CDRIVER-4086 Implement srvServiceName for initial DNS seedlist and SRV polling (#916)

* Update MONGOC_URI_SRVMAXHOSTS to lowercase for consistency
* Add support for parsing URI option srvServiceName
* Update spec tests for srvServiceName
* Add documentation for mongoc_uri_get_srv_service_name()
* Add support for srvServiceName in DNS seedlist discovery
* Add mongoc_uri_get_srv_hostname()
* Replace and rename SRV "service" with "hostname"

Author: eramongodb

src/libmongoc/doc/mongoc_uri_get_service.rst

@@ -9,17 +9,22 @@ Synopsis
 .. code-block:: c
 
   const char *
-  mongoc_uri_get_service (const mongoc_uri_t *uri);
+  mongoc_uri_get_service (const mongoc_uri_t *uri)
+     BSON_GNUC_DEPRECATED_FOR (mongoc_uri_get_srv_hostname);
 
 Parameters
 ----------
 
 * ``uri``: A :symbol:`mongoc_uri_t`.
 
-Description
------------
+Deprecated
+----------
+
+This function is deprecated and should not be used in new code.
+
+Please use :symbol:`mongoc_uri_get_srv_hostname()` instead.
 
-Returns the SRV service name of a MongoDB URI.
+Returns the SRV host and domain name of a MongoDB URI.
 
 Returns
 -------

src/libmongoc/doc/mongoc_uri_get_srv_hostname.rst

@@ -0,0 +1,27 @@
+:man_page: mongoc_uri_get_srv_hostname
+
+mongoc_uri_get_srv_hostname()
+=============================
+
+Synopsis
+--------
+
+.. code-block:: c
+
+  const char *
+  mongoc_uri_get_srv_hostname (const mongoc_uri_t *uri);
+
+Parameters
+----------
+
+* ``uri``: A :symbol:`mongoc_uri_t`.
+
+Description
+-----------
+
+Returns the SRV host and domain name of a MongoDB URI.
+
+Returns
+-------
+
+A string if this URI's scheme is "mongodb+srv://", or NULL if the scheme is "mongodb://".

src/libmongoc/doc/mongoc_uri_get_srv_service_name.rst

@@ -0,0 +1,27 @@
+:man_page: mongoc_uri_get_srv_service_name
+
+mongoc_uri_get_srv_service_name()
+=================================
+
+Synopsis
+--------
+
+.. code-block:: c
+
+  const char *
+  mongoc_uri_get_srv_service_name (const mongoc_uri_t *uri);
+
+Parameters
+----------
+
+* ``uri``: A :symbol:`mongoc_uri_t`.
+
+Description
+-----------
+
+Returns the SRV service name of a MongoDB URI.
+
+Returns
+-------
+
+A string corresponding to the value of the srvServiceName URI option if present. Otherwise, the default value "mongodb".

src/libmongoc/doc/mongoc_uri_t.rst

@@ -302,6 +302,8 @@ MONGOC_URI_SAFE                            safe                              {tr
     mongoc_uri_get_service
     mongoc_uri_get_ssl
     mongoc_uri_get_string
+    mongoc_uri_get_srv_hostname
+    mongoc_uri_get_srv_service_name
     mongoc_uri_get_tls
     mongoc_uri_get_username
     mongoc_uri_get_write_concern

src/libmongoc/src/mongoc/mongoc-client-private.h

@@ -154,7 +154,7 @@ BSON_STATIC_ASSERT2 (mongoc_cmd_rw,
  * There is no reason these should be in mongoc-client. */
 #define MONGOC_RR_DEFAULT_BUFFER_SIZE 1024
 bool
-_mongoc_client_get_rr (const char *service,
+_mongoc_client_get_rr (const char *hostname,
                        mongoc_rr_type_t rr_type,
                        mongoc_rr_data_t *rr_data,
                        size_t initial_buffer_size,

src/libmongoc/src/mongoc/mongoc-client.c

@@ -103,13 +103,13 @@ _mongoc_client_killcursors_command (mongoc_cluster_t *cluster,
 
 #ifdef MONGOC_HAVE_DNSAPI
 
-typedef bool (*mongoc_rr_callback_t) (const char *service,
+typedef bool (*mongoc_rr_callback_t) (const char *hostname,
                                       PDNS_RECORD pdns,
                                       mongoc_rr_data_t *rr_data,
                                       bson_error_t *error);
 
 static bool
-srv_callback (const char *service,
+srv_callback (const char *hostname,
               PDNS_RECORD pdns,
               mongoc_rr_data_t *rr_data,
               bson_error_t *error)
@@ -132,7 +132,7 @@ srv_callback (const char *service,
 
 /* rr_data is unused, but here to match srv_callback signature */
 static bool
-txt_callback (const char *service,
+txt_callback (const char *hostname,
               PDNS_RECORD pdns,
               mongoc_rr_data_t *rr_data,
               bson_error_t *error)
@@ -178,7 +178,7 @@ txt_callback (const char *service,
  */
 
 static bool
-_mongoc_get_rr_dnsapi (const char *service,
+_mongoc_get_rr_dnsapi (const char *hostname,
                        mongoc_rr_type_t rr_type,
                        mongoc_rr_data_t *rr_data,
                        bson_error_t *error)
@@ -209,7 +209,7 @@ _mongoc_get_rr_dnsapi (const char *service,
       callback = txt_callback;
    }
 
-   res = DnsQuery_UTF8 (service,
+   res = DnsQuery_UTF8 (hostname,
                         nst,
                         DNS_QUERY_BYPASS_CACHE,
                         NULL /* IP Address */,
@@ -229,17 +229,17 @@ _mongoc_get_rr_dnsapi (const char *service,
                          0)) {
          DNS_ERROR ("Failed to look up %s record \"%s\": %s",
                     rr_type_name,
-                    service,
+                    hostname,
                     (char *) lpMsgBuf);
       }
 
       DNS_ERROR ("Failed to look up %s record \"%s\": Unknown error",
                  rr_type_name,
-                 service);
+                 hostname);
    }
 
    if (!pdns) {
-      DNS_ERROR ("No %s records for \"%s\"", rr_type_name, service);
+      DNS_ERROR ("No %s records for \"%s\"", rr_type_name, hostname);
    }
 
    i = 0;
@@ -252,7 +252,7 @@ _mongoc_get_rr_dnsapi (const char *service,
             /* Initial DNS Seedlist Discovery Spec: a client "MUST raise an
             error when multiple TXT records are encountered". */
             callback_success = false;
-            DNS_ERROR ("Multiple TXT records for \"%s\"", service);
+            DNS_ERROR ("Multiple TXT records for \"%s\"", hostname);
          }
 
          if (rr_data) {
@@ -261,7 +261,7 @@ _mongoc_get_rr_dnsapi (const char *service,
             }
          }
 
-         if (!callback (service, pdns, rr_data, error)) {
+         if (!callback (hostname, pdns, rr_data, error)) {
             callback_success = false;
             GOTO (done);
          }
@@ -275,7 +275,7 @@ _mongoc_get_rr_dnsapi (const char *service,
 
    rr_data->count = i;
    if (i == 0) {
-      DNS_ERROR ("No matching %s records for \"%s\"", rr_type_name, service);
+      DNS_ERROR ("No matching %s records for \"%s\"", rr_type_name, hostname);
    }
    dns_success = true;
 
@@ -293,7 +293,7 @@ _mongoc_get_rr_dnsapi (const char *service,
 
 #elif (defined(MONGOC_HAVE_RES_NSEARCH) || defined(MONGOC_HAVE_RES_SEARCH))
 
-typedef bool (*mongoc_rr_callback_t) (const char *service,
+typedef bool (*mongoc_rr_callback_t) (const char *hostname,
                                       ns_msg *ns_answer,
                                       ns_rr *rr,
                                       mongoc_rr_data_t *rr_data,
@@ -318,7 +318,7 @@ _mongoc_hstrerror (int code)
 }
 
 static bool
-srv_callback (const char *service,
+srv_callback (const char *hostname,
               ns_msg *ns_answer,
               ns_rr *rr,
               mongoc_rr_data_t *rr_data,
@@ -345,7 +345,7 @@ srv_callback (const char *service,
 
    if (size < 1) {
       DNS_ERROR ("Invalid record in SRV answer for \"%s\": \"%s\"",
-                 service,
+                 hostname,
                  _mongoc_hstrerror (h_errno));
    }
 
@@ -360,7 +360,7 @@ srv_callback (const char *service,
 }
 
 static bool
-txt_callback (const char *service,
+txt_callback (const char *hostname,
               ns_msg *ns_answer,
               ns_rr *rr,
               mongoc_rr_data_t *rr_data,
@@ -375,7 +375,7 @@ txt_callback (const char *service,
 
    total = (uint16_t) ns_rr_rdlen (*rr);
    if (total < 1 || total > 255) {
-      DNS_ERROR ("Invalid TXT record size %hu for \"%s\"", total, service);
+      DNS_ERROR ("Invalid TXT record size %hu for \"%s\"", total, hostname);
    }
 
    /* a TXT record has one or more strings, each up to 255 chars, each is
@@ -426,7 +426,7 @@ txt_callback (const char *service,
  */
 
 static bool
-_mongoc_get_rr_search (const char *service,
+_mongoc_get_rr_search (const char *hostname,
                        mongoc_rr_type_t rr_type,
                        mongoc_rr_data_t *rr_data,
                        size_t initial_buffer_size,
@@ -483,26 +483,26 @@ _mongoc_get_rr_search (const char *service,
       /* thread-safe */
       res_ninit (&state);
       size =
-         res_nsearch (&state, service, ns_c_in, nst, search_buf, buffer_size);
+         res_nsearch (&state, hostname, ns_c_in, nst, search_buf, buffer_size);
 #elif defined(MONGOC_HAVE_RES_SEARCH)
-      size = res_search (service, ns_c_in, nst, search_buf, buffer_size);
+      size = res_search (hostname, ns_c_in, nst, search_buf, buffer_size);
 #endif
 
       if (size < 0) {
          DNS_ERROR ("Failed to look up %s record \"%s\": %s",
                     rr_type_name,
-                    service,
+                    hostname,
                     _mongoc_hstrerror (h_errno));
       }
    } while (size >= buffer_size);
 
    if (ns_initparse (search_buf, size, &ns_answer)) {
-      DNS_ERROR ("Invalid %s answer for \"%s\"", rr_type_name, service);
+      DNS_ERROR ("Invalid %s answer for \"%s\"", rr_type_name, hostname);
    }
 
    n = ns_msg_count (ns_answer, ns_s_an);
    if (!n) {
-      DNS_ERROR ("No %s records for \"%s\"", rr_type_name, service);
+      DNS_ERROR ("No %s records for \"%s\"", rr_type_name, hostname);
    }
 
    rr_data->count = n;
@@ -512,7 +512,7 @@ _mongoc_get_rr_search (const char *service,
          DNS_ERROR ("Invalid record %d of %s answer for \"%s\": \"%s\"",
                     i,
                     rr_type_name,
-                    service,
+                    hostname,
                     _mongoc_hstrerror (h_errno));
       }
 
@@ -532,7 +532,7 @@ _mongoc_get_rr_search (const char *service,
          /* Initial DNS Seedlist Discovery Spec: a client "MUST raise an error
           * when multiple TXT records are encountered". */
          callback_success = false;
-         DNS_ERROR ("Multiple TXT records for \"%s\"", service);
+         DNS_ERROR ("Multiple TXT records for \"%s\"", hostname);
       }
 
       num_matching_records++;
@@ -542,14 +542,14 @@ _mongoc_get_rr_search (const char *service,
          rr_data->min_ttl = ttl;
       }
 
-      if (!callback (service, &ns_answer, &resource_record, rr_data, error)) {
+      if (!callback (hostname, &ns_answer, &resource_record, rr_data, error)) {
          callback_success = false;
          GOTO (done);
       }
    }
 
    if (num_matching_records == 0) {
-      DNS_ERROR ("No matching %s records for \"%s\"", rr_type_name, service);
+      DNS_ERROR ("No matching %s records for \"%s\"", rr_type_name, hostname);
    }
 
    dns_success = true;
@@ -595,7 +595,7 @@ _mongoc_get_rr_search (const char *service,
  */
 
 bool
-_mongoc_client_get_rr (const char *service,
+_mongoc_client_get_rr (const char *hostname,
                        mongoc_rr_type_t rr_type,
                        mongoc_rr_data_t *rr_data,
                        size_t initial_buffer_size,
@@ -604,10 +604,10 @@ _mongoc_client_get_rr (const char *service,
    BSON_ASSERT (rr_data);
 
 #ifdef MONGOC_HAVE_DNSAPI
-   return _mongoc_get_rr_dnsapi (service, rr_type, rr_data, error);
+   return _mongoc_get_rr_dnsapi (hostname, rr_type, rr_data, error);
 #elif (defined(MONGOC_HAVE_RES_NSEARCH) || defined(MONGOC_HAVE_RES_SEARCH))
    return _mongoc_get_rr_search (
-      service, rr_type, rr_data, initial_buffer_size, error);
+      hostname, rr_type, rr_data, initial_buffer_size, error);
 #else
    bson_set_error (error,
                    MONGOC_ERROR_STREAM,

src/libmongoc/src/mongoc/mongoc-topology-private.h

@@ -81,7 +81,7 @@ MONGOC_DECL_SPECIAL_TS_POOL (
    NULL,
    NULL)
 
-typedef bool (*_mongoc_rr_resolver_fn) (const char *service,
+typedef bool (*_mongoc_rr_resolver_fn) (const char *hostname,
                                         mongoc_rr_type_t rr_type,
                                         mongoc_rr_data_t *rr_data,
                                         size_t initial_buffer_size,