Fix DoGlobalRequestFwd to reject the forwarding when no fwdCb is set

Author: yosuke-wolfssl

src/internal.c

@@ -8496,16 +8496,24 @@ static int DoGlobalRequestFwd(WOLFSSH* ssh,
                 isCancel ? " cancel" : "", bindAddr, bindPort);
     }
 
-    if (ret == WS_SUCCESS && wantReply) {
-        ret = SendGlobalRequestFwdSuccess(ssh, 1, bindPort);
-    }
-
     if (ret == WS_SUCCESS) {
         if (ssh->ctx->fwdCb) {
             ret = ssh->ctx->fwdCb(isCancel ? WOLFSSH_FWD_REMOTE_CLEANUP :
                         WOLFSSH_FWD_REMOTE_SETUP,
                     ssh->fwdCbCtx, bindAddr, bindPort);
         }
+        else {
+            WLOG(WS_LOG_WARN, "No forwarding callback set, rejecting request. "
+                "Set one with wolfSSH_CTX_SetFwdCb().");
+            ret = WS_UNIMPLEMENTED_E;
+        }
+    }
+
+    if (ret == WS_SUCCESS && wantReply) {
+        ret = SendGlobalRequestFwdSuccess(ssh, 1, bindPort);
+    }
+    else if (ret == WS_UNIMPLEMENTED_E && wantReply) {
+        SendGlobalRequestFwdSuccess(ssh, 0, 0);
     }
 
     if (bindAddr != NULL)