sres.c

Sofia SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification.

    return su_seterrno(EFAULT);

  for (n = 0, i = 0; answers[i]; i++) {
    if (answers[i]->sr_record->r_status ||
	answers[i]->sr_record->r_class != sres_class_in ||
	(type != 0 && answers[i]->sr_record->r_type != type)) {
      sres_free_answer(res, answers[i]);
      continue;
    }
    answers[n++] = answers[i];
  }
  answers[n] = NULL;

  sres_sort_answers(res, answers);

  return n;
}


/** Free and zero one record. */
void sres_free_answer(sres_resolver_t *res, sres_record_t *answer)
{
  if (res && answer)
    sres_cache_free_one(res->res_cache, answer);
}

/** Free and zero an array of records.
 * 
 * The array of records can be returned by sres_cached_answers() or 
 * given by callback function.
 */
void 
sres_free_answers(sres_resolver_t *res,
		  sres_record_t **answers)
{
  if (res && answers)
    sres_cache_free_answers(res->res_cache, answers);
}

/** Convert type to its name. */
char const *sres_record_type(int type, char buffer[8])
{
  switch (type) {
  case sres_type_a: return "A";
  case sres_type_ns: return "NS";
  case sres_type_mf: return "MF";
  case sres_type_cname: return "CNAME";
  case sres_type_soa: return "SOA";
  case sres_type_mb: return "MB";
  case sres_type_mg: return "MG";
  case sres_type_mr: return "MR";
  case sres_type_null: return "NULL";
  case sres_type_wks: return "WKS";
  case sres_type_ptr: return "PTR";
  case sres_type_hinfo: return "HINFO";
  case sres_type_minfo: return "MINFO";
  case sres_type_mx: return "MX";
  case sres_type_txt: return "TXT";
  case sres_type_rp: return "RP";
  case sres_type_afsdb: return "AFSDB";
  case sres_type_x25: return "X25";
  case sres_type_isdn: return "ISDN";
  case sres_type_rt: return "RT";
  case sres_type_nsap: return "NSAP";
  case sres_type_nsap_ptr: return "NSAP_PTR";
  case sres_type_sig: return "SIG";
  case sres_type_key: return "KEY";
  case sres_type_px: return "PX";
  case sres_type_gpos: return "GPOS";
  case sres_type_aaaa: return "AAAA";
  case sres_type_loc: return "LOC";
  case sres_type_nxt: return "NXT";
  case sres_type_eid: return "EID";
  case sres_type_nimloc: return "NIMLOC";
  case sres_type_srv: return "SRV";
  case sres_type_atma: return "ATMA";
  case sres_type_naptr: return "NAPTR";
  case sres_type_kx: return "KX";
  case sres_type_cert: return "CERT";
  case sres_type_a6: return "A6";
  case sres_type_dname: return "DNAME";
  case sres_type_sink: return "SINK";
  case sres_type_opt: return "OPT";

  case sres_qtype_tsig: return "TSIG";
  case sres_qtype_ixfr: return "IXFR";
  case sres_qtype_axfr: return "AXFR";
  case sres_qtype_mailb: return "MAILB";
  case sres_qtype_maila: return "MAILA";
  case sres_qtype_any: return "ANY";
    
  default:
    sprintf(buffer, "%u?", type & 65535);
    return buffer;
  }
}

/** Convert class to its name. */
char const *sres_record_class(int rclass, char buffer[8])
{
  switch (rclass) {
  case 1: return "IN";
  case 2: return "2?";
  case 3: return "CHAOS";
  case 4: return "HS";
  case 254: return "NONE";
  case 255: return "ANY";

  default:
    sprintf(buffer, "%u?", rclass & 65535);
    return buffer;
  }
}

/** Compare two records. */
int 
sres_record_compare(sres_record_t const *aa, sres_record_t const *bb)
{
  int D;
  sres_common_t const *a = aa->sr_record, *b = bb->sr_record;

  D = a->r_status - b->r_status; if (D) return D;
  D = a->r_class - b->r_class; if (D) return D;
  D = a->r_type - b->r_type; if (D) return D;

  if (a->r_status)
    return 0;
  
  switch (a->r_type) {
  case sres_type_soa: 
    {
      sres_soa_record_t const *A = aa->sr_soa, *B = bb->sr_soa;
      D = A->soa_serial - B->soa_serial; if (D) return D;
      D = strcasecmp(A->soa_mname, B->soa_mname); if (D) return D;
      D = strcasecmp(A->soa_rname, B->soa_rname); if (D) return D;
      D = A->soa_refresh - B->soa_refresh; if (D) return D;
      D = A->soa_retry - B->soa_retry; if (D) return D;
      D = A->soa_expire - B->soa_expire; if (D) return D;
      D = A->soa_minimum - B->soa_minimum; if (D) return D;
      return 0;
    }
  case sres_type_a:
    {
      sres_a_record_t const *A = aa->sr_a, *B = bb->sr_a;
      return memcmp(&A->a_addr, &B->a_addr, sizeof A->a_addr);
    }
  case sres_type_a6:
    {
      sres_a6_record_t const *A = aa->sr_a6, *B = bb->sr_a6;
      D = A->a6_prelen - B->a6_prelen; if (D) return D;
      D = !A->a6_prename - !B->a6_prename; 
      if (D == 0 && A->a6_prename && B->a6_prename)
	D = strcasecmp(A->a6_prename, B->a6_prename); if (D) return D;
      return memcmp(&A->a6_suffix, &B->a6_suffix, sizeof A->a6_suffix);
    }
  case sres_type_aaaa:
    {
      sres_aaaa_record_t const *A = aa->sr_aaaa, *B = bb->sr_aaaa;
      return memcmp(&A->aaaa_addr, &B->aaaa_addr, sizeof A->aaaa_addr);      
    }
  case sres_type_cname:
    {
      sres_cname_record_t const *A = aa->sr_cname, *B = bb->sr_cname;
      return strcmp(A->cn_cname, B->cn_cname);
    }
  case sres_type_ptr:
    {
      sres_ptr_record_t const *A = aa->sr_ptr, *B = bb->sr_ptr;
      return strcmp(A->ptr_domain, B->ptr_domain);
    }
  case sres_type_srv:
    {
      sres_srv_record_t const *A = aa->sr_srv, *B = bb->sr_srv;
      D = A->srv_priority - B->srv_priority; if (D) return D;
      /* Record with larger weight first */
      D = B->srv_weight - A->srv_weight; if (D) return D;
      D = strcmp(A->srv_target, B->srv_target); if (D) return D;
      return A->srv_port - B->srv_port;
    }
  case sres_type_naptr:
    {
      sres_naptr_record_t const *A = aa->sr_naptr, *B = bb->sr_naptr;
      D = A->na_order - B->na_order; if (D) return D;
      D = A->na_prefer - B->na_prefer; if (D) return D;
      D = strcmp(A->na_flags, B->na_flags); if (D) return D;
      D = strcmp(A->na_services, B->na_services); if (D) return D;
      D = strcmp(A->na_regexp, B->na_regexp); if (D) return D;
      return strcmp(A->na_replace, B->na_replace); 
    }
  default:
    return 0;
  }
}

/* ---------------------------------------------------------------------- */
/* Private functions */

/** Destruct */
static 
void 
sres_resolver_destructor(void *arg)
{
  sres_resolver_t *res = arg;

  assert(res);
  sres_cache_unref(res->res_cache); 
  res->res_cache = NULL;

  sres_servers_close(res, res->res_servers);

  if (res->res_config)
    su_home_unref((su_home_t *)res->res_config->c_home);

  if (res->res_updcb)
    res->res_updcb(res->res_async, INVALID_SOCKET, INVALID_SOCKET);
}

/*
 * 3571 is a prime => 
 * we hash successive id values to different parts of hash tables
 */
#define Q_PRIME 3571
#define SRES_QUERY_HASH(q) ((q)->q_hash)

HTABLE_BODIES_WITH(sres_qtable, qt, sres_query_t, SRES_QUERY_HASH,
		   unsigned, size_t);

/** Allocate a query structure */
static
sres_query_t *
sres_query_alloc(sres_resolver_t *res,
		 sres_answer_f *callback,
		 sres_context_t *context,
		 uint16_t type,
		 char const *domain)
{
  sres_query_t *query;
  size_t dlen = strlen(domain);

  if (sres_qtable_is_full(res->res_queries))
    if (sres_qtable_resize(res->res_home, res->res_queries, 0) < 0)
      return NULL;

  query = su_alloc(res->res_home, sizeof(*query) + dlen + 1);

  if (query) {
    memset(query, 0, sizeof *query);
    query->q_res = res;
    query->q_callback = callback;
    query->q_context = context;
    query->q_type = type;
    query->q_class = sres_class_in;
    query->q_timestamp = res->res_now;
    query->q_name = strcpy((char *)(query + 1), domain);

    query->q_id = sres_new_id(res); assert(query->q_id);
    query->q_i_server = res->res_i_server;
    query->q_n_servers = res->res_n_servers;
    query->q_hash = query->q_id * Q_PRIME /* + query->q_i_server */;
    
    sres_qtable_append(res->res_queries, query);

    if (res->res_schedulecb && res->res_queries->qt_used == 1)
      res->res_schedulecb(res->res_async, 2 * SRES_RETRANSMIT_INTERVAL); 
  }

  return query;
}

su_inline
void 
sres_remove_query(sres_resolver_t *res, sres_query_t *q, int all)
{
  int i;

  if (q->q_hash) {
    sres_qtable_remove(res->res_queries, q), q->q_hash = 0;

    if (all)
      for (i = 0; i <= SRES_MAX_SEARCH; i++) {
	if (q->q_subqueries[i] && q->q_subqueries[i]->q_hash) {
	  sres_qtable_remove(res->res_queries, q->q_subqueries[i]);
	  q->q_subqueries[i]->q_hash = 0;
	}
      }
  }
}

/** Remove a query from hash table and free it. */
static
void sres_free_query(sres_resolver_t *res, sres_query_t *q)
{
  int i;

  if (q == NULL)
    return;

  if (q->q_hash)
    sres_qtable_remove(res->res_queries, q), q->q_hash = 0;

  for (i = 0; i <= SRES_MAX_SEARCH; i++) {
    sres_query_t *sq;

    sq = q->q_subqueries[i];
    q->q_subqueries[i] = NULL;
    if (sq)
      sres_free_query(res, sq);
    if (q->q_subanswers[i])
      sres_cache_free_answers(res->res_cache, q->q_subanswers[i]);
    q->q_subanswers[i] = NULL;
  }
 
  su_free(res->res_home, q);
}

static
sres_record_t **
sres_combine_results(sres_resolver_t *res,
		     sres_record_t **search_results[SRES_MAX_SEARCH + 1])
{
  sres_record_t **combined_result;
  int i, j, found;

  /* Combine the results into a single list. */
  for (i = 0, found = 0; i <= SRES_MAX_SEARCH; i++)
    if (search_results[i])
      for (j = 0; search_results[i][j]; j++)
	found++;

  combined_result = su_alloc((su_home_t *)res->res_cache, 
			     (found + 1) * (sizeof combined_result[0]));
  if (combined_result) {
    for (i = 0, found = 0; i <= SRES_MAX_SEARCH; i++)
      if (search_results[i])
	for (j = 0; search_results[i][j]; j++) {
	  combined_result[found++] = search_results[i][j];
	  search_results[i][j] = NULL;
	}

    combined_result[found] = NULL;
    sres_sort_answers(res, combined_result);
  }

  for (i = 0; i <= SRES_MAX_SEARCH; i++)
    if (search_results[i])
      sres_free_answers(res, search_results[i]), search_results[i] = NULL;

  return combined_result;
}

static
int
sres_sockaddr2string(sres_resolver_t *res,
		     char name[],
		     size_t namelen,
		     struct sockaddr const *addr)
{
  name[0] = '\0';

  if (addr->sa_family == AF_INET) {
    struct sockaddr_in const *sin = (struct sockaddr_in *)addr;
    uint8_t const *in_addr = (uint8_t*)&sin->sin_addr;
    return snprintf(name, namelen, "%u.%u.%u.%u.in-addr.arpa.",
		    in_addr[3], in_addr[2], in_addr[1], in_addr[0]);
  }
#if HAVE_SIN6
  else if (addr->sa_family == AF_INET6) {
    struct sockaddr_in6 const *sin6 = (struct sockaddr_in6 *)addr;
    size_t addrsize = sizeof(sin6->sin6_addr.s6_addr);
    char *postfix;
    size_t required;
    size_t i;

    if (res->res_config->c_opt.ip6int)
      postfix = "ip6.int.";
    else
      postfix = "ip6.arpa.";

    required = addrsize * 4 + strlen(postfix);

    if (namelen <= required)
      return (int)required;

    for (i = 0; i < addrsize; i++) {
      uint8_t byte = sin6->sin6_addr.s6_addr[addrsize - i - 1];
      uint8_t hex;

      hex = byte & 0xf;
      name[4 * i] = hex > 9 ? hex + 'a' - 10 : hex + '0';
      name[4 * i + 1] = '.';
      hex = (byte >> 4) & 0xf;
      name[4 * i + 2] = hex > 9 ? hex + 'a' - 10 : hex + '0';
      name[4 * i + 3] = '.';
    }
    
    strcpy(name + 4 * i, postfix);

    return (int)required;
  }
#endif /* HAVE_SIN6 */
  else {
    su_seterrno(EAFNOSUPPORT);
    SU_DEBUG_3(("%s: %s\n", "sres_sockaddr2string", 
                su_strerror(EAFNOSUPPORT)));
    return 0;
  }
}

/** Make a domain name a top level domain name.
 *
 * The function sres_toplevel() returns a copies string @a domain and 
 * terminates it with a dot if it is not already terminated. 
 */
static
char const *
sres_toplevel(char buf[], size_t blen, char const *domain)
{
  size_t len;
  int already;

  if (!domain)
    return su_seterrno(EFAULT), (void *)NULL;

  len = strlen(domain);

  if (len >= blen)
    return su_seterrno(ENAMETOOLONG), (void *)NULL;

  already = len > 0 && domain[len - 1] == '.';

  if (already)
    return domain;

  if (len + 1 >= blen)
    return su_seterrno(ENAMETOOLONG), (void *)NULL;

  strcpy(buf, domain);
  buf[len] = '.'; buf[len + 1] = '\0';

  return buf;
}

/* ---------------------------------------------------------------------- */

static int sres_update_config(sres_resolver_t *res, int always, time_t now);
static int sres_parse_config(sres_config_t *, FILE *);
static int sres_parse_options(sres_config_t *c, char const *value);
static int sres_parse_nameserver(sres_config_t *c, char const *server);
static time_t sres_config_timestamp(sres_config_t const *c);

/** Update configuration
 *
 * @retval 0 when successful
 * @retval -1 upon an error
 */
int sres_resolver_update(sres_resolver_t *res, int always)
{
  sres_server_t **servers, **old_servers;
  int updated;

  updated = sres_update_config(res, always, time(&res->res_now));
  if (updated < 0)
    return -1;

  if (!res->res_servers || always || updated) {
    servers = sres_servers_new(res, res->res_config);
    old_servers = res->res_servers;

    res->res_i_server = 0;
    res->res_n_servers = sres_servers_count(servers);
    res->res_servers = servers;

    sres_servers_close(res, old_servers);
    su_free(res->res_home, old_servers);

    if (!servers)
      return -1;
  }

  return 0;