node.js SPDY proxy

gistfile1.js

var tls = require('tls');
var fs = require('fs');
var Buffer = require('buffer').Buffer;
var zlib = require('zlib');
var BufferList = require('bufferlist');
var Binary = require('bufferlist/binary');
var Put = require('put');
var http = require('http');

var options = 
{
  key: fs.readFileSync('test-key.pem'),
  cert: fs.readFileSync('test-cert.pem'),
};

var SPDY_VERSION        = 2;

var DATA_FRAME_ID       = 0;
var CONTROL_FRAME_ID    = 1;

var CF_SYN_STREAM       = 1;
var CF_SYN_REPLY        = 2;
var CF_RST_STREAM       = 3;
var CF_SETTINGS         = 4;
var CF_NOOP             = 5;
var CF_PING             = 6;
var CF_GOAWAY           = 7;
var CF_HEADERS          = 8;
var CF_WINDOW_UPDATE    = 9;

var FLAG_NONE           = 0x00;
var FLAG_FIN            = 0x01;
var FLAG_UNIDIRECTIONAL = 0x02;

var DICT = "optionsgetheadpostputdeletetraceacceptaccept-charsetaccept-encodingaccept-languageauthorizationexpectfromhostif-modified-sinceif-matchif-none-matchif-rangeif-unmodifiedsincemax-forwardsproxy-authorizationrangerefererteuser-agent100101200201202203204205206300301302303304305306307400401402403404405406407408409410411412413414415416417500501502503504505accept-rangesageetaglocationproxy-authenticatepublicretry-afterservervarywarningwww-authenticateallowcontent-basecontent-encodingcache-controlconnectiondatetrailertransfer-encodingupgradeviawarningcontent-languagecontent-lengthcontent-locationcontent-md5content-rangecontent-typeetagexpireslast-modifiedset-cookieMondayTuesdayWednesdayThursdayFridaySaturdaySundayJanFebMarAprMayJunJulAugSepOctNovDecchunkedtext/htmlimage/pngimage/jpgimage/gifapplication/xmlapplication/xhtmltext/plainpublicmax-agecharset=iso-8859-1utf-8gzipdeflateHTTP/1.1statusversionurl\0";

function extractHeaders(nv_data, nv_entry_count)
{
  var i, size, name, value, poscount = 2, headers = [];
  for(i=0; i<nv_entry_count; i++)
  {
    size = (nv_data[poscount++] << 8) + nv_data[poscount++];
    name = nv_data.toString('utf-8', poscount, poscount+size);

    poscount += size;

    size = (nv_data[poscount++] << 8) + nv_data[poscount++];
    value = nv_data.toString('utf-8', poscount, poscount+size);

    poscount += size;

    headers[name] = value; // todo need to handle multivalue headers
  }
  return headers;
}

function encodeHeaders(headers)
{
// todo add support for multivalue headers

  var buffer_size = 2, header_count = 0;
  for(key in headers)
  {
    if(typeof headers[key] == 'string')
    {
    buffer_size += 2;
    buffer_size += key.length;
    buffer_size += 2;
    buffer_size += headers[key].length;
    header_count++;
    }
  }

  var header_data = new Buffer(buffer_size);
  var poscount = 0;

// todo need to encode the length correctly
  header_data[poscount++] = 0; 
  header_data[poscount++] = header_count;

  for(key in headers)
  {
    if(typeof headers[key] == 'string')
    {
// todo need to encode the length correctly
    header_data[poscount++] = 0; 
    header_data[poscount++] = key.length; 

    header_data.write(key, poscount, 'binary');
    poscount += key.length;

// todo need to encode the length correctly
    header_data[poscount++] = 0; 
    header_data[poscount++] = headers[key].length; 

    header_data.write(headers[key], poscount, 'binary');
    poscount += headers[key].length;
    }
  }

  return header_data;
}

function spdySendData(sock, data, stream_id, flags)
{
  Put().word8((DATA_FRAME_ID << 7) & 0x80)
       .word24be(stream_id) // todo this should be combined with the control bit
       .word8(flags)
       .word24be(data.length)
       .put(data)
       .write(sock);
}

function spdySendHeaders(sock, headers, stream_id, flags)
{
  var headers_raw = encodeHeaders(headers);

  zlib.deflateSetDictionary(new Buffer(DICT, 'binary'));
  var compressed_headers = zlib.deflate(headers_raw);

  Put().word8((CONTROL_FRAME_ID << 7) & 0x80)
       .word8(SPDY_VERSION)
       .word16be(CF_SYN_REPLY)
       .word8(flags)
       .word24be(6 + compressed_headers.length)
       .word32be(stream_id) // todo this is really 31 bits
       .pad(2)
       .put(compressed_headers)
       .write(sock);
}

function spdyParser(sock) 
{
  var bufferList = new BufferList;
  sock.addListener('data', function (data) 
  {
    bufferList.push(data);
  });
    
// todo this probably needs to repeat until a FIN is seen in frame_flags?

  var spdyParser = Binary(bufferList)
        .getWord8('control')
        .tap(function(vars) 
             {
               vars.control_bit = vars.control >> 7 & 0x01;
             })
        .when('control_bit', CONTROL_FRAME_ID, function(vars) 
              {
                //console.log('Got control frame');

                this.getWord8('version_tmp')
                    .tap(function(vars)
                         {
                           vars.frame_version = (vars.control & 0x7F << 8) + vars.version_tmp;
                         })
                    .getWord16be('frame_type')
                    .getWord8('frame_flags')
                    .getWord24be('frame_length')
                    .when('frame_type', CF_SYN_STREAM, function(vars)
                          {
                            //console.log('Got syn stream: ' + vars.frame_length);
                            this.getWord32be('stream_id') // todo 31 bits
                                .getWord32be('assoc_stream_id') // todo 31 bits 
                                .getWord8('priority_tmp') // todo 2 bits
                                .tap(function(vars)
                                     {
                                       vars.priority = (vars.priority & 0xC0) >> 6;
                                     })
                                .skip(1)
                                .getBuffer('compressed_headers', vars.frame_length - 10)
                                .tap(function(vars)
                                     {
                                       var header_dc = zlib.inflate(vars.compressed_headers, new Buffer(DICT, 'binary'));
                                       var header_count = (header_dc[0] << 8) + header_dc[1];

                                       var headers = extractHeaders(header_dc, header_count);

                                       spdyParser.emit('spdy-headers', headers, vars.stream_id);
                                     })
                                .when('frame_flags', FLAG_FIN, function(vars)
                                 {
                                   console.log('got FLAG_FIN');
                                 })
                                .exit();
                          })
                    .when('frame_type', CF_SYN_REPLY, function(vars) { console.log('CF_SYN_REPLY not implemented yet'); })
                    .when('frame_type', CF_RST_STREAM, function(vars) { console.log('CF_RST_STREAM not implemented yet'); })
                    .when('frame_type', CF_SETTINGS, function(vars) { console.log('CF_SETTINGS not implemented yet'); })
                    .when('frame_type', CF_NOOP, function(vars) { console.log('CF_NOOP not implemented yet'); })
                    .when('frame_type', CF_PING, function(vars) { console.log('CF_PING not implemented yet'); })
                    .when('frame_type', CF_GOAWAY, function(vars) { console.log('CF_GOAWAY not implemented yet'); })
                    .when('frame_type', CF_HEADERS, function(vars) { console.log('CF_HEADERS not implemented yet'); })
                    .when('frame_type', CF_WINDOW_UPDATE, function(vars) { console.log('CF_WINDOW_UPDATE not implemented yet'); })
                    .exit();
              })
        .when('control_bit', DATA_FRAME_ID, function(vars) 
              {
                console.log('Got data frame');
                // todo
                this.exit();
              })
        .end();

  return spdyParser;
}

function proxyRequest(headers, stream_id, sock)
{
  var proxy = http.createClient(80, 'arewefastyet.com');
  var proxy_request = proxy.request(headers['method'], headers['url'], {'host': 'arewefastyet.com'});

  console.log('Making proxy request: ' + headers['method'] + ' and ' + headers['url']);

  proxy_request.addListener('response', function (proxy_response) 
  {
    proxy_response.addListener('data', function(chunk) 
    {
      spdySendData(sock, chunk, stream_id, FLAG_NONE);
    });

    proxy_response.addListener('end', function() 
    {
      spdySendData(sock, '', stream_id, FLAG_FIN);
      sock.end();
    });

    response_headers = proxy_response.headers;
    response_headers['version'] = 'HTTP/' + proxy_response.httpVersion;
    response_headers['status'] = '' + proxy_response.statusCode;

    spdySendHeaders(sock, response_headers, stream_id, FLAG_NONE);
  });

  proxy_request.end();
}

var ccount = 0;
tls.createServer(options, function (s) 
{
  ccount++;
  console.log('got client connection: ' + ccount);

  s.addListener('end', function () { console.log('Stream end: ' + ccount); ccount--; });

  var parser = spdyParser(s);
  parser.addListener('spdy-headers', function(headers, stream_id)
  {
    proxyRequest(headers, stream_id, s);
  });

}).listen(8787);

console.log('127.0.0.1:8787');