rendservice.c

关于tor匿名通信的源代码

/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char rendservice_c_id[] =
  "$Id$";

/**
 * \file rendservice.c
 * \brief The hidden-service side of rendezvous functionality.
 **/

#include "or.h"

static origin_circuit_t *find_intro_circuit(rend_intro_point_t *intro,
                                            const char *pk_digest,
                                            int desc_version);

/** Represents the mapping from a virtual port of a rendezvous service to
 * a real port on some IP.
 */
typedef struct rend_service_port_config_t {
  uint16_t virtual_port;
  uint16_t real_port;
  uint32_t real_addr;
} rend_service_port_config_t;

/** Try to maintain this many intro points per service if possible. */
#define NUM_INTRO_POINTS 3

/** If we can't build our intro circuits, don't retry for this long. */
#define INTRO_CIRC_RETRY_PERIOD (60*5)
/** Don't try to build more than this many circuits before giving up
 * for a while.*/
#define MAX_INTRO_CIRCS_PER_PERIOD 10
/** How many times will a hidden service operator attempt to connect to
 * a requested rendezvous point before giving up? */
#define MAX_REND_FAILURES 30
/** How many seconds should we spend trying to connect to a requested
 * rendezvous point before giving up? */
#define MAX_REND_TIMEOUT 30

/** Represents a single hidden service running at this OP. */
typedef struct rend_service_t {
  /* Fields specified in config file */
  char *directory; /**< where in the filesystem it stores it */
  smartlist_t *ports; /**< List of rend_service_port_config_t */
  char *intro_prefer_nodes; /**< comma-separated list of nicknames */
  char *intro_exclude_nodes; /**< comma-separated list of nicknames */
  int descriptor_version; /**< Rendezvous descriptor version that will be
                           * published. */
  /* Other fields */
  crypto_pk_env_t *private_key; /**< Permanent hidden-service key. */
  char service_id[REND_SERVICE_ID_LEN_BASE32+1]; /**< Onion address without
                                                  * '.onion' */
  char pk_digest[DIGEST_LEN]; /**< Hash of permanent hidden-service key. */
  smartlist_t *intro_nodes; /**< List of rend_intro_point_t's we have,
                             * or are trying to establish. */
  time_t intro_period_started; /**< Start of the current period to build
                                * introduction points. */
  int n_intro_circuits_launched; /**< count of intro circuits we have
                                  * established in this period. */
  rend_service_descriptor_t *desc; /**< Current hidden service descriptor. */
  time_t desc_is_dirty; /**< Time at which changes to the hidden service
                         * descriptor content occurred, or 0 if it's
                         * up-to-date. */
  time_t next_upload_time; /**< Scheduled next hidden service descriptor
                            * upload time. */
} rend_service_t;

/** A list of rend_service_t's for services run on this OP.
 */
static smartlist_t *rend_service_list = NULL;

/** Return the number of rendezvous services we have configured. */
int
num_rend_services(void)
{
  if (!rend_service_list)
    return 0;
  return smartlist_len(rend_service_list);
}

/** Release the storage held by <b>service</b>.
 */
static void
rend_service_free(rend_service_t *service)
{
  if (!service) return;
  tor_free(service->directory);
  SMARTLIST_FOREACH(service->ports, void*, p, tor_free(p));
  smartlist_free(service->ports);
  if (service->private_key)
    crypto_free_pk_env(service->private_key);
  if (service->intro_nodes) {
    SMARTLIST_FOREACH(service->intro_nodes, rend_intro_point_t *, intro,
      rend_intro_point_free(intro););
    smartlist_free(service->intro_nodes);
  }
  tor_free(service->intro_prefer_nodes);
  tor_free(service->intro_exclude_nodes);
  if (service->desc)
    rend_service_descriptor_free(service->desc);
  tor_free(service);
}

/** Release all the storage held in rend_service_list.
 */
void
rend_service_free_all(void)
{
  if (!rend_service_list) {
    return;
  }
  SMARTLIST_FOREACH(rend_service_list, rend_service_t*, ptr,
                    rend_service_free(ptr));
  smartlist_free(rend_service_list);
  rend_service_list = NULL;
}

/** Validate <b>service</b> and add it to rend_service_list if possible.
 */
static void
rend_add_service(rend_service_t *service)
{
  int i;
  rend_service_port_config_t *p;
  struct in_addr addr;

  if (!service->intro_prefer_nodes)
    service->intro_prefer_nodes = tor_strdup("");
  if (!service->intro_exclude_nodes)
    service->intro_exclude_nodes = tor_strdup("");
  service->intro_nodes = smartlist_create();

  /* If the service is configured to publish unversioned (v0) and versioned
   * descriptors (v2 or higher), split it up into two separate services. */
  if (service->descriptor_version == -1) {
    rend_service_t *v0_service = tor_malloc_zero(sizeof(rend_service_t));
    v0_service->directory = tor_strdup(service->directory);
    v0_service->ports = smartlist_create();
    SMARTLIST_FOREACH(service->ports, rend_service_port_config_t *, p, {
      rend_service_port_config_t *copy =
        tor_malloc_zero(sizeof(rend_service_port_config_t));
      memcpy(copy, p, sizeof(rend_service_port_config_t));
      smartlist_add(v0_service->ports, copy);
    });
    v0_service->intro_prefer_nodes = tor_strdup(service->intro_prefer_nodes);
    v0_service->intro_exclude_nodes = tor_strdup(service->intro_exclude_nodes);
    v0_service->intro_period_started = service->intro_period_started;
    v0_service->descriptor_version = 0; /* Unversioned descriptor. */
    rend_add_service(v0_service);

    service->descriptor_version = 2; /* Versioned descriptor. */
  }

  if (!smartlist_len(service->ports)) {
    log_warn(LD_CONFIG, "Hidden service with no ports configured; ignoring.");
    rend_service_free(service);
  } else {
    smartlist_add(rend_service_list, service);
    log_debug(LD_REND,"Configuring service with directory \"%s\"",
              service->directory);
    for (i = 0; i < smartlist_len(service->ports); ++i) {
      char addrbuf[INET_NTOA_BUF_LEN];
      p = smartlist_get(service->ports, i);
      addr.s_addr = htonl(p->real_addr);
      tor_inet_ntoa(&addr, addrbuf, sizeof(addrbuf));
      log_debug(LD_REND,"Service maps port %d to %s:%d",
                p->virtual_port, addrbuf, p->real_port);
    }
  }
}

/** Parses a real-port to virtual-port mapping and returns a new
 * rend_service_port_config_t.
 *
 * The format is: VirtualPort (IP|RealPort|IP:RealPort)?
 *
 * IP defaults to 127.0.0.1; RealPort defaults to VirtualPort.
 */
static rend_service_port_config_t *
parse_port_config(const char *string)
{
  smartlist_t *sl;
  int virtport;
  int realport;
  uint16_t p;
  uint32_t addr;
  const char *addrport;
  rend_service_port_config_t *result = NULL;

  sl = smartlist_create();
  smartlist_split_string(sl, string, " ",
                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  if (smartlist_len(sl) < 1 || smartlist_len(sl) > 2) {
    log_warn(LD_CONFIG, "Bad syntax in hidden service port configuration.");
    goto err;
  }

  virtport = (int)tor_parse_long(smartlist_get(sl,0), 10, 1, 65535, NULL,NULL);
  if (!virtport) {
    log_warn(LD_CONFIG, "Missing or invalid port %s in hidden service port "
             "configuration", escaped(smartlist_get(sl,0)));
    goto err;
  }

  if (smartlist_len(sl) == 1) {
    /* No addr:port part; use default. */
    realport = virtport;
    addr = 0x7F000001u; /* 127.0.0.1 */
  } else {
    addrport = smartlist_get(sl,1);
    if (strchr(addrport, ':') || strchr(addrport, '.')) {
      if (parse_addr_port(LOG_WARN, addrport, NULL, &addr, &p)<0) {
        log_warn(LD_CONFIG,"Unparseable address in hidden service port "
                 "configuration.");
        goto err;
      }
      realport = p?p:virtport;
    } else {
      /* No addr:port, no addr -- must be port. */
      realport = (int)tor_parse_long(addrport, 10, 1, 65535, NULL, NULL);
      if (!realport) {
        log_warn(LD_CONFIG,"Unparseable or out-of-range port %s in hidden "
                 "service port configuration.", escaped(addrport));
        goto err;
      }
      addr = 0x7F000001u; /* Default to 127.0.0.1 */
    }
  }

  result = tor_malloc(sizeof(rend_service_port_config_t));
  result->virtual_port = virtport;
  result->real_port = realport;
  result->real_addr = addr;
 err:
  SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
  smartlist_free(sl);
  return result;
}

/** Set up rend_service_list, based on the values of HiddenServiceDir and
 * HiddenServicePort in <b>options</b>.  Return 0 on success and -1 on
 * failure.  (If <b>validate_only</b> is set, parse, warn and return as
 * normal, but don't actually change the configured services.)
 */
int
rend_config_services(or_options_t *options, int validate_only)
{
  config_line_t *line;
  rend_service_t *service = NULL;
  rend_service_port_config_t *portcfg;

  if (!validate_only) {
    rend_service_free_all();
    rend_service_list = smartlist_create();
  }

  for (line = options->RendConfigLines; line; line = line->next) {
    if (!strcasecmp(line->key, "HiddenServiceDir")) {
      if (service) {
        if (validate_only)
          rend_service_free(service);
        else
          rend_add_service(service);
      }
      service = tor_malloc_zero(sizeof(rend_service_t));
      service->directory = tor_strdup(line->value);
      service->ports = smartlist_create();
      service->intro_period_started = time(NULL);
      service->descriptor_version = -1; /**< All descriptor versions. */
      continue;
    }
    if (!service) {
      log_warn(LD_CONFIG, "%s with no preceding HiddenServiceDir directive",
               line->key);
      rend_service_free(service);
      return -1;
    }
    if (!strcasecmp(line->key, "HiddenServicePort")) {
      portcfg = parse_port_config(line->value);
      if (!portcfg) {
        rend_service_free(service);
        return -1;
      }
      smartlist_add(service->ports, portcfg);
    } else if (!strcasecmp(line->key, "HiddenServiceNodes")) {
      if (service->intro_prefer_nodes) {
        log_warn(LD_CONFIG,
                 "Got multiple HiddenServiceNodes lines for a single "
                 "service.");
        rend_service_free(service);
        return -1;
      }
      service->intro_prefer_nodes = tor_strdup(line->value);
    } else if (!strcasecmp(line->key, "HiddenServiceExcludeNodes")) {
      if (service->intro_exclude_nodes) {
        log_warn(LD_CONFIG,
                 "Got multiple HiddenServiceExcludedNodes lines for "
                 "a single service.");
        rend_service_free(service);
        return -1;
      }
      service->intro_exclude_nodes = tor_strdup(line->value);
    } else {
      smartlist_t *versions;
      char *version_str;
      int i, version, ver_ok=1, versions_bitmask = 0;
      tor_assert(!strcasecmp(line->key, "HiddenServiceVersion"));
      versions = smartlist_create();
      smartlist_split_string(versions, line->value, ",",
                             SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
      for (i = 0; i < smartlist_len(versions); i++) {
        version_str = smartlist_get(versions, i);
        if (strlen(version_str) != 1 || strspn(version_str, "02") != 1) {
          log_warn(LD_CONFIG,
                   "HiddenServiceVersion can only be 0 and/or 2.");
          SMARTLIST_FOREACH(versions, char *, cp, tor_free(cp));
          smartlist_free(versions);
          rend_service_free(service);
          return -1;
        }
        version = (int)tor_parse_long(version_str, 10, 0, INT_MAX, &ver_ok,
                                      NULL);
        if (!ver_ok)
          continue;
        versions_bitmask |= 1 << version;
      }
      /* If exactly one version is set, change descriptor_version to that
       * value; otherwise leave it at -1. */
      if (versions_bitmask == 1 << 0) service->descriptor_version = 0;
      if (versions_bitmask == 1 << 2) service->descriptor_version = 2;
      SMARTLIST_FOREACH(versions, char *, cp, tor_free(cp));
      smartlist_free(versions);
    }
  }
  if (service) {
    if (validate_only)
      rend_service_free(service);
    else
      rend_add_service(service);
  }

  return 0;
}

/** Replace the old value of <b>service</b>-\>desc with one that reflects
 * the other fields in service.
 */
static void
rend_service_update_descriptor(rend_service_t *service)
{
  rend_service_descriptor_t *d;
  origin_circuit_t *circ;
  int i;
  if (service->desc) {
    rend_service_descriptor_free(service->desc);