ssh: Improve errorhandling in ssh_connection.erl

If a channel is closed by the peer while using a function with call semantics
in ssh_connection.erl return {error, closed}. Document that the functions
can return {error, timeout | closed} and not only ssh_request_status()

4 files changed, 61 insertions, 18 deletions

diff --git a/lib/ssh/doc/src/ssh_connection.xml b/lib/ssh/doc/src/ssh_connection.xml
index ff72cf7ee0..5e2926dfa6 100644
--- a/lib/ssh/doc/src/ssh_connection.xml
+++ b/lib/ssh/doc/src/ssh_connection.xml
@@ -62,6 +62,7 @@
     <p><c>ssh_request_status() = success | failure</c></p>
     <p><c>event() = {ssh_cm, ssh_connection_ref(), ssh_event_msg()} </c></p>
     <p><c>ssh_event_msg()  = data_events() | status_events() | terminal_events() </c></p>
+    <p><c>reason() = timeout | closed  </c></p>
 
     <taglist>
       <tag><b>data_events()</b></tag>
@@ -218,7 +219,7 @@
    </func>
    
    <func>
-     <name>exec(ConnectionRef, ChannelId, Command, TimeOut) -> ssh_request_status()  </name>
+     <name>exec(ConnectionRef, ChannelId, Command, TimeOut) -> ssh_request_status() | {error, reason()} </name>
      <fsummary>Request that the server start the execution of the given command.  </fsummary>
      <type>
        <v> ConnectionRef = ssh_connection_ref() </v>
@@ -274,7 +275,8 @@
    </func>
    
    <func>
-       <name>ptty_alloc(ConnectionRef, ChannelId, Options, Timeout) -> success | failure</name>
+     <name>ptty_alloc(ConnectionRef, ChannelId, Options) ->  </name>
+     <name>ptty_alloc(ConnectionRef, ChannelId, Options, Timeout) ->  > ssh_request_status() | {error, reason()}  </name>
        <fsummary>Send status replies to requests that want such replies. </fsummary>
       <type>
 	<v> ConnectionRef = ssh_connection_ref() </v>
@@ -374,7 +376,7 @@
      <func>
        <name>session_channel(ConnectionRef, Timeout) -> </name>
        <name>session_channel(ConnectionRef, InitialWindowSize,
-       MaxPacketSize, Timeout) -> {ok, ssh_channel_id()} | {error, Reason}</name>
+       MaxPacketSize, Timeout) -> {ok, ssh_channel_id()} | {error, reason()}</name>
        <fsummary>Opens a channel for a ssh session. </fsummary>
        <type>
 	 <v> ConnectionRef = ssh_connection_ref()</v>
@@ -391,7 +393,7 @@
      </func>
 
     <func>
-      <name>setenv(ConnectionRef, ChannelId, Var, Value, TimeOut) -> ssh_request_status()</name>
+      <name>setenv(ConnectionRef, ChannelId, Var, Value, TimeOut) -> ssh_request_status() | {error, reason()} </name>
       <fsummary> Environment variables may be passed to the
       shell/command to be started later.</fsummary>
       <type>
@@ -409,7 +411,7 @@
     </func>
     
     <func>
-      <name>shell(ConnectionRef, ChannelId) -> ssh_request_status()
+      <name>shell(ConnectionRef, ChannelId) -> ssh_request_status() | {error, closed}
       </name>
       <fsummary> Requests that the user's default shell (typically
       defined in /etc/passwd in UNIX systems) shall be executed at the server
@@ -426,7 +428,7 @@
     </func>
 
     <func>
-      <name>subsystem(ConnectionRef, ChannelId, Subsystem, Timeout) -> ssh_request_status()</name>
+      <name>subsystem(ConnectionRef, ChannelId, Subsystem, Timeout) -> ssh_request_status() | {error, reason()} </name>
       <fsummary>  </fsummary>
        <type>
 	 <v> ConnectionRef = ssh_connection_ref() </v>
diff --git a/lib/ssh/src/ssh_connection.erl b/lib/ssh/src/ssh_connection.erl
index 01141622d6..c66f810948 100644
--- a/lib/ssh/src/ssh_connection.erl
+++ b/lib/ssh/src/ssh_connection.erl
@@ -56,8 +56,8 @@
 %%--------------------------------------------------------------------
 
 %%--------------------------------------------------------------------
--spec session_channel(pid(), timeout()) -> {ok, channel_id()} | {error, term()}.
--spec session_channel(pid(), integer(), integer(), timeout()) -> {ok, channel_id()} | {error, term()}.
+-spec session_channel(pid(), timeout()) -> {ok, channel_id()} | {error, timeout | closed}.
+-spec session_channel(pid(), integer(), integer(), timeout()) -> {ok, channel_id()} | {error, timeout | closed}.
 
 %% Description: Opens a channel for a ssh session. A session is a
 %% remote execution of a program. The program may be a shell, an
@@ -81,7 +81,8 @@ session_channel(ConnectionHandler, InitialWindowSize,
     end.
 
 %%--------------------------------------------------------------------
--spec exec(pid(), channel_id(), string(), timeout()) -> success | failure.
+-spec exec(pid(), channel_id(), string(), timeout()) -> 
+		  success | failure | {error, timeout | closed}.
 
 %% Description: Will request that the server start the
 %% execution of the given command. 
@@ -101,8 +102,8 @@ shell(ConnectionHandler, ChannelId) ->
     ssh_connection_handler:request(ConnectionHandler, self(), ChannelId,
  				   "shell", false, <<>>, 0).
 %%--------------------------------------------------------------------
--spec subsystem(pid(), channel_id(), string(), timeout()) ->
-		       success | failure | {error, timeout}.
+-spec subsystem(pid(), channel_id(), string(), timeout()) -> 
+		       success | failure | {error, timeout | closed}.
 %%
 %% Description: Executes a predefined subsystem.
 %%--------------------------------------------------------------------
@@ -142,7 +143,7 @@ send_eof(ConnectionHandler, Channel) ->
     ssh_connection_handler:send_eof(ConnectionHandler, Channel).
 
 %%--------------------------------------------------------------------
--spec adjust_window(pid(), channel_id(), integer()) -> ok.
+-spec adjust_window(pid(), channel_id(), integer()) -> ok |  {error, closed}.
 %%
 %%
 %% Description: Adjusts the ssh flowcontrol window.
@@ -151,7 +152,8 @@ adjust_window(ConnectionHandler, Channel, Bytes) ->
     ssh_connection_handler:adjust_window(ConnectionHandler, Channel, Bytes).
 
 %%--------------------------------------------------------------------
--spec setenv(pid(), channel_id(), string(), string(), timeout()) ->  success | failure.
+-spec setenv(pid(), channel_id(), string(), string(), timeout()) ->  
+		    success | failure | {error, timeout | closed}.
 %%
 %%
 %% Description: Environment variables may be passed to the shell/command to be
@@ -183,7 +185,11 @@ reply_request(_,false, _, _) ->
     ok.
 
 %%--------------------------------------------------------------------
--spec ptty_alloc(pid(), channel_id(), proplists:proplist()) -> success | failiure.
+-spec ptty_alloc(pid(), channel_id(), proplists:proplist()) -> 
+			success | failiure | {error, closed}.
+-spec ptty_alloc(pid(), channel_id(), proplists:proplist(), timeout()) -> 
+			success | failiure | {error, timeout} | {error, closed}.
+
 %%
 %%
 %% Description: Sends a ssh connection protocol pty_req.
diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index fdb9d3b3e6..915060c426 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -289,8 +289,13 @@ renegotiate_data(ConnectionHandler) ->
 -spec close(pid(), channel_id()) -> ok.
 %%--------------------------------------------------------------------
 close(ConnectionHandler, ChannelId) ->
-    sync_send_all_state_event(ConnectionHandler, {close, ChannelId}).
-
+    case sync_send_all_state_event(ConnectionHandler, {close, ChannelId}) of
+	ok ->
+	    ok;
+	{error, closed} -> 
+	    ok
+    end.	
+	
 %%--------------------------------------------------------------------
 -spec stop(pid()) -> ok | {error, term()}.
 %%--------------------------------------------------------------------
@@ -1204,7 +1209,11 @@ sync_send_all_state_event(FsmPid, Event) ->
     sync_send_all_state_event(FsmPid, Event, infinity).
 
 sync_send_all_state_event(FsmPid, Event, Timeout) ->
-    try gen_fsm:sync_send_all_state_event(FsmPid, Event, Timeout)
+    try gen_fsm:sync_send_all_state_event(FsmPid, Event, Timeout) of
+	{closed, _Channel} ->
+	    {error, closed};
+	Result ->
+	    Result
     catch
 	exit:{noproc, _} ->
 	    {error, closed};
diff --git a/lib/ssh/test/ssh_connection_SUITE.erl b/lib/ssh/test/ssh_connection_SUITE.erl
index a73573e7fe..e3871b3feb 100644
--- a/lib/ssh/test/ssh_connection_SUITE.erl
+++ b/lib/ssh/test/ssh_connection_SUITE.erl
@@ -45,7 +45,8 @@ all() ->
      gracefull_invalid_start,
      gracefull_invalid_long_start,
      gracefull_invalid_long_start_no_nl,
-     stop_listener
+     stop_listener,
+     start_subsystem_on_closed_channel
     ].
 groups() ->
     [{openssh, [], payload() ++ ptty()}].
@@ -575,6 +576,31 @@ stop_listener(Config) when is_list(Config) ->
 	    ct:fail({unexpected, Error})
     end.
 
+start_subsystem_on_closed_channel(Config) ->
+    PrivDir = ?config(priv_dir, Config),
+    UserDir = filename:join(PrivDir, nopubkey), % to make sure we don't use public-key-auth
+    file:make_dir(UserDir),
+    SysDir = ?config(data_dir, Config),
+    {Pid, Host, Port} = ssh_test_lib:daemon([{system_dir, SysDir},
+					     {user_dir, UserDir},
+					     {password, "morot"},
+					     {subsystems, [{"echo_n", {ssh_echo_server, [4000000]}}]}]),
+
+    ConnectionRef = ssh_test_lib:connect(Host, Port, [{silently_accept_hosts, true},
+						      {user, "foo"},
+						      {password, "morot"},
+						      {user_interaction, false},
+						      {user_dir, UserDir}]),
+
+    {ok, ChannelId} = ssh_connection:session_channel(ConnectionRef, infinity),
+
+    ok = ssh_connection:close(ConnectionRef, ChannelId),
+
+    {error, closed} = ssh_connection:subsystem(ConnectionRef, ChannelId, "echo_n", infinity),
+
+    ssh:close(ConnectionRef),
+    ssh:stop_daemon(Pid).
+
 %%--------------------------------------------------------------------
 %% Internal functions ------------------------------------------------
 %%--------------------------------------------------------------------