tor/src/feature/dirparse/microdesc_parse.c

/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file microdesc_parse.c
 * \brief Code to parse and validate microdescriptors.
 **/

#include "core/or/or.h"

#include "app/config/config.h"
#include "core/or/policies.h"
#include "feature/dirparse/microdesc_parse.h"
#include "feature/dirparse/parsecommon.h"
#include "feature/dirparse/routerparse.h"
#include "feature/nodelist/microdesc.h"
#include "feature/nodelist/nickname.h"
#include "feature/nodelist/nodefamily.h"
#include "feature/relay/router.h"
#include "lib/crypt_ops/crypto_curve25519.h"
#include "lib/crypt_ops/crypto_ed25519.h"
#include "lib/crypt_ops/crypto_format.h"
#include "lib/memarea/memarea.h"

#include "feature/nodelist/microdesc_st.h"

/** List of tokens recognized in microdescriptors */
static token_rule_t microdesc_token_table[] = {
  T1_START("onion-key",        K_ONION_KEY,        NO_ARGS,     NEED_KEY_1024),
  T01("ntor-onion-key",        K_ONION_KEY_NTOR,   GE(1),       NO_OBJ ),
  T0N("id",                    K_ID,               GE(2),       NO_OBJ ),
  T0N("a",                     K_A,                GE(1),       NO_OBJ ),
  T01("family",                K_FAMILY,           CONCAT_ARGS, NO_OBJ ),
  T01("p",                     K_P,                CONCAT_ARGS, NO_OBJ ),
  T01("p6",                    K_P6,               CONCAT_ARGS, NO_OBJ ),
  A01("@last-listed",          A_LAST_LISTED,      CONCAT_ARGS, NO_OBJ ),
  END_OF_TABLE
};

/** Assuming that s starts with a microdesc, return the start of the
 * *NEXT* one.  Return NULL on "not found." */
static const char *
find_start_of_next_microdesc(const char *s, const char *eos)
{
  int started_with_annotations;
  s = eat_whitespace_eos(s, eos);
  if (!s)
    return NULL;

#define CHECK_LENGTH() STMT_BEGIN \
    if (eos - s < 32)             \
      return NULL;                \
  STMT_END

#define NEXT_LINE() STMT_BEGIN            \
    s = memchr(s, '\n', eos-s);           \
    if (!s || eos - s <= 1)               \
      return NULL;                        \
    s++;                                  \
  STMT_END

  CHECK_LENGTH();

  started_with_annotations = (*s == '@');

  if (started_with_annotations) {
    /* Start by advancing to the first non-annotation line. */
    while (*s == '@')
      NEXT_LINE();
  }
  CHECK_LENGTH();

  /* Now we should be pointed at an onion-key line.  If we are, then skip
   * it. */
  if (!strcmpstart(s, "onion-key"))
    NEXT_LINE();

  /* Okay, now we're pointed at the first line of the microdescriptor which is
     not an annotation or onion-key.  The next line that _is_ an annotation or
     onion-key is the start of the next microdescriptor. */
  while (eos - s > 32) {
    if (*s == '@' || !strcmpstart(s, "onion-key"))
      return s;
    NEXT_LINE();
  }
  return NULL;

#undef CHECK_LENGTH
#undef NEXT_LINE
}

/** Parse as many microdescriptors as are found from the string starting at
 * <b>s</b> and ending at <b>eos</b>.  If allow_annotations is set, read any
 * annotations we recognize and ignore ones we don't.
 *
 * If <b>saved_location</b> isn't SAVED_IN_CACHE, make a local copy of each
 * descriptor in the body field of each microdesc_t.
 *
 * Return all newly parsed microdescriptors in a newly allocated
 * smartlist_t. If <b>invalid_disgests_out</b> is provided, add a SHA256
 * microdesc digest to it for every microdesc that we found to be badly
 * formed. (This may cause duplicates) */
smartlist_t *
microdescs_parse_from_string(const char *s, const char *eos,
                             int allow_annotations,
                             saved_location_t where,
                             smartlist_t *invalid_digests_out)
{
  smartlist_t *tokens;
  smartlist_t *result;
  microdesc_t *md = NULL;
  memarea_t *area;
  const char *start = s;
  const char *start_of_next_microdesc;
  int flags = allow_annotations ? TS_ANNOTATIONS_OK : 0;
  const int copy_body = (where != SAVED_IN_CACHE);

  directory_token_t *tok;

  if (!eos)
    eos = s + strlen(s);

  s = eat_whitespace_eos(s, eos);
  area = memarea_new();
  result = smartlist_new();
  tokens = smartlist_new();

  while (s < eos) {
    int okay = 0;

    start_of_next_microdesc = find_start_of_next_microdesc(s, eos);
    if (!start_of_next_microdesc)
      start_of_next_microdesc = eos;

    md = tor_malloc_zero(sizeof(microdesc_t));
    {
      const char *cp = tor_memstr(s, start_of_next_microdesc-s,
                                  "onion-key");
      const int no_onion_key = (cp == NULL);
      if (no_onion_key) {
        cp = s; /* So that we have *some* junk to put in the body */
      }

      md->bodylen = start_of_next_microdesc - cp;
      md->saved_location = where;
      if (copy_body)
        md->body = tor_memdup_nulterm(cp, md->bodylen);
      else
        md->body = (char*)cp;
      md->off = cp - start;
      crypto_digest256(md->digest, md->body, md->bodylen, DIGEST_SHA256);
      if (no_onion_key) {
        log_fn(LOG_PROTOCOL_WARN, LD_DIR, "Malformed or truncated descriptor");
        goto next;
      }
    }

    if (tokenize_string(area, s, start_of_next_microdesc, tokens,
                        microdesc_token_table, flags)) {
      const char *location;
      switch (where) {
        case SAVED_NOWHERE:
          location = "download or generated string";
          break;
        case SAVED_IN_CACHE:
          location = "cache";
          break;
        case SAVED_IN_JOURNAL:
          location = "journal";
          break;
        default:
          location = "unknown location";
          break;
      }
      log_warn(LD_DIR, "Unparseable microdescriptor found in %s", location);
      goto next;
    }

    if ((tok = find_opt_by_keyword(tokens, A_LAST_LISTED))) {
      if (parse_iso_time(tok->args[0], &md->last_listed)) {
        log_warn(LD_DIR, "Bad last-listed time in microdescriptor");
        goto next;
      }
    }

    tok = find_by_keyword(tokens, K_ONION_KEY);
    if (!crypto_pk_public_exponent_ok(tok->key)) {
      log_warn(LD_DIR,
               "Relay's onion key had invalid exponent.");
      goto next;
    }
    md->onion_pkey = tor_memdup(tok->object_body, tok->object_size);
    md->onion_pkey_len = tok->object_size;
    crypto_pk_free(tok->key);

    if ((tok = find_opt_by_keyword(tokens, K_ONION_KEY_NTOR))) {
      curve25519_public_key_t k;
      tor_assert(tok->n_args >= 1);
      if (curve25519_public_from_base64(&k, tok->args[0]) < 0) {
        log_warn(LD_DIR, "Bogus ntor-onion-key in microdesc");
        goto next;
      }
      md->onion_curve25519_pkey =
        tor_memdup(&k, sizeof(curve25519_public_key_t));
    }

    smartlist_t *id_lines = find_all_by_keyword(tokens, K_ID);
    if (id_lines) {
      SMARTLIST_FOREACH_BEGIN(id_lines, directory_token_t *, t) {
        tor_assert(t->n_args >= 2);
        if (!strcmp(t->args[0], "ed25519")) {
          if (md->ed25519_identity_pkey) {
            log_warn(LD_DIR, "Extra ed25519 key in microdesc");
            smartlist_free(id_lines);
            goto next;
          }
          ed25519_public_key_t k;
          if (ed25519_public_from_base64(&k, t->args[1])<0) {
            log_warn(LD_DIR, "Bogus ed25519 key in microdesc");
            smartlist_free(id_lines);
            goto next;
          }
          md->ed25519_identity_pkey = tor_memdup(&k, sizeof(k));
        }
      } SMARTLIST_FOREACH_END(t);
      smartlist_free(id_lines);
    }

    {
      smartlist_t *a_lines = find_all_by_keyword(tokens, K_A);
      if (a_lines) {
        find_single_ipv6_orport(a_lines, &md->ipv6_addr, &md->ipv6_orport);
        smartlist_free(a_lines);
      }
    }

    if ((tok = find_opt_by_keyword(tokens, K_FAMILY))) {
      md->family = nodefamily_parse(tok->args[0],
                                    NULL,
                                    NF_WARN_MALFORMED);
    }

    if ((tok = find_opt_by_keyword(tokens, K_P))) {
      md->exit_policy = parse_short_policy(tok->args[0]);
    }
    if ((tok = find_opt_by_keyword(tokens, K_P6))) {
      md->ipv6_exit_policy = parse_short_policy(tok->args[0]);
    }

    smartlist_add(result, md);
    okay = 1;

    md = NULL;
  next:
    if (! okay && invalid_digests_out) {
      smartlist_add(invalid_digests_out,
                    tor_memdup(md->digest, DIGEST256_LEN));
    }
    microdesc_free(md);
    md = NULL;

    SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
    memarea_clear(area);
    smartlist_clear(tokens);
    s = start_of_next_microdesc;
  }

  SMARTLIST_FOREACH(tokens, directory_token_t *, t, token_clear(t));
  memarea_drop_all(area);
  smartlist_free(tokens);

  return result;
}