sres.c

sip协议栈

		char const *domain)
{
  if (socket == -1)
    return errno = EINVAL, NULL;

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

/** 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 sres_resolver_timer() is called in regular
 * intervals. It generates an error record with nonzero status if no
 * response is received.
 *
 * This function just makes sure that we have the @a socket is valid,
 * otherwise it behaves exactly like sres_query_sockaddr().
 */
sres_query_t *
sres_query_make_sockaddr(sres_resolver_t *res,
			 sres_answer_f *callback,
			 sres_context_t *context,
			 int socket,
			 uint16_t type,
			 struct sockaddr const *addr)
{
  char name[80]; 

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

  if (socket == -1)
    return errno = EINVAL, NULL;

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

  return sres_query_make(res, callback, context, socket, 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",
	      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 **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.
 *
 * 
 *
 * @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;
}

/** 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;

  for (n = 0, i = 0; answers && 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 */

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_unref(res, res->res_servers);

  if (res->res_updcb)
    res->res_updcb(res->res_async, -1, -1);
}

/*
 * 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(sres_qtable, qt, sres_query_t, SRES_QUERY_HASH);

/** 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;