import java.util.*;import java.net.*;import java.io.*;public class Peer {  public final static long BCAST_PEER = -1;  public final static long BCAST_INIT = 0;  public final static long BCAST_MIN = 1;  static Vector Peers = new Vector();  static Hashtable PeerTab = new Hashtable();  static String my_addr;  public static void main( String [] args ) {    int port = 0;    int join_port = 0;    int len;    Socket s;    ServerSocket ss;    InetAddress addr;    String st, src, cmd, msg, join;    Scanner sc;    try {      if( args.length < 3 ) {        sc = new Scanner( System.in );        System.out.print( "Enter port to listen on: " );        if( sc.hasNextInt() ) {	  port = sc.nextInt();          sc.nextLine();        }        System.out.print( "Enter peer's address to join to: " );        join = sc.nextLine();        if( join.length() > 1 ) {          System.out.print( "Enter peer's port to join to: " );          if( sc.hasNextInt() ) {            join_port = sc.nextInt();            sc.nextLine();          }        }      } else {        port = Integer.parseInt( args[0] );        join = args[1];        if( join.length() > 1 ) {          join_port = Integer.parseInt( args[2] );        }      }      if( ( port < 1024 ) || ( port > 32767 ) ) {        System.out.println( "Bad port specified" );        return;      }      ss = new ServerSocket( port );      addr = InetAddress.getLocalHost();      my_addr = addr.getHostAddress() + ":" + port;      System.out.println( "I am at: " + my_addr );      if( join.length() > 1 ) {         if( ( join_port < 1024 ) || ( join_port > 32767 ) ) {           System.out.println( "Bad join port specified" );           return;         }         // Join the network         System.out.println( "Joining" );         join( join, join_port );      }      // Enter listen loop      System.out.println( "Listening" );      while( true ) {        try {          s = ss.accept();          sc = new Scanner( read( s ) );          cmd = sc.next();          src = sc.next();          if( cmd.equals( "JOIN" ) ) {            welcome( s, src );          } else if( cmd.equals( "BCAST" ) ) {            bcast( sc.nextLong(), sc.nextLine(), src );          }          s.close();        } catch ( Exception e ) {           System.out.println( "Continuing after exception: " + e );        }      }    } catch ( Exception e ) {      System.out.println( e );    }  }  static void join( String host, int port ) {    String st;    Socket s;    Scanner sc;    try {      s = new Socket( host, port );      write( s, "JOIN " + my_addr );      st = read( s );      if( st != null ) {        sc = new Scanner( st );        while( sc.hasNext() ) {          addPeer( sc.next() );        }      }      s.close();    } catch ( Exception e ) {      System.out.println( e );      System.exit( 0 );    }  }  static void welcome( Socket s, String src ) {    int i;    int size = Peers.size();    String peer;    String resp = my_addr;    for( i = 0; i < size; i++ ) {      peer = (String) Peers.elementAt( i );      if( !peer.equals( src ) ) {        resp = resp + " " + peer;      }    }    write( s, resp );    bcast( BCAST_PEER, src, src );  }  static boolean addPeer( String peer ) {    if( PeerTab.get( peer ) == null ) {      Peers.add( peer );      PeerTab.put( peer, new SockAddr( peer ) );      return true;    }    return false;  }  public static boolean write( Socket s, String st ) {    OutputStream out;    try {      out = s.getOutputStream();      out.write( st.getBytes( "US-ASCII" ) );      out.write( 0 );      out.flush();      return true;    } catch ( Exception e ) {      System.out.println( e );      return false;    }  }  public static String read( Socket s ) {    InputStream in;    byte [] b = new byte[65536];    int len;    try {      in = s.getInputStream();      for( len = 0; in.read( b, len, 1 ) == 1; len++ ) {        if( b[len] == 0 ) {          return new String( b, 0, len, "US-ASCII" );        }      }    } catch ( Exception e ) {      System.out.println( e );    }    return null;  }  static void bcast( long time, String msg, String src ) {    Thread t;    String peer, payload;    int i, size;    SockAddr sa;    if( msg.charAt( 0 ) == ' ' ) {      msg = msg.substring( 1 );    }    if( time == BCAST_PEER ) {       if( !addPeer( msg ) ) {        return;      }    } else {      time = MsgTab.add( time, msg );      if( time < BCAST_MIN ) {        return;      }      System.out.println( "[" + my_addr + "] " + msg );    }     payload = "BCAST " + my_addr + " " + time + " " + msg;    size = Peers.size();    for( i = 0; i < size; i++ ) {      peer = (String) Peers.elementAt( i );      if( !peer.equals( src ) ) {        sa = (SockAddr) PeerTab.get( peer );        if( ( sa != null ) && sa.active ) {          t = new Thread( new Sender( sa, payload ) );          t.start();        }      }    }  }  private static class MsgTab {    final static long EXPIRY = 60000; // 1 minute expiry    static MsgTab head;    static MsgTab tail;    static Hashtable map = new Hashtable();    MsgTab next;    String payload;    long time;    public static long add( long time, String msg ) {      Date d;      MsgTab m;      long expiry;      String payload = time + " " + msg;      if( ( time != BCAST_INIT ) && map.get( payload ) != null ) {        return 0;      }      d = new Date();      m = new MsgTab();      m.time = d.getTime();      if( time == BCAST_INIT ) {        time = m.time;        m.payload = time + " " + msg;      } else {        m.payload = payload;      }        if( head == null ) {        head = m;      } else {        tail.next = m;      }      tail = m;      map.put( m.payload, m );        expiry = m.time - EXPIRY;      while( ( head != null ) && ( head.time < expiry ) ) {        map.remove( head.payload );        head = head.next;      }          return time;    }  }  static class SockAddr {    String addr = null;    int port = 0;    boolean active = false;    SockAddr( String peer ) {      String [] parts;      try {        parts = peer.split( ":" );        addr = parts[0];        port = Integer.parseInt( parts[1] );        active = true;      } catch ( Exception e ) {        System.out.println( e );        active = false;      }    }   }  static class Sender implements Runnable {    SockAddr sockaddr;    String payload;       Sender( SockAddr sa, String p ) {      sockaddr = sa;      payload = p;    }    public void run() {      Socket s;      try {        s = new Socket( sockaddr.addr, sockaddr.port );        write( s, payload );        s.close();      } catch ( Exception e ) {        sockaddr.active = false;      }    }  }}