public int receiveMessage(byte buffer[], int off, int len) throws IOException {
if (recv_packet_header_present == false) {
cis.read(recv_packet_header_buffer, 0, 5);
} else recv_packet_header_present = false;
int packet_length =
((recv_packet_header_buffer[0] & 0xff) << 24)
| ((recv_packet_header_buffer[1] & 0xff) << 16)
| ((recv_packet_header_buffer[2] & 0xff) << 8)
| ((recv_packet_header_buffer[3] & 0xff));
int padding_length = recv_packet_header_buffer[4] & 0xff;
if (packet_length > 35000 || packet_length < 12)
throw new IOException("Illegal packet size! (" + packet_length + ")");
int payload_length = packet_length - padding_length - 1;
if (payload_length < 0)
throw new IOException(
"Illegal padding_length in packet from remote (" + padding_length + ")");
if (payload_length >= len)
throw new IOException("Receive buffer too small (" + len + ", need " + payload_length + ")");
cis.read(buffer, off, payload_length);
cis.read(recv_padding_buffer, 0, padding_length);
if (recv_mac != null) {
cis.readPlain(recv_mac_buffer, 0, recv_mac_buffer.length);
recv_mac.initMac(recv_seq_number);
recv_mac.update(recv_packet_header_buffer, 0, 5);
recv_mac.update(buffer, off, payload_length);
recv_mac.update(recv_padding_buffer, 0, padding_length);
recv_mac.getMac(recv_mac_buffer_cmp, 0);
for (int i = 0; i < recv_mac_buffer.length; i++) {
if (recv_mac_buffer[i] != recv_mac_buffer_cmp[i])
throw new IOException("Remote sent corrupt MAC.");
}
}
recv_seq_number++;
if (log.isEnabled()) {
log.log(
90,
"Received "
+ Packets.getMessageName(buffer[off] & 0xff)
+ " "
+ payload_length
+ " bytes payload");
}
return payload_length;
}
public void sendMessage(byte[] message, int off, int len, int padd) throws IOException {
if (padd < 4) padd = 4;
else if (padd > 64) padd = 64;
int packet_len = 5 + len + padd; /* Minimum allowed padding is 4 */
int slack = packet_len % send_padd_blocksize;
if (slack != 0) {
packet_len += (send_padd_blocksize - slack);
}
if (packet_len < 16) packet_len = 16;
int padd_len = packet_len - (5 + len);
if (useRandomPadding) {
for (int i = 0; i < padd_len; i = i + 4) {
/*
* don't waste calls to rnd.nextInt() (by using only 8bit of the
* output). just believe me: even though we may write here up to 3
* bytes which won't be used, there is no "buffer overflow" (i.e.,
* arrayindexoutofbounds). the padding buffer is big enough =) (256
* bytes, and that is bigger than any current cipher block size + 64).
*/
int r = rnd.nextInt();
send_padding_buffer[i] = (byte) r;
send_padding_buffer[i + 1] = (byte) (r >> 8);
send_padding_buffer[i + 2] = (byte) (r >> 16);
send_padding_buffer[i + 3] = (byte) (r >> 24);
}
} else {
/* use zero padding for unencrypted traffic */
for (int i = 0; i < padd_len; i++) send_padding_buffer[i] = 0;
/* Actually this code is paranoid: we never filled any
* bytes into the padding buffer so far, therefore it should
* consist of zeros only.
*/
}
send_packet_header_buffer[0] = (byte) ((packet_len - 4) >> 24);
send_packet_header_buffer[1] = (byte) ((packet_len - 4) >> 16);
send_packet_header_buffer[2] = (byte) ((packet_len - 4) >> 8);
send_packet_header_buffer[3] = (byte) ((packet_len - 4));
send_packet_header_buffer[4] = (byte) padd_len;
cos.write(send_packet_header_buffer, 0, 5);
cos.write(message, off, len);
cos.write(send_padding_buffer, 0, padd_len);
if (send_mac != null) {
send_mac.initMac(send_seq_number);
send_mac.update(send_packet_header_buffer, 0, 5);
send_mac.update(message, off, len);
send_mac.update(send_padding_buffer, 0, padd_len);
send_mac.getMac(send_mac_buffer, 0);
cos.writePlain(send_mac_buffer, 0, send_mac_buffer.length);
}
cos.flush();
if (log.isEnabled()) {
log.log(
90, "Sent " + Packets.getMessageName(message[off] & 0xff) + " " + len + " bytes payload");
}
send_seq_number++;
}