plugin_transport_tcp.c

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/*
   This file is part of GNUnet
   Copyright (C) 2002--2015 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
 */
#include "platform.h"
#include "gnunet_hello_lib.h"
#include "gnunet_constants.h"
#include "gnunet_util_lib.h"
#include "gnunet_nat_service.h"
#include "gnunet_protocols.h"
#include "gnunet_resolver_service.h"
#include "gnunet_signatures.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "gnunet_transport_plugin.h"
#include "transport.h"
 
#define LOG(kind, ...) GNUNET_log_from (kind, "transport-tcp", __VA_ARGS__)
 
#define PLUGIN_NAME "tcp"
 
#define NAT_TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
 
struct GNUNET_CONNECTION_TransmitHandle;
 
struct GNUNET_SERVER_Handle;
 
struct GNUNET_SERVER_Client;
 
struct GNUNET_SERVER_TransmitHandle;
 
struct GNUNET_CONNECTION_Handle;
 
struct LEGACY_SERVICE_Context;
 
 
void
LEGACY_SERVICE_stop (struct LEGACY_SERVICE_Context *srv);
 
 
typedef size_t (*GNUNET_CONNECTION_TransmitReadyNotify) (void *cls,
                                                         size_t size,
                                                         void *buf);
 
struct GNUNET_CONNECTION_Credentials
{
  uid_t uid;
 
  gid_t gid;
};
 
 
typedef void (*GNUNET_SERVER_DisconnectCallback) (
  void *cls,
  struct GNUNET_SERVER_Client *client);
 
 
typedef void (*GNUNET_SERVER_ConnectCallback) (
  void *cls,
  struct GNUNET_SERVER_Client *client);
 
 
typedef int (*GNUNET_CONNECTION_AccessCheck) (
  void *cls,
  const struct GNUNET_CONNECTION_Credentials *ucred,
  const struct sockaddr *addr,
  socklen_t addrlen);
 
typedef void (*GNUNET_CONNECTION_Receiver) (void *cls,
                                            const void *buf,
                                            size_t available,
                                            const struct sockaddr *addr,
                                            socklen_t addrlen,
                                            int errCode);
 
 
void
GNUNET_CONNECTION_destroy (struct GNUNET_CONNECTION_Handle *connection);
 
 
typedef void *(*GNUNET_SERVER_MstCreateCallback) (
  void *cls,
  struct GNUNET_SERVER_Client *client);
 
 
typedef void (*GNUNET_SERVER_MstDestroyCallback) (void *cls, void *mst);
 
typedef int (*GNUNET_SERVER_MstReceiveCallback) (
  void *cls,
  void *mst,
  struct GNUNET_SERVER_Client *client,
  const char *buf,
  size_t size,
  int purge,
  int one_shot);
typedef void (*GNUNET_SERVER_MessageCallback) (
  void *cls,
  struct GNUNET_SERVER_Client *client,
  const struct GNUNET_MessageHeader *message);
 
struct GNUNET_SERVER_MessageHandler
{
  GNUNET_SERVER_MessageCallback callback;
 
  void *callback_cls;
 
  uint16_t type;
 
  uint16_t expected_size;
};
 
 
enum LEGACY_SERVICE_Options
{
  LEGACY_SERVICE_OPTION_NONE = 0,
 
  LEGACY_SERVICE_OPTION_MANUAL_SHUTDOWN = 1,
 
  LEGACY_SERVICE_OPTION_SOFT_SHUTDOWN = 2
};
 
 
void
GNUNET_SERVER_client_disconnect (struct GNUNET_SERVER_Client *client);
 
void *
GNUNET_SERVER_client_get_user_context_ (struct GNUNET_SERVER_Client *client,
                                        size_t size);
 
 
typedef int (*GNUNET_SERVER_MessageTokenizerCallback) (
  void *cls,
  void *client,
  const struct GNUNET_MessageHeader *message);
 
 
struct GNUNET_SERVER_MessageStreamTokenizer *
GNUNET_SERVER_mst_create (GNUNET_SERVER_MessageTokenizerCallback cb,
                          void *cb_cls);
 
int
GNUNET_SERVER_mst_receive (struct GNUNET_SERVER_MessageStreamTokenizer *mst,
                           void *client_identity,
                           const char *buf,
                           size_t size,
                           int purge,
                           int one_shot);
 
 
void
GNUNET_SERVER_mst_destroy (struct GNUNET_SERVER_MessageStreamTokenizer *mst);
 
 
void
GNUNET_SERVER_client_set_user_context_ (struct GNUNET_SERVER_Client *client,
                                        void *ptr,
                                        size_t size);
 
#define GNUNET_SERVER_client_get_user_context(client, type) \
  (type *) GNUNET_SERVER_client_get_user_context_ (client, sizeof(type))
 
#define GNUNET_SERVER_client_set_user_context(client, value) \
  GNUNET_SERVER_client_set_user_context_ (client, value, sizeof(*value))
 
 
struct GNUNET_SERVER_TransmitHandle *
GNUNET_SERVER_notify_transmit_ready (
  struct GNUNET_SERVER_Client *client,
  size_t size,
  struct GNUNET_TIME_Relative timeout,
  GNUNET_CONNECTION_TransmitReadyNotify callback,
  void *callback_cls);
 
void
GNUNET_SERVER_notify_transmit_ready_cancel (
  struct GNUNET_SERVER_TransmitHandle *th);
 
 
void
GNUNET_SERVER_client_keep (struct GNUNET_SERVER_Client *client);
 
 
void
GNUNET_SERVER_client_drop (struct GNUNET_SERVER_Client *client);
 
 
typedef void (*LEGACY_SERVICE_Main) (
  void *cls,
  struct GNUNET_SERVER_Handle *server,
  const struct GNUNET_CONFIGURATION_Handle *cfg);
 
 
void
GNUNET_SERVER_suspend (struct GNUNET_SERVER_Handle *server);
 
struct GNUNET_SERVER_TransmitHandle *
GNUNET_SERVER_notify_transmit_ready (
  struct GNUNET_SERVER_Client *client,
  size_t size,
  struct GNUNET_TIME_Relative timeout,
  GNUNET_CONNECTION_TransmitReadyNotify callback,
  void *callback_cls);
 
 
struct GNUNET_SERVER_Client *
GNUNET_SERVER_connect_socket (struct GNUNET_SERVER_Handle *server,
                              struct GNUNET_CONNECTION_Handle *connection);
 
 
void
GNUNET_SERVER_resume (struct GNUNET_SERVER_Handle *server);
 
void
GNUNET_SERVER_destroy (struct GNUNET_SERVER_Handle *server);
 
 
#include "tcp_connection_legacy.c"
#include "tcp_server_mst_legacy.c"
#include "tcp_server_legacy.c"
#include "tcp_service_legacy.c"
 
GNUNET_NETWORK_STRUCT_BEGIN
 
struct WelcomeMessage
{
  struct GNUNET_MessageHeader header;
 
  struct GNUNET_PeerIdentity clientIdentity;
};
 
struct TCP_NAT_ProbeMessage
{
  struct GNUNET_MessageHeader header;
 
  struct GNUNET_PeerIdentity clientIdentity;
};
GNUNET_NETWORK_STRUCT_END
 
struct TCPProbeContext
{
  struct TCPProbeContext *next;
 
  struct TCPProbeContext *prev;
 
  struct GNUNET_CONNECTION_Handle *sock;
 
  struct TCP_NAT_ProbeMessage message;
 
  struct GNUNET_CONNECTION_TransmitHandle *transmit_handle;
 
  struct Plugin *plugin;
};
 
enum TcpAddressOptions
{
  TCP_OPTIONS_NONE = 0,
 
  TCP_OPTIONS_RESERVED = 1,
 
  TCP_OPTIONS_TCP_STEALTH = 2
};
 
GNUNET_NETWORK_STRUCT_BEGIN
 
struct IPv4TcpAddress
{
  uint32_t options GNUNET_PACKED;
 
  uint32_t ipv4_addr GNUNET_PACKED;
 
  uint16_t t4_port GNUNET_PACKED;
};
 
struct IPv6TcpAddress
{
  uint32_t options GNUNET_PACKED;
 
  struct in6_addr ipv6_addr GNUNET_PACKED;
 
  uint16_t t6_port GNUNET_PACKED;
};
GNUNET_NETWORK_STRUCT_END
 
struct Plugin;
 
struct PendingMessage
{
  struct PendingMessage *next;
 
  struct PendingMessage *prev;
 
  const char *msg;
 
  GNUNET_TRANSPORT_TransmitContinuation transmit_cont;
 
  void *transmit_cont_cls;
 
  struct GNUNET_TIME_Absolute timeout;
 
  size_t message_size;
};
 
struct GNUNET_ATS_Session
{
  struct GNUNET_PeerIdentity target;
 
  struct Plugin *plugin;
 
  struct GNUNET_SERVER_Client *client;
 
  struct GNUNET_SCHEDULER_Task *nat_connection_timeout;
 
  struct PendingMessage *pending_messages_head;
 
  struct PendingMessage *pending_messages_tail;
 
  struct GNUNET_SERVER_TransmitHandle *transmit_handle;
 
  struct GNUNET_HELLO_Address *address;
 
  struct GNUNET_SCHEDULER_Task *receive_delay_task;
 
  struct GNUNET_SCHEDULER_Task *timeout_task;
 
  struct GNUNET_TIME_Absolute timeout;
 
  struct GNUNET_TIME_Absolute receive_delay;
 
  struct GNUNET_TIME_Absolute last_activity;
 
  unsigned long long bytes_in_queue;
 
  unsigned int msgs_in_queue;
 
  enum GNUNET_NetworkType scope;
 
  int expecting_welcome;
 
  int is_nat;
};
 
 
struct PrettyPrinterContext
{
  struct PrettyPrinterContext *next;
 
  struct PrettyPrinterContext *prev;
 
  struct Plugin *plugin;
 
  struct GNUNET_SCHEDULER_Task *timeout_task;
 
  struct GNUNET_RESOLVER_RequestHandle *resolver_handle;
 
  GNUNET_TRANSPORT_AddressStringCallback asc;
 
  void *asc_cls;
 
  int ipv6;
 
  uint32_t options;
 
  uint16_t port;
};
 
 
struct Plugin
{
  struct GNUNET_TRANSPORT_PluginEnvironment *env;
 
  struct GNUNET_CONNECTION_Handle *lsock;
 
  struct GNUNET_NAT_Handle *nat;
 
  struct GNUNET_CONTAINER_MultiPeerMap *sessionmap;
 
  struct LEGACY_SERVICE_Context *service;
 
  struct GNUNET_SERVER_Handle *server;
 
  struct GNUNET_SERVER_MessageHandler *handlers;
 
  struct GNUNET_CONTAINER_MultiPeerMap *nat_wait_conns;
 
  struct TCPProbeContext *probe_head;
 
  struct TCPProbeContext *probe_tail;
 
  GNUNET_TRANSPORT_SessionInfoCallback sic;
 
  void *sic_cls;
 
  struct GNUNET_SCHEDULER_Task *address_update_task;
 
  struct PrettyPrinterContext *ppc_dll_head;
 
  struct PrettyPrinterContext *ppc_dll_tail;
 
  struct WelcomeMessage my_welcome;
 
  unsigned long long max_connections;
 
  unsigned long long cur_connections;
 
  uint32_t myoptions;
 
  uint16_t open_port;
 
  uint16_t adv_port;
};
 
 
static int
get_server_addresses (const char *service_name,
                      const struct GNUNET_CONFIGURATION_Handle *cfg,
                      struct sockaddr ***addrs,
                      socklen_t **addr_lens)
{
  int disablev6;
  struct GNUNET_NETWORK_Handle *desc;
  unsigned long long port;
  char *unixpath;
  struct addrinfo hints;
  struct addrinfo *res;
  struct addrinfo *pos;
  struct addrinfo *next;
  unsigned int i;
  int resi;
  int ret;
  int abstract;
  struct sockaddr **saddrs;
  socklen_t *saddrlens;
  char *hostname;
 
  *addrs = NULL;
  *addr_lens = NULL;
  desc = NULL;
  if (GNUNET_CONFIGURATION_have_value (cfg, service_name, "DISABLEV6"))
  {
    if (GNUNET_SYSERR ==
        (disablev6 = GNUNET_CONFIGURATION_get_value_yesno (cfg,
                                                           service_name,
                                                           "DISABLEV6")))
      return GNUNET_SYSERR;
  }
  else
    disablev6 = GNUNET_NO;
 
  if (! disablev6)
  {
    /* probe IPv6 support */
    desc = GNUNET_NETWORK_socket_create (PF_INET6, SOCK_STREAM, 0);
    if (NULL == desc)
    {
      if ((ENOBUFS == errno) || (ENOMEM == errno) || (ENFILE == errno) ||
          (EACCES == errno))
      {
        GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "socket");
        return GNUNET_SYSERR;
      }
      LOG (GNUNET_ERROR_TYPE_INFO,
           _ (
             "Disabling IPv6 support for service `%s', failed to create IPv6 socket: %s\n"),
           service_name,
           strerror (errno));
      disablev6 = GNUNET_YES;
    }
    else
    {
      GNUNET_break (GNUNET_OK == GNUNET_NETWORK_socket_close (desc));
      desc = NULL;
    }
  }
 
  port = 0;
  if (GNUNET_CONFIGURATION_have_value (cfg, service_name, "PORT"))
  {
    if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (cfg,
                                                            service_name,
                                                            "PORT",
                                                            &port))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _ ("Require valid port number for service `%s' in configuration!\n"),
           service_name);
    }
    if (port > 65535)
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _ ("Require valid port number for service `%s' in configuration!\n"),
           service_name);
      return GNUNET_SYSERR;
    }
  }
 
  if (GNUNET_CONFIGURATION_have_value (cfg, service_name, "BINDTO"))
  {
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONFIGURATION_get_value_string (cfg,
                                                         service_name,
                                                         "BINDTO",
                                                         &hostname));
  }
  else
    hostname = NULL;
 
  unixpath = NULL;
  abstract = GNUNET_NO;
#ifdef AF_UNIX
  if ((GNUNET_YES ==
       GNUNET_CONFIGURATION_have_value (cfg, service_name, "UNIXPATH")) &&
      (GNUNET_OK == GNUNET_CONFIGURATION_get_value_filename (cfg,
                                                             service_name,
                                                             "UNIXPATH",
                                                             &unixpath)) &&
      (0 < strlen (unixpath)))
  {
    /* probe UNIX support */
    struct sockaddr_un s_un;
 
    if (strlen (unixpath) >= sizeof(s_un.sun_path))
    {
      LOG (GNUNET_ERROR_TYPE_WARNING,
           _ ("UNIXPATH `%s' too long, maximum length is %llu\n"),
           unixpath,
           (unsigned long long) sizeof(s_un.sun_path));
      unixpath = GNUNET_NETWORK_shorten_unixpath (unixpath);
      LOG (GNUNET_ERROR_TYPE_INFO, _ ("Using `%s' instead\n"), unixpath);
    }
#ifdef __linux__
    abstract = GNUNET_CONFIGURATION_get_value_yesno (cfg,
                                                     "TESTING",
                                                     "USE_ABSTRACT_SOCKETS");
    if (GNUNET_SYSERR == abstract)
      abstract = GNUNET_NO;
#endif
    if ((GNUNET_YES != abstract) &&
        (GNUNET_OK != GNUNET_DISK_directory_create_for_file (unixpath)))
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "mkdir", unixpath);
  }
  if (NULL != unixpath)
  {
    desc = GNUNET_NETWORK_socket_create (AF_UNIX, SOCK_STREAM, 0);
    if (NULL == desc)
    {
      if ((ENOBUFS == errno) || (ENOMEM == errno) || (ENFILE == errno) ||
          (EACCES == errno))
      {
        GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "socket");
        GNUNET_free (hostname);
        GNUNET_free (unixpath);
        return GNUNET_SYSERR;
      }
      LOG (GNUNET_ERROR_TYPE_INFO,
           _ (
             "Disabling UNIX domain socket support for service `%s', failed to create UNIX domain socket: %s\n"),
           service_name,
           strerror (errno));
      GNUNET_free (unixpath);
      unixpath = NULL;
    }
    else
    {
      GNUNET_break (GNUNET_OK == GNUNET_NETWORK_socket_close (desc));
      desc = NULL;
    }
  }
#endif
 
  if ((0 == port) && (NULL == unixpath))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _ (
           "Have neither PORT nor UNIXPATH for service `%s', but one is required\n"),
         service_name);
    GNUNET_free (hostname);
    return GNUNET_SYSERR;
  }
  if (0 == port)
  {
    saddrs = GNUNET_malloc (2 * sizeof(struct sockaddr *));
    saddrlens = GNUNET_malloc (2 * sizeof(socklen_t));
    add_unixpath (saddrs, saddrlens, unixpath, abstract);
    GNUNET_free (unixpath);
    GNUNET_free (hostname);
    *addrs = saddrs;
    *addr_lens = saddrlens;
    return 1;
  }
 
  if (NULL != hostname)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Resolving `%s' since that is where `%s' will bind to.\n",
         hostname,
         service_name);
    memset (&hints, 0, sizeof(struct addrinfo));
    if (disablev6)
      hints.ai_family = AF_INET;
    hints.ai_protocol = IPPROTO_TCP;
    if ((0 != (ret = getaddrinfo (hostname, NULL, &hints, &res))) ||
        (NULL == res))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _ ("Failed to resolve `%s': %s\n"),
           hostname,
           gai_strerror (ret));
      GNUNET_free (hostname);
      GNUNET_free (unixpath);
      return GNUNET_SYSERR;
    }
    next = res;
    i = 0;
    while (NULL != (pos = next))
    {
      next = pos->ai_next;
      if ((disablev6) && (pos->ai_family == AF_INET6))
        continue;
      i++;
    }
    if (0 == i)
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _ ("Failed to find %saddress for `%s'.\n"),
           disablev6 ? "IPv4 " : "",
           hostname);
      freeaddrinfo (res);
      GNUNET_free (hostname);
      GNUNET_free (unixpath);
      return GNUNET_SYSERR;
    }
    resi = i;
    if (NULL != unixpath)
      resi++;
    saddrs = GNUNET_malloc ((resi + 1) * sizeof(struct sockaddr *));
    saddrlens = GNUNET_malloc ((resi + 1) * sizeof(socklen_t));
    i = 0;
    if (NULL != unixpath)
    {
      add_unixpath (saddrs, saddrlens, unixpath, abstract);
      i++;
    }
    next = res;
    while (NULL != (pos = next))
    {
      next = pos->ai_next;
      if ((disablev6) && (AF_INET6 == pos->ai_family))
        continue;
      if ((IPPROTO_TCP != pos->ai_protocol) && (0 != pos->ai_protocol))
        continue;     /* not TCP */
      if ((SOCK_STREAM != pos->ai_socktype) && (0 != pos->ai_socktype))
        continue;     /* huh? */
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Service `%s' will bind to `%s'\n",
           service_name,
           GNUNET_a2s (pos->ai_addr, pos->ai_addrlen));
      if (AF_INET == pos->ai_family)
      {
        GNUNET_assert (sizeof(struct sockaddr_in) == pos->ai_addrlen);
        saddrlens[i] = pos->ai_addrlen;
        saddrs[i] = GNUNET_malloc (saddrlens[i]);
        GNUNET_memcpy (saddrs[i], pos->ai_addr, saddrlens[i]);
        ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
      }
      else
      {
        GNUNET_assert (AF_INET6 == pos->ai_family);
        GNUNET_assert (sizeof(struct sockaddr_in6) == pos->ai_addrlen);
        saddrlens[i] = pos->ai_addrlen;
        saddrs[i] = GNUNET_malloc (saddrlens[i]);
        GNUNET_memcpy (saddrs[i], pos->ai_addr, saddrlens[i]);
        ((struct sockaddr_in6 *) saddrs[i])->sin6_port = htons (port);
      }
      i++;
    }
    GNUNET_free (hostname);
    freeaddrinfo (res);
    resi = i;
  }
  else
  {
    /* will bind against everything, just set port */
    if (disablev6)
    {
      /* V4-only */
      resi = 1;
      if (NULL != unixpath)
        resi++;
      i = 0;
      saddrs = GNUNET_malloc ((resi + 1) * sizeof(struct sockaddr *));
      saddrlens = GNUNET_malloc ((resi + 1) * sizeof(socklen_t));
      if (NULL != unixpath)
      {
        add_unixpath (saddrs, saddrlens, unixpath, abstract);
        i++;
      }
      saddrlens[i] = sizeof(struct sockaddr_in);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in *) saddrs[i])->sin_len = saddrlens[i];
#endif
      ((struct sockaddr_in *) saddrs[i])->sin_family = AF_INET;
      ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
    }
    else
    {
      /* dual stack */
      resi = 2;
      if (NULL != unixpath)
        resi++;
      saddrs = GNUNET_malloc ((resi + 1) * sizeof(struct sockaddr *));
      saddrlens = GNUNET_malloc ((resi + 1) * sizeof(socklen_t));
      i = 0;
      if (NULL != unixpath)
      {
        add_unixpath (saddrs, saddrlens, unixpath, abstract);
        i++;
      }
      saddrlens[i] = sizeof(struct sockaddr_in6);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in6 *) saddrs[i])->sin6_len = saddrlens[0];
#endif
      ((struct sockaddr_in6 *) saddrs[i])->sin6_family = AF_INET6;
      ((struct sockaddr_in6 *) saddrs[i])->sin6_port = htons (port);
      i++;
      saddrlens[i] = sizeof(struct sockaddr_in);
      saddrs[i] = GNUNET_malloc (saddrlens[i]);
#if HAVE_SOCKADDR_IN_SIN_LEN
      ((struct sockaddr_in *) saddrs[i])->sin_len = saddrlens[1];
#endif
      ((struct sockaddr_in *) saddrs[i])->sin_family = AF_INET;
      ((struct sockaddr_in *) saddrs[i])->sin_port = htons (port);
    }
  }
  GNUNET_free (unixpath);
  *addrs = saddrs;
  *addr_lens = saddrlens;
  return resi;
}
 
 
/* end ancient copy-and-paste */
 
 
static void
notify_session_monitor (struct Plugin *plugin,
                        struct GNUNET_ATS_Session *session,
                        enum GNUNET_TRANSPORT_SessionState state)
{
  struct GNUNET_TRANSPORT_SessionInfo info;
 
  if (NULL == plugin->sic)
    return;
  memset (&info, 0, sizeof(info));
  info.state = state;
  info.is_inbound =
    GNUNET_HELLO_address_check_option (session->address,
                                       GNUNET_HELLO_ADDRESS_INFO_INBOUND);
  info.num_msg_pending = session->msgs_in_queue;
  info.num_bytes_pending = session->bytes_in_queue;
  if (NULL != session->receive_delay_task)
    info.receive_delay = session->receive_delay;
  info.session_timeout = session->timeout;
  info.address = session->address;
  plugin->sic (plugin->sic_cls, session, &info);
}
 
 
static void
tcp_nat_port_map_callback (void *cls,
                           void **app_ctx,
                           int add_remove,
                           enum GNUNET_NAT_AddressClass ac,
                           const struct sockaddr *addr,
                           socklen_t addrlen)
{
  struct Plugin *plugin = cls;
  struct GNUNET_HELLO_Address *address;
  struct IPv4TcpAddress t4;
  struct IPv6TcpAddress t6;
  void *arg;
  size_t args;
 
  (void) app_ctx;
  LOG (GNUNET_ERROR_TYPE_INFO,
       "NAT notification to %s address `%s'\n",
       (GNUNET_YES == add_remove) ? "add" : "remove",
       GNUNET_a2s (addr, addrlen));
  /* convert 'addr' to our internal format */
  switch (addr->sa_family)
  {
  case AF_INET:
    GNUNET_assert (addrlen == sizeof(struct sockaddr_in));
    memset (&t4, 0, sizeof(t4));
    t4.options = htonl (plugin->myoptions);
    t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
    t4.t4_port = ((struct sockaddr_in *) addr)->sin_port;
    arg = &t4;
    args = sizeof(t4);
    break;
 
  case AF_INET6:
    if (IN6_IS_ADDR_LINKLOCAL (&((struct sockaddr_in6 *) addr)->sin6_addr))
    {
      /* skip link local, we don't allow them in
       #tcp_plugin_check_address() */
      return;
    }
    GNUNET_assert (addrlen == sizeof(struct sockaddr_in6));
    memset (&t6, 0, sizeof(t6));
    GNUNET_memcpy (&t6.ipv6_addr,
                   &((struct sockaddr_in6 *) addr)->sin6_addr,
                   sizeof(struct in6_addr));
    t6.options = htonl (plugin->myoptions);
    t6.t6_port = ((struct sockaddr_in6 *) addr)->sin6_port;
    arg = &t6;
    args = sizeof(t6);
    break;
 
  default:
    GNUNET_break (0);
    return;
  }
  /* modify our published address list */
  GNUNET_assert ((args == sizeof(struct IPv4TcpAddress)) ||
                 (args == sizeof(struct IPv6TcpAddress)));
  /* TODO: use 'ac' here in the future... */
  address = GNUNET_HELLO_address_allocate (plugin->env->my_identity,
                                           PLUGIN_NAME,
                                           arg,
                                           args,
                                           GNUNET_HELLO_ADDRESS_INFO_NONE);
  plugin->env->notify_address (plugin->env->cls, add_remove, address);
  GNUNET_HELLO_address_free (address);
}
 
 
static const char *
tcp_plugin_address_to_string (void *cls, const void *addr, size_t addrlen)
{
  static char rbuf[INET6_ADDRSTRLEN + 12];
  char buf[INET6_ADDRSTRLEN];
  const void *sb;
  struct in_addr a4;
  struct in6_addr a6;
  const struct IPv4TcpAddress *t4;
  const struct IPv6TcpAddress *t6;
  int af;
  uint16_t port;
  uint32_t options;
 
  switch (addrlen)
  {
  case sizeof(struct IPv6TcpAddress):
    t6 = addr;
    af = AF_INET6;
    port = ntohs (t6->t6_port);
    options = ntohl (t6->options);
    GNUNET_memcpy (&a6, &t6->ipv6_addr, sizeof(a6));
    sb = &a6;
    break;
 
  case sizeof(struct IPv4TcpAddress):
    t4 = addr;
    af = AF_INET;
    port = ntohs (t4->t4_port);
    options = ntohl (t4->options);
    GNUNET_memcpy (&a4, &t4->ipv4_addr, sizeof(a4));
    sb = &a4;
    break;
 
  default:
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _ ("Unexpected address length: %u bytes\n"),
         (unsigned int) addrlen);
    return NULL;
  }
  if (NULL == inet_ntop (af, sb, buf, INET6_ADDRSTRLEN))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "inet_ntop");
    return NULL;
  }
  GNUNET_snprintf (rbuf,
                   sizeof(rbuf),
                   (af == AF_INET6) ? "%s.%u.[%s]:%u" : "%s.%u.%s:%u",
                   PLUGIN_NAME,
                   options,
                   buf,
                   port);
  return rbuf;
}
 
 
static int
tcp_plugin_string_to_address (void *cls,
                              const char *addr,
                              uint16_t addrlen,
                              void **buf,
                              size_t *added)
{
  struct sockaddr_storage socket_address;
  char *address;
  char *plugin;
  char *optionstr;
  uint32_t options;
 
  /* Format tcp.options.address:port */
  address = NULL;
  plugin = NULL;
  optionstr = NULL;
  if ((NULL == addr) || (0 == addrlen))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if ('\0' != addr[addrlen - 1])
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if (strlen (addr) != addrlen - 1)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  plugin = GNUNET_strdup (addr);
  optionstr = strchr (plugin, '.');
  if (NULL == optionstr)
  {
    GNUNET_break (0);
    GNUNET_free (plugin);
    return GNUNET_SYSERR;
  }
  optionstr[0] = '\0';
  optionstr++;
  options = atol (optionstr);
  address = strchr (optionstr, '.');
  if (NULL == address)
  {
    GNUNET_break (0);
    GNUNET_free (plugin);
    return GNUNET_SYSERR;
  }
  address[0] = '\0';
  address++;
 
  if (GNUNET_OK !=
      GNUNET_STRINGS_to_address_ip (address, strlen (address), &socket_address))
  {
    GNUNET_break (0);
    GNUNET_free (plugin);
    return GNUNET_SYSERR;
  }
 
  GNUNET_free (plugin);
  switch (socket_address.ss_family)
  {
  case AF_INET: {
      struct IPv4TcpAddress *t4;
      struct sockaddr_in *in4 = (struct sockaddr_in *) &socket_address;
      t4 = GNUNET_new (struct IPv4TcpAddress);
      t4->options = htonl (options);
      t4->ipv4_addr = in4->sin_addr.s_addr;
      t4->t4_port = in4->sin_port;
      *buf = t4;
      *added = sizeof(struct IPv4TcpAddress);
      return GNUNET_OK;
    }
 
  case AF_INET6: {
      struct IPv6TcpAddress *t6;
      struct sockaddr_in6 *in6 = (struct sockaddr_in6 *) &socket_address;
      t6 = GNUNET_new (struct IPv6TcpAddress);
      t6->options = htonl (options);
      t6->ipv6_addr = in6->sin6_addr;
      t6->t6_port = in6->sin6_port;
      *buf = t6;
      *added = sizeof(struct IPv6TcpAddress);
      return GNUNET_OK;
    }
 
  default:
    return GNUNET_SYSERR;
  }
}
 
 
static struct GNUNET_ATS_Session *
lookup_session_by_client (struct Plugin *plugin,
                          struct GNUNET_SERVER_Client *client)
{
  return GNUNET_SERVER_client_get_user_context (client,
                                                struct GNUNET_ATS_Session);
}
 
 
static int
tcp_plugin_disconnect_session (void *cls, struct GNUNET_ATS_Session *session)
{
  struct Plugin *plugin = cls;
  struct PendingMessage *pm;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Disconnecting session of peer `%s' address `%s'\n",
       GNUNET_i2s (&session->target),
       tcp_plugin_address_to_string (session->plugin,
                                     session->address->address,
                                     session->address->address_length));
 
  if (NULL != session->timeout_task)
  {
    GNUNET_SCHEDULER_cancel (session->timeout_task);
    session->timeout_task = NULL;
    session->timeout = GNUNET_TIME_UNIT_ZERO_ABS;
  }
 
  if (GNUNET_YES == GNUNET_CONTAINER_multipeermap_remove (plugin->sessionmap,
                                                          &session->target,
                                                          session))
  {
    GNUNET_STATISTICS_update (session->plugin->env->stats,
                              gettext_noop ("# TCP sessions active"),
                              -1,
                              GNUNET_NO);
  }
  else
  {
    GNUNET_assert (GNUNET_YES ==
                   GNUNET_CONTAINER_multipeermap_remove (plugin->nat_wait_conns,
                                                         &session->target,
                                                         session));
  }
  if (NULL != session->client)
    GNUNET_SERVER_client_set_user_context (session->client, NULL);
 
  /* clean up state */
  if (NULL != session->transmit_handle)
  {
    GNUNET_SERVER_notify_transmit_ready_cancel (session->transmit_handle);
    session->transmit_handle = NULL;
  }
  session->plugin->env->session_end (session->plugin->env->cls,
                                     session->address,
                                     session);
 
  if (NULL != session->nat_connection_timeout)
  {
    GNUNET_SCHEDULER_cancel (session->nat_connection_timeout);
    session->nat_connection_timeout = NULL;
  }
 
  while (NULL != (pm = session->pending_messages_head))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         (NULL != pm->transmit_cont)
         ? "Could not deliver message to `%s' at %s.\n"
         : "Could not deliver message to `%s' at %s, notifying.\n",
         GNUNET_i2s (&session->target),
         tcp_plugin_address_to_string (session->plugin,
                                       session->address->address,
                                       session->address->address_length));
    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);
    GNUNET_assert (0 < session->msgs_in_queue);
    session->msgs_in_queue--;
    GNUNET_assert (pm->message_size <= session->bytes_in_queue);
    session->bytes_in_queue -= pm->message_size;
    if (NULL != pm->transmit_cont)
      pm->transmit_cont (pm->transmit_cont_cls,
                         &session->target,
                         GNUNET_SYSERR,
                         pm->message_size,
                         0);
    GNUNET_free (pm);
  }
  GNUNET_assert (0 == session->msgs_in_queue);
  GNUNET_assert (0 == session->bytes_in_queue);
  notify_session_monitor (session->plugin, session, GNUNET_TRANSPORT_SS_DONE);
 
  if (NULL != session->receive_delay_task)
  {
    GNUNET_SCHEDULER_cancel (session->receive_delay_task);
    session->receive_delay_task = NULL;
  }
  if (NULL != session->client)
  {
    GNUNET_SERVER_client_disconnect (session->client);
    session->client = NULL;
  }
  GNUNET_HELLO_address_free (session->address);
  GNUNET_assert (NULL == session->transmit_handle);
  GNUNET_free (session);
  return GNUNET_OK;
}
 
 
static unsigned int
tcp_plugin_query_keepalive_factor (void *cls)
{
  return 3;
}
 
 
static void
session_timeout (void *cls)
{
  struct GNUNET_ATS_Session *s = cls;
  struct GNUNET_TIME_Relative left;
 
  s->timeout_task = NULL;
  left = GNUNET_TIME_absolute_get_remaining (s->timeout);
  if (0 != left.rel_value_us)
  {
    /* not actually our turn yet, but let's at least update
       the monitor, it may think we're about to die ... */
    notify_session_monitor (s->plugin, s, GNUNET_TRANSPORT_SS_UPDATE);
    s->timeout_task = GNUNET_SCHEDULER_add_delayed (left, &session_timeout, s);
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Session %p was idle for %s, disconnecting\n",
       s,
       GNUNET_STRINGS_relative_time_to_string (
         GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
         GNUNET_YES));
  /* call session destroy function */
  tcp_plugin_disconnect_session (s->plugin, s);
}
 
 
static void
reschedule_session_timeout (struct GNUNET_ATS_Session *s)
{
  GNUNET_assert (NULL != s->timeout_task);
  s->timeout =
    GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
}
 
 
static struct GNUNET_ATS_Session *
create_session (struct Plugin *plugin,
                const struct GNUNET_HELLO_Address *address,
                enum GNUNET_NetworkType scope,
                struct GNUNET_SERVER_Client *client,
                int is_nat)
{
  struct GNUNET_ATS_Session *session;
  struct PendingMessage *pm;
 
  if (GNUNET_YES != is_nat)
    GNUNET_assert (NULL != client);
  else
    GNUNET_assert (NULL == client);
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Creating new session for peer `%s' at address %s\n",
       GNUNET_i2s (&address->peer),
       tcp_plugin_address_to_string (plugin,
                                     address->address,
                                     address->address_length));
  session = GNUNET_new (struct GNUNET_ATS_Session);
  session->last_activity = GNUNET_TIME_absolute_get ();
  session->plugin = plugin;
  session->is_nat = is_nat;
  if (NULL != client)
  {
    session->client = client;
    GNUNET_SERVER_client_set_user_context (client, session);
  }
  session->address = GNUNET_HELLO_address_copy (address);
  session->target = address->peer;
  session->expecting_welcome = GNUNET_YES;
  session->scope = scope;
  pm = GNUNET_malloc (sizeof(struct PendingMessage)
                      + sizeof(struct WelcomeMessage));
  pm->msg = (const char *) &pm[1];
  pm->message_size = sizeof(struct WelcomeMessage);
  GNUNET_memcpy (&pm[1], &plugin->my_welcome, sizeof(struct WelcomeMessage));
  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 (session->pending_messages_head,
                               session->pending_messages_tail,
                               pm);
  session->msgs_in_queue++;
  session->bytes_in_queue += pm->message_size;
  session->timeout =
    GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
  session->timeout_task =
    GNUNET_SCHEDULER_add_delayed (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
                                  &session_timeout,
                                  session);
  notify_session_monitor (session->plugin, session, GNUNET_TRANSPORT_SS_INIT);
  if (GNUNET_YES != is_nat)
  {
    GNUNET_STATISTICS_update (plugin->env->stats,
                              gettext_noop ("# TCP sessions active"),
                              1,
                              GNUNET_NO);
    notify_session_monitor (session->plugin, session, GNUNET_TRANSPORT_SS_UP);
  }
  else
  {
    notify_session_monitor (session->plugin,
                            session,
                            GNUNET_TRANSPORT_SS_HANDSHAKE);
  }
  return session;
}
 
 
static void
process_pending_messages (struct GNUNET_ATS_Session *session);
 
 
static size_t
do_transmit (void *cls, size_t size, void *buf)
{
  struct GNUNET_ATS_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 (NULL == buf)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Timeout trying to transmit to peer `%s', discarding message queue.\n",
         GNUNET_i2s (&session->target));
    /* 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.abs_value_us <= now.abs_value_us))
    {
      GNUNET_CONTAINER_DLL_remove (session->pending_messages_head,
                                   session->pending_messages_tail,
                                   pos);
      GNUNET_assert (0 < session->msgs_in_queue);
      session->msgs_in_queue--;
      GNUNET_assert (pos->message_size <= session->bytes_in_queue);
      session->bytes_in_queue -= pos->message_size;
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Failed to transmit %lu byte message to `%s'.\n",
           (unsigned long) pos->message_size,
           GNUNET_i2s (&session->target));
      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 (NULL != pos->transmit_cont)
        pos->transmit_cont (pos->transmit_cont_cls,
                            &pid,
                            GNUNET_SYSERR,
                            pos->message_size,
                            0);
      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);
    if (0 < ret)
      notify_session_monitor (session->plugin,
                              session,
                              GNUNET_TRANSPORT_SS_UPDATE);
    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 (0 < session->msgs_in_queue);
    session->msgs_in_queue--;
    GNUNET_assert (pos->message_size <= session->bytes_in_queue);
    session->bytes_in_queue -= pos->message_size;
    GNUNET_assert (size >= pos->message_size);
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Transmitting message of type %u size %lu to peer %s at %s\n",
         ntohs (((struct GNUNET_MessageHeader *) pos->msg)->type),
         (unsigned long) pos->message_size,
         GNUNET_i2s (&session->target),
         tcp_plugin_address_to_string (session->plugin,
                                       session->address->address,
                                       session->address->address_length));
    /* FIXME: this GNUNET_memcpy can be up to 7% of our total runtime */
    GNUNET_memcpy (cbuf, pos->msg, pos->message_size);
    cbuf += pos->message_size;
    ret += pos->message_size;
    size -= pos->message_size;
    GNUNET_CONTAINER_DLL_insert_tail (hd, tl, pos);
  }
  notify_session_monitor (session->plugin, session, GNUNET_TRANSPORT_SS_UPDATE);
  /* 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 (NULL != pos->transmit_cont)
      pos->transmit_cont (pos->transmit_cont_cls,
                          &pid,
                          GNUNET_OK,
                          pos->message_size,
                          pos->message_size);  /* FIXME: include TCP overhead */
    GNUNET_free (pos);
  }
  GNUNET_assert (NULL == hd);
  GNUNET_assert (NULL == tl);
  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;
}
 
 
static void
process_pending_messages (struct GNUNET_ATS_Session *session)
{
  struct PendingMessage *pm;
 
  GNUNET_assert (NULL != session->client);
  if (NULL != session->transmit_handle)
    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);
}
 
 
static ssize_t
tcp_plugin_send (void *cls,
                 struct GNUNET_ATS_Session *session,
                 const char *msgbuf,
                 size_t msgbuf_size,
                 unsigned int priority,
                 struct GNUNET_TIME_Relative to,
                 GNUNET_TRANSPORT_TransmitContinuation cont,
                 void *cont_cls)
{
  struct Plugin *plugin = cls;
  struct PendingMessage *pm;
 
  /* create new message entry */
  pm = GNUNET_malloc (sizeof(struct PendingMessage) + msgbuf_size);
  pm->msg = (const char *) &pm[1];
  GNUNET_memcpy (&pm[1], msgbuf, msgbuf_size);
  pm->message_size = msgbuf_size;
  pm->timeout = GNUNET_TIME_relative_to_absolute (to);
  pm->transmit_cont = cont;
  pm->transmit_cont_cls = cont_cls;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Asked to transmit %lu bytes to `%s', added message to list.\n",
       (unsigned long) msgbuf_size,
       GNUNET_i2s (&session->target));
 
  if (GNUNET_YES ==
      GNUNET_CONTAINER_multipeermap_contains_value (plugin->sessionmap,
                                                    &session->target,
                                                    session))
  {
    GNUNET_assert (NULL != session->client);
    GNUNET_SERVER_client_set_timeout (session->client,
                                      GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
    GNUNET_STATISTICS_update (plugin->env->stats,
                              gettext_noop ("# bytes currently in TCP buffers"),
                              msgbuf_size,
                              GNUNET_NO);
 
    /* append pm to pending_messages list */
    GNUNET_CONTAINER_DLL_insert_tail (session->pending_messages_head,
                                      session->pending_messages_tail,
                                      pm);
    notify_session_monitor (session->plugin,
                            session,
                            GNUNET_TRANSPORT_SS_UPDATE);
    session->msgs_in_queue++;
    session->bytes_in_queue += pm->message_size;
    process_pending_messages (session);
    return msgbuf_size;
  }
  if (GNUNET_YES ==
      GNUNET_CONTAINER_multipeermap_contains_value (plugin->nat_wait_conns,
                                                    &session->target,
                                                    session))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "This NAT WAIT session for peer `%s' is not yet ready!\n",
         GNUNET_i2s (&session->target));
    GNUNET_STATISTICS_update (plugin->env->stats,
                              gettext_noop ("# bytes currently in TCP buffers"),
                              msgbuf_size,
                              GNUNET_NO);
    /* append pm to pending_messages list */
    GNUNET_CONTAINER_DLL_insert_tail (session->pending_messages_head,
                                      session->pending_messages_tail,
                                      pm);
    session->msgs_in_queue++;
    session->bytes_in_queue += pm->message_size;
    notify_session_monitor (session->plugin,
                            session,
                            GNUNET_TRANSPORT_SS_HANDSHAKE);
    return msgbuf_size;
  }
  LOG (GNUNET_ERROR_TYPE_ERROR, "Invalid session %p\n", session);
  if (NULL != cont)
    cont (cont_cls, &session->target, GNUNET_SYSERR, pm->message_size, 0);
  GNUNET_break (0);
  GNUNET_free (pm);
  return GNUNET_SYSERR; /* session does not exist here */
}
 
 
struct GNUNET_ATS_SessionItCtx
{
  const struct GNUNET_HELLO_Address *address;
 
  struct GNUNET_ATS_Session *result;
};
 
 
static int
session_lookup_it (void *cls,
                   const struct GNUNET_PeerIdentity *key,
                   void *value)
{
  struct GNUNET_ATS_SessionItCtx *si_ctx = cls;
  struct GNUNET_ATS_Session *session = value;
 
  if (0 != GNUNET_HELLO_address_cmp (si_ctx->address, session->address))
    return GNUNET_YES;
  si_ctx->result = session;
  return GNUNET_NO;
}
 
 
static void
nat_connect_timeout (void *cls)
{
  struct GNUNET_ATS_Session *session = cls;
 
  session->nat_connection_timeout = NULL;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "NAT WAIT connection to `%4s' at `%s' could not be established, removing session\n",
       GNUNET_i2s (&session->target),
       tcp_plugin_address_to_string (session->plugin,
                                     session->address->address,
                                     session->address->address_length));
  tcp_plugin_disconnect_session (session->plugin, session);
}
 
 
static void
tcp_plugin_update_session_timeout (void *cls,
                                   const struct GNUNET_PeerIdentity *peer,
                                   struct GNUNET_ATS_Session *session)
{
  reschedule_session_timeout (session);
}
 
 
static void
delayed_done (void *cls)
{
  struct GNUNET_ATS_Session *session = cls;
 
  session->receive_delay_task = NULL;
  reschedule_session_timeout (session);
  GNUNET_SERVER_receive_done (session->client, GNUNET_OK);
}
 
 
static void
tcp_plugin_update_inbound_delay (void *cls,
                                 const struct GNUNET_PeerIdentity *peer,
                                 struct GNUNET_ATS_Session *session,
                                 struct GNUNET_TIME_Relative delay)
{
  if (NULL == session->receive_delay_task)
    return;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "New inbound delay %s\n",
       GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_NO));
  session->receive_delay = GNUNET_TIME_relative_to_absolute (delay);
  GNUNET_SCHEDULER_cancel (session->receive_delay_task);
  session->receive_delay_task =
    GNUNET_SCHEDULER_add_delayed (delay, &delayed_done, session);
}
 
 
static struct GNUNET_ATS_Session *
tcp_plugin_get_session (void *cls, const struct GNUNET_HELLO_Address *address)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session = NULL;
  int af;
  const void *sb;
  size_t sbs;
  struct GNUNET_CONNECTION_Handle *sa;
  struct sockaddr_in a4;
  struct sockaddr_in6 a6;
  const struct IPv4TcpAddress *t4;
  const struct IPv6TcpAddress *t6;
  unsigned int options;
  enum GNUNET_NetworkType net_type;
  unsigned int is_natd = GNUNET_NO;
  size_t addrlen;
 
#ifdef TCP_STEALTH
  struct GNUNET_NETWORK_Handle *s;
#endif
 
  addrlen = address->address_length;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Trying to get session for `%s' address of peer `%s'\n",
       tcp_plugin_address_to_string (plugin,
                                     address->address,
                                     address->address_length),
       GNUNET_i2s (&address->peer));
 
  if (GNUNET_HELLO_address_check_option (address,
                                         GNUNET_HELLO_ADDRESS_INFO_INBOUND))
  {
    GNUNET_break (0);
    return NULL;
  }
 
  /* look for existing session */
  if (GNUNET_YES == GNUNET_CONTAINER_multipeermap_contains (plugin->sessionmap,
                                                            &address->peer))
  {
    struct GNUNET_ATS_SessionItCtx si_ctx;
 
    si_ctx.address = address;
    si_ctx.result = NULL;
    GNUNET_CONTAINER_multipeermap_get_multiple (plugin->sessionmap,
                                                &address->peer,
                                                &session_lookup_it,
                                                &si_ctx);
    if (NULL != si_ctx.result)
    {
      session = si_ctx.result;
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Found existing session for `%s' address `%s'\n",
           GNUNET_i2s (&address->peer),
           tcp_plugin_address_to_string (plugin,
                                         address->address,
                                         address->address_length));
      return session;
    }
    /* This is a bit of a hack, limiting TCP to never allow more than
       one TCP connection to any given peer at the same time.
       Without this, peers sometimes disagree about which of the TCP
       connections they should use, causing one side to believe that
       they transmit successfully, while the other receives nothing. */return NULL; /* Refuse to have more than one TCP connection per
                      peer pair at the same time. */
  }
 
  if (addrlen == sizeof(struct IPv6TcpAddress))
  {
    GNUNET_assert (NULL != address->address);  /* make static analysis happy */
    t6 = address->address;
    options = t6->options;
    af = AF_INET6;
    memset (&a6, 0, sizeof(a6));
#if HAVE_SOCKADDR_IN_SIN_LEN
    a6.sin6_len = sizeof(a6);
#endif
    a6.sin6_family = AF_INET6;
    a6.sin6_port = t6->t6_port;
    if (t6->t6_port == 0)
      is_natd = GNUNET_YES;
    GNUNET_memcpy (&a6.sin6_addr, &t6->ipv6_addr, sizeof(struct in6_addr));
    sb = &a6;
    sbs = sizeof(a6);
  }
  else if (addrlen == sizeof(struct IPv4TcpAddress))
  {
    GNUNET_assert (NULL != address->address);  /* make static analysis happy */
    t4 = address->address;
    options = t4->options;
    af = AF_INET;
    memset (&a4, 0, sizeof(a4));
#if HAVE_SOCKADDR_IN_SIN_LEN
    a4.sin_len = sizeof(a4);
#endif
    a4.sin_family = AF_INET;
    a4.sin_port = t4->t4_port;
    if (t4->t4_port == 0)
      is_natd = GNUNET_YES;
    a4.sin_addr.s_addr = t4->ipv4_addr;
    sb = &a4;
    sbs = sizeof(a4);
  }
  else
  {
    GNUNET_STATISTICS_update (
      plugin->env->stats,
      gettext_noop ("# requests to create session with invalid address"),
      1,
      GNUNET_NO);
    return NULL;
  }
 
  net_type = plugin->env->get_address_type (plugin->env->cls, sb, sbs);
  GNUNET_break (net_type != GNUNET_NT_UNSPECIFIED);
 
  if ((is_natd == GNUNET_YES) && (addrlen == sizeof(struct IPv6TcpAddress)))
  {
    /* NAT client only works with IPv4 addresses */
    return NULL;
  }
 
  if (plugin->cur_connections >= plugin->max_connections)
  {
    /* saturated */
    return NULL;
  }
 
  if ((is_natd == GNUNET_YES) &&
      (GNUNET_YES ==
       GNUNET_CONTAINER_multipeermap_contains (plugin->nat_wait_conns,
                                               &address->peer)))
  {
    /* Only do one NAT punch attempt per peer identity */
    return NULL;
  }
 
  if ((is_natd == GNUNET_YES) && (NULL != plugin->nat) &&
      (GNUNET_NO ==
       GNUNET_CONTAINER_multipeermap_contains (plugin->nat_wait_conns,
                                               &address->peer)))
  {
    struct sockaddr_in local_sa;
 
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Found valid IPv4 NAT address (creating session)!\n");
    session = create_session (plugin, address, net_type, NULL, GNUNET_YES);
    session->nat_connection_timeout =
      GNUNET_SCHEDULER_add_delayed (NAT_TIMEOUT, &nat_connect_timeout, session);
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_CONTAINER_multipeermap_put (
                     plugin->nat_wait_conns,
                     &session->target,
                     session,
                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
 
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Created NAT WAIT connection to `%s' at `%s'\n",
         GNUNET_i2s (&session->target),
         GNUNET_a2s (sb, sbs));
    memset (&local_sa, 0, sizeof(local_sa));
    local_sa.sin_family = AF_INET;
    local_sa.sin_port = htons (plugin->open_port);
    /* We leave sin_address at 0, let the kernel figure it out,
       even if our bind() is more specific.  (May want to reconsider
       later.) */
    if (GNUNET_OK == GNUNET_NAT_request_reversal (plugin->nat, &local_sa, &a4))
      return session;
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Running NAT client for `%s' at `%s' failed\n",
         GNUNET_i2s (&session->target),
         GNUNET_a2s (sb, sbs));
    tcp_plugin_disconnect_session (plugin, session);
    return NULL;
  }
 
  /* create new outbound session */
  if (0 != (options & TCP_OPTIONS_TCP_STEALTH))
  {
#ifdef TCP_STEALTH
    s = GNUNET_NETWORK_socket_create (af, SOCK_STREAM, 0);
    if (NULL == s)
    {
      GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING | GNUNET_ERROR_TYPE_BULK,
                           "socket");
      sa = NULL;
    }
    else
    {
      if ((GNUNET_OK !=
           GNUNET_NETWORK_socket_setsockopt (s,
                                             IPPROTO_TCP,
                                             TCP_STEALTH,
                                             &session->target,
                                             sizeof(
                                               struct GNUNET_PeerIdentity))) ||
          (GNUNET_OK !=
           GNUNET_NETWORK_socket_setsockopt (s,
                                             IPPROTO_TCP,
                                             TCP_STEALTH_INTEGRITY,
                                             &plugin->my_welcome,
                                             sizeof(struct WelcomeMessage))))
      {
        /* TCP STEALTH not supported by kernel */
        GNUNET_break (GNUNET_OK == GNUNET_NETWORK_socket_close (s));
        sa = NULL;
      }
      else
      {
        sa = GNUNET_CONNECTION_connect_socket (s, sb, sbs);
      }
    }
#else
    sa = NULL;
#endif
  }
  else
  {
    sa = GNUNET_CONNECTION_create_from_sockaddr (af, sb, sbs);
  }
  if (NULL == sa)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Failed to create connection to `%s' at `%s'\n",
         GNUNET_i2s (&address->peer),
         GNUNET_a2s (sb, sbs));
    return NULL;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Asked to transmit to `%s', creating fresh session using address `%s'.\n",
       GNUNET_i2s (&address->peer),
       GNUNET_a2s (sb, sbs));
 
  session = create_session (plugin,
                            address,
                            net_type,
                            GNUNET_SERVER_connect_socket (plugin->server, sa),
                            GNUNET_NO);
  (void) GNUNET_CONTAINER_multipeermap_put (
    plugin->sessionmap,
    &session->target,
    session,
    GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
  /* Send TCP Welcome */
  process_pending_messages (session);
 
  return session;
}
 
 
static int
session_disconnect_it (void *cls,
                       const struct GNUNET_PeerIdentity *key,
                       void *value)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session = value;
 
  GNUNET_STATISTICS_update (session->plugin->env->stats,
                            gettext_noop (
                              "# transport-service disconnect requests for TCP"),
                            1,
                            GNUNET_NO);
  tcp_plugin_disconnect_session (plugin, session);
  return GNUNET_YES;
}
 
 
static void
tcp_plugin_disconnect (void *cls, const struct GNUNET_PeerIdentity *target)
{
  struct Plugin *plugin = cls;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Disconnecting peer `%s'\n",
       GNUNET_i2s (target));
  GNUNET_CONTAINER_multipeermap_get_multiple (plugin->sessionmap,
                                              target,
                                              &session_disconnect_it,
                                              plugin);
  GNUNET_CONTAINER_multipeermap_get_multiple (plugin->nat_wait_conns,
                                              target,
                                              &session_disconnect_it,
                                              plugin);
}
 
 
static void
append_port (void *cls, const char *hostname)
{
  struct PrettyPrinterContext *ppc = cls;
  struct Plugin *plugin = ppc->plugin;
  char *ret;
 
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "append_port called with hostname `%s'\n",
              hostname);
  if (NULL == hostname)
  {
    /* Final call, done */
    ppc->resolver_handle = NULL;
    GNUNET_CONTAINER_DLL_remove (plugin->ppc_dll_head,
                                 plugin->ppc_dll_tail,
                                 ppc);
    ppc->asc (ppc->asc_cls, NULL, GNUNET_OK);
    GNUNET_free (ppc);
    return;
  }
  if (GNUNET_YES == ppc->ipv6)
    GNUNET_asprintf (&ret,
                     "%s.%u.[%s]:%d",
                     PLUGIN_NAME,
                     ppc->options,
                     hostname,
                     ppc->port);
  else
    GNUNET_asprintf (&ret,
                     "%s.%u.%s:%d",
                     PLUGIN_NAME,
                     ppc->options,
                     hostname,
                     ppc->port);
  ppc->asc (ppc->asc_cls, ret, GNUNET_OK);
  GNUNET_free (ret);
}
 
 
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;
  struct PrettyPrinterContext *ppc;
  const void *sb;
  size_t sbs;
  struct sockaddr_in a4;
  struct sockaddr_in6 a6;
  const struct IPv4TcpAddress *t4;
  const struct IPv6TcpAddress *t6;
  uint16_t port;
  uint32_t options;
 
  if (sizeof(struct IPv6TcpAddress) == addrlen)
  {
    t6 = addr;
    memset (&a6, 0, sizeof(a6));
    a6.sin6_family = AF_INET6;
    a6.sin6_port = t6->t6_port;
    GNUNET_memcpy (&a6.sin6_addr, &t6->ipv6_addr, sizeof(struct in6_addr));
    port = ntohs (t6->t6_port);
    options = ntohl (t6->options);
    sb = &a6;
    sbs = sizeof(a6);
  }
  else if (sizeof(struct IPv4TcpAddress) == addrlen)
  {
    t4 = addr;
    memset (&a4, 0, sizeof(a4));
    a4.sin_family = AF_INET;
    a4.sin_port = t4->t4_port;
    a4.sin_addr.s_addr = t4->ipv4_addr;
    port = ntohs (t4->t4_port);
    options = ntohl (t4->options);
    sb = &a4;
    sbs = sizeof(a4);
  }
  else
  {
    /* invalid address */
    LOG (GNUNET_ERROR_TYPE_WARNING,
         _ ("Unexpected address length: %u bytes\n"),
         (unsigned int) addrlen);
    asc (asc_cls, NULL, GNUNET_SYSERR);
    asc (asc_cls, NULL, GNUNET_OK);
    return;
  }
  ppc = GNUNET_new (struct PrettyPrinterContext);
  ppc->plugin = plugin;
  if (addrlen == sizeof(struct IPv6TcpAddress))
    ppc->ipv6 = GNUNET_YES;
  else
    ppc->ipv6 = GNUNET_NO;
  ppc->asc = asc;
  ppc->asc_cls = asc_cls;
  ppc->port = port;
  ppc->options = options;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Starting DNS reverse lookup\n");
  ppc->resolver_handle = GNUNET_RESOLVER_hostname_get (sb,
                                                       sbs,
                                                       ! numeric,
                                                       timeout,
                                                       &append_port,
                                                       ppc);
  if (NULL == ppc->resolver_handle)
  {
    GNUNET_break (0);
    GNUNET_free (ppc);
    return;
  }
  GNUNET_CONTAINER_DLL_insert (plugin->ppc_dll_head, plugin->ppc_dll_tail, ppc);
}
 
 
static int
tcp_plugin_check_address (void *cls, const void *addr, size_t addrlen)
{
  struct Plugin *plugin = cls;
  const struct IPv4TcpAddress *v4;
  const struct IPv6TcpAddress *v6;
 
  if ((addrlen != sizeof(struct IPv4TcpAddress)) &&
      (addrlen != sizeof(struct IPv6TcpAddress)))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
 
  if (addrlen == sizeof(struct IPv4TcpAddress))
  {
    struct sockaddr_in s4;
 
    v4 = (const struct IPv4TcpAddress *) addr;
    if (0 != memcmp (&v4->options, &plugin->myoptions, sizeof(uint32_t)))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    memset (&s4, 0, sizeof(s4));
    s4.sin_family = AF_INET;
#if HAVE_SOCKADDR_IN_SIN_LEN
    s4.sin_len = sizeof(s4);
#endif
    s4.sin_port = v4->t4_port;
    s4.sin_addr.s_addr = v4->ipv4_addr;
 
    if (GNUNET_OK !=
        GNUNET_NAT_test_address (plugin->nat, &s4, sizeof(struct sockaddr_in)))
      return GNUNET_SYSERR;
  }
  else
  {
    struct sockaddr_in6 s6;
 
    v6 = (const struct IPv6TcpAddress *) addr;
    if (IN6_IS_ADDR_LINKLOCAL (&v6->ipv6_addr))
    {
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }
    if (0 != memcmp (&v6->options, &plugin->myoptions, sizeof(uint32_t)))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
    memset (&s6, 0, sizeof(s6));
    s6.sin6_family = AF_INET6;
#if HAVE_SOCKADDR_IN_SIN_LEN
    s6.sin6_len = sizeof(s6);
#endif
    s6.sin6_port = v6->t6_port;
    s6.sin6_addr = v6->ipv6_addr;
 
    if (GNUNET_OK != GNUNET_NAT_test_address (plugin->nat,
                                              &s6,
                                              sizeof(struct sockaddr_in6)))
      return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}
 
 
static void
handle_tcp_nat_probe (void *cls,
                      struct GNUNET_SERVER_Client *client,
                      const struct GNUNET_MessageHeader *message)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session;
  const struct TCP_NAT_ProbeMessage *tcp_nat_probe;
  size_t alen;
  void *vaddr;
  struct IPv4TcpAddress *t4;
  struct IPv6TcpAddress *t6;
  const struct sockaddr_in *s4;
  const struct sockaddr_in6 *s6;
 
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Received NAT probe\n");
  /* We have received a TCP NAT probe, meaning we (hopefully) initiated
   * a connection to this peer by running gnunet-nat-client.  This peer
   * received the punch message and now wants us to use the new connection
   * as the default for that peer.  Do so and then send a WELCOME message
   * so we can really be connected!
   */if (ntohs (message->size) != sizeof(struct TCP_NAT_ProbeMessage))
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
 
  tcp_nat_probe = (const struct TCP_NAT_ProbeMessage *) message;
  if (0 == memcmp (&tcp_nat_probe->clientIdentity,
                   plugin->env->my_identity,
                   sizeof(struct GNUNET_PeerIdentity)))
  {
    /* refuse connections from ourselves */
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
 
  session = GNUNET_CONTAINER_multipeermap_get (plugin->nat_wait_conns,
                                               &tcp_nat_probe->clientIdentity);
  if (NULL == session)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG, "Did NOT find session for NAT probe!\n");
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Found session for NAT probe!\n");
 
  if (NULL != session->nat_connection_timeout)
  {
    GNUNET_SCHEDULER_cancel (session->nat_connection_timeout);
    session->nat_connection_timeout = NULL;
  }
 
  if (GNUNET_OK != GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    tcp_plugin_disconnect_session (plugin, session);
    return;
  }
  GNUNET_assert (
    GNUNET_YES ==
    GNUNET_CONTAINER_multipeermap_remove (plugin->nat_wait_conns,
                                          &tcp_nat_probe->clientIdentity,
                                          session));
  GNUNET_SERVER_client_set_user_context (client, session);
  (void) GNUNET_CONTAINER_multipeermap_put (
    plugin->sessionmap,
    &session->target,
    session,
    GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
  session->last_activity = GNUNET_TIME_absolute_get ();
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Found address `%s' for incoming connection\n",
       GNUNET_a2s (vaddr, alen));
  switch (((const struct sockaddr *) vaddr)->sa_family)
  {
  case AF_INET:
    s4 = vaddr;
    t4 = GNUNET_new (struct IPv4TcpAddress);
    t4->options = htonl (TCP_OPTIONS_NONE);
    t4->t4_port = s4->sin_port;
    t4->ipv4_addr = s4->sin_addr.s_addr;
    session->address =
      GNUNET_HELLO_address_allocate (&tcp_nat_probe->clientIdentity,
                                     PLUGIN_NAME,
                                     &t4,
                                     sizeof(struct IPv4TcpAddress),
                                     GNUNET_HELLO_ADDRESS_INFO_NONE);
    break;
 
  case AF_INET6:
    s6 = vaddr;
    t6 = GNUNET_new (struct IPv6TcpAddress);
    t6->options = htonl (TCP_OPTIONS_NONE);
    t6->t6_port = s6->sin6_port;
    GNUNET_memcpy (&t6->ipv6_addr, &s6->sin6_addr, sizeof(struct in6_addr));
    session->address =
      GNUNET_HELLO_address_allocate (&tcp_nat_probe->clientIdentity,
                                     PLUGIN_NAME,
                                     &t6,
                                     sizeof(struct IPv6TcpAddress),
                                     GNUNET_HELLO_ADDRESS_INFO_NONE);
    break;
 
  default:
    GNUNET_break_op (0);
    LOG (GNUNET_ERROR_TYPE_DEBUG, "Bad address for incoming connection!\n");
    GNUNET_free (vaddr);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    tcp_plugin_disconnect_session (plugin, session);
    return;
  }
  GNUNET_free (vaddr);
  GNUNET_break (NULL == session->client);
  session->client = client;
  GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP sessions active"),
                            1,
                            GNUNET_NO);
  process_pending_messages (session);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}
 
 
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 GNUNET_HELLO_Address *address;
  struct GNUNET_ATS_Session *session;
  size_t alen;
  void *vaddr;
  struct IPv4TcpAddress t4;
  struct IPv6TcpAddress t6;
  const struct sockaddr_in *s4;
  const struct sockaddr_in6 *s6;
 
  if (0 == memcmp (&wm->clientIdentity,
                   plugin->env->my_identity,
                   sizeof(struct GNUNET_PeerIdentity)))
  {
    /* refuse connections from ourselves */
    if (GNUNET_OK == GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
    {
      LOG (GNUNET_ERROR_TYPE_INFO,
           "Received WELCOME message from my own identity `%s' on address `%s'\n",
           GNUNET_i2s (&wm->clientIdentity),
           GNUNET_a2s (vaddr, alen));
      GNUNET_free (vaddr);
    }
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
 
  if (GNUNET_OK == GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received WELCOME message from `%s' on address `%s'\n",
         GNUNET_i2s (&wm->clientIdentity),
         GNUNET_a2s (vaddr, alen));
    GNUNET_free (vaddr);
  }
  GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP WELCOME messages received"),
                            1,
                            GNUNET_NO);
  session = lookup_session_by_client (plugin, client);
  if (NULL != session)
  {
    if (GNUNET_OK == GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Found existing session %p for peer `%s'\n",
           session,
           GNUNET_a2s (vaddr, alen));
      GNUNET_free (vaddr);
    }
  }
  else
  {
    if (GNUNET_OK == GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
    {
      if (alen == sizeof(struct sockaddr_in))
      {
        s4 = vaddr;
        memset (&t4, '\0', sizeof(t4));
        t4.options = htonl (TCP_OPTIONS_NONE);
        t4.t4_port = s4->sin_port;
        t4.ipv4_addr = s4->sin_addr.s_addr;
        address =
          GNUNET_HELLO_address_allocate (&wm->clientIdentity,
                                         PLUGIN_NAME,
                                         &t4,
                                         sizeof(t4),
                                         GNUNET_HELLO_ADDRESS_INFO_INBOUND);
      }
      else if (alen == sizeof(struct sockaddr_in6))
      {
        s6 = vaddr;
        memset (&t6, '\0', sizeof(t6));
        t6.options = htonl (TCP_OPTIONS_NONE);
        t6.t6_port = s6->sin6_port;
        GNUNET_memcpy (&t6.ipv6_addr, &s6->sin6_addr, sizeof(struct in6_addr));
        address =
          GNUNET_HELLO_address_allocate (&wm->clientIdentity,
                                         PLUGIN_NAME,
                                         &t6,
                                         sizeof(t6),
                                         GNUNET_HELLO_ADDRESS_INFO_INBOUND);
      }
      else
      {
        GNUNET_break (0);
        GNUNET_free (vaddr);
        GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
        return;
      }
      session = create_session (plugin,
                                address,
                                plugin->env->get_address_type (plugin->env->cls,
                                                               vaddr,
                                                               alen),
                                client,
                                GNUNET_NO);
      GNUNET_break (GNUNET_NT_UNSPECIFIED != session->scope);
      GNUNET_HELLO_address_free (address);
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Creating new%s session %p for peer `%s' client %p\n",
           GNUNET_HELLO_address_check_option (session->address,
                                              GNUNET_HELLO_ADDRESS_INFO_INBOUND)
           ? " inbound"
           : "",
           session,
           tcp_plugin_address_to_string (plugin,
                                         session->address->address,
                                         session->address->address_length),
           client);
      GNUNET_free (vaddr);
      (void) GNUNET_CONTAINER_multipeermap_put (
        plugin->sessionmap,
        &session->target,
        session,
        GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
      /* Notify transport and ATS about new session */
      plugin->env->session_start (plugin->env->cls,
                                  session->address,
                                  session,
                                  session->scope);
    }
    else
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Did not obtain TCP socket address for incoming connection\n");
      GNUNET_break (0);
      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
      return;
    }
  }
 
  if (GNUNET_YES != session->expecting_welcome)
  {
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  session->last_activity = GNUNET_TIME_absolute_get ();
  session->expecting_welcome = GNUNET_NO;
 
  process_pending_messages (session);
  GNUNET_SERVER_client_set_timeout (client,
                                    GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}
 
 
static void
handle_tcp_data (void *cls,
                 struct GNUNET_SERVER_Client *client,
                 const struct GNUNET_MessageHeader *message)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session;
  struct GNUNET_TIME_Relative delay;
  uint16_t type;
 
  type = ntohs (message->type);
  if ((GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == type) ||
      (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE == type))
  {
    /* We don't want to propagate WELCOME and NAT Probe messages up! */
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  session = lookup_session_by_client (plugin, client);
  if (NULL == session)
  {
    /* No inbound session found */
    void *vaddr = NULL;
    size_t alen;
 
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_SERVER_client_get_address (client, &vaddr, &alen));
    LOG (GNUNET_ERROR_TYPE_ERROR,
         "Received unexpected %u bytes of type %u from `%s'\n",
         (unsigned int) ntohs (message->size),
         (unsigned int) ntohs (message->type),
         GNUNET_a2s (vaddr, alen));
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    GNUNET_free (vaddr);
    return;
  }
  if (GNUNET_YES == session->expecting_welcome)
  {
    /* Session is expecting WELCOME message */
    void *vaddr = NULL;
    size_t alen;
 
    GNUNET_SERVER_client_get_address (client, &vaddr, &alen);
    LOG (GNUNET_ERROR_TYPE_ERROR,
         "Received unexpected %u bytes of type %u from `%s'\n",
         (unsigned int) ntohs (message->size),
         (unsigned int) ntohs (message->type),
         GNUNET_a2s (vaddr, alen));
    GNUNET_break_op (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    GNUNET_free (vaddr);
    return;
  }
 
  session->last_activity = GNUNET_TIME_absolute_get ();
  {
    void *vaddr = NULL;
    size_t alen;
 
    GNUNET_SERVER_client_get_address (client, &vaddr, &alen);
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Passing %u bytes of type %u from `%s' at %s to transport service.\n",
         (unsigned int) ntohs (message->size),
         (unsigned int) ntohs (message->type),
         GNUNET_i2s (&session->target),
         GNUNET_a2s (vaddr, alen));
    GNUNET_free (vaddr);
  }
 
  GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# bytes received via TCP"),
                            ntohs (message->size),
                            GNUNET_NO);
 
  GNUNET_assert (
    GNUNET_CONTAINER_multipeermap_contains_value (plugin->sessionmap,
                                                  &session->target,
                                                  session));
  delay =
    plugin->env->receive (plugin->env->cls, session->address, session, message);
  reschedule_session_timeout (session);
  if (0 == delay.rel_value_us)
  {
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
  }
  else
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Throttling receiving from `%s' for %s\n",
         GNUNET_i2s (&session->target),
         GNUNET_STRINGS_relative_time_to_string (delay, GNUNET_YES));
    GNUNET_SERVER_disable_receive_done_warning (client);
    GNUNET_assert (NULL == session->receive_delay_task);
    session->receive_delay_task =
      GNUNET_SCHEDULER_add_delayed (delay, &delayed_done, session);
  }
}
 
 
static void
connect_notify (void *cls, struct GNUNET_SERVER_Client *client)
{
  struct Plugin *plugin = cls;
 
  if (NULL == client)
    return;
  plugin->cur_connections++;
  GNUNET_STATISTICS_set (plugin->env->stats,
                         gettext_noop ("# TCP server connections active"),
                         plugin->cur_connections,
                         GNUNET_NO);
  GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP server connect events"),
                            1,
                            GNUNET_NO);
  if (plugin->cur_connections != plugin->max_connections)
    return;
  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
              _ ("TCP connection limit reached, suspending server\n"));
  GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP service suspended"),
                            1,
                            GNUNET_NO);
  GNUNET_SERVER_suspend (
    plugin->server); /* Maximum number of connections rechead */
}
 
 
static void
disconnect_notify (void *cls, struct GNUNET_SERVER_Client *client)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session;
 
  if (NULL == client)
    return;
  GNUNET_assert (plugin->cur_connections >= 1);
  plugin->cur_connections--;
  session = lookup_session_by_client (plugin, client);
  if (NULL == session)
    return; /* unknown, nothing to do */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying session of `%s' with %s due to network-level disconnect.\n",
       GNUNET_i2s (&session->target),
       tcp_plugin_address_to_string (session->plugin,
                                     session->address->address,
                                     session->address->address_length));
 
  if (plugin->cur_connections == plugin->max_connections)
  {
    GNUNET_STATISTICS_update (session->plugin->env->stats,
                              gettext_noop ("# TCP service resumed"),
                              1,
                              GNUNET_NO);
    GNUNET_SERVER_resume (plugin->server);  /* Resume server  */
  }
  GNUNET_STATISTICS_set (plugin->env->stats,
                         gettext_noop ("# TCP server connections active"),
                         plugin->cur_connections,
                         GNUNET_NO);
  GNUNET_STATISTICS_update (session->plugin->env->stats,
                            gettext_noop (
                              "# network-level TCP disconnect events"),
                            1,
                            GNUNET_NO);
  tcp_plugin_disconnect_session (plugin, session);
}
 
 
static size_t
notify_send_probe (void *cls, size_t size, void *buf)
{
  struct TCPProbeContext *tcp_probe_ctx = cls;
  struct Plugin *plugin = tcp_probe_ctx->plugin;
  size_t ret;
 
  tcp_probe_ctx->transmit_handle = NULL;
  GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
                               plugin->probe_tail,
                               tcp_probe_ctx);
  if (NULL == buf)
  {
    GNUNET_CONNECTION_destroy (tcp_probe_ctx->sock);
    GNUNET_free (tcp_probe_ctx);
    return 0;
  }
  GNUNET_assert (size >= sizeof(tcp_probe_ctx->message));
  GNUNET_memcpy (buf, &tcp_probe_ctx->message, sizeof(tcp_probe_ctx->message));
  GNUNET_SERVER_connect_socket (tcp_probe_ctx->plugin->server,
                                tcp_probe_ctx->sock);
  ret = sizeof(tcp_probe_ctx->message);
  GNUNET_free (tcp_probe_ctx);
  return ret;
}
 
 
static void
try_connection_reversal (void *cls,
                         const struct sockaddr *addr,
                         socklen_t addrlen)
{
  struct Plugin *plugin = cls;
  struct GNUNET_CONNECTION_Handle *sock;
  struct TCPProbeContext *tcp_probe_ctx;
 
  sock = GNUNET_CONNECTION_create_from_sockaddr (AF_INET, addr, addrlen);
  if (NULL == sock)
  {
    /* failed for some odd reason (out of sockets?); ignore attempt */
    return;
  }
 
  tcp_probe_ctx = GNUNET_new (struct TCPProbeContext);
  tcp_probe_ctx->message.header.size =
    htons (sizeof(struct TCP_NAT_ProbeMessage));
  tcp_probe_ctx->message.header.type =
    htons (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE);
  tcp_probe_ctx->message.clientIdentity = *plugin->env->my_identity;
  tcp_probe_ctx->plugin = plugin;
  tcp_probe_ctx->sock = sock;
  GNUNET_CONTAINER_DLL_insert (plugin->probe_head,
                               plugin->probe_tail,
                               tcp_probe_ctx);
  tcp_probe_ctx->transmit_handle =
    GNUNET_CONNECTION_notify_transmit_ready (sock,
                                             ntohs (tcp_probe_ctx->message
                                                    .header.size),
                                             GNUNET_TIME_UNIT_FOREVER_REL,
                                             &notify_send_probe,
                                             tcp_probe_ctx);
}
 
 
static enum GNUNET_NetworkType
tcp_plugin_get_network (void *cls, struct GNUNET_ATS_Session *session)
{
  return session->scope;
}
 
 
static enum GNUNET_NetworkType
tcp_plugin_get_network_for_address (void *cls,
                                    const struct GNUNET_HELLO_Address *address)
{
  struct Plugin *plugin = cls;
  size_t addrlen;
  struct sockaddr_in a4;
  struct sockaddr_in6 a6;
  const struct IPv4TcpAddress *t4;
  const struct IPv6TcpAddress *t6;
  const void *sb;
  size_t sbs;
 
  addrlen = address->address_length;
  if (addrlen == sizeof(struct IPv6TcpAddress))
  {
    GNUNET_assert (NULL != address->address);  /* make static analysis happy */
    t6 = address->address;
    memset (&a6, 0, sizeof(a6));
#if HAVE_SOCKADDR_IN_SIN_LEN
    a6.sin6_len = sizeof(a6);
#endif
    a6.sin6_family = AF_INET6;
    a6.sin6_port = t6->t6_port;
    GNUNET_memcpy (&a6.sin6_addr, &t6->ipv6_addr, sizeof(struct in6_addr));
    sb = &a6;
    sbs = sizeof(a6);
  }
  else if (addrlen == sizeof(struct IPv4TcpAddress))
  {
    GNUNET_assert (NULL != address->address);  /* make static analysis happy */
    t4 = address->address;
    memset (&a4, 0, sizeof(a4));
#if HAVE_SOCKADDR_IN_SIN_LEN
    a4.sin_len = sizeof(a4);
#endif
    a4.sin_family = AF_INET;
    a4.sin_port = t4->t4_port;
    a4.sin_addr.s_addr = t4->ipv4_addr;
    sb = &a4;
    sbs = sizeof(a4);
  }
  else
  {
    GNUNET_break (0);
    return GNUNET_NT_UNSPECIFIED;
  }
  return plugin->env->get_address_type (plugin->env->cls, sb, sbs);
}
 
 
static int
send_session_info_iter (void *cls,
                        const struct GNUNET_PeerIdentity *peer,
                        void *value)
{
  struct Plugin *plugin = cls;
  struct GNUNET_ATS_Session *session = value;
 
  notify_session_monitor (plugin, session, GNUNET_TRANSPORT_SS_INIT);
  /* FIXME: cannot tell if this is up or not from current
     session state... */
  notify_session_monitor (plugin, session, GNUNET_TRANSPORT_SS_UP);
  return GNUNET_OK;
}
 
 
static void
tcp_plugin_setup_monitor (void *cls,
                          GNUNET_TRANSPORT_SessionInfoCallback sic,
                          void *sic_cls)
{
  struct Plugin *plugin = cls;
 
  plugin->sic = sic;
  plugin->sic_cls = sic_cls;
  if (NULL != sic)
  {
    GNUNET_CONTAINER_multipeermap_iterate (plugin->sessionmap,
                                           &send_session_info_iter,
                                           plugin);
    /* signal end of first iteration */
    sic (sic_cls, NULL, NULL);
  }
}
 
 
void *
libgnunet_plugin_transport_tcp_init (void *cls)
{
  static const struct GNUNET_SERVER_MessageHandler my_handlers[] =
  { { &handle_tcp_welcome,
      NULL,
      GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME,
      sizeof(struct WelcomeMessage) },
    { &handle_tcp_nat_probe,
      NULL,
      GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE,
      sizeof(struct TCP_NAT_ProbeMessage) },
    { &handle_tcp_data, NULL, GNUNET_MESSAGE_TYPE_ALL, 0 },
    { NULL, NULL, 0, 0 } };
  struct GNUNET_TRANSPORT_PluginEnvironment *env = cls;
  struct GNUNET_TRANSPORT_PluginFunctions *api;
  struct Plugin *plugin;
  struct LEGACY_SERVICE_Context *service;
  unsigned long long aport;
  unsigned long long bport;
  unsigned long long max_connections;
  unsigned int i;
  struct GNUNET_TIME_Relative idle_timeout;
 
#ifdef TCP_STEALTH
  struct GNUNET_NETWORK_Handle *const *lsocks;
#endif
  int ret;
  int ret_s;
  struct sockaddr **addrs;
  socklen_t *addrlens;
 
  if (NULL == env->receive)
  {
    /* run in 'stub' mode (i.e. as part of gnunet-peerinfo), don't fully
       initialize the plugin or the API */
    api = GNUNET_new (struct GNUNET_TRANSPORT_PluginFunctions);
    api->cls = NULL;
    api->address_pretty_printer = &tcp_plugin_address_pretty_printer;
    api->address_to_string = &tcp_plugin_address_to_string;
    api->string_to_address = &tcp_plugin_string_to_address;
    return api;
  }
 
  GNUNET_assert (NULL != env->cfg);
  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (env->cfg,
                                                          "transport-tcp",
                                                          "MAX_CONNECTIONS",
                                                          &max_connections))
    max_connections = 128;
 
  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)))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _ ("Require valid port number for service `%s' in configuration!\n"),
         "transport-tcp");
    return NULL;
  }
  if (0 == aport)
    aport = bport;
  if (0 == bport)
    aport = 0;
  if (0 != bport)
  {
    service = LEGACY_SERVICE_start ("transport-tcp",
                                    env->cfg,
                                    LEGACY_SERVICE_OPTION_NONE);
    if (NULL == service)
    {
      LOG (GNUNET_ERROR_TYPE_WARNING, _ ("Failed to start service.\n"));
      return NULL;
    }
  }
  else
    service = NULL;
 
  api = NULL;
  plugin = GNUNET_new (struct Plugin);
  plugin->sessionmap =
    GNUNET_CONTAINER_multipeermap_create (max_connections, GNUNET_YES);
  plugin->max_connections = max_connections;
  plugin->open_port = bport;
  plugin->adv_port = aport;
  plugin->env = env;
  plugin->my_welcome.header.size = htons (sizeof(struct WelcomeMessage));
  plugin->my_welcome.header.type =
    htons (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME);
  plugin->my_welcome.clientIdentity = *plugin->env->my_identity;
 
  if ((NULL != service) &&
      (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
                                                           "transport-tcp",
                                                           "TCP_STEALTH")))
  {
#ifdef TCP_STEALTH
    plugin->myoptions |= TCP_OPTIONS_TCP_STEALTH;
    lsocks = LEGACY_SERVICE_get_listen_sockets (service);
    if (NULL != lsocks)
    {
      uint32_t len = sizeof(struct WelcomeMessage);
 
      for (i = 0; NULL != lsocks[i]; i++)
      {
        if (
          (GNUNET_OK !=
           GNUNET_NETWORK_socket_setsockopt (lsocks[i],
                                             IPPROTO_TCP,
                                             TCP_STEALTH,
                                             env->my_identity,
                                             sizeof(
                                               struct GNUNET_PeerIdentity))) ||
          (GNUNET_OK !=
           GNUNET_NETWORK_socket_setsockopt (lsocks[i],
                                             IPPROTO_TCP,
                                             TCP_STEALTH_INTEGRITY_LEN,
                                             &len,
                                             sizeof(len))))
        {
          /* TCP STEALTH not supported by kernel */
          GNUNET_assert (0 == i);
          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                      _ ("TCP_STEALTH not supported on this platform.\n"));
          goto die;
        }
      }
    }
#else
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _ ("TCP_STEALTH not supported on this platform.\n"));
    goto die;
#endif
  }
 
  if ((NULL != service) &&
      (GNUNET_SYSERR !=
       (ret_s =
          get_server_addresses ("transport-tcp", env->cfg, &addrs, &addrlens))))
  {
    for (ret = ret_s - 1; ret >= 0; ret--)
      LOG (GNUNET_ERROR_TYPE_INFO,
           "Binding to address `%s'\n",
           GNUNET_a2s (addrs[ret], addrlens[ret]));
    plugin->nat = GNUNET_NAT_register (env->cfg,
                                       "transport-tcp",
                                       IPPROTO_TCP,
                                       (unsigned int) ret_s,
                                       (const struct sockaddr **) addrs,
                                       addrlens,
                                       &tcp_nat_port_map_callback,
                                       &try_connection_reversal,
                                       plugin);
    for (ret = ret_s - 1; ret >= 0; ret--)
      GNUNET_free (addrs[ret]);
    GNUNET_free (addrs);
    GNUNET_free (addrlens);
  }
  else
  {
    plugin->nat = GNUNET_NAT_register (plugin->env->cfg,
                                       "transport-tcp",
                                       IPPROTO_TCP,
                                       0,
                                       NULL,
                                       NULL,
                                       NULL,
                                       &try_connection_reversal,
                                       plugin);
  }
  api = GNUNET_new (struct GNUNET_TRANSPORT_PluginFunctions);
  api->cls = plugin;
  api->send = &tcp_plugin_send;
  api->get_session = &tcp_plugin_get_session;
  api->disconnect_session = &tcp_plugin_disconnect_session;
  api->query_keepalive_factor = &tcp_plugin_query_keepalive_factor;
  api->disconnect_peer = &tcp_plugin_disconnect;
  api->address_pretty_printer = &tcp_plugin_address_pretty_printer;
  api->check_address = &tcp_plugin_check_address;
  api->address_to_string = &tcp_plugin_address_to_string;
  api->string_to_address = &tcp_plugin_string_to_address;
  api->get_network = &tcp_plugin_get_network;
  api->get_network_for_address = &tcp_plugin_get_network_for_address;
  api->update_session_timeout = &tcp_plugin_update_session_timeout;
  api->update_inbound_delay = &tcp_plugin_update_inbound_delay;
  api->setup_monitor = &tcp_plugin_setup_monitor;
  plugin->service = service;
  if (NULL != service)
  {
    plugin->server = LEGACY_SERVICE_get_server (service);
  }
  else
  {
    if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_time (env->cfg,
                                                          "transport-tcp",
                                                          "TIMEOUT",
                                                          &idle_timeout))
    {
      GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
                                 "transport-tcp",
                                 "TIMEOUT");
      goto die;
    }
    plugin->server = GNUNET_SERVER_create_with_sockets (NULL,
                                                        plugin,
                                                        NULL,
                                                        idle_timeout,
                                                        GNUNET_YES);
  }
  plugin->handlers = GNUNET_malloc (sizeof(my_handlers));
  GNUNET_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_SERVER_connect_notify (plugin->server, &connect_notify, plugin);
  GNUNET_SERVER_disconnect_notify (plugin->server, &disconnect_notify, plugin);
  plugin->nat_wait_conns =
    GNUNET_CONTAINER_multipeermap_create (16, GNUNET_YES);
  if (0 != bport)
    LOG (GNUNET_ERROR_TYPE_INFO,
         _ ("TCP transport listening on port %llu\n"),
         bport);
  else
    LOG (GNUNET_ERROR_TYPE_INFO,
         _ ("TCP transport not listening on any port (client only)\n"));
  if ((aport != bport) && (0 != bport))
    LOG (GNUNET_ERROR_TYPE_INFO,
         _ ("TCP transport advertises itself as being on port %llu\n"),
         aport);
  /* Initially set connections to 0 */
  GNUNET_STATISTICS_set (plugin->env->stats,
                         gettext_noop ("# TCP sessions active"),
                         0,
                         GNUNET_NO);
  return api;
 
die:
  if (NULL != plugin->nat)
    GNUNET_NAT_unregister (plugin->nat);
  GNUNET_CONTAINER_multipeermap_destroy (plugin->sessionmap);
  if (NULL != service)
    LEGACY_SERVICE_stop (service);
  GNUNET_free (plugin);
  GNUNET_free (api);
  return NULL;
}
 
 
void *
libgnunet_plugin_transport_tcp_done (void *cls)
{
  struct GNUNET_TRANSPORT_PluginFunctions *api = cls;
  struct Plugin *plugin = api->cls;
  struct TCPProbeContext *tcp_probe;
  struct PrettyPrinterContext *cur;
  struct PrettyPrinterContext *next;
 
  if (NULL == plugin)
  {
    GNUNET_free (api);
    return NULL;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Shutting down TCP plugin\n");
 
  /* Removing leftover sessions */
  GNUNET_CONTAINER_multipeermap_iterate (plugin->sessionmap,
                                         &session_disconnect_it,
                                         plugin);
  /* Removing leftover NAT sessions */
  GNUNET_CONTAINER_multipeermap_iterate (plugin->nat_wait_conns,
                                         &session_disconnect_it,
                                         plugin);
 
  for (cur = plugin->ppc_dll_head; NULL != cur; cur = next)
  {
    next = cur->next;
    GNUNET_CONTAINER_DLL_remove (plugin->ppc_dll_head,
                                 plugin->ppc_dll_tail,
                                 cur);
    GNUNET_RESOLVER_request_cancel (cur->resolver_handle);
    cur->asc (cur->asc_cls, NULL, GNUNET_OK);
    GNUNET_free (cur);
  }
 
  if (NULL != plugin->service)
    LEGACY_SERVICE_stop (plugin->service);
  else
    GNUNET_SERVER_destroy (plugin->server);
  GNUNET_free (plugin->handlers);
  if (NULL != plugin->nat)
    GNUNET_NAT_unregister (plugin->nat);
  while (NULL != (tcp_probe = plugin->probe_head))
  {
    GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
                                 plugin->probe_tail,
                                 tcp_probe);
    GNUNET_CONNECTION_destroy (tcp_probe->sock);
    GNUNET_free (tcp_probe);
  }
  GNUNET_CONTAINER_multipeermap_destroy (plugin->nat_wait_conns);
  GNUNET_CONTAINER_multipeermap_destroy (plugin->sessionmap);
  GNUNET_break (0 == plugin->cur_connections);
  GNUNET_free (plugin);
  GNUNET_free (api);
  return NULL;
}
 
 
/* end of plugin_transport_tcp.c */