Fix handler crashes handling

We try to send a 500 error only if we didn't send the response
headers yet. If they were, then we have no way to be sure the
response was fully sent, nor should we assume anything about
how this will be handled client-side, so we do nothing more
and in both cases close the connection.

1 files changed, 9 insertions, 4 deletions

diff --git a/src/cowboy_http_req.erl b/src/cowboy_http_req.erl
index 7a0e3a7..b0a0232 100644
--- a/src/cowboy_http_req.erl
+++ b/src/cowboy_http_req.erl
@@ -473,7 +473,7 @@ reply(Status, Headers, Req=#http_req{resp_body=Body}) ->
 -spec reply(http_status(), http_headers(), iodata(), #http_req{})
 	-> {ok, #http_req{}}.
 reply(Status, Headers, Body, Req=#http_req{socket=Socket,
-		transport=Transport, connection=Connection,
+		transport=Transport, connection=Connection, pid=ReqPid,
 		method=Method, resp_state=waiting, resp_headers=RespHeaders}) ->
 	RespConn = response_connection(Headers, Connection),
 	ContentLen = case Body of {CL, _} -> CL; _ -> iolist_size(Body) end,
@@ -488,6 +488,7 @@ reply(Status, Headers, Body, Req=#http_req{socket=Socket,
 		{_, {_, StreamFun}} -> Transport:send(Socket, Head), StreamFun();
 		{_, _} -> Transport:send(Socket, [Head, Body])
 	end,
+	ReqPid ! {?MODULE, resp_sent},
 	{ok, Req#http_req{connection=RespConn, resp_state=done,
 		resp_headers=[], resp_body= <<>>}}.
 
@@ -500,8 +501,9 @@ chunked_reply(Status, Req) ->
 %% @see cowboy_http_req:chunk/2
 -spec chunked_reply(http_status(), http_headers(), #http_req{})
 	-> {ok, #http_req{}}.
-chunked_reply(Status, Headers, Req=#http_req{socket=Socket, transport=Transport,
-		connection=Connection, resp_state=waiting, resp_headers=RespHeaders}) ->
+chunked_reply(Status, Headers, Req=#http_req{socket=Socket,
+		transport=Transport, connection=Connection, pid=ReqPid,
+		resp_state=waiting, resp_headers=RespHeaders}) ->
 	RespConn = response_connection(Headers, Connection),
 	Head = response_head(Status, Headers, RespHeaders, [
 		{<<"Connection">>, atom_to_connection(Connection)},
@@ -510,6 +512,7 @@ chunked_reply(Status, Headers, Req=#http_req{socket=Socket, transport=Transport,
 		{<<"Server">>, <<"Cowboy">>}
 	]),
 	Transport:send(Socket, Head),
+	ReqPid ! {?MODULE, resp_sent},
 	{ok, Req#http_req{connection=RespConn, resp_state=chunks,
 		resp_headers=[], resp_body= <<>>}}.
 
@@ -524,14 +527,16 @@ chunk(Data, #http_req{socket=Socket, transport=Transport, resp_state=chunks}) ->
 		<<"\r\n">>, Data, <<"\r\n">>]).
 
 %% @doc Send an upgrade reply.
+%% @private
 -spec upgrade_reply(http_status(), http_headers(), #http_req{})
 	-> {ok, #http_req{}}.
 upgrade_reply(Status, Headers, Req=#http_req{socket=Socket, transport=Transport,
-		resp_state=waiting, resp_headers=RespHeaders}) ->
+		pid=ReqPid, resp_state=waiting, resp_headers=RespHeaders}) ->
 	Head = response_head(Status, Headers, RespHeaders, [
 		{<<"Connection">>, <<"Upgrade">>}
 	]),
 	Transport:send(Socket, Head),
+	ReqPid ! {?MODULE, resp_sent},
 	{ok, Req#http_req{resp_state=done, resp_headers=[], resp_body= <<>>}}.
 
 %% Misc API.