CDRIVER-3653 use handshake metadata for connection checks

- Update change stream wire version check
- Update transaction wire version check
- Update auth commands to use handshake description to construct commands.

Author: kevinAlbs

src/libmongoc/CMakeLists.txt

@@ -983,6 +983,7 @@ set (test-libmongoc-sources
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-server-description.c
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-server-selection-errors.c
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-server-selection.c
+   ${PROJECT_SOURCE_DIR}/tests/test-mongoc-server-stream.c
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-set.c
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-socket.c
    ${PROJECT_SOURCE_DIR}/tests/test-mongoc-speculative-auth.c

src/libmongoc/doc/mongoc_client_get_handshake_description.rst

@@ -0,0 +1,50 @@
+:man_page: mongoc_client_get_handshake_description
+
+mongoc_client_get_handshake_description()
+=========================================
+
+Synopsis
+--------
+
+.. code-block:: c
+
+   mongoc_server_description_t *
+   mongoc_client_get_handshake_description (mongoc_client_t *client,
+                                            uint32_t server_id,
+                                            bson_t *opts,
+                                            bson_error_t *error);
+
+Returns a description constructed from the initial handshake response to a server.
+
+Description
+-----------
+
+:symbol:`mongoc_client_get_handshake_description` is distinct from :symbol:`mongoc_client_get_server_description`. :symbol:`mongoc_client_get_server_description` returns a server description constructed from monitoring, which may differ from the server description constructed from the connection handshake.
+
+:symbol:`mongoc_client_get_handshake_description` does not attempt to establish a connection to the server if a connection was not already established. It will complete authentication on a single-threaded client if the connection has not yet been used by an operation.
+
+To establish a connection on a single-threaded client, ensure the server is selectable (the monitoring connection is the only connection made to the server). This can be done with a function like :symbol:`mongoc_client_select_server`, or any function which performs server selection.
+
+To establish a connection on a pooled client, send a command (e.g. ping) to the server.
+
+Use this function only for building a language driver that wraps the C Driver. When writing applications in C, higher-level functions automatically select a suitable server.
+
+Parameters
+----------
+
+* ``client``: A :symbol:`mongoc_client_t`.
+* ``server_id``: The ID of the server. This can be obtained from the server description of :symbol:`mongoc_client_select_server`.
+* ``opts``: Unused. Pass ``NULL``.
+* ``error``: An optional location for a :symbol:`bson_error_t <errors>` or ``NULL``.
+
+Returns
+-------
+
+A :symbol:`mongoc_server_description_t` that must be freed with :symbol:`mongoc_server_description_destroy`. If a connection has not been successfully established to a server, returns NULL and ``error`` is filled out.
+
+
+See Also
+--------
+
+- :symbol:`mongoc_client_select_server` To select a server from read preferences.
+- :symbol:`mongoc_client_get_server_description` To obtain the server description from monitoring for a server.

src/libmongoc/doc/mongoc_client_t.rst

@@ -61,6 +61,7 @@ Example
     mongoc_client_get_database_names_with_opts
     mongoc_client_get_default_database
     mongoc_client_get_gridfs
+    mongoc_client_get_handshake_description
     mongoc_client_get_max_bson_size
     mongoc_client_get_max_message_size
     mongoc_client_get_read_concern

src/libmongoc/src/mongoc/mongoc-change-stream.c

@@ -15,6 +15,7 @@
  */
 
 #include <bson/bson.h>
+#include "mongoc-cluster-private.h"
 #include "mongoc-change-stream-private.h"
 #include "mongoc-collection-private.h"
 #include "mongoc-client-private.h"
@@ -235,23 +236,12 @@ _make_cursor (mongoc_change_stream_t *stream)
    bson_t reply;
    bson_t getmore_opts = BSON_INITIALIZER;
    bson_iter_t iter;
-   mongoc_server_description_t *sd;
-   uint32_t server_id;
+   mongoc_server_stream_t *server_stream;
 
    BSON_ASSERT (stream);
    BSON_ASSERT (!stream->cursor);
    bson_init (&command);
    bson_copy_to (&(stream->opts.extra), &command_opts);
-   sd = mongoc_client_select_server (
-      stream->client, false /* for_writes */, stream->read_prefs, &stream->err);
-   if (!sd) {
-      goto cleanup;
-   }
-   server_id = mongoc_server_description_id (sd);
-   bson_append_int32 (&command_opts, "serverId", 8, server_id);
-   bson_append_int32 (&getmore_opts, "serverId", 8, server_id);
-   stream->max_wire_version = sd->max_wire_version;
-   mongoc_server_description_destroy (sd);
 
    if (bson_iter_init_find (&iter, &command_opts, "sessionId")) {
       if (!_mongoc_client_session_from_iter (
@@ -289,6 +279,19 @@ _make_cursor (mongoc_change_stream_t *stream)
       goto cleanup;
    }
 
+   server_stream = mongoc_cluster_stream_for_reads (
+      &stream->client->cluster, stream->read_prefs, cs, &reply, &stream->err);
+   if (!server_stream) {
+      bson_destroy (&stream->err_doc);
+      bson_copy_to (&reply, &stream->err_doc);
+      bson_destroy (&reply);
+      goto cleanup;
+   }
+   bson_append_int32 (&command_opts, "serverId", 8, server_stream->sd->id);
+   bson_append_int32 (&getmore_opts, "serverId", 8, server_stream->sd->id);
+   stream->max_wire_version = server_stream->sd->max_wire_version;
+   mongoc_server_stream_cleanup (server_stream);
+
    if (stream->read_concern && !bson_has_field (&command_opts, "readConcern")) {
       mongoc_read_concern_append (stream->read_concern, &command_opts);
    }

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

@@ -16,6 +16,7 @@
 
 
 #include "mongoc-client-session-private.h"
+#include "mongoc-cluster-private.h"
 #include "mongoc-trace-private.h"
 #include "mongoc-client-private.h"
 #include "mongoc-rand-private.h"
@@ -1110,16 +1111,16 @@ mongoc_client_session_start_transaction (mongoc_client_session_t *session,
                                          const mongoc_transaction_opt_t *opts,
                                          bson_error_t *error)
 {
-   mongoc_server_description_t *sd;
+   mongoc_server_stream_t *server_stream = NULL;
    bool ret;
 
    ENTRY;
    BSON_ASSERT (session);
 
    ret = true;
-   sd = mongoc_client_select_server (
-      session->client, true /* primary */, NULL, error);
-   if (!sd) {
+   server_stream = mongoc_cluster_stream_for_writes (
+      &session->client->cluster, session, NULL /* reply */, error);
+   if (!server_stream) {
       ret = false;
       GOTO (done);
    }
@@ -1133,8 +1134,9 @@ mongoc_client_session_start_transaction (mongoc_client_session_t *session,
       GOTO (done);
    }
 
-   if (sd->max_wire_version < 7 ||
-       (sd->max_wire_version < 8 && sd->type == MONGOC_SERVER_MONGOS)) {
+   if (server_stream->sd->max_wire_version < 7 ||
+       (server_stream->sd->max_wire_version < 8 &&
+        server_stream->sd->type == MONGOC_SERVER_MONGOS)) {
       bson_set_error (error,
                       MONGOC_ERROR_TRANSACTION,
                       MONGOC_ERROR_TRANSACTION_INVALID_STATE,
@@ -1204,7 +1206,7 @@ mongoc_client_session_start_transaction (mongoc_client_session_t *session,
    session->recovery_token = NULL;
 
 done:
-   mongoc_server_description_destroy (sd);
+   mongoc_server_stream_cleanup (server_stream);
    return ret;
 }
 

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

@@ -3142,3 +3142,27 @@ mongoc_client_set_server_api (mongoc_client_t *client,
    bson_mutex_unlock (&client->topology->mutex);
    return true;
 }
+
+mongoc_server_description_t *
+mongoc_client_get_handshake_description (mongoc_client_t *client,
+                                         uint32_t server_id,
+                                         bson_t *opts,
+                                         bson_error_t *error)
+{
+   mongoc_server_stream_t *server_stream;
+   mongoc_server_description_t *sd;
+
+   server_stream = mongoc_cluster_stream_for_server (&client->cluster,
+                                                     server_id,
+                                                     false /* reconnect */,
+                                                     NULL /* client session */,
+                                                     NULL /* reply */,
+                                                     error);
+   if (!server_stream) {
+      return NULL;
+   }
+
+   sd = mongoc_server_description_new_copy (server_stream->sd);
+   mongoc_server_stream_cleanup (server_stream);
+   return sd;
+}

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

@@ -274,6 +274,12 @@ mongoc_client_set_server_api (mongoc_client_t *client,
                               const mongoc_server_api_t *api,
                               bson_error_t *error);
 
+MONGOC_EXPORT (mongoc_server_description_t *)
+mongoc_client_get_handshake_description (mongoc_client_t *client,
+                                         uint32_t server_id,
+                                         bson_t *opts,
+                                         bson_error_t *error);
+
 BSON_END_DECLS
 
 

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

@@ -70,7 +70,7 @@ _run_command (mongoc_cluster_t *cluster,
    /* Drivers must not append session ids to auth commands per sessions spec. */
    parts.prohibit_lsid = true;
    server_stream = _mongoc_cluster_create_server_stream (
-      cluster->client->topology, sd->id, stream, error);
+      cluster->client->topology, sd, stream, error);
    if (!server_stream) {
       /* error was set by mongoc_topology_description_server_by_id */
       bson_init (reply);

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

@@ -83,7 +83,7 @@ _mongoc_cluster_auth_node_cyrus (mongoc_cluster_t *cluster,
       TRACE ("SASL: authenticating (step %d)", sasl.step);
 
       server_stream = _mongoc_cluster_create_server_stream (
-         cluster->client->topology, sd->id, stream, error);
+         cluster->client->topology, sd, stream, error);
 
       if (!server_stream) {
          bson_destroy (&cmd);

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

@@ -45,13 +45,8 @@ typedef struct _mongoc_cluster_node_t {
    mongoc_stream_t *stream;
    char *connection_address;
    uint32_t generation;
-
-   /* TODO CDRIVER-3653, these fields are unused. */
-   int32_t max_wire_version;
-   int32_t min_wire_version;
-   int32_t max_write_batch_size;
-   int32_t max_bson_obj_size;
-   int32_t max_msg_size;
+   /* handshake_sd is a server description created from the handshake on the stream. */
+   mongoc_server_description_t *handshake_sd;
 } mongoc_cluster_node_t;
 
 typedef struct _mongoc_cluster_t {
@@ -172,7 +167,7 @@ _mongoc_cluster_get_conversation_id (const bson_t *reply);
 
 mongoc_server_stream_t *
 _mongoc_cluster_create_server_stream (mongoc_topology_t *topology,
-                                      uint32_t server_id,
+                                      const mongoc_server_description_t *sd,
                                       mongoc_stream_t *stream,
                                       bson_error_t *error /* OUT */);
 

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

@@ -223,7 +223,7 @@ _mongoc_cluster_auth_node_sspi (mongoc_cluster_t *cluster,
       }
 
       server_stream = _mongoc_cluster_create_server_stream (
-         cluster->client->topology, sd->id, stream, error);
+         cluster->client->topology, sd, stream, error);
 
       if (!server_stream ||
           !mongoc_cmd_parts_assemble (&parts, server_stream, error)) {