private void ProcessPacketError(uint size, uint opcode, uint nIP, ushort nUDPPort,
Exception ex)
{
string strName = string.Empty;
ED2KServer pServer = MuleApplication.Instance.ServerList.GetServerByIPUDP(nIP, nUDPPort);
if (pServer != null)
{
strName = " (" + pServer.ServerName + ")";
}
MpdUtilities.DebugLogWarning(false,
string.Format("Error: Failed to process server UDP packet from {0}:{1}{2} opcode=0x{3} size={4} - {5}",
MpdUtilities.IP2String(nIP), nUDPPort, strName, opcode, size, ex.Message), ex);
}
public virtual int DecryptReceivedClient(byte[] pbyBufIn, int nBufLen,
out byte[] ppbyBufOut, uint dwIP, out uint nReceiverVerifyKey, out uint nSenderVerifyKey)
{
int nResult = nBufLen;
ppbyBufOut = pbyBufIn;
nReceiverVerifyKey = 0;
nSenderVerifyKey = 0;
if (nResult <= CRYPT_HEADER_WITHOUTPADDING /*|| !MuleApplication.Instance.Preference.IsClientCryptLayerSupported()*/)
{
return(nResult);
}
switch (pbyBufIn[0])
{
case MuleConstants.PROTOCOL_EMULEPROT:
case MuleConstants.PROTOCOL_KADEMLIAPACKEDPROT:
case MuleConstants.PROTOCOL_KADEMLIAHEADER:
case MuleConstants.PROTOCOL_UDPRESERVEDPROT1:
case MuleConstants.PROTOCOL_UDPRESERVEDPROT2:
case MuleConstants.PROTOCOL_PACKEDPROT:
return(nResult); // no encrypted packet (see description on top)
}
// might be an encrypted packet, try to decrypt
RC4Key keyReceiveKey = null;
uint dwValue = 0;
// check the marker bit which type this packet could be and which key to test first, this is only an indicator since old clients have it set random
// see the header for marker bits explanation
byte byCurrentTry = (byte)(((pbyBufIn[0] & 0x03) == 3) ? 1 : (pbyBufIn[0] & 0x03));
byte byTries;
if (MuleApplication.Instance.KadEngine.Preference == null)
{
// if kad never run, no point in checking anything except for ed2k encryption
byTries = 1;
byCurrentTry = 1;
}
else
{
byTries = 3;
}
bool bKadRecvKeyUsed = false;
bool bKad = false;
do
{
byTries--;
MD5 md5 = MD5.Create();
byte[] rawHash = null;
if (byCurrentTry == 0)
{
// kad packet with NodeID as key
bKad = true;
bKadRecvKeyUsed = false;
if (MuleApplication.Instance.KadEngine.Preference != null)
{
byte[] achKeyData = new byte[18];
Array.Copy(MuleApplication.Instance.KadEngine.Preference.KadID.Bytes, 0, achKeyData, 0, 16);
Array.Copy(pbyBufIn, 1, achKeyData, 16, 2); // random key part sent from remote client
rawHash = md5.ComputeHash(achKeyData);
}
}
else if (byCurrentTry == 1)
{
// ed2k packet
bKad = false;
bKadRecvKeyUsed = false;
byte[] achKeyData = new byte[23];
MpdUtilities.Md4Cpy(achKeyData, MuleApplication.Instance.Preference.UserHash);
achKeyData[20] = MAGICVALUE_UDP;
Array.Copy(BitConverter.GetBytes(dwIP), 0, achKeyData, 16, 4);
Array.Copy(pbyBufIn, 1, achKeyData, 21, 2); // random key part sent from remote client
rawHash = md5.ComputeHash(achKeyData);
}
else if (byCurrentTry == 2)
{
// kad packet with ReceiverKey as key
bKad = true;
bKadRecvKeyUsed = true;
if (MuleApplication.Instance.KadEngine.Preference != null)
{
byte[] achKeyData = new byte[6];
Array.Copy(BitConverter.GetBytes(MuleApplication.Instance.KadEngine.Preference.GetUDPVerifyKey(dwIP)),
achKeyData, 4);
Array.Copy(pbyBufIn, 1, achKeyData, 4, 2); // random key part sent from remote client
rawHash = md5.ComputeHash(achKeyData);
}
}
else
{
Debug.Assert(false);
}
MuleUtilities.RC4CreateKey(rawHash, 16, ref keyReceiveKey, true);
byte[] outBuf = new byte[4];
MuleUtilities.RC4Crypt(pbyBufIn, 3, outBuf, 0, 4, keyReceiveKey);
dwIP = BitConverter.ToUInt32(outBuf, 0);
byCurrentTry = (byte)((byCurrentTry + 1) % 3);
} while (dwValue != MAGICVALUE_UDP_SYNC_CLIENT && byTries > 0); // try to decrypt as ed2k as well as kad packet if needed (max 3 rounds)
if (dwValue == MAGICVALUE_UDP_SYNC_CLIENT)
{
// yup this is an encrypted packet
// debugoutput notices
// the following cases are "allowed" but shouldn't happen given that there is only our implementation yet
if (bKad && (pbyBufIn[0] & 0x01) != 0)
{
MpdUtilities.DebugLog(
string.Format("Received obfuscated UDP packet from clientIP: {0} with wrong key marker bits (kad packet, ed2k bit)", MpdUtilities.IP2String(dwIP)));
}
else if (bKad && !bKadRecvKeyUsed && (pbyBufIn[0] & 0x02) != 0)
{
MpdUtilities.DebugLog(
string.Format("Received obfuscated UDP packet from clientIP: {0} with wrong key marker bits (kad packet, nodeid key, recvkey bit)", MpdUtilities.IP2String(dwIP)));
}
else if (bKad && bKadRecvKeyUsed && (pbyBufIn[0] & 0x02) == 0)
{
MpdUtilities.DebugLog(
string.Format("Received obfuscated UDP packet from clientIP: {0} with wrong key marker bits (kad packet, recvkey key, nodeid bit)", MpdUtilities.IP2String(dwIP)));
}
byte byPadLen;
byte[] outBuf = new byte[1];
MuleUtilities.RC4Crypt(pbyBufIn, 7, outBuf, 0, 1, keyReceiveKey);
byPadLen = outBuf[0];
nResult -= CRYPT_HEADER_WITHOUTPADDING;
if (nResult <= byPadLen)
{
MpdUtilities.DebugLogError(
string.Format("Invalid obfuscated UDP packet from clientIP: {0}, Paddingsize ({1}) larger than received bytes",
MpdUtilities.IP2String(dwIP), byPadLen));
return(nBufLen); // pass through, let the Receivefunction do the errorhandling on this junk
}
if (byPadLen > 0)
{
MuleUtilities.RC4Crypt(null, null, byPadLen, keyReceiveKey);
}
nResult -= byPadLen;
if (bKad)
{
if (nResult <= 8)
{
MpdUtilities.DebugLogError(
string.Format("Obfuscated Kad packet with mismatching size (verify keys missing) received from clientIP: {0}",
MpdUtilities.IP2String(dwIP)));
return(nBufLen); // pass through, let the Receivefunction do the errorhandling on this junk;
}
// read the verify keys
outBuf = new byte[4];
MuleUtilities.RC4Crypt(pbyBufIn, (int)(CRYPT_HEADER_WITHOUTPADDING + byPadLen),
outBuf, 0, 4, keyReceiveKey);
nReceiverVerifyKey = BitConverter.ToUInt32(outBuf, 0);
MuleUtilities.RC4Crypt(pbyBufIn, (int)(CRYPT_HEADER_WITHOUTPADDING + byPadLen + 4),
outBuf, 0, 4, keyReceiveKey);
nSenderVerifyKey = BitConverter.ToUInt32(outBuf, 0);
nResult -= 8;
}
ppbyBufOut = new byte[nResult];
Array.Copy(pbyBufIn, (nBufLen - nResult), ppbyBufOut, 0, nResult);
MuleUtilities.RC4Crypt(ppbyBufOut, ppbyBufOut, (uint)nResult, keyReceiveKey);
MuleApplication.Instance.Statistics.AddDownDataOverheadCrypt((uint)(nBufLen - nResult));
//DEBUG_ONLY( MpdUtilities.DebugLog(("Received obfuscated UDP packet from clientIP: %s, Key: %s, RKey: %u, SKey: %u"), MpdUtilities.IP2String(dwIP), bKad ? (bKadRecvKeyUsed ? ("ReceiverKey") : ("NodeID")) : ("UserHash")
// , nReceiverVerifyKey != 0 ? *nReceiverVerifyKey : 0, nSenderVerifyKey != 0 ? *nSenderVerifyKey : 0) );
return(nResult); // done
}
else
{
MpdUtilities.DebugLogWarning(
string.Format("Obfuscated packet expected but magicvalue mismatch on UDP packet from clientIP: {0}, Possible RecvKey: {1}",
MpdUtilities.IP2String(dwIP), MuleApplication.Instance.KadEngine.Preference.GetUDPVerifyKey(dwIP)));
return(nBufLen); // pass through, let the Receivefunction do the errorhandling on this junk
}
}