node.js SCGI server using node-binary

scgi.js

/* requires substack/node-binary and dependencies (npm install binary) */
/* also don't forget node.js */

var net = require('net');
var Binary = require('binary');

exports.attach = function attach(server) {
    if ('number' == typeof server) {
        var port = server;
        server = net.createServer();
        server.listen(port);
    }
    server.on('connection', function connectionHandler(socket) {
        var headers = {};
        Binary.stream(socket)
            .scan('len', ':')
            .tap(function(vars) {
                if (isNaN(vars.len*1)) {socket.end(); return; }
                var len = vars.len*1;
                if (len == 0) { socket.end(); return;}
                this.loop(function(end, vars) {
                    this.scan('key', new Buffer([0]))
                        .scan('value', new Buffer([0]))
                        .tap(function (vars) {
                            headers[vars.key.toString()] = vars.value;
                            len -= vars.key.length + vars.value.length + 2;
                            if (len == 0) end();
                        })
                });
            })
            .skip(1) // and the data?
            .buffer('data', function(vars) {
                var l = 0;
                if (headers['CONTENT_LENGTH']) l = headers['CONTENT_LENGTH'].toString('ascii')*1;
                if (isNaN(l)) return 0;
                return l;
            })
            .tap(function(vars) {
                server.emit('request', socket, headers, vars.data);
            });
    });
    return server;
}