sres.c

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

    return (void)su_seterrno(ENETDOWN), (sres_query_t *)NULL;

  query = sres_query_alloc(res, callback, context, type, domain);

  if (query && sres_send_dns_query(res, query) != 0)
    sres_free_query(res, query), query = NULL;

  return query;
}

/**Search DNS.
 *
 * Sends DNS queries with specified @a type and @a name to the DNS server. 
 * If the @a name does not contain enought dots, the search domains are
 * appended to the name and resulting domain name are also queried. When
 * answer to all the search domains is received, the @a callback function
 * is called with @a context and combined records from answers as arguments.
 * 
 * The sres resolver takes care of retransmitting the queries if a root
 * object is associate with the resolver or if sres_resolver_timer() is
 * called in regular intervals. It generates an error record with nonzero
 * status if no response is received.
 *
 * @param res pointer to resolver object
 * @param callback pointer to completion function
 * @param context argument given to the completion function
 * @param type record type to search (or sres_qtype_any for any record)
 * @param name host or domain name to search from DNS
 *
 * @ERRORS
 * @ERROR EFAULT @a res or @a domain point outside the address space
 * @ERROR ENAMETOOLONG @a domain is longer than SRES_MAXDNAME
 * @ERROR ENETDOWN no DNS servers configured
 * @ERROR ENOMEM memory exhausted
 *
 * @sa sres_query(), sres_blocking_search(), sres_search_cached_answers().
 */
sres_query_t *
sres_search(sres_resolver_t *res,
	    sres_answer_f *callback,
	    sres_context_t *context,
	    uint16_t type,
	    char const *name)
{
  char const *domain = name;
  sres_query_t *query = NULL;
  size_t dlen;
  unsigned dots; char const *dot;
  char b[8];

  SU_DEBUG_9(("sres_search(%p, %p, %s, \"%s\") called\n",
			  (void *)res, (void *)context, sres_record_type(type, b), domain));

  if (res == NULL || domain == NULL)
    return su_seterrno(EFAULT), (void *)NULL;

  dlen = strlen(domain);
  if (dlen > SRES_MAXDNAME ||
      (dlen == SRES_MAXDNAME && domain[dlen - 1] != '.')) {
    su_seterrno(ENAMETOOLONG);
    return NULL;
  }

  sres_resolver_update(res, 0);

  if (res->res_n_servers == 0)
    return (void)su_seterrno(ENETDOWN), (sres_query_t *)NULL;

  if (domain[dlen - 1] == '.')
    /* Domain ends with dot - do not search */
    dots = res->res_config->c_opt.ndots;
  else if (sres_has_search_domain(res))
    for (dots = 0, dot = strchr(domain, '.');
	 dots < res->res_config->c_opt.ndots && dot; 
	 dots++, dot = strchr(dot + 1, '.'))
      ;
  else
    dots = 0;

  query = sres_query_alloc(res, callback, context, type, domain);

  if (query) {
    /* Create sub-query for each search domain */
    if (dots < res->res_config->c_opt.ndots) {
      sres_query_t *sub;
      int i, subs;
      size_t len;
      char const *const *domains = res->res_config->c_search;
      char search[SRES_MAXDNAME + 1];

      assert(dlen < SRES_MAXDNAME);

      memcpy(search, domain, dlen);
      search[dlen++] = '.';
      search[dlen] = '\0';

      for (i = 0, subs = 0; i <= SRES_MAX_SEARCH; i++) {
	if (domains[i]) {
	  len = strlen(domains[i]);
	  
	  if (dlen + len + 1 > SRES_MAXDNAME)
	    continue;

	  memcpy(search + dlen, domains[i], len);
	  search[dlen + len] = '.';
	  search[dlen + len + 1] = '\0';
	  sub = sres_query_alloc(res, sres_answer_subquery, (void *)query,
				 type, search);

	  if (sub == NULL) {
	  }
	  else if (sres_send_dns_query(res, sub) == 0) {
	    query->q_subqueries[i] = sub;
	  }
	  else {
	    sres_free_query(res, sub), sub = NULL;
	  }
	  subs += sub != NULL;
	}
      }

      query->q_n_subs = subs;
    }

    if (sres_send_dns_query(res, query) != 0) {
      if (!query->q_n_subs)
	sres_free_query(res, query), query = NULL;
      else
	query->q_id = 0;
    }
  }

  return query;
}

/** Make a reverse DNS query.
 *
 * Send a query to DNS server with specified @a type and domain name formed
 * from the socket address @a addr. The sres resolver takes care of
 * retransmitting the query if a root object is associate with the resolver or
 * if sres_resolver_timer() is called in regular intervals. It generates an
 * error record with nonzero status if no response is received.
 *
 * @param res pointer to resolver
 * @param callback function called when query is answered or times out
 * @param context pointer given as an extra argument to @a callback function
 * @param type record type to query (or sres_qtype_any for any record)
 * @param addr socket address structure
 * 
 * The @a type should be #sres_type_ptr. The @a addr should contain either
 * IPv4 (AF_INET) or IPv6 (AF_INET6) address.
 *
 * If the #SRES_OPTIONS environment variable, #RES_OPTIONS environment
 * variable, or an "options" entry in resolv.conf file contains an option
 * "ip6-dotint", the IPv6 addresses are resolved using suffix ".ip6.int"
 * instead of the standard ".ip6.arpa" suffix.
 *
 * @ERRORS
 * @ERROR EAFNOSUPPORT address family specified in @a addr is not supported
 * @ERROR ENETDOWN no DNS servers configured
 * @ERROR EFAULT @a res or @a addr point outside the address space
 * @ERROR ENOMEM memory exhausted
 *
 * @sa sres_query(), sres_blocking_query_sockaddr(),
 * sres_cached_answers_sockaddr()
 *
 */
sres_query_t *
sres_query_sockaddr(sres_resolver_t *res,
		    sres_answer_f *callback,
		    sres_context_t *context,
		    uint16_t type,
		    struct sockaddr const *addr)
{
  char name[80]; 

  if (!res || !addr)
    return su_seterrno(EFAULT), (void *)NULL;

  if (!sres_sockaddr2string(res, name, sizeof(name), addr))
    return NULL;

  return sres_query(res, callback, context, type, name);
}


/** Make a DNS query.
 *
 * @deprecated Use sres_query() instead.
 */
sres_query_t *
sres_query_make(sres_resolver_t *res,
		sres_answer_f *callback,
		sres_context_t *context,
		int dummy,
		uint16_t type,
		char const *domain)
{
  return sres_query(res, callback, context, type, domain);
}

/** Make a reverse DNS query.
 *
 * @deprecated Use sres_query_sockaddr() instead.
 */
sres_query_t *
sres_query_make_sockaddr(sres_resolver_t *res,
			 sres_answer_f *callback,
			 sres_context_t *context,
			 int dummy,
			 uint16_t type,
			 struct sockaddr const *addr)
{
  char name[80]; 

  if (!res || !addr)
    return su_seterrno(EFAULT), (void *)NULL;

  if (!sres_sockaddr2string(res, name, sizeof(name), addr))
    return NULL;

  return sres_query_make(res, callback, context, dummy, type, name);
}


/** Bind a query with another callback and context pointer.
 *
 * @param query pointer to a query object to bind
 * @param callback pointer to new callback function (may be NULL)
 * @param context pointer to callback context (may be NULL)
*/
void sres_query_bind(sres_query_t *query,
                     sres_answer_f *callback,
                     sres_context_t *context)
{
  if (query) {
    query->q_callback = callback;
    query->q_context = context;
  }
}

/**Get a list of matching (type/domain) records from cache.
 *
 * @return
 * pointer to an array of pointers to cached records, or
 * NULL if no entry was found.
 *
 * @ERRORS
 * @ERROR ENAMETOOLONG @a domain is longer than SRES_MAXDNAME
 * @ERROR ENOENT no cached records were found
 * @ERROR EFAULT @a res or @a domain point outside the address space
 * @ERROR ENOMEM memory exhausted
 */
sres_record_t **
sres_cached_answers(sres_resolver_t *res,
		    uint16_t type,
		    char const *domain)
{
  sres_record_t **result;
  char rooted_domain[SRES_MAXDNAME];

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

  domain = sres_toplevel(rooted_domain, sizeof rooted_domain, domain);

  if (!domain)
    return NULL;
  
  if (!sres_cache_get(res->res_cache, type, domain, &result))
    return su_seterrno(ENOENT), (void *)NULL;

  return result;
}

/**Search for a list of matching (type/name) records from cache.
 *
 * @return
 * pointer to an array of pointers to cached records, or
 * NULL if no entry was found.
 *
 * @ERRORS
 * @ERROR ENAMETOOLONG @a name or resulting domain is longer than SRES_MAXDNAME
 * @ERROR ENOENT no cached records were found
 * @ERROR EFAULT @a res or @a domain point outside the address space
 * @ERROR ENOMEM memory exhausted
 *
 * @sa sres_search(), sres_cached_answers()
 */
sres_record_t **
sres_search_cached_answers(sres_resolver_t *res,
			   uint16_t type,
			   char const *name)
{
  char const *domain = name;
  sres_record_t **search_results[SRES_MAX_SEARCH + 1] = { NULL };
  char rooted_domain[SRES_MAXDNAME];
  unsigned dots; char const *dot;
  size_t found = 0;
  int i;

  SU_DEBUG_9(("sres_search_cached_answers(%p, %s, \"%s\") called\n",
	      (void *)res, sres_record_type(type, rooted_domain), domain));

  if (!res || !name)
    return su_seterrno(EFAULT), (void *)NULL;

  if (sres_has_search_domain(res))
    for (dots = 0, dot = strchr(domain, '.');
	 dots < res->res_config->c_opt.ndots && dot; 
	 dots++, dot = strchr(dot + 1, '.'))
      ;
  else
    dots = 0;

  domain = sres_toplevel(rooted_domain, sizeof rooted_domain, domain);

  if (!domain)
    return NULL;

  if (sres_cache_get(res->res_cache, type, domain, &search_results[0]))
    found = 1;

  if (dots < res->res_config->c_opt.ndots) {
    char const *const *domains = res->res_config->c_search;
    size_t dlen = strlen(domain);

    for (i = 0; domains[i] && i < SRES_MAX_SEARCH; i++) {
      size_t len = strlen(domains[i]);
      if (dlen + len + 1 >= SRES_MAXDNAME)
	continue;
      if (domain != rooted_domain)
	domain = memcpy(rooted_domain, domain, dlen);
      memcpy(rooted_domain + dlen, domains[i], len);
      strcpy(rooted_domain + dlen + len, ".");
      if (sres_cache_get(res->res_cache, type, domain, search_results + i + 1))
	found++;
    }
  }

  if (found == 0)
    return su_seterrno(ENOENT), (void *)NULL;

  if (found == 1) {
    for (i = 0; i <= SRES_MAX_SEARCH; i++)
      if (search_results[i])
	return search_results[i];
  }

  return sres_combine_results(res, search_results);
}

/**Get a list of matching (type/domain) reverse records from cache.
 *
 * @param res pointer to resolver
 * @param type record type to query (or sres_qtype_any for any record)
 * @param addr socket address structure
 * 
 * The @a type should be #sres_type_ptr. The @a addr should contain either
 * IPv4 (AF_INET) or IPv6 (AF_INET6) address.
 *
 * If the #SRES_OPTIONS environment variable, #RES_OPTIONS environment
 * variable or an "options" entry in resolv.conf file contains an option
 * "ip6-dotint", the IPv6 addresses are resolved using suffix ".ip6.int"
 * instead of default ".ip6.arpa".
 *
 * @retval 
 * pointer to an array of pointers to cached records, or
 * NULL if no entry was found.
 *
 * @ERRORS
 * @ERROR EAFNOSUPPORT address family specified in @a addr is not supported
 * @ERROR ENOENT no cached records were found
 * @ERROR EFAULT @a res or @a addr point outside the address space
 * @ERROR ENOMEM memory exhausted
 */
sres_record_t **
sres_cached_answers_sockaddr(sres_resolver_t *res,
			     uint16_t type,
			     struct sockaddr const *addr)
{
  sres_record_t **result;
  char name[80];

  if (!res || !addr)
    return su_seterrno(EFAULT), (void *)NULL;

  if (!sres_sockaddr2string(res, name, sizeof name, addr))
    return NULL;

  if (!sres_cache_get(res->res_cache, type, name, &result))
    su_seterrno(ENOENT), (void *)NULL;

  return result;
}

/** Set the priority of the matching cached SRV record.
 *
 * The SRV records with the domain name, target and port are matched and
 * their priority value is adjusted. This function is used to implement
 * greylisting of SIP servers.
 *
 * @param res      pointer to resolver
 * @param domain   domain name of the SRV record(s) to modify
 * @param target   SRV target of the SRV record(s) to modify
 * @param port     port number of SRV record(s) to modify 
 *                 (in host byte order) 
 * @param ttl      new ttl for SRV records of the domain
 * @param priority new priority value (0=highest, 65535=lowest)
 *
 * @sa sres_cache_set_srv_priority()
 * 
 * @NEW_1_12_8
 */
int sres_set_cached_srv_priority(sres_resolver_t *res,
				 char const *domain,
				 char const *target,
				 uint16_t port,
				 uint32_t ttl,
				 uint16_t priority)
{
  char rooted_domain[SRES_MAXDNAME];

  if (res == NULL || res->res_cache == NULL)
    return su_seterrno(EFAULT);

  domain = sres_toplevel(rooted_domain, sizeof rooted_domain, domain);

  if (!domain)
    return -1;

  return sres_cache_set_srv_priority(res->res_cache, 
				     domain, target, port, 
				     ttl, priority);
}


/** Sort answers. */
int
sres_sort_answers(sres_resolver_t *res, sres_record_t **answers)
{
  int i, j;

  if (res == NULL || answers == NULL)
    return su_seterrno(EFAULT);

  if (answers[0] == NULL || answers[1] == NULL)
    return 0;

  /* Simple insertion sorting */
  /*
   * We do not use qsort because we want later extend this to sort 
   * local A records first etc.
   */
  for (i = 1; answers[i]; i++) {
    for (j = 0; j < i; j++) {
      if (sres_record_compare(answers[i], answers[j]) < 0)
	break;
    }
    if (j < i) {
      sres_record_t *r = answers[i];
      for (; j < i; i--) {
	answers[i] = answers[i - 1];
      }
      answers[j] = r;
    }
  }

  return 0;
}

/** Sort and filter query results */
int
sres_filter_answers(sres_resolver_t *res, 
		    sres_record_t **answers, 
		    uint16_t type)
{		    
  int i, n;

  if (res == NULL || answers == NULL)