From cdd7f1eb5ce6a34347a3ed57d7cd91cebf166673 Mon Sep 17 00:00:00 2001 From: Niklas Hofmann Date: Fri, 8 Aug 2014 11:05:17 +0200 Subject: [PATCH] use uuid for hostname and service name, because we exchange all important information via service type and TXT record --- src/discovery.c | 134 +++++++++++++++++++++++++++++------------------- 1 file changed, 81 insertions(+), 53 deletions(-) diff --git a/src/discovery.c b/src/discovery.c index d31fc56d..ea1f6b73 100644 --- a/src/discovery.c +++ b/src/discovery.c @@ -18,6 +18,7 @@ #include #define MESHLINK_MDNS_SERVICE_TYPE "_meshlink._tcp" +#define MESHLINK_MDNS_NAME_KEY "name" #define MESHLINK_MDNS_FINGERPRINT_KEY "fingerprint" static void discovery_entry_group_callback(AvahiServer *server, AvahiSEntryGroup *group, AvahiEntryGroupState state, void *userdata) @@ -26,7 +27,6 @@ static void discovery_entry_group_callback(AvahiServer *server, AvahiSEntryGroup // asserts assert(mesh != NULL); - assert(mesh->name != NULL); assert(mesh->avahi_server != NULL); assert(mesh->avahi_poll != NULL); @@ -35,11 +35,12 @@ static void discovery_entry_group_callback(AvahiServer *server, AvahiSEntryGroup { case AVAHI_ENTRY_GROUP_ESTABLISHED: /* The entry group has been established successfully */ - fprintf(stderr, "Service '%s' successfully established.\n", mesh->name); + fprintf(stderr, "Service successfully established.\n"); break; case AVAHI_ENTRY_GROUP_COLLISION: - fprintf(stderr, "Service name collision '%s'\n", mesh->name); + fprintf(stderr, "Service collision\n"); + // @TODO can we just set a new name and retry? break; case AVAHI_ENTRY_GROUP_FAILURE : @@ -57,6 +58,8 @@ static void discovery_entry_group_callback(AvahiServer *server, AvahiSEntryGroup static void discovery_create_services(meshlink_handle_t *mesh) { + char *txt_name = NULL; + // asserts assert(mesh != NULL); assert(mesh->name != NULL); @@ -64,7 +67,7 @@ static void discovery_create_services(meshlink_handle_t *mesh) assert(mesh->avahi_server != NULL); assert(mesh->avahi_poll != NULL); - fprintf(stderr, "Adding service '%s'\n", mesh->name); + fprintf(stderr, "Adding service\n"); /* Ifthis is the first time we're called, let's create a new entry group */ if(!mesh->avahi_group) @@ -76,13 +79,24 @@ static void discovery_create_services(meshlink_handle_t *mesh) } } - /* Create txt record */ - char txt_fingerprint[MESHLINK_FINGERPRINTLEN + sizeof(MESHLINK_MDNS_FINGERPRINT_KEY) + 2]; - snprintf(txt_fingerprint, sizeof(txt_fingerprint), "%s=%s", MESHLINK_MDNS_FINGERPRINT_KEY, meshlink_get_fingerprint(mesh, meshlink_get_node(mesh, mesh->name))); + /* Create txt records */ + size_t txt_name_len = sizeof(MESHLINK_MDNS_NAME_KEY) + 1 + strlen(mesh->name) + 1; + txt_name = malloc(txt_name_len); + snprintf(txt_name, txt_name_len, "%s=%s", MESHLINK_MDNS_NAME_KEY, mesh->name); + + char txt_fingerprint[sizeof(MESHLINK_MDNS_FINGERPRINT_KEY) + 1 + MESHLINK_FINGERPRINTLEN + 1]; + snprintf(txt_fingerprint, sizeof(txt_fingerprint), "%s=%s", MESHLINK_MDNS_FINGERPRINT_KEY, meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self)); + + // Generate a name for the service (actually we do not care) + uuid_t srvname; + uuid_generate(srvname); + + char srvnamestr[36+1]; + uuid_unparse_lower(srvname, srvnamestr); /* Add the service */ int ret = 0; - if((ret = avahi_server_add_service(mesh->avahi_server, mesh->avahi_group, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, 0, mesh->name, MESHLINK_MDNS_SERVICE_TYPE, NULL, NULL, atoi(mesh->myport), txt_fingerprint, NULL)) < 0) + if((ret = avahi_server_add_service(mesh->avahi_server, mesh->avahi_group, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, 0, srvnamestr, MESHLINK_MDNS_SERVICE_TYPE, NULL, NULL, atoi(mesh->myport), txt_name, txt_fingerprint, NULL)) < 0) { fprintf(stderr, "Failed to add service: %s\n", avahi_strerror(ret)); goto fail; @@ -95,10 +109,14 @@ static void discovery_create_services(meshlink_handle_t *mesh) goto fail; } - return; + goto done; fail: avahi_simple_poll_quit(mesh->avahi_poll); + +done: + if(txt_name) + free(txt_name); } static void discovery_server_callback(AvahiServer *server, AvahiServerState state, void * userdata) @@ -127,14 +145,15 @@ static void discovery_server_callback(AvahiServer *server, AvahiServerState stat assert(mesh->avahi_server != NULL); assert(mesh->avahi_poll != NULL); - fprintf(stderr, "Host name collision with '%s'\n", avahi_server_get_host_name(mesh->avahi_server)); - /* A host name collision happened. Let's pick a new name for the server */ - /* - char *new_name = avahi_alternative_host_name(avahi_server_get_host_name(mesh->avahi_server)); - fprintf(stderr, "Host name collision, retrying with '%s'\n", new_name); - int result = avahi_server_set_host_name(mesh->avahi_server, new_name); - avahi_free(new_name); + uuid_t hostname; + uuid_generate(hostname); + + char hostnamestr[36+1]; + uuid_unparse_lower(hostname, hostnamestr); + + fprintf(stderr, "Host name collision, retrying with '%s'\n", hostnamestr); + int result = avahi_server_set_host_name(mesh->avahi_server, hostnamestr); if(result < 0) { @@ -142,7 +161,6 @@ static void discovery_server_callback(AvahiServer *server, AvahiServerState stat avahi_simple_poll_quit(mesh->avahi_poll); return; } - */ } break; @@ -233,53 +251,63 @@ static void discovery_resolve_callback(AvahiSServiceResolver *resolver, AvahiIfI avahi_free(strtxt); // retrieve fingerprint - AvahiStringList *fgli = avahi_string_list_find(txt, MESHLINK_MDNS_FINGERPRINT_KEY); - meshlink_node_t *node = meshlink_get_node(mesh, name); - - fprintf(stderr, "%p, %p, %s, %s\n", fgli, node, avahi_string_list_get_text(fgli), meshlink_get_fingerprint(mesh, node)); + AvahiStringList *node_name_li = avahi_string_list_find(txt, MESHLINK_MDNS_NAME_KEY); + AvahiStringList *node_fp_li = avahi_string_list_find(txt, MESHLINK_MDNS_FINGERPRINT_KEY); - if(node && fgli && strcmp(avahi_string_list_get_text(fgli) + strlen(MESHLINK_MDNS_FINGERPRINT_KEY) + 1, meshlink_get_fingerprint(mesh, node)) == 0 ) + if(node_name_li != NULL && node_fp_li != NULL) { - fprintf(stderr, "Node %s is part of the mesh network.\n", node->name); + char *node_name = avahi_string_list_get_text(node_name_li) + strlen(MESHLINK_MDNS_NAME_KEY) + 1; + char *node_fp = avahi_string_list_get_text(node_fp_li) + strlen(MESHLINK_MDNS_FINGERPRINT_KEY) + 1; - sockaddr_t naddress; - memset(&naddress, 0, sizeof(naddress)); - - switch(address->proto) - { - case AVAHI_PROTO_INET: - { - naddress.in.sin_family = AF_INET; - naddress.in.sin_port = port; - naddress.in.sin_addr.s_addr = address->data.ipv4.address; - } - break; - - case AVAHI_PROTO_INET6: - { - naddress.in6.sin6_family = AF_INET6; - naddress.in6.sin6_port = port; - memcpy(naddress.in6.sin6_addr.s6_addr, address->data.ipv6.address, sizeof(naddress.in6.sin6_addr.s6_addr)); - } - break; - - default: - naddress.unknown.family = AF_UNKNOWN; - break; - } + meshlink_node_t *node = meshlink_get_node(mesh, node_name); - if(naddress.unknown.family != AF_UNKNOWN) + if(node != NULL) { - meshlink_hint_address(mesh, node, (struct sockaddr*)&naddress); + fprintf(stderr, "Node %s is part of the mesh network.\n", node->name); + + sockaddr_t naddress; + memset(&naddress, 0, sizeof(naddress)); + + switch(address->proto) + { + case AVAHI_PROTO_INET: + { + naddress.in.sin_family = AF_INET; + naddress.in.sin_port = port; + naddress.in.sin_addr.s_addr = address->data.ipv4.address; + } + break; + + case AVAHI_PROTO_INET6: + { + naddress.in6.sin6_family = AF_INET6; + naddress.in6.sin6_port = port; + memcpy(naddress.in6.sin6_addr.s6_addr, address->data.ipv6.address, sizeof(naddress.in6.sin6_addr.s6_addr)); + } + 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); + } + else + { + fprintf(stderr, "Could not resolve node %s to a known address family type.\n", node->name); + } } else { - fprintf(stderr, "Could not resolve node %s to a known address family type.\n", node->name); + fprintf(stderr, "Node %s is not part of the mesh network.\n", node_name); } } else { - fprintf(stderr, "Node %s is not part of the mesh network.\n", node ? node->name : "n/a"); + fprintf(stderr, "TXT records missing.\n"); } } break; @@ -375,7 +403,7 @@ bool discovery_start(meshlink_handle_t *mesh) goto fail; } - // generate random host name + // generate some unique host name (we actually do not care about it) uuid_t hostname; uuid_generate(hostname); -- 2.39.5