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package com.seaofnodes.simple;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URI;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
// Why-Oh-Why is this needed?
// Pass in a URI and a port.
// Opens the client; client has to open a websocket at the given port.
// Connects, handshakes.
// Thereafter you can call get/put to swap frames with client.
class SimpleWebSocket extends ServerSocket {
final InputStream _in;
final OutputStream _out;
SimpleWebSocket(URI uri, int port) throws IOException, NoSuchAlgorithmException {
super(port);
// Launch client
java.awt.Desktop.getDesktop().browse(uri);
// Look for client; get in/out streams
Socket sock = accept();
_in = sock. getInputStream();
_out = sock.getOutputStream();
// Establish web socket with handshake; easier with a buffered reader
BufferedReader br = new BufferedReader(new InputStreamReader(_in));
String key = null;
while( br.ready() ) {
String line = br.readLine();
if( line.startsWith("Sec-WebSocket-Key: ") )
key = line.substring(19);
}
assert key!=null;
// Magic handshake
byte[] response = ("HTTP/1.1 101 Switching Protocols\r\n"
+ "Connection: Upgrade\r\n"
+ "Upgrade: websocket\r\n"
+ "Sec-WebSocket-Accept: "
+ Base64.getEncoder().encodeToString(MessageDigest.getInstance("SHA-1").digest((key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes( StandardCharsets.UTF_8 )))
+ "\r\n\r\n").getBytes( StandardCharsets.UTF_8 );
_out.write(response,0,response.length);
}
final byte[] _ins = new byte[1024];
final byte[] _str = new byte[1024];
final byte[] _key = new byte[4];
int _x, _len;
private int rawget() { assert _x<_len; return _ins[_x++]&0xFF; }
// TODO: Flip to Direct Byte Buffer, this is just a poor-mans version
private void flipRead() throws IOException {
// Move _x to _len to offset 0
System.arraycopy(_ins,_x,_ins,0,(_len-_x));
_len = _len-_x;
_x=0;
// Read more
int len = _in.read(_ins,_len,_ins.length-_len);
if( len == -1 )
throw Utils.TODO(); // EOF
_len += len;
}
// Block until you read at least len
private void atLeast(int len) throws IOException {
if( _x+len <= _len ) return;
flipRead();
}
// Classic read from browser client. Encoded, so decoded here
public String get() throws IOException {
atLeast(1); // Need 1 byte for opcode
int op = rawget();
if( (op&0x80)!=0x80 ) // FIN bit not set?
throw Utils.TODO( "Multi-part from client: " + op ); // Multipart message
op &= 0x7F; // Strip FIN bit
switch( op&15) {
case 1: {
atLeast(5); // Min message length
// Message length
int len = rawget()-128;
if( len > 125 ) {
if( len > 126 )
throw Utils.TODO(); // Multi-byte length
len = (rawget()<<8) | rawget();
}
atLeast(len+4); // Rest of message
// Encoding key
_key[0] = (byte)rawget();
_key[1] = (byte)rawget();
_key[2] = (byte)rawget();
_key[3] = (byte)rawget();
// Decode bytes
for( int i=0; i<len; i++ )
_str[i] = (byte)(rawget() ^ _key[i & 3]);
return new String(_str,0,len);
}
// Client closes
case 8: return null;
// Ping
case 9:
// Send a PONG back. TODO: echo PING data in the PONG
_out.write(0x8A); // FIN + PONG
_out.write(0x00); // LENGTH==0
return get();
// Not (yet) implemented: continuation frames, ping/pong
default:
throw Utils.TODO("Unexpected op from client: "+op); // Multi-part message
}
}
// Classic put to browser client. No encoding.
public void put(String msg) throws IOException {
int len = msg.length();
if( len <= 125 ) {
_out.write(129); // FIN, opcode 1 - whole text message
_out.write(len);
for( int i=0; i<msg.length(); i++ )
_out.write(msg.charAt(i));
return;
}
if( len > 65535 )
throw Utils.TODO("MOAR LENGTH");
_out.write(129); // FIN, opcode 1 - whole text message
_out.write(126); // Length is 16b
_out.write(len>>>8);
_out.write(len&255);
for( int i=0; i<msg.length(); i++ )
_out.write(msg.charAt(i));
}
@Override public void close() throws IOException {
if( _out != null ) {
_out.write(0b10001000);
_out.flush();
}
super.close();
}
}
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