Always build legacy_hello_cmd with legacy hello command

Author: alcaeus

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

@@ -541,7 +541,7 @@ mongoc_client_pool_set_server_api (mongoc_client_pool_t *pool,
 
    pool->api = mongoc_server_api_copy (api);
    bson_mutex_lock (&pool->topology->mutex);
-   _mongoc_topology_scanner_set_server_api (pool->topology->scanner, api);
+   _mongoc_topology_set_server_api (pool->topology, api);
    bson_mutex_unlock (&pool->topology->mutex);
    return true;
 }

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

@@ -3122,7 +3122,7 @@ mongoc_client_set_server_api (mongoc_client_t *client,
 
    client->api = mongoc_server_api_copy (api);
    bson_mutex_lock (&client->topology->mutex);
-   _mongoc_topology_scanner_set_server_api (client->topology->scanner, api);
+   _mongoc_topology_set_server_api (client->topology, api);
    bson_mutex_unlock (&client->topology->mutex);
    return true;
 }

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

@@ -230,3 +230,7 @@ mongoc_topology_rescan_srv (mongoc_topology_t *topology);
 bool
 mongoc_topology_should_rescan_srv (mongoc_topology_t *topology);
 #endif
+
+void
+_mongoc_topology_set_server_api (mongoc_topology_t *topology,
+                                 const mongoc_server_api_t *api);

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

@@ -109,15 +109,16 @@ _add_hello (mongoc_topology_scanner_t *ts)
    mongoc_server_api_t *api = ts->api;
 
    BSON_APPEND_INT32 (&ts->hello_cmd, "hello", 1);
+   BSON_APPEND_BOOL (&ts->hello_cmd, "helloOk", true);
+
+   BSON_APPEND_INT32 (&ts->legacy_hello_cmd, HANDSHAKE_CMD_LEGACY_HELLO, 1);
+   BSON_APPEND_BOOL (&ts->legacy_hello_cmd, "helloOk", true);
 
    if (api) {
       BSON_APPEND_INT32 (&ts->legacy_hello_cmd, "hello", 1);
 
       _mongoc_cmd_append_server_api (&ts->hello_cmd, api);
       _mongoc_cmd_append_server_api (&ts->legacy_hello_cmd, api);
-   } else {
-      BSON_APPEND_INT32 (&ts->legacy_hello_cmd, HANDSHAKE_CMD_LEGACY_HELLO, 1);
-      BSON_APPEND_BOOL (&ts->legacy_hello_cmd, "helloOk", true);
    }
 }
 
@@ -260,7 +261,7 @@ _build_handshake_cmd (mongoc_topology_scanner_t *ts)
    char buf[16];
 
    bson_destroy (doc);
-   bson_copy_to (&ts->legacy_hello_cmd, doc);
+   bson_copy_to (ts->api ? &ts->hello_cmd : &ts->legacy_hello_cmd, doc);
 
    BSON_APPEND_DOCUMENT_BEGIN (doc, HANDSHAKE_FIELD, &subdoc);
    res = _mongoc_handshake_build_doc_with_application (&subdoc, ts->appname);
@@ -288,7 +289,7 @@ const bson_t *
 _mongoc_topology_scanner_get_monitoring_cmd (mongoc_topology_scanner_t *ts,
                                              bool hello_ok)
 {
-   return hello_ok ? &ts->hello_cmd : &ts->legacy_hello_cmd;
+   return hello_ok || ts->api ? &ts->hello_cmd : &ts->legacy_hello_cmd;
 }
 
 /* Caller must lock topology->mutex to protect handshake_cmd. This
@@ -309,7 +310,7 @@ _mongoc_topology_scanner_get_handshake_cmd (mongoc_topology_scanner_t *ts)
 
    /* If the doc turned out to be too big */
    if (!ts->handshake_ok_to_send) {
-      return &ts->legacy_hello_cmd;
+      return ts->api ? &ts->hello_cmd : &ts->legacy_hello_cmd;
    }
 
    return &ts->handshake_cmd;

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

@@ -1824,3 +1824,23 @@ _topology_collect_errors (mongoc_topology_t *topology, bson_error_t *error_out)
                  sizeof (error_out->message));
    bson_string_free (error_message, true);
 }
+
+/* Caller must lock topology->mutex to protect handshake_cmd. */
+void
+_mongoc_topology_set_server_api (mongoc_topology_t *topology,
+                                 const mongoc_server_api_t *api)
+{
+   mongoc_server_description_t *server_description;
+   int i;
+
+   BSON_ASSERT (topology);
+   BSON_ASSERT (api);
+
+   /* Set hello_ok for all server descriptions */
+   for (i = 0; i < topology->description.servers->items_len; i++) {
+      server_description = topology->description.servers->items[i].item;
+      server_description->hello_ok = true;
+   }
+
+   _mongoc_topology_scanner_set_server_api (topology->scanner, api);
+}