/*
     This file is part of GNUnet
     Copyright (C) 2003-2013 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file transport/plugin_transport_smtp.c
 * @brief Implementation of the SMTP transport service
 * @author Christian Grothoff
 * @author Renaldo Ferreira
 */

#include "platform.h"
#include "gnunet_util.h"
#include "gnunet_constants.h"
#include "gnunet_protocols.h"
#include "gnunet_transport.h"
#include "gnunet_stats_service.h"
#include <libesmtp.h>
#include <signal.h>


/**
 * The default maximum size of each outbound SMTP message.
 */
#define SMTP_MESSAGE_SIZE 65528

#define DEBUG_SMTP GNUNET_EXTRA_LOGGING

#define FILTER_STRING_SIZE 64

/* how long can a line in base64 encoded
   mime text be? (in characters, excluding "\n") */
#define MAX_CHAR_PER_LINE 76

#define EBUF_LEN 128

/**
 * Host-Address in a SMTP network.
 */
typedef struct {
  /**
   * Filter line that every sender must include in the E-mails such
   * that the receiver can effectively filter out the GNUnet traffic
   * from the E-mail.
   */
  char filter[FILTER_STRING_SIZE];

  /**
   * Claimed E-mail address of the sender.
   * Format is "foo@bar.com" with null termination, padded to be
   * of a multiple of 8 bytes long.
   */
  char senderAddress[0];
} EmailAddress;

GNUNET_NETWORK_STRUCT_BEGIN

/**
 * Encapsulation of a GNUnet message in the SMTP mail body (before
 * base64 encoding).
 */
typedef struct {
  GNUNET_MessageHeader header;

  /**
   * What is the identity of the sender (GNUNET_hash of public key)
   */
  GNUNET_PeerIdentity sender;
} SMTPMessage;
GNUNET_NETWORK_STRUCT_END

/* *********** globals ************* */

/**
 * apis (our advertised API and the core api )
 */
static GNUNET_CoreAPIForTransport *core_api;

static struct GNUNET_GE_Context *ectx;

/**
 * Thread that listens for inbound messages
 */
static struct GNUNET_ThreadHandle *dispatchThread;

/**
 * Flag to indicate that server has been shut down.
 */
static int smtp_shutdown = GNUNET_YES;

/**
 * Set to the SMTP server hostname (and port) for outgoing messages.
 */
static char *smtp_server_name;

static char *pipename;

/**
 * Lock for uses of libesmtp (not thread-safe).
 */
static struct GNUNET_Mutex *lock;

/**
 * Old handler for SIGPIPE (kept to be able to restore).
 */
static struct sigaction old_handler;

static char *email;

static GNUNET_TransportAPI smtpAPI;

static GNUNET_Stats_ServiceAPI *stats;

static int stat_bytesReceived;

static int stat_bytesSent;

static int stat_bytesDropped;

/**
 * How many e-mails are we allowed to send per hour?
 */
static unsigned long long rate_limit;

static GNUNET_CronTime last_transmission;


/* ********************* the real stuff ******************* */

#define strAUTOncmp(a, b) strncmp(a, b, strlen(b))

/**
 * Listen to the pipe, decode messages and send to core.
 */
static void *
listenAndDistribute(void *unused)
{
  char *line;
  unsigned int linesize;
  SMTPMessage *mp;
  FILE *fdes;
  char *retl;
  char *out;
  unsigned int size;
  GNUNET_TransportPacket *coreMP;
  int fd;
  unsigned int pos;

  linesize = ((GNUNET_MAX_BUFFER_SIZE * 4 / 3) + 8) * (MAX_CHAR_PER_LINE + 2) / MAX_CHAR_PER_LINE;      /* maximum size of a line supported */
  line = GNUNET_malloc(linesize + 2);   /* 2 bytes for off-by-one errors, just to be safe... */

#define READLINE(l, limit) \
  do { retl = fgets(l, (limit), fdes);                          \
       if ((retl == NULL) || (smtp_shutdown == GNUNET_YES)) { \
           goto END; \
         } \
       if (core_api->load_monitor != NULL) \
       GNUNET_network_monitor_notify_transmission (core_api->load_monitor, GNUNET_ND_DOWNLOAD, strlen(retl)); \
    } while (0)


  while (smtp_shutdown == GNUNET_NO)
    {
      fd = OPEN(pipename, O_RDONLY | O_ASYNC);
      if (fd == -1)
        {
          if (smtp_shutdown == GNUNET_NO)
            GNUNET_thread_sleep(5 * GNUNET_CRON_SECONDS);
          continue;
        }
      fdes = fdopen(fd, "r");
      while (smtp_shutdown == GNUNET_NO)
        {
          /* skip until end of header */
          do
            {
              READLINE(line, linesize);
            }
          while ((line[0] != '\r') && (line[0] != '\n')); /* expect newline */
          READLINE(line, linesize);     /* read base64 encoded message; decode, process */
          pos = 0;
          while (1)
            {
              pos = strlen(line) - 1;   /* ignore new line */
              READLINE(&line[pos], linesize - pos); /* read base64 encoded message; decode, process */
              if ((line[pos] == '\r') || (line[pos] == '\n'))
                break;          /* empty line => end of message! */
            }
          size = GNUNET_STRINGS_base64_decode(line, pos, &out);
          if (size < sizeof(SMTPMessage))
            {
              GNUNET_GE_BREAK(ectx, 0);
              GNUNET_free(out);
              goto END;
            }

          mp = (SMTPMessage *)&out[size - sizeof(SMTPMessage)];
          if (ntohs(mp->header.size) != size)
            {
              GNUNET_GE_LOG(ectx,
                            GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
                            _("Received malformed message via %s. Ignored.\n"),
                            "SMTP");
#if DEBUG_SMTP
              GNUNET_GE_LOG(ectx,
                            GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
                            "Size returned by base64=%d, in the msg=%d.\n", size,
                            ntohl(mp->size));
#endif
              GNUNET_free(out);
              goto END;
            }
          if (stats != NULL)
            stats->change(stat_bytesReceived, size);
          coreMP = GNUNET_new(GNUNET_TransportPacket);
          coreMP->msg = out;
          coreMP->size = size - sizeof(SMTPMessage);
          coreMP->tsession = NULL;
          coreMP->sender = mp->sender;
#if DEBUG_SMTP
          GNUNET_GE_LOG(ectx, GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
                        "SMTP message passed to the core.\n");
#endif

          core_api->receive(coreMP);
        }
END:
#if DEBUG_SMTP
      GNUNET_GE_LOG(ectx, GNUNET_GE_DEBUG | GNUNET_GE_REQUEST | GNUNET_GE_USER,
                    "SMTP message processed.\n");
#endif
      if (fdes != NULL)
        fclose(fdes);
    }
  GNUNET_free(line);
  return NULL;
}

/* *************** API implementation *************** */

/**
 * Verify that a hello-Message is correct (a node is reachable at that
 * address). Since the reply will be asynchronous, a method must be
 * called on success.
 *
 * @param hello the hello message to verify
 *        (the signature/crc have been verified before)
 * @return GNUNET_OK on success, GNUNET_SYSERR on error
 */
static int
api_verify_hello(const GNUNET_MessageHello * hello)
{
  const EmailAddress *maddr;

  maddr = (const EmailAddress *)&hello[1];
  if ((ntohs(hello->header.size) !=
       sizeof(GNUNET_MessageHello) + ntohs(hello->senderAddressSize)) ||
      (maddr->senderAddress
       [ntohs(hello->senderAddressSize) - 1 - FILTER_STRING_SIZE] != '\0'))
    {
      GNUNET_GE_BREAK(ectx, 0);
      return GNUNET_SYSERR;     /* obviously invalid */
    }
  if (NULL == strstr(maddr->filter, ": "))
    return GNUNET_SYSERR;
  return GNUNET_OK;
}

/**
 * Create a hello-Message for the current node. The hello is created
 * without signature and without a timestamp. The GNUnet core will
 * GNUNET_RSA_sign the message and add an expiration time.
 *
 * @return hello on success, NULL on error
 */
static GNUNET_MessageHello *
api_create_hello()
{
  GNUNET_MessageHello *msg;
  char *filter;
  EmailAddress *haddr;
  int i;

  GNUNET_GC_get_configuration_value_string(core_api->cfg, "SMTP", "FILTER",
                                           "X-mailer: GNUnet", &filter);
  if (NULL == strstr(filter, ": "))
    {
      GNUNET_GE_LOG(ectx, GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
                    _("SMTP filter string to invalid, lacks ': '\n"));
      GNUNET_free(filter);
      return NULL;
    }

  if (strlen(filter) > FILTER_STRING_SIZE)
    {
      filter[FILTER_STRING_SIZE] = '\0';
      GNUNET_GE_LOG(ectx, GNUNET_GE_WARNING | GNUNET_GE_BULK | GNUNET_GE_USER,
                    _("SMTP filter string to long, capped to `%s'\n"), filter);
    }
  i = (strlen(email) + 8) & (~7);       /* make multiple of 8 */
  msg =
    GNUNET_malloc(sizeof(GNUNET_MessageHello) + sizeof(EmailAddress) + i);
  memset(msg, 0, sizeof(GNUNET_MessageHello) + sizeof(EmailAddress) + i);
  haddr = (EmailAddress *)&msg[1];
  memset(&haddr->filter[0], 0, FILTER_STRING_SIZE);
  strcpy(&haddr->filter[0], filter);
  GNUNET_memcpy(&haddr->senderAddress[0], email, strlen(email) + 1);
  msg->senderAddressSize = htons(strlen(email) + 1 + sizeof(EmailAddress));
  msg->protocol = htons(GNUNET_TRANSPORT_PROTOCOL_NUMBER_SMTP);
  msg->MTU = htonl(smtpAPI.mtu);
  msg->header.size = htons(GNUNET_sizeof_hello(msg));
  if (api_verify_hello(msg) == GNUNET_SYSERR)
    GNUNET_GE_ASSERT(ectx, 0);
  GNUNET_free(filter);
  return msg;
}

struct GetMessageClosure {
  unsigned int esize;
  unsigned int pos;
  char *ebody;
};

static const char *
get_message(void **buf, int *len, void *cls)
{
  struct GetMessageClosure *gmc = cls;

  *buf = NULL;
  if (len == NULL)
    {
      gmc->pos = 0;
      return NULL;
    }
  if (gmc->pos == gmc->esize)
    return NULL;                /* done */
  *len = gmc->esize;
  gmc->pos = gmc->esize;
  return gmc->ebody;
}

/**
 * Send a message to the specified remote node.
 *
 * @param tsession the GNUNET_MessageHello identifying the remote node
 * @param msg what to send
 * @param size the size of the message
 * @param important is this message important enough to override typical limits?
 * @return GNUNET_SYSERR on error, GNUNET_OK on success
 */
static int
api_send(GNUNET_TSession * tsession, const void *msg, const unsigned int size,
         int important)
{
  const GNUNET_MessageHello *hello;
  const EmailAddress *haddr;
  char *m;
  char *filter;
  char *fvalue;
  SMTPMessage *mp;
  struct GetMessageClosure gm_cls;
  smtp_session_t session;
  smtp_message_t message;
  smtp_recipient_t recipient;

#define EBUF_LEN 128
  char ebuf[EBUF_LEN];
  GNUNET_CronTime now;

  if (smtp_shutdown == GNUNET_YES)
    return GNUNET_SYSERR;
  if ((size == 0) || (size > smtpAPI.mtu))
    {
      GNUNET_GE_BREAK(ectx, 0);
      return GNUNET_SYSERR;
    }
  now = GNUNET_get_time();
  if ((important != GNUNET_YES) &&
      ((now - last_transmission) * rate_limit) < GNUNET_CRON_HOURS)
    return GNUNET_NO;           /* rate too high */
  last_transmission = now;

  hello = (const GNUNET_MessageHello *)tsession->internal;
  if (hello == NULL)
    return GNUNET_SYSERR;
  GNUNET_mutex_lock(lock);
  session = smtp_create_session();
  if (session == NULL)
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_ERROR | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_IMMEDIATE, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_create_session", smtp_strerror(smtp_errno(), ebuf,
                                                         EBUF_LEN));
      GNUNET_mutex_unlock(lock);
      return GNUNET_SYSERR;
    }
  if (0 == smtp_set_server(session, smtp_server_name))
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_ERROR | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_IMMEDIATE, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_set_server", smtp_strerror(smtp_errno(), ebuf,
                                                     EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      return GNUNET_SYSERR;
    }
  haddr = (const EmailAddress *)&hello[1];
  message = smtp_add_message(session);
  if (message == NULL)
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_add_message", smtp_strerror(smtp_errno(), ebuf,
                                                      EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      return GNUNET_SYSERR;
    }
  smtp_set_header(message, "To", NULL, haddr->senderAddress);
  smtp_set_header(message, "From", NULL, email);

  filter = GNUNET_strdup(haddr->filter);
  fvalue = strstr(filter, ": ");
  GNUNET_GE_ASSERT(NULL, NULL != fvalue);
  fvalue[0] = '\0';
  fvalue += 2;
  if (0 == smtp_set_header(message, filter, fvalue))
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_set_header", smtp_strerror(smtp_errno(), ebuf,
                                                     EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      GNUNET_free(filter);
      return GNUNET_SYSERR;
    }
  GNUNET_free(filter);
  m = GNUNET_malloc(size + sizeof(SMTPMessage));
  GNUNET_memcpy(m, msg, size);
  mp = (SMTPMessage *)&m[size];
  mp->header.size = htons(size + sizeof(SMTPMessage));
  mp->header.type = htons(0);
  mp->sender = *core_api->my_identity;
  gm_cls.ebody = NULL;
  gm_cls.pos = 0;
  gm_cls.esize = GNUNET_STRINGS_base64_encode(m, size + sizeof(SMTPMessage), &gm_cls.ebody);
  GNUNET_free(m);
  if (0 == smtp_size_set_estimate(message, gm_cls.esize))
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_size_set_estimate", smtp_strerror(smtp_errno(), ebuf,
                                                            EBUF_LEN));
    }
  if (0 == smtp_set_messagecb(message, &get_message, &gm_cls))
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_set_messagecb", smtp_strerror(smtp_errno(), ebuf,
                                                        EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      GNUNET_free(gm_cls.ebody);
      return GNUNET_SYSERR;
    }
  recipient = smtp_add_recipient(message, haddr->senderAddress);
  if (recipient == NULL)
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_add_recipient", smtp_strerror(smtp_errno(), ebuf,
                                                        EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      return GNUNET_SYSERR;
    }
  if (0 == smtp_start_session(session))
    {
      GNUNET_GE_LOG(ectx,
                    GNUNET_GE_WARNING | GNUNET_GE_ADMIN | GNUNET_GE_USER |
                    GNUNET_GE_BULK, _("SMTP: `%s' failed: %s.\n"),
                    "smtp_start_session", smtp_strerror(smtp_errno(), ebuf,
                                                        EBUF_LEN));
      smtp_destroy_session(session);
      GNUNET_mutex_unlock(lock);
      GNUNET_free(gm_cls.ebody);
      return GNUNET_SYSERR;
    }
  if (stats != NULL)
    stats->change(stat_bytesSent, size);
  if (core_api->load_monitor != NULL)
    GNUNET_network_monitor_notify_transmission(core_api->load_monitor,
                                               GNUNET_ND_UPLOAD, gm_cls.esize);
  smtp_message_reset_status(message);   /* this is needed to plug a 28-byte/message memory leak in libesmtp */
  smtp_destroy_session(session);
  GNUNET_mutex_unlock(lock);
  GNUNET_free(gm_cls.ebody);
  return GNUNET_OK;
}

/**
 * Establish a connection to a remote node.
 * @param hello the hello-Message for the target node
 * @param tsessionPtr the session handle that is to be set
 * @param may_reuse can we re-use an existing connection?
 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
 */
static int
api_connect(const GNUNET_MessageHello * hello, GNUNET_TSession ** tsessionPtr,
            int may_reuse)
{
  GNUNET_TSession *tsession;

  tsession = GNUNET_new(GNUNET_TSession);
  tsession->internal = GNUNET_malloc(GNUNET_sizeof_hello(hello));
  tsession->peer = hello->senderIdentity;
  GNUNET_memcpy(tsession->internal, hello, GNUNET_sizeof_hello(hello));
  tsession->ttype = smtpAPI.protocol_number;
  (*tsessionPtr) = tsession;
  return GNUNET_OK;
}

/**
 * Disconnect from a remote node.
 *
 * @param tsession the session that is closed
 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
 */
static int
api_disconnect(GNUNET_TSession * tsession)
{
  if (tsession != NULL)
    {
      if (tsession->internal != NULL)
        GNUNET_free(tsession->internal);
      GNUNET_free(tsession);
    }
  return GNUNET_OK;
}

/**
 * Start the server process to receive inbound traffic.
 * @return GNUNET_OK on success, GNUNET_SYSERR if the operation failed
 */
static int
api_start_transport_server()
{
  smtp_shutdown = GNUNET_NO;
  /* initialize SMTP network */
  dispatchThread = GNUNET_thread_create(&listenAndDistribute, NULL, 1024 * 4);
  if (dispatchThread == NULL)
    {
      GNUNET_GE_DIE_STRERROR(ectx,
                             GNUNET_GE_ADMIN | GNUNET_GE_BULK | GNUNET_GE_FATAL,
                             "pthread_create");
      return GNUNET_SYSERR;
    }
  return GNUNET_OK;
}

/**
 * Shutdown the server process (stop receiving inbound traffic). Maybe
 * restarted later!
 */
static int
api_stop_transport_server()
{
  void *unused;

  smtp_shutdown = GNUNET_YES;
  GNUNET_thread_stop_sleep(dispatchThread);
  GNUNET_thread_join(dispatchThread, &unused);
  return GNUNET_OK;
}

/**
 * Convert SMTP hello to an IP address (always fails).
 */
static int
api_hello_to_address(const GNUNET_MessageHello * hello, void **sa,
                     unsigned int *sa_len)
{
  return GNUNET_SYSERR;
}

/**
 * Always fails.
 */
static int
api_associate(GNUNET_TSession * tsession)
{
  return GNUNET_SYSERR;         /* SMTP connections can never be associated */
}

/**
 * Always succeeds (for now; we should look at adding
 * frequency limits to SMTP in the future!).
 */
static int
api_test_would_try(GNUNET_TSession * tsession, unsigned int size,
                   int important)
{
  return GNUNET_OK;             /* we always try... */
}

/**
 * The exported method. Makes the core api available via a global and
 * returns the smtp transport API.
 */
GNUNET_TransportAPI *
inittransport_smtp(struct GNUNET_CoreAPIForTransport * core)
{
  unsigned long long mtu;
  struct sigaction sa;

  core_api = core;
  ectx = core->ectx;
  if (!GNUNET_GC_have_configuration_value(core_api->cfg, "SMTP", "EMAIL"))
    {
      GNUNET_GE_LOG(ectx, GNUNET_GE_ERROR | GNUNET_GE_BULK | GNUNET_GE_USER,
                    _
                      ("No email-address specified, can not start SMTP transport.\n"));
      return NULL;
    }
  GNUNET_GC_get_configuration_value_number(core_api->cfg, "SMTP", "MTU", 1200,
                                           SMTP_MESSAGE_SIZE,
                                           SMTP_MESSAGE_SIZE, &mtu);
  GNUNET_GC_get_configuration_value_number(core_api->cfg, "SMTP", "RATELIMIT",
                                           0, 0, 1024 * 1024, &rate_limit);
  stats = core_api->service_request("stats");
  if (stats != NULL)
    {
      stat_bytesReceived =
        stats->create(gettext_noop("# bytes received via SMTP"));
      stat_bytesSent = stats->create(gettext_noop("# bytes sent via SMTP"));
      stat_bytesDropped =
        stats->create(gettext_noop("# bytes dropped by SMTP (outgoing)"));
    }
  GNUNET_GC_get_configuration_value_filename(core_api->cfg, "SMTP", "PIPE", &pipename);
  unlink(pipename);
  if (0 != mkfifo(pipename, S_IWUSR | S_IRUSR | S_IWGRP | S_IWOTH))
    {
      GNUNET_GE_LOG_STRERROR(ectx,
                             GNUNET_GE_ADMIN | GNUNET_GE_BULK | GNUNET_GE_FATAL,
                             "mkfifo");
      GNUNET_free(pipename);
      core_api->service_release(stats);
      stats = NULL;
      return NULL;
    }
  /* we need to allow the mailer program to send us messages;
   * easiest done by giving it write permissions (see Mantis #1142) */
  if (0 != chmod(pipename, S_IWUSR | S_IRUSR | S_IWGRP | S_IWOTH))
    GNUNET_GE_LOG_STRERROR(ectx,
                           GNUNET_GE_ADMIN | GNUNET_GE_BULK |
                           GNUNET_GE_WARNING, "chmod");
  GNUNET_GC_get_configuration_value_string(core_api->cfg, "SMTP", "EMAIL", NULL,
                                           &email);
  lock = GNUNET_mutex_create(GNUNET_NO);
  GNUNET_GC_get_configuration_value_string(core_api->cfg, "SMTP", "SERVER",
                                           "localhost:25", &smtp_server_name);
  sa.sa_handler = SIG_IGN;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  sigaction(SIGPIPE, &sa, &old_handler);

  smtpAPI.protocol_number = GNUNET_TRANSPORT_PROTOCOL_NUMBER_SMTP;
  smtpAPI.mtu = mtu - sizeof(SMTPMessage);
  smtpAPI.cost = 50;
  smtpAPI.hello_verify = &api_verify_hello;
  smtpAPI.hello_create = &api_create_hello;
  smtpAPI.connect = &api_connect;
  smtpAPI.send = &api_send;
  smtpAPI.associate = &api_associate;
  smtpAPI.disconnect = &api_disconnect;
  smtpAPI.server_start = &api_start_transport_server;
  smtpAPI.server_stop = &api_stop_transport_server;
  smtpAPI.hello_to_address = &api_hello_to_address;
  smtpAPI.send_now_test = &api_test_would_try;
  return &smtpAPI;
}

void
donetransport_smtp()
{
  sigaction(SIGPIPE, &old_handler, NULL);
  GNUNET_free(smtp_server_name);
  if (stats != NULL)
    {
      core_api->service_release(stats);
      stats = NULL;
    }
  GNUNET_mutex_destroy(lock);
  lock = NULL;
  unlink(pipename);
  GNUNET_free(pipename);
  pipename = NULL;
  GNUNET_free(email);
  email = NULL;
}

/* end of smtp.c */