 4056df316ed0ed27cd1fb391e08ee836ddc998da..7e2955eb52ba5d096e2e9c69b8865b9dbd84c7d8 100644 (file)
--- a/src/meshlink_internal.h
+++ b/src/meshlink_internal.h
@@ -159,6 +159,9 @@ struct meshlink_handle {
 
        // Thread management
        pthread_t thread;
+       pthread_cond_t cond;
+       pthread_mutex_t discovery_mutex;
+       pthread_cond_t discovery_cond;
        bool threadstarted;
        bool discovery_threadstarted;