CDRIVER-3940 Fix missing versioned API options in server monitor (#770)

* Rename method to indicate that the full handshake command is returned

* Rename _mongoc_topology_get_ismaster

* Add method to expose "hello" command without handshake information

* CDRIVER-3940 Fix missing versioned API options in server monitor

Author: alcaeus

src/libmongoc/src/mongoc/mongoc-cluster.c

@@ -770,7 +770,7 @@ _mongoc_stream_run_ismaster (mongoc_cluster_t *cluster,
    BSON_ASSERT (cluster);
    BSON_ASSERT (stream);
 
-   command = _mongoc_topology_get_ismaster (cluster->client->topology);
+   command = _mongoc_topology_get_handshake_cmd (cluster->client->topology);
 
    if (cluster->requires_auth || negotiate_sasl_supported_mechs) {
       copied_command = bson_copy (command);

src/libmongoc/src/mongoc/mongoc-server-monitor.c

@@ -326,10 +326,12 @@ _server_monitor_polling_ismaster (mongoc_server_monitor_t *server_monitor,
                                   bson_error_t *error)
 {
    bson_t cmd;
+   const bson_t *hello;
    bool ret;
 
-   bson_init (&cmd);
-   bson_append_int32 (&cmd, "isMaster", 8, 1);
+   hello = _mongoc_topology_scanner_get_hello_cmd (server_monitor->topology->scanner);
+   bson_copy_to (hello, &cmd);
+
    _server_monitor_append_cluster_time (server_monitor, &cmd);
    ret = _server_monitor_send_and_recv_opquery (
       server_monitor, &cmd, ismaster_reply, error);
@@ -603,10 +605,13 @@ _server_monitor_awaitable_ismaster (mongoc_server_monitor_t *server_monitor,
                                     bool *cancelled,
                                     bson_error_t *error)
 {
-   bson_t cmd = BSON_INITIALIZER;
+   bson_t cmd;
+   const bson_t *hello;
    bool ret = false;
 
-   bson_append_int32 (&cmd, "isMaster", 8, 1);
+   hello = _mongoc_topology_scanner_get_hello_cmd (server_monitor->topology->scanner);
+   bson_copy_to (hello, &cmd);
+
    _server_monitor_append_cluster_time (server_monitor, &cmd);
    bson_append_document (&cmd, "topologyVersion", 15, topology_version);
    bson_append_int32 (
@@ -775,7 +780,7 @@ _server_monitor_setup_connection (mongoc_server_monitor_t *server_monitor,
    /* Update the start time just before the handshake. */
    *start_us = _now_us ();
    /* Perform handshake. */
-   handshake = _mongoc_topology_get_ismaster (server_monitor->topology);
+   handshake = _mongoc_topology_get_handshake_cmd (server_monitor->topology);
    bson_destroy (&cmd);
    bson_copy_to (handshake, &cmd);
    _server_monitor_append_cluster_time (server_monitor, &cmd);

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

@@ -197,7 +197,7 @@ void
 _mongoc_topology_do_blocking_scan (mongoc_topology_t *topology,
                                    bson_error_t *error);
 const bson_t *
-_mongoc_topology_get_ismaster (mongoc_topology_t *topology);
+_mongoc_topology_get_handshake_cmd (mongoc_topology_t *topology);
 void
 _mongoc_topology_request_scan (mongoc_topology_t *topology);
 

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

@@ -194,7 +194,10 @@ _mongoc_topology_scanner_get_speculative_auth_mechanism (
    const mongoc_uri_t *uri);
 
 const bson_t *
-_mongoc_topology_scanner_get_ismaster (mongoc_topology_scanner_t *ts);
+_mongoc_topology_scanner_get_hello_cmd (mongoc_topology_scanner_t *ts);
+
+const bson_t *
+_mongoc_topology_scanner_get_handshake_cmd (mongoc_topology_scanner_t *ts);
 
 bool
 mongoc_topology_scanner_has_node_for_host (mongoc_topology_scanner_t *ts,

src/libmongoc/src/mongoc/mongoc-topology-scanner.c

@@ -273,12 +273,18 @@ _build_ismaster_with_handshake (mongoc_topology_scanner_t *ts)
    return res;
 }
 
+const bson_t *
+_mongoc_topology_scanner_get_hello_cmd (mongoc_topology_scanner_t *ts)
+{
+   return &ts->ismaster_cmd;
+}
+
 /* Caller must lock topology->mutex to protect ismaster_cmd_with_handshake. This
  * is called at the start of the scan in _mongoc_topology_run_background, when a
  * node is added in _mongoc_topology_reconcile_add_nodes, or when running an
  * ismaster directly on a node in _mongoc_stream_run_ismaster. */
 const bson_t *
-_mongoc_topology_scanner_get_ismaster (mongoc_topology_scanner_t *ts)
+_mongoc_topology_scanner_get_handshake_cmd (mongoc_topology_scanner_t *ts)
 {
    /* If this is the first time using the node or if it's the first time
     * using it after a failure, build handshake doc */
@@ -311,7 +317,7 @@ _begin_ismaster_cmd (mongoc_topology_scanner_node_t *node,
       /* The node's been used before and not failed recently */
       bson_copy_to (&ts->ismaster_cmd, &cmd);
    } else {
-      bson_copy_to (_mongoc_topology_scanner_get_ismaster (ts), &cmd);
+      bson_copy_to (_mongoc_topology_scanner_get_handshake_cmd (ts), &cmd);
    }
 
    if (node->ts->negotiate_sasl_supported_mechs &&

src/libmongoc/src/mongoc/mongoc-topology.c

@@ -1578,7 +1578,7 @@ _mongoc_topology_end_sessions_cmd (mongoc_topology_t *topology, bson_t *cmd)
 /*
  *--------------------------------------------------------------------------
  *
- * _mongoc_topology_get_ismaster --
+ * _mongoc_topology_get_handshake_cmd --
  *
  *       Locks topology->mutex and retrieves (possibly constructing) the
  *       handshake on the topology scanner.
@@ -1589,11 +1589,11 @@ _mongoc_topology_end_sessions_cmd (mongoc_topology_t *topology, bson_t *cmd)
  *--------------------------------------------------------------------------
  */
 const bson_t *
-_mongoc_topology_get_ismaster (mongoc_topology_t *topology)
+_mongoc_topology_get_handshake_cmd (mongoc_topology_t *topology)
 {
    const bson_t *cmd;
    bson_mutex_lock (&topology->mutex);
-   cmd = _mongoc_topology_scanner_get_ismaster (topology->scanner);
+   cmd = _mongoc_topology_scanner_get_handshake_cmd (topology->scanner);
    bson_mutex_unlock (&topology->mutex);
    return cmd;
 }