/**
* Handle MCS info from server (server info, encryption info and channel information)
*
* @param mcs_data Data received from server
*/
public void processMcsData(RdpPacket_Localised mcs_data)
throws RdesktopException, CryptoException {
logger.debug("Secure.processMcsData");
int tag = 0, len = 0, length = 0, nexttag = 0;
mcs_data.incrementPosition(21); // header (T.124 stuff, probably)
len = mcs_data.get8();
if ((len & 0x00000080) != 0) {
len = mcs_data.get8();
}
while (mcs_data.getPosition() < mcs_data.getEnd()) {
tag = mcs_data.getLittleEndian16();
length = mcs_data.getLittleEndian16();
if (length <= 4) return;
nexttag = mcs_data.getPosition() + length - 4;
switch (tag) {
case (Secure.SEC_TAG_SRV_INFO):
processSrvInfo(mcs_data);
break;
case (Secure.SEC_TAG_SRV_CRYPT):
this.processCryptInfo(mcs_data);
break;
case (Secure.SEC_TAG_SRV_CHANNELS):
/*
* FIXME: We should parse this information and use it to map
* RDP5 channels to MCS channels
*/
break;
default:
throw new RdesktopException("Not implemented! Tag:" + tag + "not recognized!");
}
mcs_data.setPosition(nexttag);
}
}
/**
* Read encryption information from a Secure layer PDU, obtaining and storing level of encryption
* and any keys received
*
* @param data Packet to read encryption information from
* @return Size of RC4 key
* @throws RdesktopException
*/
public int parseCryptInfo(RdpPacket_Localised data) throws RdesktopException {
logger.debug("Secure.parseCryptInfo");
int encryption_level = 0, random_length = 0, RSA_info_length = 0;
int tag = 0, length = 0;
int next_tag = 0, end = 0;
int rc4_key_size = 0;
rc4_key_size = data.getLittleEndian32(); // 1 = 40-Bit 2 = 128 Bit
encryption_level = data.getLittleEndian32(); // 1 = low, 2 = medium,
// 3 = high
if (encryption_level == 0) { // no encryption
return 0;
}
random_length = data.getLittleEndian32();
RSA_info_length = data.getLittleEndian32();
if (random_length != SEC_RANDOM_SIZE) {
throw new RdesktopException(
"Wrong Size of Random! Got" + random_length + "expected" + SEC_RANDOM_SIZE);
}
this.server_random = new byte[random_length];
data.copyToByteArray(this.server_random, 0, data.getPosition(), random_length);
data.incrementPosition(random_length);
end = data.getPosition() + RSA_info_length;
if (end > data.getEnd()) {
logger.debug("Reached end of crypt info prematurely ");
return 0;
}
// data.incrementPosition(12); // unknown bytes
int flags = data.getLittleEndian32(); // in_uint32_le(s, flags); // 1
// = RDP4-style, 0x80000002 =
// X.509
logger.debug("Flags = 0x" + Integer.toHexString(flags));
if ((flags & 1) != 0) {
logger.debug(("We're going for the RDP4-style encryption"));
data.incrementPosition(8); // in_uint8s(s, 8); // unknown
while (data.getPosition() < data.getEnd()) {
tag = data.getLittleEndian16();
length = data.getLittleEndian16();
next_tag = data.getPosition() + length;
switch (tag) {
case (Secure.SEC_TAG_PUBKEY):
if (!parsePublicKey(data)) {
return 0;
}
break;
case (Secure.SEC_TAG_KEYSIG):
// Microsoft issued a key but we don't care
break;
default:
throw new RdesktopException("Unimplemented decrypt tag " + tag);
}
data.setPosition(next_tag);
}
if (data.getPosition() == data.getEnd()) {
return rc4_key_size;
} else {
logger.warn("End not reached!");
return 0;
}
} else {
logger.debug(("We're going for the RDP5-style encryption"));
// data.incrementPosition(4); // number of certificates
int num_certs = data.getLittleEndian32();
int cacert_len = data.getLittleEndian32();
data.incrementPosition(cacert_len);
int cert_len = data.getLittleEndian32();
data.incrementPosition(cert_len);
readCert = true;
return rc4_key_size;
}
}
/**
* Read server info from packet, specifically the RDP version of the server
*
* @param mcs_data Packet to read
*/
private void processSrvInfo(RdpPacket_Localised mcs_data) {
Options.server_rdp_version = mcs_data.getLittleEndian16(); // in_uint16_le(s,
// g_server_rdp_version);
logger.debug(("Server RDP version is " + Options.server_rdp_version));
if (1 == Options.server_rdp_version) Options.use_rdp5 = false;
}