+package Plack::App::Proxy::WebSocket;
+# ABSTRACT: proxy HTTP and WebSocket connections
+
+use warnings FATAL => 'all';
+use strict;
+
+use AnyEvent::Handle;
+use AnyEvent::Socket;
+use HTTP::Request;
+use HTTP::Response;
+use Plack::Request;
+use URI;
+
+use parent 'Plack::App::Proxy';
+
+=head1 SYNOPSIS
+
+ use Plack::App::Proxy::WebSocket;
+ use Plack::Builder;
+
+ builder {
+ mount "/socket.io" => Plack::App::Proxy::WebSocket->new(
+ remote => "http://localhost:9000/socket.io",
+ preserve_host_header => 1,
+ )->to_app;
+ };
+
+=head1 DESCRIPTION
+
+This is a subclass of L<Plack::App::Proxy> that adds support for proxying
+WebSocket connections. It has no extra dependencies or configuration options
+beyond what L<Plack::App::Proxy> requires or provides, so it may be an easy
+drop-in replacement. Read the documentation of that module for advanced usage
+not covered by the L<SYNOPSIS>.
+
+This subclass necessarily requires extra L<PSGI> server features in order to
+work. The server must support C<psgi.streaming> and C<psgix.io>. It is also
+highly recommended to choose a C<psgi.nonblocking> server, though that isn't
+strictly required; performance may suffer greatly without it. L<Twiggy> is an
+excellent choice for this application.
+
+This module is B<EXPERIMENTAL>. I use it in development and it works
+swimmingly for me, but it is completely untested in production scenarios.
+
+=head1 CAVEATS
+
+Some servers (e.g. L<Starman>) ignore the C<Connection> HTTP response header
+and use their own values, but WebSocket clients expect the value of that
+header to be C<Upgrade>. This module cannot work on such servers. Your best
+bet is to use a non-blocking server like L<Twiggy> that doesn't mess with the
+C<Connection> header.
+
+=cut
+
+sub call {
+ my ($self, $env) = @_;
+ my $req = Plack::Request->new($env);
+
+ # detect the websocket handshake or just proxy as usual
+ lc($req->header('Upgrade') || "") eq 'websocket' or return $self->SUPER::call($env);
+
+ $env->{'psgi.streaming'} or die "Plack server support for psgi.streaming is required";
+ my $client_fh = $env->{'psgix.io'} or die "Plack server support for the psgix.io extension is required";
+
+ my $url = $self->build_url_from_env($env) or return [502, [], ["Bad Gateway"]];
+ my $uri = URI->new($url);
+
+ sub {
+ my $res = shift;
+
+ # set up an event loop if the server is blocking
+ my $cv;
+ unless ($env->{'psgi.nonblocking'}) {
+ $env->{'psgi.errors'}->print("Plack server support for psgi.nonblocking is highly recommended.\n");
+ $cv = AE::cv;
+ }
+
+ tcp_connect $uri->host, $uri->port, sub {
+ my $server_fh = shift;
+
+ # return 502 if connection to server fails
+ unless ($server_fh) {
+ $res->([502, [], ["Bad Gateway"]]);
+ $cv->send if $cv;
+ return;
+ }
+
+ my $client = AnyEvent::Handle->new(fh => $client_fh);
+ my $server = AnyEvent::Handle->new(fh => $server_fh);
+
+ # forward request from the client, modifying the host and origin
+ my $headers = $req->headers->clone;
+ my $host = $uri->host_port;
+ $headers->header(Host => $host, Origin => "http://$host");
+ my $hs = HTTP::Request->new('GET', $uri->path, $headers);
+ $hs->protocol($req->protocol);
+ $server->push_write($hs->as_string);
+
+ my $buffer = "";
+ my $writer;
+
+ # buffer the exchange between the client and server
+ $client->on_read(sub {
+ my $hdl = shift;
+ my $buf = delete $hdl->{rbuf};
+ $server->push_write($buf);
+ });
+ $server->on_read(sub {
+ my $hdl = shift;
+ my $buf = delete $hdl->{rbuf};
+
+ if ($writer) {
+ $writer->write($buf);
+ return;
+ }
+
+ if (($buffer .= $buf) =~ s/^(.+\r?\n\r?\n)//s) {
+ my $http = HTTP::Response->parse($1);
+ my @headers;
+ $http->headers->remove_header('Status');
+ $http->headers->scan(sub { push @headers, @_ });
+ $writer = $res->([$http->code, [@headers]]);
+ $writer->write($buffer) if $buffer;
+ $buffer = undef;
+ }
+ });
+
+ # shut down the sockets and exit the loop if an error occurs
+ $client->on_error(sub {
+ $client->destroy;
+ $server->push_shutdown;
+ $cv->send if $cv;
+ $writer->close if $writer;
+ });
+ $server->on_error(sub {
+ $server->destroy;
+ # get the client handle's attention
+ $writer->close;
+ });
+ };
+
+ $cv->recv if $cv;
+ };
+};
+
+1;
projects / chaz / p5-Plack-App-Proxy-WebSocket / commitdiff
