Exemplo n.º 1
0
  /** the famous ping. */
  private void doICMP(Packet p) {

    int type_code = p.buf[5] >>> 16;
    if (Logging.LOG) Logging.wr('P');
    if (Logging.LOG) Logging.hexVal(type_code);
    if (type_code == 0x0800) {
      // TODO check received ICMP checksum
      p.buf[5] = 0; // echo replay plus clear checksum,
      p.buf[5] = Ip.chkSum(p.buf, 5, p.len - 20); // echo replay (0x0000)
      // plus checksum
    } else {
      p.len = 0;
    }
  }
Exemplo n.º 2
0
  /**
   * Set data from String into the packet
   *
   * @param p packet
   * @param off offset in 32-bit words
   * @param s String source
   */
  public static void setData(Packet p, int off, String s) {

    int[] buf = p.buf;
    int cnt = s.length();
    // copy buffer
    int k = 0;
    for (int i = 0; i < cnt; i += 4) {
      for (int j = 0; j < 4; ++j) {
        k <<= 8;
        if (i + j < cnt) k += s.charAt(i + j);
      }
      buf[off + (i >>> 2)] = k;
    }

    p.len = (off << 2) + cnt;
  }
Exemplo n.º 3
0
  /**
   * Process one IP packet. Change buffer and set length to get a packet sent back. called from
   * Net.loop().
   */
  public void receive(Packet p) {

    int i;
    int[] buf = p.buf;
    int len;

    i = buf[0];
    len = i & 0xffff; // length from IP header
    // NO options are assumed in ICMP/TCP/IP...
    // => copy if options present
    // but we just drop it now - too lazy
    if (len > p.len || (i >>> 24 != 0x45)) {
      if (Logging.LOG) Logging.wr("IP options -> discard");
      ejip.returnPacket(p); // packet to short or ip options => drop it
      return;
    } else {
      p.len = len; // correct for to long packets
    }

    // TODO fragmentation
    if (Ip.chkSum(buf, 0, 20) != 0) {
      ejip.returnPacket(p);
      if (Logging.LOG) Logging.wr("wrong IP checksum ");
      return;
    }

    int prot = (buf[2] >> 16) & 0xff; // protocol
    if (prot == PROT_ICMP) {
      doICMP(p);
      ip.doIp(p, prot);
    } else if (prot == Tcp.PROTOCOL) {
      if (Ejip.TCP_ENABLED) {
        // that's the new TCP processing
        tcp.process(p);
      } else {
        ejip.returnPacket(p); // mark packet free				
      }
    } else if (prot == Udp.PROTOCOL) {
      udp.process(p); // Udp generates the reply
    } else {
      ejip.returnPacket(p); // mark packet free
    }
  }