Pattern matching error.

[aklaim]

During a call of hackney_socks5:do_handshake, in part:

case gen_tcp:recv(Socket, 2, ?TIMEOUT) of
                {ok, << 5, 0 >>} ->
                    do_connection(Socket, Host, Port);
                Error ->
                    Error
            end;

gen_tcp:recv can return {ok, SomeValue} which is counted as an error and returns up the call stack as a {ok, SomeValue}.

The problem is that hackney:connect/5 in the part:

     case maybe_proxy(Transport, Host, Port, Options) of
        {ok, Ref, AbsolutePath} ->
            Request = make_request(Method, URL, Headers, Body,
                                   Options, AbsolutePath),
            send_request(Ref, Request);
        {ok, Ref} ->
            Request = make_request(Method, URL, Headers, Body, Options, false),
            send_request(Ref, Request);
        Error ->
            Error
    end;

is waiting for {ok, Ref} in case of success. Because of this, the value of which was return by gen_tcp:recv will be considered as valid and its further use will lead to error.

The error occurs in the case of using socks5 proxy which does not work properly, but at the same time available for gen_tcp:send.

I attach an image with debugging this error. It is hard to understand where is the problem because of long call stack.

It can be fixed by adding:

 {ok, _Reply} ->
                  {error, unknown_reply};

in hackney_socks5:do_handshake:

   case gen_tcp:recv(Socket, 2, ?TIMEOUT) of
                {ok, << 5, 0 >>} ->
                    do_connection(Socket, Host, Port);
                {ok, _Reply} ->
                  {error, unknown_reply};   %% FIX
                Error ->
                    Error
            end;