2 This file is part of GNUnet
3 Copyright (C) 2003-2013 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
22 * @file transport/plugin_transport_smtp.c
23 * @brief Implementation of the SMTP transport service
24 * @author Christian Grothoff
25 * @author Renaldo Ferreira
29 #include "gnunet_util.h"
30 #include "gnunet_constants.h"
31 #include "gnunet_protocols.h"
32 #include "gnunet_transport.h"
33 #include "gnunet_stats_service.h"
39 * The default maximum size of each outbound SMTP message.
41 #define SMTP_MESSAGE_SIZE 65528
43 #define DEBUG_SMTP GNUNET_EXTRA_LOGGING
45 #define FILTER_STRING_SIZE 64
47 /* how long can a line in base64 encoded
48 mime text be? (in characters, excluding "\n") */
49 #define MAX_CHAR_PER_LINE 76
54 * Host-Address in a SMTP network.
60 * Filter line that every sender must include in the E-mails such
61 * that the receiver can effectively filter out the GNUnet traffic
64 char filter[FILTER_STRING_SIZE];
67 * Claimed E-mail address of the sender.
68 * Format is "foo@bar.com" with null termination, padded to be
69 * of a multiple of 8 bytes long.
71 char senderAddress[0];
75 GNUNET_NETWORK_STRUCT_BEGIN
78 * Encapsulation of a GNUnet message in the SMTP mail body (before
83 GNUNET_MessageHeader header;
86 * What is the identity of the sender (GNUNET_hash of public key)
88 GNUNET_PeerIdentity sender;
91 GNUNET_NETWORK_STRUCT_END
93 /* *********** globals ************* */
96 * apis (our advertised API and the core api )
98 static GNUNET_CoreAPIForTransport *core_api;
100 static struct GNUNET_GE_Context *ectx;
103 * Thread that listens for inbound messages
105 static struct GNUNET_ThreadHandle *dispatchThread;
108 * Flag to indicate that server has been shut down.
110 static int smtp_shutdown = GNUNET_YES;
113 * Set to the SMTP server hostname (and port) for outgoing messages.
115 static char *smtp_server_name;
117 static char *pipename;
120 * Lock for uses of libesmtp (not thread-safe).
122 static struct GNUNET_Mutex *lock;
125 * Old handler for SIGPIPE (kept to be able to restore).
127 static struct sigaction old_handler;
131 static GNUNET_TransportAPI smtpAPI;
133 static GNUNET_Stats_ServiceAPI *stats;
135 static int stat_bytesReceived;
137 static int stat_bytesSent;
139 static int stat_bytesDropped;
142 * How many e-mails are we allowed to send per hour?
144 static unsigned long long rate_limit;
146 static GNUNET_CronTime last_transmission;
149 /* ********************* the real stuff ******************* */
151 #define strAUTOncmp(a,b) strncmp(a,b,strlen(b))
154 * Listen to the pipe, decode messages and send to core.
157 listenAndDistribute (void *unused)
160 unsigned int linesize;
166 GNUNET_TransportPacket *coreMP;
170 linesize = ((GNUNET_MAX_BUFFER_SIZE * 4 / 3) + 8) * (MAX_CHAR_PER_LINE + 2) / MAX_CHAR_PER_LINE; /* maximum size of a line supported */
171 line = GNUNET_malloc (linesize + 2); /* 2 bytes for off-by-one errors, just to be safe... */
173 #define READLINE(l,limit) \
174 do { retl = fgets(l, (limit), fdes); \
175 if ( (retl == NULL) || (smtp_shutdown == GNUNET_YES)) {\
178 if (core_api->load_monitor != NULL) \
179 GNUNET_network_monitor_notify_transmission(core_api->load_monitor, GNUNET_ND_DOWNLOAD, strlen(retl)); \
183 while (smtp_shutdown == GNUNET_NO)
185 fd = OPEN (pipename, O_RDONLY | O_ASYNC);
188 if (smtp_shutdown == GNUNET_NO)
189 GNUNET_thread_sleep (5 * GNUNET_CRON_SECONDS);
192 fdes = fdopen (fd, "r");
193 while (smtp_shutdown == GNUNET_NO)
195 /* skip until end of header */
198 READLINE (line, linesize);
200 while ((line[0] != '\r') && (line[0] != '\n')); /* expect newline */
201 READLINE (line, linesize); /* read base64 encoded message; decode, process */
205 pos = strlen (line) - 1; /* ignore new line */
206 READLINE (&line[pos], linesize - pos); /* read base64 encoded message; decode, process */
207 if ((line[pos] == '\r') || (line[pos] == '\n'))
208 break; /* empty line => end of message! */
210 size = GNUNET_STRINGS_base64_decode (line, pos, &out);
211 if (size < sizeof (SMTPMessage))
213 GNUNET_GE_BREAK (ectx, 0);
218 mp = (SMTPMessage *) &out[size - sizeof (SMTPMessage)];
219 if (ntohs (mp->header.size) != size)
222 GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
223 _("Received malformed message via %s. Ignored.\n"),
227 GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
228 "Size returned by base64=%d, in the msg=%d.\n", size,
235 stats->change (stat_bytesReceived, size);
236 coreMP = GNUNET_new (GNUNET_TransportPacket);
238 coreMP->size = size - sizeof (SMTPMessage);
239 coreMP->tsession = NULL;
240 coreMP->sender = mp->sender;
242 GNUNET_GE_LOG (ectx, GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
243 "SMTP message passed to the core.\n");
246 core_api->receive (coreMP);
250 GNUNET_GE_LOG (ectx, GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
251 "SMTP message processed.\n");
260 /* *************** API implementation *************** */
263 * Verify that a hello-Message is correct (a node is reachable at that
264 * address). Since the reply will be asynchronous, a method must be
267 * @param hello the hello message to verify
268 * (the signature/crc have been verified before)
269 * @return GNUNET_OK on success, GNUNET_SYSERR on error
272 api_verify_hello (const GNUNET_MessageHello * hello)
274 const EmailAddress *maddr;
276 maddr = (const EmailAddress *) &hello[1];
277 if ((ntohs (hello->header.size) !=
278 sizeof (GNUNET_MessageHello) + ntohs (hello->senderAddressSize)) ||
279 (maddr->senderAddress
280 [ntohs (hello->senderAddressSize) - 1 - FILTER_STRING_SIZE] != '\0'))
282 GNUNET_GE_BREAK (ectx, 0);
283 return GNUNET_SYSERR; /* obviously invalid */
285 if (NULL == strstr (maddr->filter, ": "))
286 return GNUNET_SYSERR;
291 * Create a hello-Message for the current node. The hello is created
292 * without signature and without a timestamp. The GNUnet core will
293 * GNUNET_RSA_sign the message and add an expiration time.
295 * @return hello on success, NULL on error
297 static GNUNET_MessageHello *
300 GNUNET_MessageHello *msg;
305 GNUNET_GC_get_configuration_value_string (core_api->cfg, "SMTP", "FILTER",
306 "X-mailer: GNUnet", &filter);
307 if (NULL == strstr (filter, ": "))
309 GNUNET_GE_LOG (ectx, GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
310 _("SMTP filter string to invalid, lacks ': '\n"));
311 GNUNET_free (filter);
315 if (strlen (filter) > FILTER_STRING_SIZE)
317 filter[FILTER_STRING_SIZE] = '\0';
318 GNUNET_GE_LOG (ectx, GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
319 _("SMTP filter string to long, capped to `%s'\n"), filter);
321 i = (strlen (email) + 8) & (~7); /* make multiple of 8 */
323 GNUNET_malloc (sizeof (GNUNET_MessageHello) + sizeof (EmailAddress) + i);
324 memset (msg, 0, sizeof (GNUNET_MessageHello) + sizeof (EmailAddress) + i);
325 haddr = (EmailAddress *) &msg[1];
326 memset (&haddr->filter[0], 0, FILTER_STRING_SIZE);
327 strcpy (&haddr->filter[0], filter);
328 memcpy (&haddr->senderAddress[0], email, strlen (email) + 1);
329 msg->senderAddressSize = htons (strlen (email) + 1 + sizeof (EmailAddress));
330 msg->protocol = htons (GNUNET_TRANSPORT_PROTOCOL_NUMBER_SMTP);
331 msg->MTU = htonl (smtpAPI.mtu);
332 msg->header.size = htons (GNUNET_sizeof_hello (msg));
333 if (api_verify_hello (msg) == GNUNET_SYSERR)
334 GNUNET_GE_ASSERT (ectx, 0);
335 GNUNET_free (filter);
339 struct GetMessageClosure
347 get_message (void **buf, int *len, void *cls)
349 struct GetMessageClosure *gmc = cls;
357 if (gmc->pos == gmc->esize)
358 return NULL; /* done */
360 gmc->pos = gmc->esize;
365 * Send a message to the specified remote node.
367 * @param tsession the GNUNET_MessageHello identifying the remote node
368 * @param msg what to send
369 * @param size the size of the message
370 * @param important is this message important enough to override typical limits?
371 * @return GNUNET_SYSERR on error, GNUNET_OK on success
374 api_send (GNUNET_TSession * tsession, const void *msg, const unsigned int size,
377 const GNUNET_MessageHello *hello;
378 const EmailAddress *haddr;
383 struct GetMessageClosure gm_cls;
384 smtp_session_t session;
385 smtp_message_t message;
386 smtp_recipient_t recipient;
392 if (smtp_shutdown == GNUNET_YES)
393 return GNUNET_SYSERR;
394 if ((size == 0) || (size > smtpAPI.mtu))
396 GNUNET_GE_BREAK (ectx, 0);
397 return GNUNET_SYSERR;
399 now = GNUNET_get_time ();
400 if ((important != GNUNET_YES) &&
401 ((now - last_transmission) * rate_limit) < GNUNET_CRON_HOURS)
402 return GNUNET_NO; /* rate too high */
403 last_transmission = now;
405 hello = (const GNUNET_MessageHello *) tsession->internal;
407 return GNUNET_SYSERR;
408 GNUNET_mutex_lock (lock);
409 session = smtp_create_session ();
413 GNUNET_GE_ERROR | GNUNET_GE_ADMIN | GNUNET_GE_USER |
414 GNUNET_GE_IMMEDIATE, _("SMTP: `%s' failed: %s.\n"),
415 "smtp_create_session", smtp_strerror (smtp_errno (), ebuf,
417 GNUNET_mutex_unlock (lock);
418 return GNUNET_SYSERR;
420 if (0 == smtp_set_server (session, smtp_server_name))
423 GNUNET_GE_ERROR | GNUNET_GE_ADMIN | GNUNET_GE_USER |
424 GNUNET_GE_IMMEDIATE, _("SMTP: `%s' failed: %s.\n"),
425 "smtp_set_server", smtp_strerror (smtp_errno (), ebuf,
427 smtp_destroy_session (session);
428 GNUNET_mutex_unlock (lock);
429 return GNUNET_SYSERR;
431 haddr = (const EmailAddress *) &hello[1];
432 message = smtp_add_message (session);
436 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
437 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
438 "smtp_add_message", smtp_strerror (smtp_errno (), ebuf,
440 smtp_destroy_session (session);
441 GNUNET_mutex_unlock (lock);
442 return GNUNET_SYSERR;
444 smtp_set_header (message, "To", NULL, haddr->senderAddress);
445 smtp_set_header (message, "From", NULL, email);
447 filter = GNUNET_strdup (haddr->filter);
448 fvalue = strstr (filter, ": ");
449 GNUNET_GE_ASSERT (NULL, NULL != fvalue);
452 if (0 == smtp_set_header (message, filter, fvalue))
455 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
456 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
457 "smtp_set_header", smtp_strerror (smtp_errno (), ebuf,
459 smtp_destroy_session (session);
460 GNUNET_mutex_unlock (lock);
461 GNUNET_free (filter);
462 return GNUNET_SYSERR;
464 GNUNET_free (filter);
465 m = GNUNET_malloc (size + sizeof (SMTPMessage));
466 memcpy (m, msg, size);
467 mp = (SMTPMessage *) &m[size];
468 mp->header.size = htons (size + sizeof (SMTPMessage));
469 mp->header.type = htons (0);
470 mp->sender = *core_api->my_identity;
473 gm_cls.esize = GNUNET_STRINGS_base64_encode (m, size + sizeof (SMTPMessage), &gm_cls.ebody);
475 if (0 == smtp_size_set_estimate (message, gm_cls.esize))
478 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
479 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
480 "smtp_size_set_estimate", smtp_strerror (smtp_errno (), ebuf,
483 if (0 == smtp_set_messagecb (message, &get_message, &gm_cls))
486 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
487 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
488 "smtp_set_messagecb", smtp_strerror (smtp_errno (), ebuf,
490 smtp_destroy_session (session);
491 GNUNET_mutex_unlock (lock);
492 GNUNET_free (gm_cls.ebody);
493 return GNUNET_SYSERR;
495 recipient = smtp_add_recipient (message, haddr->senderAddress);
496 if (recipient == NULL)
499 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
500 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
501 "smtp_add_recipient", smtp_strerror (smtp_errno (), ebuf,
503 smtp_destroy_session (session);
504 GNUNET_mutex_unlock (lock);
505 return GNUNET_SYSERR;
507 if (0 == smtp_start_session (session))
510 GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
511 GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
512 "smtp_start_session", smtp_strerror (smtp_errno (), ebuf,
514 smtp_destroy_session (session);
515 GNUNET_mutex_unlock (lock);
516 GNUNET_free (gm_cls.ebody);
517 return GNUNET_SYSERR;
520 stats->change (stat_bytesSent, size);
521 if (core_api->load_monitor != NULL)
522 GNUNET_network_monitor_notify_transmission (core_api->load_monitor,
523 GNUNET_ND_UPLOAD, gm_cls.esize);
524 smtp_message_reset_status (message); /* this is needed to plug a 28-byte/message memory leak in libesmtp */
525 smtp_destroy_session (session);
526 GNUNET_mutex_unlock (lock);
527 GNUNET_free (gm_cls.ebody);
532 * Establish a connection to a remote node.
533 * @param hello the hello-Message for the target node
534 * @param tsessionPtr the session handle that is to be set
535 * @param may_reuse can we re-use an existing connection?
536 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
539 api_connect (const GNUNET_MessageHello * hello, GNUNET_TSession ** tsessionPtr,
542 GNUNET_TSession *tsession;
544 tsession = GNUNET_new (GNUNET_TSession);
545 tsession->internal = GNUNET_malloc (GNUNET_sizeof_hello (hello));
546 tsession->peer = hello->senderIdentity;
547 memcpy (tsession->internal, hello, GNUNET_sizeof_hello (hello));
548 tsession->ttype = smtpAPI.protocol_number;
549 (*tsessionPtr) = tsession;
554 * Disconnect from a remote node.
556 * @param tsession the session that is closed
557 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
560 api_disconnect (GNUNET_TSession * tsession)
562 if (tsession != NULL)
564 if (tsession->internal != NULL)
565 GNUNET_free (tsession->internal);
566 GNUNET_free (tsession);
572 * Start the server process to receive inbound traffic.
573 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
576 api_start_transport_server ()
578 smtp_shutdown = GNUNET_NO;
579 /* initialize SMTP network */
580 dispatchThread = GNUNET_thread_create (&listenAndDistribute, NULL, 1024 * 4);
581 if (dispatchThread == NULL)
583 GNUNET_GE_DIE_STRERROR (ectx,
584 GNUNET_GE_ADMIN | GNUNET_GE_BULK | GNUNET_GE_FATAL,
586 return GNUNET_SYSERR;
592 * Shutdown the server process (stop receiving inbound traffic). Maybe
596 api_stop_transport_server ()
600 smtp_shutdown = GNUNET_YES;
601 GNUNET_thread_stop_sleep (dispatchThread);
602 GNUNET_thread_join (dispatchThread, &unused);
607 * Convert SMTP hello to an IP address (always fails).
610 api_hello_to_address (const GNUNET_MessageHello * hello, void **sa,
611 unsigned int *sa_len)
613 return GNUNET_SYSERR;
620 api_associate (GNUNET_TSession * tsession)
622 return GNUNET_SYSERR; /* SMTP connections can never be associated */
626 * Always succeeds (for now; we should look at adding
627 * frequency limits to SMTP in the future!).
630 api_test_would_try (GNUNET_TSession * tsession, unsigned int size,
633 return GNUNET_OK; /* we always try... */
637 * The exported method. Makes the core api available via a global and
638 * returns the smtp transport API.
640 GNUNET_TransportAPI *
641 inittransport_smtp (struct GNUNET_CoreAPIForTransport * core)
643 unsigned long long mtu;
648 if (!GNUNET_GC_have_configuration_value (core_api->cfg, "SMTP", "EMAIL"))
650 GNUNET_GE_LOG (ectx, GNUNET_GE_ERROR | GNUNET_GE_BULK | GNUNET_GE_USER,
652 ("No email-address specified, can not start SMTP transport.\n"));
655 GNUNET_GC_get_configuration_value_number (core_api->cfg, "SMTP", "MTU", 1200,
657 SMTP_MESSAGE_SIZE, &mtu);
658 GNUNET_GC_get_configuration_value_number (core_api->cfg, "SMTP", "RATELIMIT",
659 0, 0, 1024 * 1024, &rate_limit);
660 stats = core_api->service_request ("stats");
664 stats->create (gettext_noop ("# bytes received via SMTP"));
665 stat_bytesSent = stats->create (gettext_noop ("# bytes sent via SMTP"));
667 stats->create (gettext_noop ("# bytes dropped by SMTP (outgoing)"));
669 GNUNET_GC_get_configuration_value_filename (core_api->cfg, "SMTP", "PIPE", &pipename);
671 if (0 != mkfifo (pipename, S_IWUSR | S_IRUSR | S_IWGRP | S_IWOTH))
673 GNUNET_GE_LOG_STRERROR (ectx,
674 GNUNET_GE_ADMIN | GNUNET_GE_BULK | GNUNET_GE_FATAL,
676 GNUNET_free (pipename);
677 core_api->service_release (stats);
681 /* we need to allow the mailer program to send us messages;
682 * easiest done by giving it write permissions (see Mantis #1142) */
683 if (0 != chmod (pipename, S_IWUSR | S_IRUSR | S_IWGRP | S_IWOTH))
684 GNUNET_GE_LOG_STRERROR (ectx,
685 GNUNET_GE_ADMIN | GNUNET_GE_BULK |
686 GNUNET_GE_WARNING, "chmod");
687 GNUNET_GC_get_configuration_value_string (core_api->cfg, "SMTP", "EMAIL", NULL,
689 lock = GNUNET_mutex_create (GNUNET_NO);
690 GNUNET_GC_get_configuration_value_string (core_api->cfg, "SMTP", "SERVER",
691 "localhost:25", &smtp_server_name);
692 sa.sa_handler = SIG_IGN;
693 sigemptyset (&sa.sa_mask);
695 sigaction (SIGPIPE, &sa, &old_handler);
697 smtpAPI.protocol_number = GNUNET_TRANSPORT_PROTOCOL_NUMBER_SMTP;
698 smtpAPI.mtu = mtu - sizeof (SMTPMessage);
700 smtpAPI.hello_verify = &api_verify_hello;
701 smtpAPI.hello_create = &api_create_hello;
702 smtpAPI.connect = &api_connect;
703 smtpAPI.send = &api_send;
704 smtpAPI.associate = &api_associate;
705 smtpAPI.disconnect = &api_disconnect;
706 smtpAPI.server_start = &api_start_transport_server;
707 smtpAPI.server_stop = &api_stop_transport_server;
708 smtpAPI.hello_to_address = &api_hello_to_address;
709 smtpAPI.send_now_test = &api_test_would_try;
714 donetransport_smtp ()
716 sigaction (SIGPIPE, &old_handler, NULL);
717 GNUNET_free (smtp_server_name);
720 core_api->service_release (stats);
723 GNUNET_mutex_destroy (lock);
726 GNUNET_free (pipename);