Fix #1684 WebSocket proxy behind a buffered proxy.

The given patch fixes incoming WebSocket traffic behind buffered Proxies
like NGINX.

NGINX buffers multiple requests from the Browser into one frame and sends that to pveproxy,
before this patch we then processed the first message of the frame and cleared the buffer which
may contained more messages.
With this patch we process each message and clear the buffer right.

This fixes the "NoVNC blank screen" problem users reported on the forums.

diff --git a/PVE/APIServer/AnyEvent.pm b/PVE/APIServer/AnyEvent.pm
index 382eab4b7c64d0119c1ed5ea43368782a8dbded1..eac788bc25dc36ae6d3e11fb36418a0e14efd80a 100755 (executable)
--- a/PVE/APIServer/AnyEvent.pm
+++ b/PVE/APIServer/AnyEvent.pm
@@ -429,70 +429,71 @@ sub websocket_proxy {
            my $hdlreader = sub {
                my ($hdl) = @_;
 
-               my $len = length($hdl->{rbuf});
-               return if $len < 2;
+               while (my $len = length($hdl->{rbuf})) {
+                   return if $len < 2;
 
-               my $hdr = unpack('C', substr($hdl->{rbuf}, 0, 1));
-               my $opcode = $hdr & 0b00001111;
-               my $fin = $hdr & 0b10000000;
+                   my $hdr = unpack('C', substr($hdl->{rbuf}, 0, 1));
+                   my $opcode = $hdr & 0b00001111;
+                   my $fin = $hdr & 0b10000000;
 
-               die "received fragmented websocket frame\n" if !$fin;
+                   die "received fragmented websocket frame\n" if !$fin;
 
-               my $rsv = $hdr & 0b01110000;
-               die "received websocket frame with RSV flags\n" if $rsv;
+                   my $rsv = $hdr & 0b01110000;
+                   die "received websocket frame with RSV flags\n" if $rsv;
 
-               my $payload_len = unpack 'C', substr($hdl->{rbuf}, 1, 1);
+                   my $payload_len = unpack 'C', substr($hdl->{rbuf}, 1, 1);
 
-               my $masked = $payload_len & 0b10000000;
-               die "received unmasked websocket frame from client\n" if !$masked;
+                   my $masked = $payload_len & 0b10000000;
+                   die "received unmasked websocket frame from client\n" if !$masked;
 
-               my $offset = 2;
-               $payload_len = $payload_len & 0b01111111;
-               if ($payload_len == 126) {
-                   return if $len < 4;
-                   $payload_len = unpack('n', substr($hdl->{rbuf}, $offset, 2));
-                   $offset += 2;
-               } elsif ($payload_len == 127) {
-                   return if $len < 10;
-                   $payload_len = unpack('Q>', substr($hdl->{rbuf}, $offset, 8));
-                   $offset += 8;
-               }
+                   my $offset = 2;
+                   $payload_len = $payload_len & 0b01111111;
+                   if ($payload_len == 126) {
+                       return if $len < 4;
+                       $payload_len = unpack('n', substr($hdl->{rbuf}, $offset, 2));
+                       $offset += 2;
+                   } elsif ($payload_len == 127) {
+                       return if $len < 10;
+                       $payload_len = unpack('Q>', substr($hdl->{rbuf}, $offset, 8));
+                       $offset += 8;
+                   }
 
-               die "received too large websocket frame (len = $payload_len)\n"
-                   if ($payload_len > $max_payload_size) || ($payload_len < 0);
+                   die "received too large websocket frame (len = $payload_len)\n"
+                       if ($payload_len > $max_payload_size) || ($payload_len < 0);
 
-               return if $len < ($offset + 4 + $payload_len);
+                   return if $len < ($offset + 4 + $payload_len);
 
-               my $data = substr($hdl->{rbuf}, 0, $len, ''); # now consume data
+                   my $data = substr($hdl->{rbuf}, 0, $offset + 4 + $payload_len, ''); # now consume data
 
-               my @mask = (unpack('C', substr($data, $offset+0, 1)),
-                           unpack('C', substr($data, $offset+1, 1)),
-                           unpack('C', substr($data, $offset+2, 1)),
-                           unpack('C', substr($data, $offset+3, 1)));
+                   my @mask = (unpack('C', substr($data, $offset+0, 1)),
+                       unpack('C', substr($data, $offset+1, 1)),
+                       unpack('C', substr($data, $offset+2, 1)),
+                       unpack('C', substr($data, $offset+3, 1)));
 
-               $offset += 4;
+                   $offset += 4;
 
-               my $payload = substr($data, $offset, $payload_len);
+                   my $payload = substr($data, $offset, $payload_len);
 
-               for (my $i = 0; $i < $payload_len; $i++) {
-                   my $d = unpack('C', substr($payload, $i, 1));
-                   my $n = $d ^ $mask[$i % 4];
-                   substr($payload, $i, 1, pack('C', $n));
-               }
+                   for (my $i = 0; $i < $payload_len; $i++) {
+                       my $d = unpack('C', substr($payload, $i, 1));
+                       my $n = $d ^ $mask[$i % 4];
+                       substr($payload, $i, 1, pack('C', $n));
+                   }
 
-               $payload = decode_base64($payload) if !$binary;
+                   $payload = decode_base64($payload) if !$binary;
 
-               if ($opcode == 1 || $opcode == 2) {
-                   $reqstate->{proxyhdl}->push_write($payload) if $reqstate->{proxyhdl};
-               } elsif ($opcode == 8) {
-                   my $statuscode = unpack ("n", $payload);
-                   print "websocket received close. status code: '$statuscode'\n" if $self->{debug};
+                   if ($opcode == 1 || $opcode == 2) {
+                       $reqstate->{proxyhdl}->push_write($payload) if $reqstate->{proxyhdl};
+                   } elsif ($opcode == 8) {
+                       my $statuscode = unpack ("n", $payload);
+                       print "websocket received close. status code: '$statuscode'\n" if $self->{debug};
                    if ($reqstate->{proxyhdl}) {
-                       $reqstate->{proxyhdl}->push_shutdown();
+                               $reqstate->{proxyhdl}->push_shutdown();
+                   }
+                       $hdl->push_shutdown();
+                   } else {
+                       die "received unhandled websocket opcode $opcode\n";
                    }
-                   $hdl->push_shutdown();
-               } else {
-                   die "received unhandled websocket opcode $opcode\n";
                }
            };