--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/ch/ethz/ssh2/transport/TransportConnection.java	Thu Dec 03 11:23:55 2015 -0800
@@ -0,0 +1,319 @@
+/*
+ * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
+ * Please refer to the LICENSE.txt for licensing details.
+ */
+package ch.ethz.ssh2.transport;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.security.SecureRandom;
+
+import ch.ethz.ssh2.PacketFormatException;
+import ch.ethz.ssh2.compression.Compressor;
+import ch.ethz.ssh2.crypto.cipher.BlockCipher;
+import ch.ethz.ssh2.crypto.cipher.CipherInputStream;
+import ch.ethz.ssh2.crypto.cipher.CipherOutputStream;
+import ch.ethz.ssh2.crypto.cipher.NullCipher;
+import ch.ethz.ssh2.crypto.digest.MAC;
+import ch.ethz.ssh2.log.Logger;
+import ch.ethz.ssh2.packets.Packets;
+
+/**
+ * TransportConnection.
+ *
+ * @author Christian Plattner
+ * @version $Id: TransportConnection.java 144 2014-04-25 12:48:25Z dkocher@sudo.ch $
+ */
+public class TransportConnection {
+    private static final Logger log = Logger.getLogger(TransportConnection.class);
+
+    int send_seq_number = 0;
+
+    int recv_seq_number = 0;
+
+    CipherInputStream cis;
+
+    CipherOutputStream cos;
+
+    boolean useRandomPadding;
+
+    /* Depends on current MAC and CIPHER */
+
+    MAC send_mac;
+
+    byte[] send_mac_buffer;
+
+    int send_padd_blocksize = 8;
+
+    MAC recv_mac;
+
+    byte[] recv_mac_buffer;
+
+    byte[] recv_mac_buffer_cmp;
+
+    int recv_padd_blocksize = 8;
+
+    Compressor recv_comp;
+
+    Compressor send_comp;
+
+    boolean can_compress;
+
+    byte[] recv_comp_buffer;
+
+    byte[] send_comp_buffer;
+
+    /* won't change */
+
+    final byte[] send_padding_buffer = new byte[256];
+
+    final byte[] send_packet_header_buffer = new byte[5];
+
+    final byte[] recv_padding_buffer = new byte[256];
+
+    final byte[] recv_packet_header_buffer = new byte[5];
+
+    boolean recv_packet_header_present = false;
+
+    ClientServerHello csh;
+
+    final SecureRandom rnd;
+
+    public TransportConnection(InputStream is, OutputStream os, SecureRandom rnd) {
+        this.cis = new CipherInputStream(new NullCipher(), is);
+        this.cos = new CipherOutputStream(new NullCipher(), os);
+        this.rnd = rnd;
+    }
+
+    public void changeRecvCipher(BlockCipher bc, MAC mac) {
+        cis.changeCipher(bc);
+        recv_mac = mac;
+        recv_mac_buffer = (mac != null) ? new byte[mac.size()] : null;
+        recv_mac_buffer_cmp = (mac != null) ? new byte[mac.size()] : null;
+        recv_padd_blocksize = bc.getBlockSize();
+
+        if (recv_padd_blocksize < 8) {
+            recv_padd_blocksize = 8;
+        }
+    }
+
+    public void changeSendCipher(BlockCipher bc, MAC mac) {
+        if ((bc instanceof NullCipher) == false) {
+            /* Only use zero byte padding for the first few packets */
+            useRandomPadding = true;
+            /* Once we start encrypting, there is no way back */
+        }
+
+        cos.changeCipher(bc);
+        send_mac = mac;
+        send_mac_buffer = (mac != null) ? new byte[mac.size()] : null;
+        send_padd_blocksize = bc.getBlockSize();
+
+        if (send_padd_blocksize < 8) {
+            send_padd_blocksize = 8;
+        }
+    }
+
+    public void changeRecvCompression(Compressor comp) {
+        recv_comp = comp;
+
+        if (comp != null) {
+            recv_comp_buffer = new byte[comp.getBufferSize()];
+        }
+    }
+
+    public void changeSendCompression(Compressor comp) {
+        send_comp = comp;
+
+        if (comp != null) {
+            send_comp_buffer = new byte[comp.getBufferSize()];
+        }
+    }
+
+    public void sendMessage(byte[] message) throws IOException {
+        sendMessage(message, 0, message.length, 0);
+    }
+
+    public void sendMessage(byte[] message, int off, int len) throws IOException {
+        sendMessage(message, off, len, 0);
+    }
+
+    public int getPacketOverheadEstimate() {
+        // return an estimate for the paket overhead (for send operations)
+        return 5 + 4 + (send_padd_blocksize - 1) + send_mac_buffer.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;
+        }
+
+        if (send_comp != null && can_compress) {
+            len = send_comp.compress(message, off, len, send_comp_buffer);
+            message = send_comp_buffer;
+        }
+
+        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.isDebugEnabled()) {
+            log.debug("Sent " + Packets.getMessageName(message[off] & 0xff) + " " + len + " bytes payload");
+        }
+
+        send_seq_number++;
+    }
+
+    public int peekNextMessageLength() throws IOException {
+        if (recv_packet_header_present == false) {
+            cis.read(recv_packet_header_buffer, 0, 5);
+            recv_packet_header_present = true;
+        }
+
+        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 > TransportManager.MAX_PACKET_SIZE || packet_length < 12) {
+            throw new PacketFormatException(String.format("Illegal packet size (%d)", packet_length));
+        }
+
+        int payload_length = packet_length - padding_length - 1;
+
+        if (payload_length < 0) {
+            throw new PacketFormatException(String.format("Illegal padding_length in packet from remote (%d)", padding_length));
+        }
+
+        return payload_length;
+    }
+
+    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 > TransportManager.MAX_PACKET_SIZE || packet_length < 12) {
+            throw new PacketFormatException(String.format("Illegal packet size (%d)", packet_length));
+        }
+
+        int payload_length = packet_length - padding_length - 1;
+
+        if (payload_length < 0) {
+            throw new PacketFormatException(String.format("Illegal padding_length in packet from remote (%d)", 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.isDebugEnabled()) {
+            log.debug("Received " + Packets.getMessageName(buffer[off] & 0xff) + " " + payload_length
+                      + " bytes payload");
+        }
+
+        if (recv_comp != null && can_compress) {
+            int[] uncomp_len = new int[] {payload_length};
+            buffer = recv_comp.uncompress(buffer, off, uncomp_len);
+            return uncomp_len[0];
+        }
+        else {
+            return payload_length;
+        }
+    }
+
+    public void startCompression() {
+        can_compress = true;
+    }
+}