dirserv.c

关于tor匿名通信的源代码

/* Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char dirserv_c_id[] =
  "$Id$";

#define DIRSERV_PRIVATE
#include "or.h"

/**
 * \file dirserv.c
 * \brief Directory server core implementation. Manages directory
 * contents and generates directories.
 */

/** How far in the future do we allow a router to get? (seconds) */
#define ROUTER_ALLOW_SKEW (60*60*12)
/** How many seconds do we wait before regenerating the directory? */
#define DIR_REGEN_SLACK_TIME 30
/** If we're a cache, keep this many networkstatuses around from non-trusted
 * directory authorities. */
#define MAX_UNTRUSTED_NETWORKSTATUSES 16

/** If a v1 directory is older than this, discard it. */
#define MAX_V1_DIRECTORY_AGE (30*24*60*60)
/** If a v1 running-routers is older than this, discard it. */
#define MAX_V1_RR_AGE (7*24*60*60)

extern time_t time_of_process_start; /* from main.c */

/** Do we need to regenerate the directory when someone asks for it? */
static time_t the_directory_is_dirty = 1;
static time_t runningrouters_is_dirty = 1;
static time_t the_v2_networkstatus_is_dirty = 1;

/** Most recently generated encoded signed v1 directory. (v1 auth dirservers
 * only.) */
static cached_dir_t *the_directory = NULL;

/** For authoritative directories: the current (v1) network status. */
static cached_dir_t the_runningrouters = { NULL, NULL, 0, 0, 0, -1 };

static void directory_remove_invalid(void);
static cached_dir_t *dirserv_regenerate_directory(void);
static char *format_versions_list(config_line_t *ln);
struct authdir_config_t;
static int add_fingerprint_to_dir(const char *nickname, const char *fp,
                                  struct authdir_config_t *list);
static uint32_t dirserv_router_get_status(const routerinfo_t *router,
                                          const char **msg);
static uint32_t
dirserv_get_status_impl(const char *fp, const char *nickname,
                        const char *address,
                        uint32_t addr, uint16_t or_port,
                        const char *platform, const char *contact,
                        const char **msg, int should_log);
static void clear_cached_dir(cached_dir_t *d);
static signed_descriptor_t *get_signed_descriptor_by_fp(const char *fp,
                                                        int extrainfo,
                                                        time_t publish_cutoff);
static int dirserv_add_extrainfo(extrainfo_t *ei, const char **msg);

/************** Fingerprint handling code ************/

#define FP_NAMED   1  /**< Listed in fingerprint file. */
#define FP_INVALID 2  /**< Believed invalid. */
#define FP_REJECT  4  /**< We will not publish this router. */
#define FP_BADDIR  8  /**< We'll tell clients to avoid using this as a dir. */
#define FP_BADEXIT 16  /**< We'll tell clients not to use this as an exit. */
#define FP_UNNAMED 32 /**< Another router has this name in fingerprint file. */

/** Encapsulate a nickname and an FP_* status; target of status_by_digest
 * map. */
typedef struct router_status_t {
  char nickname[MAX_NICKNAME_LEN+1];
  uint32_t status;
} router_status_t;

/** List of nickname-\>identity fingerprint mappings for all the routers
 * that we name.  Used to prevent router impersonation. */
typedef struct authdir_config_t {
  strmap_t *fp_by_name; /**< Map from lc nickname to fingerprint. */
  digestmap_t *status_by_digest; /**< Map from digest to router_status_t. */
} authdir_config_t;

/** Should be static; exposed for testing. */
static authdir_config_t *fingerprint_list = NULL;

/** Allocate and return a new, empty, authdir_config_t. */
static authdir_config_t *
authdir_config_new(void)
{
  authdir_config_t *list = tor_malloc_zero(sizeof(authdir_config_t));
  list->fp_by_name = strmap_new();
  list->status_by_digest = digestmap_new();
  return list;
}

/** Add the fingerprint <b>fp</b> for the nickname <b>nickname</b> to
 * the smartlist of fingerprint_entry_t's <b>list</b>. Return 0 if it's
 * new, or 1 if we replaced the old value.
 */
/* static */ int
add_fingerprint_to_dir(const char *nickname, const char *fp,
                       authdir_config_t *list)
{
  char *fingerprint;
  char d[DIGEST_LEN];
  router_status_t *status;
  tor_assert(nickname);
  tor_assert(fp);
  tor_assert(list);

  fingerprint = tor_strdup(fp);
  tor_strstrip(fingerprint, " ");
  if (base16_decode(d, DIGEST_LEN, fingerprint, strlen(fingerprint))) {
    log_warn(LD_DIRSERV, "Couldn't decode fingerprint \"%s\"",
             escaped(fp));
    tor_free(fingerprint);
    return 0;
  }

  if (!strcasecmp(nickname, UNNAMED_ROUTER_NICKNAME)) {
    log_warn(LD_DIRSERV, "Tried to add a mapping for reserved nickname %s",
             UNNAMED_ROUTER_NICKNAME);
    tor_free(fingerprint);
    return 0;
  }

  status = digestmap_get(list->status_by_digest, d);
  if (!status) {
    status = tor_malloc_zero(sizeof(router_status_t));
    digestmap_set(list->status_by_digest, d, status);
  }

  if (nickname[0] != '!') {
    char *old_fp = strmap_get_lc(list->fp_by_name, nickname);
    if (old_fp && !strcasecmp(fingerprint, old_fp)) {
      tor_free(fingerprint);
    } else {
      tor_free(old_fp);
      strmap_set_lc(list->fp_by_name, nickname, fingerprint);
    }
    status->status |= FP_NAMED;
    strlcpy(status->nickname, nickname, sizeof(status->nickname));
  } else {
    tor_free(fingerprint);
    if (!strcasecmp(nickname, "!reject")) {
      status->status |= FP_REJECT;
    } else if (!strcasecmp(nickname, "!invalid")) {
      status->status |= FP_INVALID;
    } else if (!strcasecmp(nickname, "!baddir")) {
      status->status |= FP_BADDIR;
    } else if (!strcasecmp(nickname, "!badexit")) {
      status->status |= FP_BADEXIT;
    }
  }
  return 0;
}

/** Add the nickname and fingerprint for this OR to the
 * global list of recognized identity key fingerprints. */
int
dirserv_add_own_fingerprint(const char *nickname, crypto_pk_env_t *pk)
{
  char fp[FINGERPRINT_LEN+1];
  if (crypto_pk_get_fingerprint(pk, fp, 0)<0) {
    log_err(LD_BUG, "Error computing fingerprint");
    return -1;
  }
  if (!fingerprint_list)
    fingerprint_list = authdir_config_new();
  add_fingerprint_to_dir(nickname, fp, fingerprint_list);
  return 0;
}

/** Load the nickname-\>fingerprint mappings stored in the approved-routers
 * file.  The file format is line-based, with each non-blank holding one
 * nickname, some space, and a fingerprint for that nickname.  On success,
 * replace the current fingerprint list with the new list and return 0.  On
 * failure, leave the current fingerprint list untouched, and
 * return -1. */
int
dirserv_load_fingerprint_file(void)
{
  char *fname;
  char *cf;
  char *nickname, *fingerprint;
  authdir_config_t *fingerprint_list_new;
  int result;
  config_line_t *front=NULL, *list;
  or_options_t *options = get_options();

  fname = get_datadir_fname("approved-routers");
  log_info(LD_GENERAL,
           "Reloading approved fingerprints from \"%s\"...", fname);

  cf = read_file_to_str(fname, RFTS_IGNORE_MISSING, NULL);
  if (!cf) {
    if (options->NamingAuthoritativeDir) {
      log_warn(LD_FS, "Cannot open fingerprint file '%s'. Failing.", fname);
      tor_free(fname);
      return -1;
    } else {
      log_info(LD_FS, "Cannot open fingerprint file '%s'. That's ok.", fname);
      tor_free(fname);
      return 0;
    }
  }
  tor_free(fname);

  result = config_get_lines(cf, &front);
  tor_free(cf);
  if (result < 0) {
    log_warn(LD_CONFIG, "Error reading from fingerprint file");
    return -1;
  }

  fingerprint_list_new = authdir_config_new();

  for (list=front; list; list=list->next) {
    nickname = list->key; fingerprint = list->value;
    if (strlen(nickname) > MAX_NICKNAME_LEN) {
      log_notice(LD_CONFIG,
                 "Nickname '%s' too long in fingerprint file. Skipping.",
                 nickname);
      continue;
    }
    if (!is_legal_nickname(nickname) &&
        strcasecmp(nickname, "!reject") &&
        strcasecmp(nickname, "!invalid") &&
        strcasecmp(nickname, "!badexit")) {
      log_notice(LD_CONFIG,
                 "Invalid nickname '%s' in fingerprint file. Skipping.",
                 nickname);
      continue;
    }
    if (strlen(fingerprint) != FINGERPRINT_LEN ||
        !crypto_pk_check_fingerprint_syntax(fingerprint)) {
      log_notice(LD_CONFIG,
                 "Invalid fingerprint (nickname '%s', "
                 "fingerprint %s). Skipping.",
                 nickname, fingerprint);
      continue;
    }
    if (0==strcasecmp(nickname, DEFAULT_CLIENT_NICKNAME)) {
      /* If you approved an OR called "client", then clients who use
       * the default nickname could all be rejected.  That's no good. */
      log_notice(LD_CONFIG,
                 "Authorizing nickname '%s' would break "
                 "many clients; skipping.",
                 DEFAULT_CLIENT_NICKNAME);
      continue;
    }
    if (0==strcasecmp(nickname, UNNAMED_ROUTER_NICKNAME)) {
      /* If you approved an OR called "unnamed", then clients will be
       * confused. */
      log_notice(LD_CONFIG,
                 "Authorizing nickname '%s' is not allowed; skipping.",
                 UNNAMED_ROUTER_NICKNAME);
      continue;
    }
    if (add_fingerprint_to_dir(nickname, fingerprint, fingerprint_list_new)
        != 0)
      log_notice(LD_CONFIG, "Duplicate nickname '%s'.", nickname);
  }

  config_free_lines(front);
  dirserv_free_fingerprint_list();
  fingerprint_list = fingerprint_list_new;
  /* Delete any routers whose fingerprints we no longer recognize */
  directory_remove_invalid();
  return 0;
}

/** Check whether <b>router</b> has a nickname/identity key combination that
 * we recognize from the fingerprint list, or an IP we automatically act on
 * according to our configuration.  Return the appropriate router status.
 *
 * If the status is 'FP_REJECT' and <b>msg</b> is provided, set
 * *<b>msg</b> to an explanation of why. */
static uint32_t
dirserv_router_get_status(const routerinfo_t *router, const char **msg)
{
  char d[DIGEST_LEN];

  if (crypto_pk_get_digest(router->identity_pkey, d)) {
    log_warn(LD_BUG,"Error computing fingerprint");
    if (msg)
      *msg = "Bug: Error computing fingerprint";
    return FP_REJECT;
  }

  return dirserv_get_status_impl(d, router->nickname,
                                 router->address,
                                 router->addr, router->or_port,
                                 router->platform, router->contact_info,
                                 msg, 1);
}

/** Return true if there is no point in downloading the router described by
 * <b>rs</b> because this directory would reject it. */
int
dirserv_would_reject_router(routerstatus_t *rs)
{
  uint32_t res;

  res = dirserv_get_status_impl(rs->identity_digest, rs->nickname,
                                "", /* address is only used in logs */
                                rs->addr, rs->or_port,
                                NULL, NULL,
                                NULL, 0);

  return (res & FP_REJECT) != 0;
}

/** Helper: Based only on the ID/Nickname combination,
 * return FP_UNNAMED (unnamed), FP_NAMED (named), or 0 (neither).
 */
static uint32_t
dirserv_get_name_status(const char *id_digest, const char *nickname)
{
  char fp[HEX_DIGEST_LEN+1];
  char *fp_by_name;

  base16_encode(fp, sizeof(fp), id_digest, DIGEST_LEN);

  if ((fp_by_name =
       strmap_get_lc(fingerprint_list->fp_by_name, nickname))) {
    if (!strcasecmp(fp, fp_by_name)) {
      return FP_NAMED;
    } else {
      return FP_UNNAMED; /* Wrong fingerprint. */
    }
  }
  return 0;
}

/** Helper: As dirserv_get_router_status, but takes the router fingerprint
 * (hex, no spaces), nickname, address (used for logging only), IP address, OR
 * port, platform (logging only) and contact info (logging only) as arguments.
 *
 * If should_log is false, do not log messages.  (There's not much point in
 * logging that we're rejecting servers we'll not download.)
 */
static uint32_t
dirserv_get_status_impl(const char *id_digest, const char *nickname,
                        const char *address,
                        uint32_t addr, uint16_t or_port,
                        const char *platform, const char *contact,
                        const char **msg, int should_log)
{
  int reject_unlisted = get_options()->AuthDirRejectUnlisted;
  uint32_t result = 0;
  router_status_t *status_by_digest;

  if (!fingerprint_list)
    fingerprint_list = authdir_config_new();

  if (should_log)
    log_debug(LD_DIRSERV, "%d fingerprints, %d digests known.",
              strmap_size(fingerprint_list->fp_by_name),
              digestmap_size(fingerprint_list->status_by_digest));

  result = dirserv_get_name_status(id_digest, nickname);
  if (result & FP_NAMED) {
    if (should_log)
      log_debug(LD_DIRSERV,"Good fingerprint for '%s'",nickname);
  }
  if (result & FP_UNNAMED) {
    if (should_log) {
      char *esc_contact = esc_for_log(contact);
      log_info(LD_DIRSERV,
               "Mismatched fingerprint for '%s'. "
               "ContactInfo '%s', platform '%s'.)",
               nickname,
               esc_contact,