[Xen-devel] [PATCH 3 of 4] oxenstored: handle unknown operations by returning an error to the client

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1323448556 0
# Node ID 74f94e15bfe1dad412d0342aeabdbd895657f54f
# Parent  18c0807a0504791bcb6e083866def9c4862a119a
oxenstored: handle unknown operations by returning an error to the client

Previous an unknown operation would be decoded as a Not_found exception which
would bubble all the way up to the try ... with surrounding the call to
main_loop where it would be logged and ignored.

This would leave the guest hanging waiting for a response to the invalid
request.

Instead introduce a specific "Invalid" operation. Higher level functionality,
such as Process.process_packet, already handles operations which are not
understood with an error reply due to the final wildcard entry in
Process.function_of_type but explicitly handle Invalid this way to make it
clear what is going on.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 18c0807a0504 -r 74f94e15bfe1 tools/ocaml/libs/xb/op.ml
--- a/tools/ocaml/libs/xb/op.ml Fri Dec 09 16:19:36 2011 +0000
+++ b/tools/ocaml/libs/xb/op.ml Fri Dec 09 16:35:56 2011 +0000
@@ -19,8 +19,7 @@ type operation = Debug | Directory | Rea
                  Transaction_end | Introduce | Release |
                  Getdomainpath | Write | Mkdir | Rm |
                  Setperms | Watchevent | Error | Isintroduced |
-                 Resume | Set_target
-               | Restrict 
+                 Resume | Set_target | Restrict | Invalid
 
 let operation_c_mapping =
        [| Debug; Directory; Read; Getperms;
@@ -41,7 +40,7 @@ let array_search el a =
 let of_cval i =
        if i >= 0 && i < size
        then operation_c_mapping.(i)
-       else raise Not_found
+       else Invalid
 
 let to_cval op =
        array_search op operation_c_mapping
@@ -69,3 +68,4 @@ let to_string ty =
        | Resume                -> "RESUME"
        | Set_target            -> "SET_TARGET"
        | Restrict              -> "RESTRICT"
+       | Invalid               -> "INVALID"
diff -r 18c0807a0504 -r 74f94e15bfe1 tools/ocaml/libs/xb/xb.mli
--- a/tools/ocaml/libs/xb/xb.mli        Fri Dec 09 16:19:36 2011 +0000
+++ b/tools/ocaml/libs/xb/xb.mli        Fri Dec 09 16:35:56 2011 +0000
@@ -23,6 +23,7 @@ module Op :
       | Resume
       | Set_target
       | Restrict
+      | Invalid (* Not a valid wire operation *)
     val operation_c_mapping : operation array
     val size : int
     val array_search : 'a -> 'a array -> int
diff -r 18c0807a0504 -r 74f94e15bfe1 tools/ocaml/xenstored/process.ml
--- a/tools/ocaml/xenstored/process.ml  Fri Dec 09 16:19:36 2011 +0000
+++ b/tools/ocaml/xenstored/process.ml  Fri Dec 09 16:35:56 2011 +0000
@@ -324,7 +324,8 @@ let function_of_type ty =
        | Xenbus.Xb.Op.Resume            -> reply_ack do_resume
        | Xenbus.Xb.Op.Set_target        -> reply_ack do_set_target
        | Xenbus.Xb.Op.Restrict          -> reply_ack do_restrict
-       | _                       -> reply_ack do_error
+       | Xenbus.Xb.Op.Invalid           -> reply_ack do_error
+       | _                              -> reply_ack do_error
 
 let input_handle_error ~cons ~doms ~fct ~ty ~con ~t ~rid ~data =
        let reply_error e =
diff -r 18c0807a0504 -r 74f94e15bfe1 tools/ocaml/xenstored/xenstored.ml
--- a/tools/ocaml/xenstored/xenstored.ml        Fri Dec 09 16:19:36 2011 +0000
+++ b/tools/ocaml/xenstored/xenstored.ml        Fri Dec 09 16:35:56 2011 +0000
@@ -43,9 +43,7 @@ let process_connection_fds store cons do
                        debug "closing socket connection"
                in
        let process_fdset_with fds fct =
-               List.iter (fun fd ->
-                          try try_fct fct (Connections.find cons fd)
-                          with Not_found -> ()) fds
+               List.iter (fun fd -> try_fct fct (Connections.find cons fd)) fds
        in
        process_fdset_with rset Process.do_input;
        process_fdset_with wset Process.do_output

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