replicaset: validate name in locate_master

Currently, the name validation is not used, when locate_master()
is called. It makes an explicit call via the connection to obtain a
future object in order to figure out, whether the node is a master.

We should not make any calls to a replica until the time, we definitely
know, that its name and uuid was validated. Let's use replica_call
instead of conn.call.

Follow-up tarantool#426

NO_DOC=bugfix

test/replicaset-luatest/vconnect_test.lua

@@ -187,3 +187,30 @@ test_group.test_async_no_yield = function(g)
         ivshard.storage._call = _G._call
     end)
 end
+
+--
+-- Test, that during master search name is validated.
+--
+test_group.test_locate_master = function()
+    -- Replace name with the bad one.
+    local new_cfg = table.deepcopy(global_cfg)
+    local cfg_rs = new_cfg.sharding.replicaset
+    cfg_rs.replicas.bad = cfg_rs.replicas.replica
+    cfg_rs.replicas.replica = nil
+    local _, rs = next(vreplicaset.buildall(new_cfg))
+
+    -- Avoid noop in locate_master.
+    rs.master = nil
+    rs.is_master_auto = true
+    -- Retry, until the connection is established and
+    -- name mismach error is encountered.
+    local ok, is_nop, last_err
+    t.helpers.retrying(timeout_opts, function()
+        ok, is_nop, last_err = rs:locate_master()
+        t.assert_not_equals(last_err, nil)
+    end)
+
+    t.assert_equals(last_err.name, 'INSTANCE_NAME_MISMATCH')
+    t.assert_equals(is_nop, false)
+    t.assert_equals(ok, false)
+end

test/router/router.result

@@ -1525,7 +1525,8 @@ table.sort(error_messages)
 ...
 error_messages
 ---
-- - Use replica:detach_conn(...) instead of replica.detach_conn(...)
+- - Use replica:check_is_connected(...) instead of replica.check_is_connected(...)
+  - Use replica:detach_conn(...) instead of replica.detach_conn(...)
   - Use replica:is_connected(...) instead of replica.is_connected(...)
   - Use replica:safe_uri(...) instead of replica.safe_uri(...)
 ...

vshard/replicaset.lua

@@ -1060,7 +1060,7 @@ local function replicaset_locate_master(replicaset)
     local func = 'vshard.storage._call'
     local args = {'info'}
     local const_timeout = consts.MASTER_SEARCH_TIMEOUT
-    local ok, res, err, f
+    local ok, res, err
     local master = replicaset.master
     if master then
         local sync_opts = {timeout = const_timeout}
@@ -1091,17 +1091,20 @@ local function replicaset_locate_master(replicaset)
     local futures = {}
     local timeout = const_timeout
     local deadline = fiber_clock() + timeout
-    local async_opts = {is_async = true}
+    local async_opts = {is_async = true, timeout = timeout}
     local replicaset_id = replicaset.id
     for replica_id, replica in pairs(replicaset.replicas) do
-        local conn = replicaset_connect_to_replica(replicaset, replica)
-        if conn:is_connected() then
-            ok, f = pcall(conn.call, conn, func, args, async_opts)
-            if not ok then
-                last_err = lerror.make(f)
+        replicaset_connect_to_replica(replicaset, replica)
+        ok, err = replica:check_is_connected()
+        if ok then
+            ok, res, err = replica_call(replica, func, args, async_opts)
+            if not ok and err ~= nil then
+                last_err = err
             else
-                futures[replica_id] = f
+                futures[replica_id] = res
             end
+        elseif err ~= nil then
+            last_err = err
         end
     end
     local master_id
@@ -1201,6 +1204,16 @@ local replica_mt = {
             return replica.conn and replica.conn:is_connected() and
                 conn_vconnect_check_or_close(replica.conn)
         end,
+        -- Does the same thing as is_connected(), but returns true or nil, err.
+        check_is_connected = function(replica)
+            if not replica.conn then
+                return nil, lerror.from_string("%s.conn is nil")
+            end
+            if not replica.conn:is_connected() then
+                return nil, lerror.from_string('%s.conn is not connected')
+            end
+            return conn_vconnect_check_or_close(replica.conn)
+        end,
         safe_uri = function(replica)
             local uri = luri.parse(replica.uri)
             uri.password = nil