private SSUState AssembleFragments(SSUHeader header, BufRefLen reader, byte info, ushort cursize)
{
var fragnr = info >> 4;
var fragcount = info & 0x0f;
if (fragnr == fragcount - 1)
{
ASignonTime = reader.Read32();
reader.Seek(reader.Length - Session.RemoteRouter.Certificate.SignatureLength);
ASign = new I2PSignature(reader, Session.RemoteRouter.Certificate);
}
else
{
Fragments[fragnr] = reader.ReadBufLen(cursize);
}
if (Fragments.Any(f => f == null))
{
return(this);
}
Session.RemoteRouter = new I2PRouterIdentity(new BufRefLen(Fragments.SelectMany(f => f.ToByteArray()).ToArray()));
return(VerifyRemoteSignature());
}
public virtual SSUState DatagramReceived(BufRefLen recv, IPEndPoint RemoteEP)
{
// Verify the MAC
var reader = new BufRefLen(recv);
var header = new SSUHeader(reader);
var recvencr = header.EncryptedBuf;
var macstate = VerifyMAC(header, CurrentMACKey);
var usekey = CurrentPayloadKey;
switch (macstate)
{
case MACHealth.AbandonSession: return(null);
case MACHealth.Missmatch: return(this);
case MACHealth.UseOurIntroKey:
usekey = Session.MyRouterContext.IntroKey;
break;
}
// Decrypt
Cipher.Init(false, usekey.ToParametersWithIV(header.IV));
Cipher.ProcessBytes(recvencr);
header.SkipExtendedHeaders(reader);
return(HandleMessage(header, reader));
}
internal void ReportRelayResponse(SSUHeader header, RelayResponse response, IPEndPoint ep)
{
if (RelayResponseReceived != null)
{
lock ( RelayResponseReceivedLock )
{
RelayResponseReceived(header, response, ep);
}
}
}
protected MACHealth VerifyMAC(SSUHeader header, BufLen key)
{
var macdata = new BufLen[] {
header.MACDataBuf,
header.IV,
BufUtils.Flip16BL((ushort)((ushort)header.MACDataBuf.Length ^ I2PConstants.SSU_PROTOCOL_VERSION))
};
var recvhash = I2PHMACMD5Digest.Generate(macdata, key, MACBuf);
var ok = header.MAC.Equals(recvhash);
if (ok)
{
IntroMACsReceived = 0;
}
else
{
DebugUtils.LogDebug(() => string.Format("SSU {0}: {1} Current MAC check fail. Payload {2} bytes. ",
this, Session.DebugId, header.MACDataBuf.Length));
if ((int)DebugUtils.LogLevel <= (int)DebugUtils.LogLevels.Debug)
{
if (Session.IntroKey != null)
{
var recvhashi = I2PHMACMD5Digest.Generate(macdata, new BufLen(Session.IntroKey), MACBuf);
var oki = header.MAC.Equals(recvhashi);
DebugUtils.Log("SSU " + this.ToString() + ": " + Session.DebugId + ". " +
"Session Intro key match: " + oki.ToString());
}
}
var recvhash2 = I2PHMACMD5Digest.Generate(macdata, new BufLen(Session.MyRouterContext.IntroKey), MACBuf);
var ok2 = header.MAC.Equals(recvhash2);
DebugUtils.LogDebug(() => string.Format("SSU {0}: {1} My intro MAC key match: {3}. Payload {2} bytes. ",
this, Session.DebugId, header.MACDataBuf.Length, ok2));
if (ok2)
{
if (++IntroMACsReceived > 5)
{
var reason = string.Format("SSU {0}: {1}. {2} intro key matches in a row. The other side seems to have started a new session.",
this, Session.DebugId, IntroMACsReceived);
DebugUtils.Log(reason);
return(MACHealth.AbandonSession);
}
return(MACHealth.UseOurIntroKey);
}
}
return(ok ? MACHealth.Match : MACHealth.Missmatch);
}
public override SSUState HandleMessage(SSUHeader header, BufRefLen reader)
{
#if LOG_ALL_TRANSPORT
Logging.LogTransport($"SSU RelayRequestState: {Session.DebugId} Received {header.MessageType}");
#endif
if (header.MessageType == SSUHeader.MessageTypes.RelayResponse)
{
var response = new RelayResponse(reader);
return(HandleRelayResponse(response));
}
return(this);
}
public override SSUState HandleMessage(SSUHeader header, BufRefLen reader)
{
switch (header.MessageType)
{
case SSUHeader.MessageTypes.SessionRequest:
var req = new SessionRequest(reader, I2PPublicKey.DefaultAsymetricKeyCert);
DebugUtils.Log("SSU SessionCreatedState " + Session.DebugId + " : OK SessionRequest received.");
BufUtils.DHI2PToSessionAndMAC(out Session.SharedKey, out Session.MACKey,
req.XKey.ModPow(PrivateKey.ToBigInteger(), I2PConstants.ElGamalP));
Session.Host.ReportedAddress(new IPAddress(req.Address.ToByteArray()));
// TODO: Remove comment when relaying is implemented
/*
* if ( header.ExtendedOptions != null )
* {
* if ( header.ExtendedOptions.Length == 2 && ( ( header.ExtendedOptions[0] & 0x01 ) != 0 ) )
* {
* RelayTag = BufUtils.RandomUint();
* }
* }*/
Request = req;
SendSessionCreated();
return(this);
case SSUHeader.MessageTypes.RelayResponse:
DebugUtils.LogDebug(() => string.Format("SSU SessionCreatedState {0}: RelayResponse received from {1}.",
Session.DebugId, (Session.RemoteEP == null ? "<null>" : Session.RemoteEP.ToString())));
var response = new RelayResponse(reader);
Session.Host.ReportRelayResponse(header, response, Session.RemoteEP);
break;
case SSUHeader.MessageTypes.SessionConfirmed:
return(ParseSessionConfirmed(header, reader));
case SSUHeader.MessageTypes.PeerTest:
HandleIncomingPeerTestPackage(reader);
break;
default:
DebugUtils.Log("SSU SessionCreatedState: Session " + Session.DebugId + " Unexpected Message: " + header.MessageType.ToString());
break;
}
return(this);
}
void Host_RelayResponseReceived(SSUHeader header, RelayResponse response, IPEndPoint ep)
{
if (header.MessageType == SSUHeader.MessageTypes.RelayResponse)
{
if (ep.Address.Equals(CurrentIntroducer.EndPoint.Address))
{
HandleRelayResponse(response);
}
else
{
Logging.LogTransport(
$"SSU RelayRequestState: {Session.DebugId} RelayResponse from {ep.Address} received. Waiting for response from {CurrentIntroducer.EndPoint.Address}.");
}
}
}
public override SSUState HandleMessage(SSUHeader header, BufRefLen reader)
{
if (header.MessageType == SSUHeader.MessageTypes.SessionCreated)
{
#if LOG_ALL_TRANSPORT
Logging.LogTransport("SSU SessionConfirmedState " + Session.DebugId + ": Unexpected message received: " + header.MessageType.ToString());
#endif
return(this);
}
Logging.LogTransport("SSU SessionConfirmedState: Session " + Session.DebugId + " established. " +
header.MessageType.ToString() + " received. Moving to Established state.");
var next = new EstablishedState(Session);
Session.ReportConnectionEstablished();
return(next.HandleMessage(header, reader));
}
private SSUState ParseSessionConfirmed(SSUHeader header, BufRefLen reader)
{
var info = reader.Read8();
var cursize = reader.ReadFlip16();
if (Fragments != null)
{
return(AssembleFragments(header, reader, info, cursize));
}
if ((info & 0x0f) == 1)
{
var cursizedata = reader.ReadBufRefLen(cursize);
Session.RemoteRouter = new I2PRouterIdentity(cursizedata);
ASignonTime = reader.Read32();
reader.Seek(reader.Length - Session.RemoteRouter.Certificate.SignatureLength);
ASign = new I2PSignature(reader, Session.RemoteRouter.Certificate);
return(VerifyRemoteSignature());
}
Fragments = new List <BufLen>(new BufLen[info & 0x0f]);
return(AssembleFragments(header, reader, info, cursize));
}
public override SSUState HandleMessage(SSUHeader header, BufRefLen reader)
{
var tstime = SSUHost.SSUDateTime(header.TimeStamp);
if (header.MessageType != SSUHeader.MessageTypes.SessionCreated)
{
#if LOG_ALL_TRANSPORT
Logging.LogTransport("SSU SessionRequestState: Received unexpected message " + tstime.ToString() + " : " + header.Flag.ToString());
#endif
return(this);
}
SCMessage = new SessionCreated(reader, Session.RemoteRouter.Certificate);
Session.RelayTag = SCMessage.RelayTag;
Y = new I2PPublicKey((BufRefLen)SCMessage.Y, Session.RemoteRouter.Certificate);
BufUtils.DHI2PToSessionAndMAC(out Session.SharedKey, out Session.MACKey,
Y.ToBigInteger().ModPow(PrivateKey.ToBigInteger(), I2PConstants.ElGamalP));
var ipaddr = new IPAddress(SCMessage.Address.ToByteArray());
ushort port = SCMessage.Port.PeekFlip16(0);
Session.SignOnTimeB = SCMessage.SignOnTime.Peek32(0);
var btime = SSUHost.SSUDateTime(BufUtils.Flip32(Session.SignOnTimeB));
#if LOG_ALL_TRANSPORT
Logging.LogTransport("SSU SessionRequestState " + Session.DebugId + " : Received SessionCreated. " + tstime.ToString() + " : " + btime.ToString());
#endif
Session.Host.ReportedAddress(ipaddr);
if (!I2PSignature.SupportedSignatureType(Session.RemoteRouter.Certificate.SignatureType))
{
throw new SignatureCheckFailureException("SSU SessionRequestState " + Session.DebugId + " : " +
"Received non supported signature type: " +
Session.RemoteRouter.Certificate.SignatureType.ToString());
}
var cipher = new CbcBlockCipher(new AesEngine());
cipher.Init(false, Session.SharedKey.ToParametersWithIV(header.IV));
cipher.ProcessBytes(SCMessage.SignatureEncrBuf);
var baddr = new BufLen(Session.RemoteEP.Address.GetAddressBytes());
var sign = new I2PSignature((BufRefLen)SCMessage.Signature, Session.RemoteRouter.Certificate);
var sok = I2PSignature.DoVerify(
Session.RemoteRouter.SigningPublicKey, sign,
X.Key, Y.Key,
SCMessage.Address, SCMessage.Port,
baddr, BufUtils.Flip16BL((ushort)Session.RemoteEP.Port),
SCMessage.RelayTag, SCMessage.SignOnTime);
#if LOG_ALL_TRANSPORT
Logging.LogTransport("SSU SessionRequestState: Signature check: " + sok.ToString() + ". " + Session.RemoteRouter.Certificate.SignatureType.ToString());
#endif
if (!sok)
{
throw new SignatureCheckFailureException("SSU SessionRequestState " + Session.DebugId + ": Received SessionCreated signature check failed." +
Session.RemoteRouter.Certificate.ToString());
}
var relaytag = SCMessage.RelayTag.PeekFlip32(0);
if (relaytag != 0)
{
Session.Host.IntroductionRelayOffered(
new IntroducerInfo(
Session.RemoteEP.Address,
(ushort)Session.RemoteEP.Port,
Session.IntroKey, relaytag));
}
Logging.LogTransport("SSU SessionRequestState: Session " + Session.DebugId + " created. Moving to SessionConfirmedState.");
Session.ReportConnectionEstablished();
return(new SessionConfirmedState(Session, this));
}
// MAC verified and packet dectrypted public abstract SSUState HandleMessage(SSUHeader header, BufRefLen reader);
/**
* From PacketBuilder.java
* -----8<-----
* @param packet prepared packet with the first 32 bytes empty and a length
* whose size is mod 16.
* As of 0.9.7, length non-mod-16 is allowed; the
* last 1-15 bytes are included in the MAC calculation but are not encrypted.
* -----8<-----
*/
protected void SendMessage(
IPEndPoint dest,
SSUHeader.MessageTypes message,
BufLen mackey,
BufLen cryptokey,
SendMessageGenerator gen,
SendMessageGenerator genextrapadding)
{
var start = Session.Host.SendBuffers.Pop();
var writer = new BufRefLen(start);
var header = new SSUHeader(writer, message);
if (!gen(start, writer))
{
return;
}
// Do not cut to datalen & ~0xf as that might make data at the end unencrypted
var datapadding = BufUtils.Get16BytePadding(writer - start);
writer.Write(BufUtils.Random(datapadding));
var datalen = writer - start;
var encryptedbuf = new BufLen(start, 32, datalen - 32);
// TODO: Adding extra padding does not seem to work
if (genextrapadding != null)
{
if (!genextrapadding(start, writer))
{
return;
}
}
var packetlen = writer - start;
var data = new BufLen(start, 0, packetlen);
var hmac = new BufLen(data, 32);
SendMessageCipher.Init(true, cryptokey.ToParametersWithIV(header.IV));
SendMessageCipher.ProcessBytes(encryptedbuf);
I2PHMACMD5Digest.Generate(new BufLen[] {
hmac,
header.IV,
BufUtils.Flip16BL((ushort)((ushort)hmac.Length ^ I2PConstants.SSU_PROTOCOL_VERSION))
}, mackey, header.MAC);
#if LOG_ALL_TRANSPORT
DebugUtils.Log(string.Format("SSUState SendMessage {0}: encrlen {1} bytes [0x{1:X}] (padding {2} bytes [0x{2:X}]), " +
"hmac {3} bytes [0x{3:X}], sendlen {4} bytes [0x{4:X}]",
Session.DebugId,
encryptedbuf.Length,
datapadding,
hmac.Length,
data.Length));
#endif
DataSent();
Session.Host.Send(dest, data);
}
public override SSUState HandleMessage(SSUHeader header, BufRefLen reader)
{
DataSent();
#if LOG_ALL_TRANSPORT
DebugUtils.Log("SSU EstablishedState +" + Session.TransportInstance.ToString() + "+ received: " +
header.MessageType.ToString() + ": " + SSUHost.SSUDateTime(header.TimeStamp).ToString());
#endif
switch (header.MessageType)
{
case SSUHeader.MessageTypes.Data:
try
{
var datamsg = new SSUDataMessage(reader, Session.Defragmenter);
if (datamsg.ExplicitAcks != null)
{
Session.Fragmenter.GotAck(datamsg.ExplicitAcks);
}
if (datamsg.AckBitfields != null)
{
Session.Fragmenter.GotAck(datamsg.AckBitfields);
}
if (datamsg.NewMessages != null)
{
foreach (var msg in datamsg.NewMessages)
{
var i2npmsg = I2NPMessage.ReadHeader5((BufRefLen)msg.GetPayload());
#if LOG_ALL_TRANSPORT
DebugUtils.Log("SSU EstablishedState +" + Session.TransportInstance.ToString() + "+ complete message " +
msg.MessageId.ToString() + ": " + i2npmsg.Expiration.ToString());
#endif
if (i2npmsg.MessageType == I2PCore.Tunnel.I2NP.Messages.I2NPMessage.MessageTypes.DeliveryStatus)
{
if (((DeliveryStatusMessage)i2npmsg.Message).IsNetworkId((ulong)I2PConstants.I2P_NETWORK_ID))
{
continue;
}
}
Session.MessageReceived(i2npmsg);
}
}
}
catch (Exception ex)
{
DebugUtils.Log("EstablishedState: SSUHost.SSUMessageTypes.Data", ex);
}
break;
case SSUHeader.MessageTypes.SessionDestroyed:
DebugUtils.LogDebug(() => string.Format("SSU EstablishedState {0}: SessionDestroyed received.", Session.DebugId));
SendSessionDestroyed();
return(null);
case SSUHeader.MessageTypes.PeerTest:
HandleIncomingPeerTestPackage(reader);
break;
case SSUHeader.MessageTypes.RelayResponse:
DebugUtils.LogDebug(() => string.Format("SSU EstablishedState {0}: RelayResponse received from {1}.",
Session.DebugId, Session.RemoteEP));
var response = new RelayResponse(reader);
Session.Host.ReportRelayResponse(header, response, Session.RemoteEP);
break;
case SSUHeader.MessageTypes.RelayIntro:
var intro = new RelayIntro(reader);
DebugUtils.LogDebug(() => $"SSU EstablishedState {Session.DebugId}: RelayIntro received from {Session.RemoteEP} for {intro.AliceEndpoint}.");
Session.Host.Send(intro.AliceEndpoint, new BufLen(new byte[0]));
break;
case SSUHeader.MessageTypes.RelayRequest:
// if ( !SSUHost.IntroductionSupported ) throw new Exception( "SSU relay introduction not supported" );
DebugUtils.LogDebug(() => string.Format("SSU EstablishedState {0}: Relay introduction not supported.", Session.DebugId));
break;
case SSUHeader.MessageTypes.SessionRequest:
DebugUtils.LogDebug(() => string.Format("SSU EstablishedState {0}: SessionRequest received. Ending session.", Session.DebugId));
SendSessionDestroyed();
return(null);
default:
DebugUtils.LogDebug(() => string.Format("SSU EstablishedState {0}: Unexpected message received: {1}.",
Session.DebugId, header.MessageType));
break;
}
return(this);
}