/* This file is part of GNUnet (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Christian Grothoff (and other contributing authors) GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @file transport/plugin_transport_tcp.c * @brief Implementation of the TCP transport service * @author Christian Grothoff */ #include "platform.h" #include "gnunet_hello_lib.h" #include "gnunet_connection_lib.h" #include "gnunet_container_lib.h" #include "gnunet_os_lib.h" #include "gnunet_protocols.h" #include "gnunet_resolver_service.h" #include "gnunet_server_lib.h" #include "gnunet_service_lib.h" #include "gnunet_signatures.h" #include "gnunet_statistics_service.h" #include "gnunet_transport_service.h" #include "plugin_transport.h" #include "transport.h" #define DEBUG_TCP GNUNET_NO /** * How long until we give up on transmitting the welcome message? */ #define HOSTNAME_RESOLVE_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5) /** * Initial handshake message for a session. */ struct WelcomeMessage { /** * Type is GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME. */ struct GNUNET_MessageHeader header; /** * Identity of the node connecting (TCP client) */ struct GNUNET_PeerIdentity clientIdentity; }; /** * Encapsulation of all of the state of the plugin. */ struct Plugin; /** * Information kept for each message that is yet to * be transmitted. */ struct PendingMessage { /** * This is a doubly-linked list. */ struct PendingMessage *next; /** * This is a doubly-linked list. */ struct PendingMessage *prev; /** * The pending message */ const char *msg; /** * Continuation function to call once the message * has been sent. Can be NULL if there is no * continuation to call. */ GNUNET_TRANSPORT_TransmitContinuation transmit_cont; /** * Closure for transmit_cont. */ void *transmit_cont_cls; /** * Timeout value for the pending message. */ struct GNUNET_TIME_Absolute timeout; /** * So that the gnunet-service-transport can group messages together, * these pending messages need to accept a message buffer and size * instead of just a GNUNET_MessageHeader. */ size_t message_size; }; /** * Session handle for TCP connections. */ struct Session { /** * Stored in a linked list. */ struct Session *next; /** * Pointer to the global plugin struct. */ struct Plugin *plugin; /** * The client (used to identify this connection) */ struct GNUNET_SERVER_Client *client; /** * Messages currently pending for transmission * to this peer, if any. */ struct PendingMessage *pending_messages_head; /** * Messages currently pending for transmission * to this peer, if any. */ struct PendingMessage *pending_messages_tail; /** * Handle for pending transmission request. */ struct GNUNET_CONNECTION_TransmitHandle *transmit_handle; /** * To whom are we talking to (set to our identity * if we are still waiting for the welcome message) */ struct GNUNET_PeerIdentity target; /** * ID of task used to delay receiving more to throttle sender. */ GNUNET_SCHEDULER_TaskIdentifier receive_delay_task; /** * Address of the other peer (either based on our 'connect' * call or on our 'accept' call). */ void *connect_addr; /** * Last activity on this connection. Used to select preferred * connection. */ struct GNUNET_TIME_Absolute last_activity; /** * Length of connect_addr. */ size_t connect_alen; /** * Are we still expecting the welcome message? (GNUNET_YES/GNUNET_NO) */ int expecting_welcome; /** * Was this a connection that was inbound (we accepted)? (GNUNET_YES/GNUNET_NO) */ int inbound; }; /** * Encapsulation of all of the state of the plugin. */ struct Plugin { /** * Our environment. */ struct GNUNET_TRANSPORT_PluginEnvironment *env; /** * The listen socket. */ struct GNUNET_CONNECTION_Handle *lsock; /** * List of open TCP sessions. */ struct Session *sessions; /** * Handle for the statistics service. */ struct GNUNET_STATISTICS_Handle *statistics; /** * Handle to the network service. */ struct GNUNET_SERVICE_Context *service; /** * Handle to the server for this service. */ struct GNUNET_SERVER_Handle *server; /** * Copy of the handler array where the closures are * set to this struct's instance. */ struct GNUNET_SERVER_MessageHandler *handlers; /** * Handle for request of hostname resolution, non-NULL if pending. */ struct GNUNET_RESOLVER_RequestHandle *hostname_dns; /** * ID of task used to update our addresses when one expires. */ GNUNET_SCHEDULER_TaskIdentifier address_update_task; /** * Port that we are actually listening on. */ uint16_t open_port; /** * Port that the user said we would have visible to the * rest of the world. */ uint16_t adv_port; }; /** * Find the session handle for the given client. * * @return NULL if no matching session exists */ static struct Session * find_session_by_client (struct Plugin *plugin, const struct GNUNET_SERVER_Client *client) { struct Session *ret; ret = plugin->sessions; while ((ret != NULL) && (client != ret->client)) ret = ret->next; return ret; } /** * Create a new session. Also queues a welcome message. * * @param plugin us * @param target peer to connect to * @param client client to use * @return new session object */ static struct Session * create_session (struct Plugin *plugin, const struct GNUNET_PeerIdentity *target, struct GNUNET_SERVER_Client *client) { struct Session *ret; struct PendingMessage *pm; struct WelcomeMessage welcome; GNUNET_assert (client != NULL); GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Creating new session for peer `%4s'\n", GNUNET_i2s (target)); ret = GNUNET_malloc (sizeof (struct Session)); ret->last_activity = GNUNET_TIME_absolute_get (); ret->plugin = plugin; ret->next = plugin->sessions; plugin->sessions = ret; ret->client = client; ret->target = *target; ret->expecting_welcome = GNUNET_YES; pm = GNUNET_malloc (sizeof (struct PendingMessage) + sizeof (struct WelcomeMessage)); pm->msg = (const char*) &pm[1]; pm->message_size = sizeof (struct WelcomeMessage); welcome.header.size = htons (sizeof (struct WelcomeMessage)); welcome.header.type = htons (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME); welcome.clientIdentity = *plugin->env->my_identity; memcpy (&pm[1], &welcome, sizeof (welcome)); pm->timeout = GNUNET_TIME_UNIT_FOREVER_ABS; GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes currently in TCP buffers"), pm->message_size, GNUNET_NO); GNUNET_CONTAINER_DLL_insert (ret->pending_messages_head, ret->pending_messages_tail, pm); GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# TCP sessions active"), 1, GNUNET_NO); return ret; } /** * If we have pending messages, ask the server to * transmit them (schedule the respective tasks, etc.) * * @param session for which session should we do this */ static void process_pending_messages (struct Session *session); /** * Function called to notify a client about the socket * being ready to queue more data. "buf" will be * NULL and "size" zero if the socket was closed for * writing in the meantime. * * @param cls closure * @param size number of bytes available in buf * @param buf where the callee should write the message * @return number of bytes written to buf */ static size_t do_transmit (void *cls, size_t size, void *buf) { struct Session *session = cls; struct GNUNET_PeerIdentity pid; struct Plugin *plugin; struct PendingMessage *pos; struct PendingMessage *hd; struct PendingMessage *tl; struct GNUNET_TIME_Absolute now; char *cbuf; size_t ret; session->transmit_handle = NULL; plugin = session->plugin; if (buf == NULL) { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Timeout trying to transmit to peer `%4s', discarding message queue.\n", GNUNET_i2s (&session->target)); #endif /* timeout; cancel all messages that have already expired */ hd = NULL; tl = NULL; ret = 0; now = GNUNET_TIME_absolute_get (); while ( (NULL != (pos = session->pending_messages_head)) && (pos->timeout.value <= now.value) ) { GNUNET_CONTAINER_DLL_remove (session->pending_messages_head, session->pending_messages_tail, pos); #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Failed to transmit %u byte message to `%4s'.\n", pos->message_size, GNUNET_i2s (&session->target)); #endif ret += pos->message_size; GNUNET_CONTAINER_DLL_insert_after (hd, tl, tl, pos); } /* do this call before callbacks (so that if callbacks destroy session, they have a chance to cancel actions done by this call) */ process_pending_messages (session); pid = session->target; /* no do callbacks and do not use session again since the callbacks may abort the session */ while (NULL != (pos = hd)) { GNUNET_CONTAINER_DLL_remove (hd, tl, pos); if (pos->transmit_cont != NULL) pos->transmit_cont (pos->transmit_cont_cls, &pid, GNUNET_SYSERR); GNUNET_free (pos); } GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes currently in TCP buffers"), - (int64_t) ret, GNUNET_NO); GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes discarded by TCP (timeout)"), ret, GNUNET_NO); return 0; } /* copy all pending messages that would fit */ ret = 0; cbuf = buf; hd = NULL; tl = NULL; while (NULL != (pos = session->pending_messages_head)) { if (ret + pos->message_size > size) break; GNUNET_CONTAINER_DLL_remove (session->pending_messages_head, session->pending_messages_tail, pos); GNUNET_assert (size >= pos->message_size); memcpy (cbuf, pos->msg, pos->message_size); cbuf += pos->message_size; ret += pos->message_size; size -= pos->message_size; GNUNET_CONTAINER_DLL_insert_after (hd, tl, tl, pos); } /* schedule 'continuation' before callbacks so that callbacks that cancel everything don't cause us to use a session that no longer exists... */ process_pending_messages (session); session->last_activity = GNUNET_TIME_absolute_get (); pid = session->target; /* we'll now call callbacks that may cancel the session; hence we should not use 'session' after this point */ while (NULL != (pos = hd)) { GNUNET_CONTAINER_DLL_remove (hd, tl, pos); if (pos->transmit_cont != NULL) pos->transmit_cont (pos->transmit_cont_cls, &pid, GNUNET_OK); GNUNET_free (pos); } GNUNET_assert (hd == NULL); GNUNET_assert (tl == NULL); #if DEBUG_TCP > 1 GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Transmitting %u bytes\n", ret); #endif GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes currently in TCP buffers"), - (int64_t) ret, GNUNET_NO); GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes transmitted via TCP"), ret, GNUNET_NO); return ret; } /** * If we have pending messages, ask the server to * transmit them (schedule the respective tasks, etc.) * * @param session for which session should we do this */ static void process_pending_messages (struct Session *session) { struct PendingMessage *pm; GNUNET_assert (session->client != NULL); if (session->transmit_handle != NULL) return; if (NULL == (pm = session->pending_messages_head)) return; session->transmit_handle = GNUNET_SERVER_notify_transmit_ready (session->client, pm->message_size, GNUNET_TIME_absolute_get_remaining (pm->timeout), &do_transmit, session); } /** * Functions with this signature are called whenever we need * to close a session due to a disconnect or failure to * establish a connection. * * @param session session to close down */ static void disconnect_session (struct Session *session) { struct Session *prev; struct Session *pos; struct PendingMessage *pm; #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Disconnecting from `%4s' at %s (session %p).\n", GNUNET_i2s (&session->target), (session->connect_addr != NULL) ? GNUNET_a2s (session->connect_addr, session->connect_alen) : "*", session); #endif /* remove from session list */ prev = NULL; pos = session->plugin->sessions; while (pos != session) { prev = pos; pos = pos->next; } if (prev == NULL) session->plugin->sessions = session->next; else prev->next = session->next; /* clean up state */ if (session->transmit_handle != NULL) { GNUNET_CONNECTION_notify_transmit_ready_cancel (session->transmit_handle); session->transmit_handle = NULL; } while (NULL != (pm = session->pending_messages_head)) { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", pm->transmit_cont != NULL ? "Could not deliver message to `%4s'.\n" : "Could not deliver message to `%4s', notifying.\n", GNUNET_i2s (&session->target)); #endif GNUNET_STATISTICS_update (session->plugin->env->stats, gettext_noop ("# bytes currently in TCP buffers"), - (int64_t) pm->message_size, GNUNET_NO); GNUNET_STATISTICS_update (session->plugin->env->stats, gettext_noop ("# bytes discarded by TCP (disconnect)"), pm->message_size, GNUNET_NO); GNUNET_CONTAINER_DLL_remove (session->pending_messages_head, session->pending_messages_tail, pm); if (NULL != pm->transmit_cont) pm->transmit_cont (pm->transmit_cont_cls, &session->target, GNUNET_SYSERR); GNUNET_free (pm); } GNUNET_break (session->client != NULL); if (session->receive_delay_task != GNUNET_SCHEDULER_NO_TASK) { GNUNET_SCHEDULER_cancel (session->plugin->env->sched, session->receive_delay_task); GNUNET_SERVER_receive_done (session->client, GNUNET_SYSERR); } GNUNET_SERVER_client_drop (session->client); GNUNET_STATISTICS_update (session->plugin->env->stats, gettext_noop ("# TCP sessions active"), -1, GNUNET_NO); GNUNET_free_non_null (session->connect_addr); GNUNET_free (session); } /** * Given two otherwise equivalent sessions, pick the better one. * * @param s1 one session (also default) * @param s2 other session * @return "better" session (more active) */ static struct Session * select_better_session (struct Session *s1, struct Session *s2) { if (s1 == NULL) return s2; if (s2 == NULL) return s1; if ( (s1->expecting_welcome == GNUNET_NO) && (s2->expecting_welcome == GNUNET_YES) ) return s1; if ( (s1->expecting_welcome == GNUNET_YES) && (s2->expecting_welcome == GNUNET_NO) ) return s2; if (s1->last_activity.value < s2->last_activity.value) return s2; if (s1->last_activity.value > s2->last_activity.value) return s1; if ( (GNUNET_YES == s1->inbound) && (GNUNET_NO == s2->inbound) ) return s1; if ( (GNUNET_NO == s1->inbound) && (GNUNET_YES == s2->inbound) ) return s2; return s1; } /** * Function that can be used by the transport service to transmit * a message using the plugin. Note that in the case of a * peer disconnecting, the continuation MUST be called * prior to the disconnect notification itself. This function * will be called with this peer's HELLO message to initiate * a fresh connection to another peer. * * @param cls closure * @param target who should receive this message * @param msg the message to transmit * @param msgbuf_size number of bytes in 'msg' * @param priority how important is the message (most plugins will * ignore message priority and just FIFO) * @param timeout how long to wait at most for the transmission (does not * require plugins to discard the message after the timeout, * just advisory for the desired delay; most plugins will ignore * this as well) * @param addr the address to use (can be NULL if the plugin * is "on its own" (i.e. re-use existing TCP connection)) * @param addrlen length of the address in bytes * @param force_address GNUNET_YES if the plugin MUST use the given address, * GNUNET_NO means the plugin may use any other address and * GNUNET_SYSERR means that only reliable existing * bi-directional connections should be used (regardless * of address) * @param cont continuation to call once the message has * been transmitted (or if the transport is ready * for the next transmission call; or if the * peer disconnected...); can be NULL * @param cont_cls closure for cont * @return number of bytes used (on the physical network, with overheads); * -1 on hard errors (i.e. address invalid); 0 is a legal value * and does NOT mean that the message was not transmitted (DV) */ static ssize_t tcp_plugin_send (void *cls, const struct GNUNET_PeerIdentity *target, const char *msg, size_t msgbuf_size, uint32_t priority, struct GNUNET_TIME_Relative timeout, const void *addr, size_t addrlen, int force_address, GNUNET_TRANSPORT_TransmitContinuation cont, void *cont_cls) { struct Plugin *plugin = cls; struct Session *session; struct Session *cand_session; struct Session *next; struct PendingMessage *pm; struct GNUNET_CONNECTION_Handle *sa; int af; GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes TCP was asked to transmit"), msgbuf_size, GNUNET_NO); /* FIXME: we could do this a cheaper with a hash table where we could restrict the iteration to entries that match the target peer... */ cand_session = NULL; next = plugin->sessions; while (NULL != (session = next)) { next = session->next; GNUNET_assert (session->client != NULL); if (0 != memcmp (target, &session->target, sizeof (struct GNUNET_PeerIdentity))) continue; if ( ( (GNUNET_SYSERR == force_address) && (session->expecting_welcome == GNUNET_NO) ) || (GNUNET_NO == force_address) ) { cand_session = select_better_session (cand_session, session); continue; } if (GNUNET_SYSERR == force_address) continue; GNUNET_break (GNUNET_YES == force_address); if (addr == NULL) { GNUNET_break (0); break; } if (session->inbound == GNUNET_YES) continue; if (addrlen != session->connect_alen) continue; if (0 != memcmp (session->connect_addr, addr, addrlen)) continue; cand_session = select_better_session (cand_session, session); } session = cand_session; if ( (session == NULL) && (addr == NULL) ) { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Asked to transmit to `%4s' without address and I have no existing connection (failing).\n", GNUNET_i2s (target)); #endif GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes discarded by TCP (no address and no connection)"), msgbuf_size, GNUNET_NO); return -1; } if (session == NULL) { if (sizeof (struct sockaddr_in) == addrlen) { af = AF_INET; } else if (sizeof (struct sockaddr_in6) == addrlen) { af = AF_INET6; } else { GNUNET_break_op (0); return -1; } sa = GNUNET_CONNECTION_create_from_sockaddr (plugin->env->sched, af, addr, addrlen, GNUNET_SERVER_MAX_MESSAGE_SIZE); if (sa == NULL) { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Failed to create connection to `%4s' at `%s'\n", GNUNET_i2s (target), GNUNET_a2s (addr, addrlen)); #endif GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes discarded by TCP (failed to connect)"), msgbuf_size, GNUNET_NO); return -1; } #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Asked to transmit to `%4s', creating fresh session using address `%s'.\n", GNUNET_i2s (target), GNUNET_a2s (addr, addrlen)); #endif session = create_session (plugin, target, GNUNET_SERVER_connect_socket (plugin->server, sa)); session->connect_addr = GNUNET_malloc (addrlen); memcpy (session->connect_addr, addr, addrlen); session->connect_alen = addrlen; } GNUNET_assert (session != NULL); GNUNET_assert (session->client != NULL); GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes currently in TCP buffers"), msgbuf_size, GNUNET_NO); /* create new message entry */ pm = GNUNET_malloc (sizeof (struct PendingMessage) + msgbuf_size); pm->msg = (const char*) &pm[1]; memcpy (&pm[1], msg, msgbuf_size); pm->message_size = msgbuf_size; pm->timeout = GNUNET_TIME_relative_to_absolute (timeout); pm->transmit_cont = cont; pm->transmit_cont_cls = cont_cls; /* append pm to pending_messages list */ GNUNET_CONTAINER_DLL_insert_after (session->pending_messages_head, session->pending_messages_tail, session->pending_messages_tail, pm); #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Asked to transmit %u bytes to `%s', added message to list.\n", msgbuf_size, GNUNET_i2s (target)); #endif process_pending_messages (session); return msgbuf_size; } /** * Function that can be called to force a disconnect from the * specified neighbour. This should also cancel all previously * scheduled transmissions. Obviously the transmission may have been * partially completed already, which is OK. The plugin is supposed * to close the connection (if applicable) and no longer call the * transmit continuation(s). * * Finally, plugin MUST NOT call the services's receive function to * notify the service that the connection to the specified target was * closed after a getting this call. * * @param cls closure * @param target peer for which the last transmission is * to be cancelled */ static void tcp_plugin_disconnect (void *cls, const struct GNUNET_PeerIdentity *target) { struct Plugin *plugin = cls; struct Session *session; struct Session *next; struct PendingMessage *pm; #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Asked to cancel session with `%4s'\n", GNUNET_i2s (target)); #endif next = plugin->sessions; while (NULL != (session = next)) { next = session->next; if (0 != memcmp (target, &session->target, sizeof (struct GNUNET_PeerIdentity))) continue; pm = session->pending_messages_head; while (pm != NULL) { pm->transmit_cont = NULL; pm->transmit_cont_cls = NULL; pm = pm->next; } disconnect_session (session); } } /** * Context for address to string conversion. */ struct PrettyPrinterContext { /** * Function to call with the result. */ GNUNET_TRANSPORT_AddressStringCallback asc; /** * Clsoure for 'asc'. */ void *asc_cls; /** * Port to add after the IP address. */ uint16_t port; }; /** * Append our port and forward the result. * * @param cls the 'struct PrettyPrinterContext*' * @param hostname hostname part of the address */ static void append_port (void *cls, const char *hostname) { struct PrettyPrinterContext *ppc = cls; char *ret; if (hostname == NULL) { ppc->asc (ppc->asc_cls, NULL); GNUNET_free (ppc); return; } GNUNET_asprintf (&ret, "%s:%d", hostname, ppc->port); ppc->asc (ppc->asc_cls, ret); GNUNET_free (ret); } /** * Convert the transports address to a nice, human-readable * format. * * @param cls closure * @param type name of the transport that generated the address * @param addr one of the addresses of the host, NULL for the last address * the specific address format depends on the transport * @param addrlen length of the address * @param numeric should (IP) addresses be displayed in numeric form? * @param timeout after how long should we give up? * @param asc function to call on each string * @param asc_cls closure for asc */ static void tcp_plugin_address_pretty_printer (void *cls, const char *type, const void *addr, size_t addrlen, int numeric, struct GNUNET_TIME_Relative timeout, GNUNET_TRANSPORT_AddressStringCallback asc, void *asc_cls) { struct Plugin *plugin = cls; const struct sockaddr_in *v4; const struct sockaddr_in6 *v6; struct PrettyPrinterContext *ppc; if ((addrlen != sizeof (struct sockaddr_in)) && (addrlen != sizeof (struct sockaddr_in6))) { /* invalid address */ GNUNET_break_op (0); asc (asc_cls, NULL); return; } ppc = GNUNET_malloc (sizeof (struct PrettyPrinterContext)); ppc->asc = asc; ppc->asc_cls = asc_cls; if (addrlen == sizeof (struct sockaddr_in)) { v4 = (const struct sockaddr_in *) addr; ppc->port = ntohs (v4->sin_port); } else { v6 = (const struct sockaddr_in6 *) addr; ppc->port = ntohs (v6->sin6_port); } GNUNET_RESOLVER_hostname_get (plugin->env->sched, plugin->env->cfg, addr, addrlen, !numeric, timeout, &append_port, ppc); } /** * Check if the given port is plausible (must be either * our listen port or our advertised port). If it is * neither, we return one of these two ports at random. * * @param plugin global variables * @param in_port port number to check * @return either in_port or a more plausible port */ static uint16_t check_port (struct Plugin *plugin, uint16_t in_port) { if ((in_port == plugin->adv_port) || (in_port == plugin->open_port)) return in_port; return (GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 2) == 0) ? plugin->open_port : plugin->adv_port; } /** * Another peer has suggested an address for this peer and transport * plugin. Check that this could be a valid address. * * @param cls closure, our 'struct Plugin*' * @param addr pointer to the address * @param addrlen length of addr * @return GNUNET_OK if this is a plausible address for this peer * and transport */ static int tcp_plugin_check_address (void *cls, void *addr, size_t addrlen) { struct Plugin *plugin = cls; char buf[sizeof (struct sockaddr_in6)]; struct sockaddr_in *v4; struct sockaddr_in6 *v6; if ((addrlen != sizeof (struct sockaddr_in)) && (addrlen != sizeof (struct sockaddr_in6))) { GNUNET_break_op (0); return GNUNET_SYSERR; } memcpy (buf, addr, sizeof (struct sockaddr_in6)); if (addrlen == sizeof (struct sockaddr_in)) { v4 = (struct sockaddr_in *) buf; v4->sin_port = htons (check_port (plugin, ntohs (v4->sin_port))); } else { v6 = (struct sockaddr_in6 *) buf; v6->sin6_port = htons (check_port (plugin, ntohs (v6->sin6_port))); } #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Informing transport service about my address `%s'.\n", GNUNET_a2s (addr, addrlen)); #endif return GNUNET_OK; } /** * We've received a welcome from this peer via TCP. Possibly create a * fresh client record and send back our welcome. * * @param cls closure * @param client identification of the client * @param message the actual message */ static void handle_tcp_welcome (void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) { struct Plugin *plugin = cls; const struct WelcomeMessage *wm = (const struct WelcomeMessage *) message; struct Session *session; size_t alen; void *vaddr; #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Received %s message from a `%4s/%p'.\n", "WELCOME", GNUNET_i2s (&wm->clientIdentity), client); #endif GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# TCP WELCOME messages received"), 1, GNUNET_NO); session = find_session_by_client (plugin, client); if (session == NULL) { GNUNET_SERVER_client_keep (client); session = create_session (plugin, &wm->clientIdentity, client); session->inbound = GNUNET_YES; if (GNUNET_OK == GNUNET_SERVER_client_get_address (client, &vaddr, &alen)) { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Found address `%s' for incoming connection %p\n", GNUNET_a2s (vaddr, alen), client); #endif session->connect_addr = vaddr; session->connect_alen = alen; } else { #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Did not obtain TCP socket address for incoming connection\n"); #endif } #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Creating new session %p for connection %p\n", session, client); #endif process_pending_messages (session); } if (session->expecting_welcome != GNUNET_YES) { GNUNET_break_op (0); GNUNET_SERVER_receive_done (client, GNUNET_SYSERR); return; } session->last_activity = GNUNET_TIME_absolute_get (); session->expecting_welcome = GNUNET_NO; GNUNET_SERVER_receive_done (client, GNUNET_OK); } /** * Task to signal the server that we can continue * receiving from the TCP client now. * * @param cls the 'struct Session*' * @param tc task context (unused) */ static void delayed_done (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) { struct Session *session = cls; struct GNUNET_TIME_Relative delay; session->receive_delay_task = GNUNET_SCHEDULER_NO_TASK; delay = session->plugin->env->receive (session->plugin->env->cls, &session->target, NULL, 0, NULL, 0); if (delay.value == 0) GNUNET_SERVER_receive_done (session->client, GNUNET_OK); else session->receive_delay_task = GNUNET_SCHEDULER_add_delayed (session->plugin->env->sched, delay, &delayed_done, session); } /** * We've received data for this peer via TCP. Unbox, * compute latency and forward. * * @param cls closure * @param client identification of the client * @param message the actual message */ static void handle_tcp_data (void *cls, struct GNUNET_SERVER_Client *client, const struct GNUNET_MessageHeader *message) { struct Plugin *plugin = cls; struct Session *session; struct GNUNET_TIME_Relative delay; if (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == ntohs(message->type)) { /* We don't want to propagate WELCOME messages up! */ GNUNET_SERVER_receive_done (client, GNUNET_OK); return; } session = find_session_by_client (plugin, client); if ( (NULL == session) || (GNUNET_NO != session->expecting_welcome)) { GNUNET_SERVER_receive_done (client, GNUNET_SYSERR); return; } session->last_activity = GNUNET_TIME_absolute_get (); #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Passing %u bytes of type %u from `%4s' to transport service.\n", (unsigned int) ntohs (message->size), (unsigned int) ntohs (message->type), GNUNET_i2s (&session->target)); #endif GNUNET_STATISTICS_update (plugin->env->stats, gettext_noop ("# bytes received via TCP"), ntohs (message->size), GNUNET_NO); delay = plugin->env->receive (plugin->env->cls, &session->target, message, 1, session->connect_addr, session->connect_alen); if (delay.value == 0) GNUNET_SERVER_receive_done (client, GNUNET_OK); else session->receive_delay_task = GNUNET_SCHEDULER_add_delayed (session->plugin->env->sched, delay, &delayed_done, session); } /** * Handlers for the various TCP messages. */ static struct GNUNET_SERVER_MessageHandler my_handlers[] = { {&handle_tcp_welcome, NULL, GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME, sizeof (struct WelcomeMessage)}, {&handle_tcp_data, NULL, GNUNET_MESSAGE_TYPE_ALL, 0}, {NULL, NULL, 0, 0} }; /** * Functions with this signature are called whenever a peer * is disconnected on the network level. * * @param cls closure * @param client identification of the client */ static void disconnect_notify (void *cls, struct GNUNET_SERVER_Client *client) { struct Plugin *plugin = cls; struct Session *session; if (client == NULL) return; session = find_session_by_client (plugin, client); if (session == NULL) return; /* unknown, nothing to do */ #if DEBUG_TCP GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, "tcp", "Destroying session of `%4s' with %s (%p) due to network-level disconnect.\n", GNUNET_i2s (&session->target), (session->connect_addr != NULL) ? GNUNET_a2s (session->connect_addr, session->connect_alen) : "*", client); #endif disconnect_session (session); } /** * Add the IP of our network interface to the list of * our external IP addresses. */ static int process_interfaces (void *cls, const char *name, int isDefault, const struct sockaddr *addr, socklen_t addrlen) { struct Plugin *plugin = cls; int af; struct sockaddr_in *v4; struct sockaddr_in6 *v6; af = addr->sa_family; if (af == AF_INET) { v4 = (struct sockaddr_in *) addr; v4->sin_port = htons (plugin->adv_port); } else { GNUNET_assert (af == AF_INET6); v6 = (struct sockaddr_in6 *) addr; v6->sin6_port = htons (plugin->adv_port); } GNUNET_log_from (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK, "tcp", _("Found address `%s' (%s)\n"), GNUNET_a2s (addr, addrlen), name); plugin->env->notify_address (plugin->env->cls, "tcp", addr, addrlen, GNUNET_TIME_UNIT_FOREVER_REL); return GNUNET_OK; } /** * Function called by the resolver for each address obtained from DNS * for our own hostname. Add the addresses to the list of our * external IP addresses. * * @param cls closure * @param addr one of the addresses of the host, NULL for the last address * @param addrlen length of the address */ static void process_hostname_ips (void *cls, const struct sockaddr *addr, socklen_t addrlen) { struct Plugin *plugin = cls; if (addr == NULL) { plugin->hostname_dns = NULL; return; } process_interfaces (plugin, "", GNUNET_YES, addr, addrlen); } /** * Entry point for the plugin. */ void * libgnunet_plugin_transport_tcp_init (void *cls) { struct GNUNET_TRANSPORT_PluginEnvironment *env = cls; struct GNUNET_TRANSPORT_PluginFunctions *api; struct Plugin *plugin; struct GNUNET_SERVICE_Context *service; unsigned long long aport; unsigned long long bport; unsigned int i; service = GNUNET_SERVICE_start ("transport-tcp", env->sched, env->cfg); if (service == NULL) { GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, "tcp", _ ("Failed to start service for `%s' transport plugin.\n"), "tcp"); return NULL; } aport = 0; if ((GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (env->cfg, "transport-tcp", "PORT", &bport)) || (bport > 65535) || ((GNUNET_OK == GNUNET_CONFIGURATION_get_value_number (env->cfg, "transport-tcp", "ADVERTISED-PORT", &aport)) && (aport > 65535))) { GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR, "tcp", _ ("Require valid port number for service `%s' in configuration!\n"), "transport-tcp"); GNUNET_SERVICE_stop (service); return NULL; } if (aport == 0) aport = bport; plugin = GNUNET_malloc (sizeof (struct Plugin)); plugin->open_port = bport; plugin->adv_port = aport; plugin->env = env; plugin->lsock = NULL; plugin->statistics = NULL; api = GNUNET_malloc (sizeof (struct GNUNET_TRANSPORT_PluginFunctions)); api->cls = plugin; api->send = &tcp_plugin_send; api->disconnect = &tcp_plugin_disconnect; api->address_pretty_printer = &tcp_plugin_address_pretty_printer; api->check_address = &tcp_plugin_check_address; plugin->service = service; plugin->server = GNUNET_SERVICE_get_server (service); plugin->handlers = GNUNET_malloc (sizeof (my_handlers)); memcpy (plugin->handlers, my_handlers, sizeof (my_handlers)); for (i = 0; i < sizeof (my_handlers) / sizeof (struct GNUNET_SERVER_MessageHandler); i++) plugin->handlers[i].callback_cls = plugin; GNUNET_SERVER_add_handlers (plugin->server, plugin->handlers); GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, "tcp", _("TCP transport listening on port %llu\n"), bport); if (aport != bport) GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, "tcp", _("TCP transport advertises itself as being on port %llu\n"), aport); GNUNET_SERVER_disconnect_notify (plugin->server, &disconnect_notify, plugin); /* FIXME: do the two calls below periodically again and not just once (since the info we get might change...) */ GNUNET_OS_network_interfaces_list (&process_interfaces, plugin); plugin->hostname_dns = GNUNET_RESOLVER_hostname_resolve (env->sched, env->cfg, AF_UNSPEC, HOSTNAME_RESOLVE_TIMEOUT, &process_hostname_ips, plugin); return api; } /** * Exit point from the plugin. */ void * libgnunet_plugin_transport_tcp_done (void *cls) { struct GNUNET_TRANSPORT_PluginFunctions *api = cls; struct Plugin *plugin = api->cls; struct Session *session; while (NULL != (session = plugin->sessions)) disconnect_session (session); if (NULL != plugin->hostname_dns) { GNUNET_RESOLVER_request_cancel (plugin->hostname_dns); plugin->hostname_dns = NULL; } GNUNET_SERVICE_stop (plugin->service); GNUNET_free (plugin->handlers); GNUNET_free (plugin); GNUNET_free (api); return NULL; } /* end of plugin_transport_tcp.c */