Method read

java/com/jcraft/jsch/Session.java:914–1052

(Buffer buf)

  private int s2ccipher_size=8;
  private int c2scipher_size=8;
  public Buffer read(Buffer buf) throws Exception{
    int j=0;
    while(true){
      buf.reset();
      io.getByte(buf.buffer, buf.index, s2ccipher_size); 
      buf.index+=s2ccipher_size;
      if(s2ccipher!=null){
        s2ccipher.update(buf.buffer, 0, s2ccipher_size, buf.buffer, 0);
      }
      j=((buf.buffer[0]<<24)&0xff000000)|
        ((buf.buffer[1]<<16)&0x00ff0000)|
        ((buf.buffer[2]<< 8)&0x0000ff00)|
        ((buf.buffer[3]    )&0x000000ff);
      // RFC 4253 6.1. Maximum Packet Length
      if(j<5 || j>PACKET_MAX_SIZE){
        start_discard(buf, s2ccipher, s2cmac, j, PACKET_MAX_SIZE);
      }
      int need = j+4-s2ccipher_size;
      //if(need<0){
      //  throw new IOException("invalid data");
      //}
      if((buf.index+need)>buf.buffer.length){
        byte[] foo=new byte[buf.index+need];
        System.arraycopy(buf.buffer, 0, foo, 0, buf.index);
        buf.buffer=foo;
      }

      if((need%s2ccipher_size)!=0){
        String message="Bad packet length "+need;
        if(JSch.getLogger().isEnabled(Logger.FATAL)){
          JSch.getLogger().log(Logger.FATAL, message); 
        }
        start_discard(buf, s2ccipher, s2cmac, j, PACKET_MAX_SIZE-s2ccipher_size);
      }

      if(need>0){
	io.getByte(buf.buffer, buf.index, need); buf.index+=(need);
	if(s2ccipher!=null){
	  s2ccipher.update(buf.buffer, s2ccipher_size, need, buf.buffer, s2ccipher_size);
	}
      }

      if(s2cmac!=null){
	s2cmac.update(seqi);
	s2cmac.update(buf.buffer, 0, buf.index);

        s2cmac.doFinal(s2cmac_result1, 0);
	io.getByte(s2cmac_result2, 0, s2cmac_result2.length);
        if(!java.util.Arrays.equals(s2cmac_result1, s2cmac_result2)){
          if(need > PACKET_MAX_SIZE){
            throw new IOException("MAC Error");
          }
          start_discard(buf, s2ccipher, s2cmac, j, PACKET_MAX_SIZE-need);
          continue;
	}
      }

      seqi++;