CP-54393: VNC console idle timeout

This commit adds idle timeout feature for vnc console connections.

Key changes:
- Add idle timeout detection by monitoring RFB keyEvent and
  pointerEvent.
- Add callback function to `proxy` to parse the RFB messages and
  determine if the connection is idle or not.

Signed-off-by: Stephen Cheng <[email protected]>

Author: stephenchengCloud

ocaml/libs/xapi-stdext/lib/xapi-stdext-unix/unixext.ml

@@ -338,7 +338,8 @@ module CBuf = struct
     in
     let read = Unix.read fd x.buffer next len in
     if read = 0 then x.r_closed <- true ;
-    x.len <- x.len + read
+    x.len <- x.len + read ;
+    (x.buffer, read, next)
 end
 
 exception Process_still_alive
@@ -381,11 +382,21 @@ let with_polly f =
   let finally () = Polly.close polly in
   Xapi_stdext_pervasives.Pervasiveext.finally (fun () -> f polly) finally
 
-let proxy (a : Unix.file_descr) (b : Unix.file_descr) =
+exception Close_proxy
+
+let proxy ?should_close ?(poll_timeout = -1) (a : Unix.file_descr)
+    (b : Unix.file_descr) =
   let size = 64 * 1024 in
   (* [a'] is read from [a] and will be written to [b] *)
   (* [b'] is read from [b] and will be written to [a] *)
   let a' = CBuf.empty size and b' = CBuf.empty size in
+
+  let close_proxy () =
+    Unix.shutdown a Unix.SHUTDOWN_ALL ;
+    Unix.shutdown b Unix.SHUTDOWN_ALL ;
+    raise Close_proxy
+  in
+
   Unix.set_nonblock a ;
   Unix.set_nonblock b ;
   with_polly @@ fun polly ->
@@ -413,13 +424,22 @@ let proxy (a : Unix.file_descr) (b : Unix.file_descr) =
         Polly.upd polly a a_events ;
       if Polly.Events.(b_events <> empty) then
         Polly.upd polly b b_events ;
-      Polly.wait_fold polly 4 (-1) () (fun _polly fd events () ->
+      Polly.wait_fold polly 4 poll_timeout (Bytes.empty, 0, 0)
+        (fun _polly fd events acc ->
           (* Do the writing before the reading *)
           if Polly.Events.(test out events) then
             if a = fd then CBuf.write b' a else CBuf.write a' b ;
           if Polly.Events.(test inp events) then
-            if a = fd then CBuf.read a' a else CBuf.read b' b
-      ) ;
+            if a = fd then (
+              ignore (CBuf.read a' a) ;
+              acc
+            ) else
+              CBuf.read b' b
+          else
+            acc
+      )
+      |> fun data ->
+      Option.iter (fun cb -> if cb data then close_proxy ()) should_close ;
       (* If there's nothing else to read or write then signal the other end *)
       List.iter
         (fun (buf, fd) ->

ocaml/libs/xapi-stdext/lib/xapi-stdext-unix/unixext.mli

@@ -126,7 +126,12 @@ exception Process_still_alive
 
 val kill_and_wait : ?signal:int -> ?timeout:float -> int -> unit
 
-val proxy : Unix.file_descr -> Unix.file_descr -> unit
+val proxy :
+     ?should_close:(bytes * int * int -> bool)
+  -> ?poll_timeout:int
+  -> Unix.file_descr
+  -> Unix.file_descr
+  -> unit
 
 val really_read : Unix.file_descr -> bytes -> int -> int -> unit
 

ocaml/xapi/console.ml

@@ -126,7 +126,87 @@ let address_of_console __context console : address option =
     ) ;
   address_option
 
-let real_proxy' vnc_port s =
+module Console_idle_monitor = struct
+  let get_idle_timeout_config ~__context ~vm =
+    try
+      let idle_timeout =
+        if Db.VM.get_is_control_domain ~__context ~self:vm then
+          let host = Helpers.get_localhost ~__context in
+          Db.Host.get_console_idle_timeout ~__context ~self:host
+        else
+          let pool = Helpers.get_pool ~__context in
+          Db.Pool.get_vm_console_idle_timeout ~__context ~self:pool
+      in
+      if idle_timeout > 0L then Some (Int64.to_float idle_timeout) else None
+    with _ -> None
+
+  let is_active messages =
+    List.exists
+      (function
+        | Rfb_client_msgtype_parser.KeyEvent
+        | Rfb_client_msgtype_parser.PointerEvent
+        | Rfb_client_msgtype_parser.QEMUClientMessage ->
+            true
+        | _ ->
+            false
+        )
+      messages
+
+  let timed_out ~idle_timeout_seconds ~last_activity =
+    let elapsed = Mtime_clock.count last_activity in
+    Mtime.Span.to_float_ns elapsed /. 1e9 > idle_timeout_seconds
+
+  (* Create an idle timeout callback for the console,
+     if idle timeout, then close the proxy *)
+  let create_idle_timeout_callback ~__context ~vm =
+    match get_idle_timeout_config ~__context ~vm with
+    | Some idle_timeout_seconds -> (
+        let module P = Rfb_client_msgtype_parser in
+        let state = ref (Some (P.create (), Mtime_clock.counter ())) in
+        (* Return true for idle timeout to close the proxy,
+            otherwise return false to keep the proxy open *)
+        fun (buf, read_len, offset) ->
+          match !state with
+          | None ->
+              false
+          | Some (rfb_parser, last_activity) ->
+              let ok msgs =
+                if is_active msgs then (
+                  state := Some (rfb_parser, Mtime_clock.counter ()) ;
+                  false
+                ) else
+                  let timeout_result =
+                    timed_out ~idle_timeout_seconds ~last_activity
+                  in
+                  if timeout_result then
+                    debug
+                      "Console connection idle timeout exceeded for VM %s \
+                       (timeout: %.1fs)"
+                      (Ref.string_of vm) idle_timeout_seconds ;
+                  timeout_result
+              in
+              let error msg =
+                debug "RFB parse error: %s" msg ;
+                state := None ;
+                false
+              in
+              Bytes.sub_string buf offset read_len
+              |> rfb_parser
+              |> Result.fold ~ok ~error
+      )
+    | None ->
+        Fun.const false
+end
+
+let get_poll_timeout =
+  let poll_period_timeout = !Xapi_globs.proxy_poll_period_timeout in
+  if poll_period_timeout < 0. then
+    -1
+  else
+    Float.to_int (poll_period_timeout *. 1000.)
+(* convert to milliseconds *)
+
+let real_proxy' ~__context ~vm vnc_port s =
   try
     Http_svr.headers s (Http.http_200_ok ()) ;
     let vnc_sock =
@@ -141,7 +221,12 @@ let real_proxy' vnc_port s =
     debug "Connected; running proxy (between fds: %d and %d)"
       (Unixext.int_of_file_descr vnc_sock)
       (Unixext.int_of_file_descr s') ;
-    Unixext.proxy vnc_sock s' ;
+
+    let poll_timeout = get_poll_timeout in
+    let should_close =
+      Console_idle_monitor.create_idle_timeout_callback ~__context ~vm
+    in
+    Unixext.proxy ~should_close ~poll_timeout vnc_sock s' ;
     debug "Proxy exited"
   with exn -> debug "error: %s" (ExnHelper.string_of_exn exn)
 
@@ -153,7 +238,7 @@ let real_proxy __context vm _ _ vnc_port s =
   in
   if Connection_limit.try_add vm_id is_limit_enabled then
     finally (* Ensure we drop the vm connection count if exceptions occur *)
-      (fun () -> real_proxy' vnc_port s)
+      (fun () -> real_proxy' ~__context ~vm vnc_port s)
       (fun () -> Connection_limit.drop vm_id)
   else
     Http_svr.headers s (Http.http_503_service_unavailable ())

ocaml/xapi/xapi_globs.ml

@@ -450,6 +450,11 @@ let xha_timeout = "timeout"
 
 let message_limit = ref 10000
 
+(* The timeout (in seconds) for event polling in the proxy loop.
+   If set to a positive value, the poll will wake up periodically,
+   which is useful for implementing features like idle timeout or periodic inspection of proxy buffers. *)
+let proxy_poll_period_timeout = ref 5.0
+
 let xapi_message_script = ref "mail-alarm"
 
 (* Emit a warning if more than this amount of clock skew detected *)
@@ -1783,6 +1788,14 @@ let other_options =
     , (fun () -> string_of_float !vm_sysprep_wait)
     , "Time in seconds to wait for VM to recognise inserted CD"
     )
+  ; ( "proxy_poll_period_timeout"
+    , Arg.Set_float proxy_poll_period_timeout
+    , (fun () -> string_of_float !proxy_poll_period_timeout)
+    , "Timeout (in seconds) for event polling in network proxy loops. When \
+       positive, the proxy will wake up periodically to check tasks like vnc \
+       idle timeouts or perform other maintenance tasks. Set to -1 to wait \
+       indefinitely for network events without periodic wake-ups."
+    )
   ]
 
 (* The options can be set with the variable xapiflags in /etc/sysconfig/xapi.