File 0988-ssh-Send-ssh_msg_channel_failure-according-to-RFC-42.patch of Package erlang

From ac1be24b1fe60a4f2831e65b39dd76731868bc6b Mon Sep 17 00:00:00 2001
From: Hans Nilsson <hans@erlang.org>
Date: Fri, 25 Sep 2020 10:18:07 +0200
Subject: [PATCH] ssh: Send ssh_msg_channel_failure according to RFC 4254

---
 lib/ssh/src/ssh_connection.erl | 29 ++++++++++++++++-------------
 lib/ssh/src/ssh_message.erl    | 26 +++++++++++++++++++-------
 2 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/lib/ssh/src/ssh_connection.erl b/lib/ssh/src/ssh_connection.erl
index 9b9d66aaa8..06dbba0dd9 100644
--- a/lib/ssh/src/ssh_connection.erl
+++ b/lib/ssh/src/ssh_connection.erl
@@ -727,20 +727,23 @@ handle_msg(#ssh_msg_channel_request{request_type = "env"},
     %% The client SHOULD ignore env requests. 
     {[], Connection};
 
-handle_msg(#ssh_msg_channel_request{recipient_channel = ChannelId,
-				    request_type = _Other,
-				    want_reply = WantReply},
+handle_msg(#ssh_msg_channel_request{recipient_channel = ChannelId},
 	   #connection{channel_cache = Cache} = Connection, _) ->
-    if WantReply == true ->
-		case ssh_client_channel:cache_lookup(Cache, ChannelId) of
-		    #channel{remote_id = RemoteId}  -> 
-			FailMsg = channel_failure_msg(RemoteId),
-			{[{connection_reply, FailMsg}], Connection};
-		    undefined -> %% Chanel has been closed
-			{[], Connection}
-		end;
-       true ->
-	    {[], Connection}
+    %% Not a valid request_type. All valid types are handling the
+    %% parameter checking in their own clauses above.
+    %% 
+    %% The special ReqType faulty_msg signals that something went
+    %% wrong found during decoding.
+    %%
+    %% RFC4254 says:
+    %% "If the request is not recognized or is not
+    %% supported for the channel, SSH_MSG_CHANNEL_FAILURE is returned."
+    case ssh_client_channel:cache_lookup(Cache, ChannelId) of
+        #channel{remote_id = RemoteId}  -> 
+            FailMsg = channel_failure_msg(RemoteId),
+            {[{connection_reply, FailMsg}], Connection};
+        undefined -> %% Chanel has been closed
+            {[], Connection}
     end;
 
 handle_msg(#ssh_msg_global_request{name = _Type,
diff --git a/lib/ssh/src/ssh_message.erl b/lib/ssh/src/ssh_message.erl
index e5ab449b8b..fab9c50867 100644
--- a/lib/ssh/src/ssh_message.erl
+++ b/lib/ssh/src/ssh_message.erl
@@ -366,13 +366,25 @@ decode(<<?BYTE(?SSH_MSG_CHANNEL_CLOSE),  ?UINT32(Recipient)>>) ->
        recipient_channel = Recipient
       };
 decode(<<?BYTE(?SSH_MSG_CHANNEL_REQUEST), ?UINT32(Recipient),
-	 ?DEC_BIN(RequestType,__0), ?BYTE(Bool), Data/binary>>) ->
-    #ssh_msg_channel_request{
-       recipient_channel = Recipient,
-       request_type = ?unicode_list(RequestType),
-       want_reply = erl_boolean(Bool),
-       data  = Data
-      };
+	 ?DEC_BIN(RequestType,__0), ?BYTE(Bool), Data/binary>>=Bytes) ->
+    try
+        #ssh_msg_channel_request{
+           recipient_channel = Recipient,
+           request_type = ?unicode_list(RequestType),
+           want_reply = erl_boolean(Bool),
+           data  = Data
+          }
+    catch _:_ ->
+            %% Faulty, RFC4254 says:
+            %% "If the request is not recognized or is not
+            %% supported for the channel, SSH_MSG_CHANNEL_FAILURE is returned."
+            %% So we provoke such a message to be sent
+            #ssh_msg_channel_request{
+               recipient_channel = Recipient,
+               request_type = faulty_msg,
+               data = Bytes
+              }
+    end;
 decode(<<?BYTE(?SSH_MSG_CHANNEL_SUCCESS),  ?UINT32(Recipient)>>) ->
     #ssh_msg_channel_success{
        recipient_channel = Recipient
-- 
2.26.2