dirvote.c

关于tor匿名通信的源代码

            lowest_id = rs->status.identity_digest;
        }
      });
      if (!lowest_id) /* we're out of routers. */
        break;

      memset(flag_counts, 0, sizeof(int)*smartlist_len(flags));
      smartlist_clear(matching_descs);
      smartlist_clear(chosen_flags);
      smartlist_clear(versions);

      /* Okay, go through all the entries for this digest. */
      SMARTLIST_FOREACH(votes, networkstatus_t *, v, {
        if (index[v_sl_idx] >= size[v_sl_idx])
          continue; /* out of entries. */
        rs = smartlist_get(v->routerstatus_list, index[v_sl_idx]);
        if (memcmp(rs->status.identity_digest, lowest_id, DIGEST_LEN))
          continue; /* doesn't include this router. */
        /* At this point, we know that we're looking at a routersatus with
         * identity "lowest".
         */
        ++index[v_sl_idx];
        ++n_listing;

        smartlist_add(matching_descs, rs);
        if (rs->version && rs->version[0])
          smartlist_add(versions, rs->version);

        /* Tally up all the flags. */
        for (i = 0; i < n_voter_flags[v_sl_idx]; ++i) {
          if (rs->flags & (U64_LITERAL(1) << i))
            ++flag_counts[flag_map[v_sl_idx][i]];
        }
        if (rs->flags & (U64_LITERAL(1) << named_flag[v_sl_idx])) {
          if (chosen_name && strcmp(chosen_name, rs->status.nickname)) {
            log_notice(LD_DIR, "Conflict on naming for router: %s vs %s",
                       chosen_name, rs->status.nickname);
            naming_conflict = 1;
          }
          chosen_name = rs->status.nickname;
        }
      });

      /* We don't include this router at all unless more than half of
       * the authorities we believe in list it. */
      if (n_listing <= total_authorities/2)
        continue;

      /* Figure out the most popular opinion of what the most recent
       * routerinfo and its contents are. */
      rs = compute_routerstatus_consensus(matching_descs);
      /* Copy bits of that into rs_out. */
      tor_assert(!memcmp(lowest_id, rs->status.identity_digest, DIGEST_LEN));
      memcpy(rs_out.identity_digest, lowest_id, DIGEST_LEN);
      memcpy(rs_out.descriptor_digest, rs->status.descriptor_digest,
             DIGEST_LEN);
      rs_out.addr = rs->status.addr;
      rs_out.published_on = rs->status.published_on;
      rs_out.dir_port = rs->status.dir_port;
      rs_out.or_port = rs->status.or_port;

      if (chosen_name && !naming_conflict) {
        strlcpy(rs_out.nickname, chosen_name, sizeof(rs_out.nickname));
      } else {
        strlcpy(rs_out.nickname, rs->status.nickname, sizeof(rs_out.nickname));
      }

      if (consensus_method == 1) {
        is_named = chosen_named_idx >= 0 &&
          (!naming_conflict && flag_counts[chosen_named_idx]);
      } else {
        const char *d = strmap_get_lc(name_to_id_map, rs_out.nickname);
        if (!d) {
          is_named = is_unnamed = 0;
        } else if (!memcmp(d, lowest_id, DIGEST_LEN)) {
          is_named = 1; is_unnamed = 0;
        } else {
          is_named = 0; is_unnamed = 1;
        }
      }

      /* Set the flags. */
      smartlist_add(chosen_flags, (char*)"s"); /* for the start of the line. */
      SMARTLIST_FOREACH(flags, const char *, fl,
      {
        if (!strcmp(fl, "Named")) {
          if (is_named)
            smartlist_add(chosen_flags, (char*)fl);
        } else if (!strcmp(fl, "Unnamed") && consensus_method >= 2) {
          if (is_unnamed)
            smartlist_add(chosen_flags, (char*)fl);
        } else {
          if (flag_counts[fl_sl_idx] > n_flag_voters[fl_sl_idx]/2)
            smartlist_add(chosen_flags, (char*)fl);
        }
      });

      /* Pick the version. */
      if (smartlist_len(versions)) {
        sort_version_list(versions, 0);
        chosen_version = get_most_frequent_member(versions);
      } else {
        chosen_version = NULL;
      }

      /* Okay!! Now we can write the descriptor... */
      /*     First line goes into "buf". */
      routerstatus_format_entry(buf, sizeof(buf), &rs_out, NULL, 1);
      smartlist_add(chunks, tor_strdup(buf));
      /*     Second line is all flags.  The "\n" is missing. */
      smartlist_add(chunks,
                    smartlist_join_strings(chosen_flags, " ", 0, NULL));
      /*     Now the version line. */
      if (chosen_version) {
        smartlist_add(chunks, tor_strdup("\nv "));
        smartlist_add(chunks, tor_strdup(chosen_version));
      }
      smartlist_add(chunks, tor_strdup("\n"));

      /* And the loop is over and we move on to the next router */
    }

    tor_free(index);
    tor_free(size);
    tor_free(n_voter_flags);
    tor_free(n_flag_voters);
    for (i = 0; i < smartlist_len(votes); ++i)
      tor_free(flag_map[i]);
    tor_free(flag_map);
    tor_free(flag_counts);
    tor_free(named_flag);
    tor_free(unnamed_flag);
    strmap_free(name_to_id_map, NULL);
    smartlist_free(matching_descs);
    smartlist_free(chosen_flags);
    smartlist_free(versions);
  }

  /* Add a signature. */
  {
    char digest[DIGEST_LEN];
    char fingerprint[HEX_DIGEST_LEN+1];
    char signing_key_fingerprint[HEX_DIGEST_LEN+1];

    char buf[4096];
    smartlist_add(chunks, tor_strdup("directory-signature "));

    /* Compute the hash of the chunks. */
    hash_list_members(digest, chunks);

    /* Get the fingerprints */
    crypto_pk_get_fingerprint(identity_key, fingerprint, 0);
    crypto_pk_get_fingerprint(signing_key, signing_key_fingerprint, 0);

    /* add the junk that will go at the end of the line. */
    tor_snprintf(buf, sizeof(buf), "%s %s\n", fingerprint,
                 signing_key_fingerprint);
    /* And the signature. */
    if (router_append_dirobj_signature(buf, sizeof(buf), digest,
                                       signing_key)) {
      log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
      return NULL; /* This leaks, but it should never happen. */
    }
    smartlist_add(chunks, tor_strdup(buf));
  }

  result = smartlist_join_strings(chunks, "", 0, NULL);

  tor_free(client_versions);
  tor_free(server_versions);
  smartlist_free(flags);
  SMARTLIST_FOREACH(chunks, char *, cp, tor_free(cp));
  smartlist_free(chunks);

  {
    networkstatus_t *c;
    if (!(c = networkstatus_parse_vote_from_string(result, NULL, 0))) {
      log_err(LD_BUG,"Generated a networkstatus consensus we couldn't "
              "parse.");
      tor_free(result);
      return NULL;
    }
    networkstatus_vote_free(c);
  }

  return result;
}

/** Given a consensus vote <b>target</b> and a set of detached signatures in
 * <b>sigs</b> that correspond to the same consensus, check whether there are
 * any new signatures in <b>src_voter_list</b> that should be added to
 * <b>target.  (A signature should be added if we have no signature for that
 * voter in <b>target</b> yet, or if we have no verifiable signature and the
 * new signature is verifiable.)  Return the number of signatures added or
 * changed, or -1 if the document signed by <b>sigs</b> isn't the same
 * document as <b>target</b>. */
int
networkstatus_add_detached_signatures(networkstatus_t *target,
                                      ns_detached_signatures_t *sigs,
                                      const char **msg_out)
{
  int r = 0;
  tor_assert(sigs);
  tor_assert(target);
  tor_assert(!target->is_vote);

  /* Do the times seem right? */
  if (target->valid_after != sigs->valid_after) {
    *msg_out = "Valid-After times do not match "
      "when adding detached signatures to consensus";
    return -1;
  }
  if (target->fresh_until != sigs->fresh_until) {
    *msg_out = "Fresh-until times do not match "
      "when adding detached signatures to consensus";
    return -1;
  }
  if (target->valid_until != sigs->valid_until) {
    *msg_out = "Valid-until times do not match "
      "when adding detached signatures to consensus";
    return -1;
  }
  /* Are they the same consensus? */
  if (memcmp(target->networkstatus_digest, sigs->networkstatus_digest,
             DIGEST_LEN)) {
    *msg_out = "Digest mismatch when adding detached signatures to consensus";
    return -1;
  }

  /* For each voter in src... */
  SMARTLIST_FOREACH(sigs->signatures, networkstatus_voter_info_t *, src_voter,
    {
      char voter_identity[HEX_DIGEST_LEN+1];
      networkstatus_voter_info_t *target_voter =
        networkstatus_get_voter_by_id(target, src_voter->identity_digest);
      authority_cert_t *cert;

      base16_encode(voter_identity, sizeof(voter_identity),
                    src_voter->identity_digest, DIGEST_LEN);
      log_info(LD_DIR, "Looking at signature from %s", voter_identity);
      /* If the target doesn't know about this voter, then forget it. */
      if (!target_voter) {
        log_info(LD_DIR, "We do not know about %s", voter_identity);
        continue;
      }

      /* If the target already has a good signature from this voter, then skip
       * this one. */
      if (target_voter->good_signature) {
        log_info(LD_DIR, "We already have a good signature from %s",
                         voter_identity);
        continue;
      }

      /* Try checking the signature if we haven't already. */
      if (!src_voter->good_signature && !src_voter->bad_signature) {
        cert = authority_cert_get_by_digests(src_voter->identity_digest,
                                             src_voter->signing_key_digest);
        if (cert) {
          networkstatus_check_voter_signature(target, src_voter, cert);
        }
      }
      /* If this signature is good, or we don't have any signature yet,
       * then add it. */
      if (src_voter->good_signature || !target_voter->signature) {
        log_info(LD_DIR, "Adding signature from %s", voter_identity);
        ++r;
        tor_free(target_voter->signature);
        target_voter->signature =
          tor_memdup(src_voter->signature, src_voter->signature_len);
        memcpy(target_voter->signing_key_digest, src_voter->signing_key_digest,
               DIGEST_LEN);
        target_voter->signature_len = src_voter->signature_len;
        target_voter->good_signature = 1;
        target_voter->bad_signature = 0;
      } else {
        log_info(LD_DIR, "Not adding signature from %s", voter_identity);
      }
    });

  return r;
}

/** Return a newly allocated string holding the detached-signatures document
 * corresponding to the signatures on <b>consensus</b>. */
char *
networkstatus_get_detached_signatures(networkstatus_t *consensus)
{
  smartlist_t *elements;
  char buf[4096];
  char *result = NULL;
  int n_sigs = 0;
  tor_assert(consensus);
  tor_assert(! consensus->is_vote);

  elements = smartlist_create();

  {
    char va_buf[ISO_TIME_LEN+1], fu_buf[ISO_TIME_LEN+1],
      vu_buf[ISO_TIME_LEN+1];
    char d[HEX_DIGEST_LEN+1];

    base16_encode(d, sizeof(d), consensus->networkstatus_digest, DIGEST_LEN);
    format_iso_time(va_buf, consensus->valid_after);
    format_iso_time(fu_buf, consensus->fresh_until);
    format_iso_time(vu_buf, consensus->valid_until);

    tor_snprintf(buf, sizeof(buf),
                 "consensus-digest %s\n"
                 "valid-after %s\n"
                 "fresh-until %s\n"
                 "valid-until %s\n", d, va_buf, fu_buf, vu_buf);
    smartlist_add(elements, tor_strdup(buf));
  }

  SMARTLIST_FOREACH(consensus->voters, networkstatus_voter_info_t *, v,
    {
      char sk[HEX_DIGEST_LEN+1];
      char id[HEX_DIGEST_LEN+1];
      if (!v->signature || v->bad_signature)
        continue;
      ++n_sigs;
      base16_encode(sk, sizeof(sk), v->signing_key_digest, DIGEST_LEN);
      base16_encode(id, sizeof(id), v->identity_digest, DIGEST_LEN);
      tor_snprintf(buf, sizeof(buf),
                   "directory-signature %s %s\n-----BEGIN SIGNATURE-----\n",
                   id, sk);
      smartlist_add(elements, tor_strdup(buf));
      base64_encode(buf, sizeof(buf), v->signature, v->signature_len);
      strlcat(buf, "-----END SIGNATURE-----\n", sizeof(buf));
      smartlist_add(elements, tor_strdup(buf));
    });

  result = smartlist_join_strings(elements, "", 0, NULL);

  SMARTLIST_FOREACH(elements, char *, cp, tor_free(cp));
  smartlist_free(elements);
  if (!n_sigs)
    tor_free(result);
  return result;
}

/** Release all storage held in <b>s</b>. */
void
ns_detached_signatures_free(ns_detached_signatures_t *s)
{
  if (s->signatures) {
    SMARTLIST_FOREACH(s->signatures, networkstatus_voter_info_t *, v,
      {
        tor_free(v->signature);
        tor_free(v);
      });
    smartlist_free(s->signatures);
  }
  tor_free(s);
}

/* =====
 * Certificate functions
 * ===== */

/** Allocate and return a new authority_cert_t with the same contents as
 * <b>cert</b>. */
authority_cert_t *
authority_cert_dup(authority_cert_t *cert)
{
  authority_cert_t *out = tor_malloc(sizeof(authority_cert_t));
  tor_assert(cert);

  memcpy(out, cert, sizeof(authority_cert_t));
  /* Now copy pointed-to things. */