dird: reset or use client connection handshake modes saved in the cli…

…ent-config

- reset all modes to kUndefined after reloading the config
- safe the successful connection mode in the config
- use the last saved connection mode for future connections
- adapted some comments

core/src/dird/dird_conf.cc

@@ -3794,6 +3794,18 @@ static void PrintConfigCb(ResourceItem *items, int i, PoolMem &cfg_str, bool hid
    }
 }
 
+static void ResetAllClientConnectionHandshakeModes(ConfigurationParser &my_config)
+{
+  CommonResourceHeader *header = nullptr;
+  do {
+    header = my_config.GetNextRes(R_CLIENT, header);
+    ClientResource *client = reinterpret_cast<ClientResource*>(header);
+    if (client) {
+      client->connection_successful_handshake_ = ClientConnectionHandshakeMode::kUndefined;
+    }
+  } while (header);
+}
+
 static void ConfigReadyCallback(ConfigurationParser &my_config)
 {
   CreateAndAddUserAgentConsoleResource(my_config);
@@ -3805,6 +3817,8 @@ static void ConfigReadyCallback(ConfigurationParser &my_config)
       {R_MSGS, "R_MSGS"},         {R_COUNTER, "R_COUNTER"}, {R_PROFILE, "R_PROFILE"},
       {R_CONSOLE, "R_CONSOLE"},   {R_DEVICE, "R_DEVICE"}};
   my_config.InitializeQualifiedResourceNameTypeConverter(map);
+
+  ResetAllClientConnectionHandshakeModes(my_config);
 }
 
 static bool AddResourceCopyToEndOfChain(UnionOfResources *res_to_add, int type)

core/src/dird/fd_cmds.cc

@@ -165,10 +165,16 @@ bool ConnectToFileDaemon(JobControlRecord *jcr, int retry_interval, int max_retr
    bool tcp_connect_failed = false;
    int connect_tries = 3; /* as a finish-hook for the UseWaitingClient mechanism */
 
-   /* try the connection mode in case a client that cannot do Tls
-    * immediately without cleartext md5-handshake first */
-   jcr->connection_handshake_try_ = ClientConnectionHandshakeMode::kTlsFirst;
-   jcr->res.client->connection_successful_handshake_ = ClientConnectionHandshakeMode::kUndefined;
+   /* try the connection modes starting with tls directly,
+    * in case there is a client that cannot do Tls immediately then
+    * fall back to cleartext md5-handshake */
+   if (jcr->res.client->connection_successful_handshake_ == ClientConnectionHandshakeMode::kUndefined
+    || jcr->res.client->connection_successful_handshake_ == ClientConnectionHandshakeMode::kFailed) {
+      jcr->connection_handshake_try_ = ClientConnectionHandshakeMode::kTlsFirst;
+   } else {
+      /* if there is a stored mode from a previous connection then use this */
+      jcr->connection_handshake_try_ = jcr->res.client->connection_successful_handshake_;
+   }
 
    do { /* while (tcp_connect_failed ...) */
      /* connect the tcp socket */