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i2pd/SSUSession.cpp

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#include <boost/bind.hpp>
#include <cryptopp/dh.h>
#include <cryptopp/sha.h>
#include "CryptoConst.h"
#include "Log.h"
#include "Timestamp.h"
#include "RouterContext.h"
#include "Transports.h"
#include "SSU.h"
#include "SSUSession.h"
namespace i2p
{
namespace transport
{
SSUSession::SSUSession (SSUServer& server, boost::asio::ip::udp::endpoint& remoteEndpoint,
std::shared_ptr<const i2p::data::RouterInfo> router, bool peerTest ): TransportSession (router),
m_Server (server), m_RemoteEndpoint (remoteEndpoint), m_Timer (GetService ()),
m_PeerTest (peerTest),m_State (eSessionStateUnknown), m_IsSessionKey (false), m_RelayTag (0),
m_NumSentBytes (0), m_NumReceivedBytes (0), m_Data (*this)
{
m_CreationTime = i2p::util::GetSecondsSinceEpoch ();
}
SSUSession::~SSUSession ()
{
}
boost::asio::io_service& SSUSession::GetService ()
{
return IsV6 () ? m_Server.GetServiceV6 () : m_Server.GetService ();
}
void SSUSession::CreateAESandMacKey (const uint8_t * pubKey)
{
CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
uint8_t sharedKey[256];
if (!dh.Agree (sharedKey, m_DHKeysPair->privateKey, pubKey))
{
LogPrint (eLogError, "Couldn't create shared key");
return;
};
uint8_t * sessionKey = m_SessionKey, * macKey = m_MacKey;
if (sharedKey[0] & 0x80)
{
sessionKey[0] = 0;
memcpy (sessionKey + 1, sharedKey, 31);
memcpy (macKey, sharedKey + 31, 32);
}
else if (sharedKey[0])
{
memcpy (sessionKey, sharedKey, 32);
memcpy (macKey, sharedKey + 32, 32);
}
else
{
// find first non-zero byte
uint8_t * nonZero = sharedKey + 1;
while (!*nonZero)
{
nonZero++;
if (nonZero - sharedKey > 32)
{
LogPrint ("First 32 bytes of shared key is all zeros. Ignored");
return;
}
}
memcpy (sessionKey, nonZero, 32);
CryptoPP::SHA256().CalculateDigest(macKey, nonZero, 64 - (nonZero - sharedKey));
}
m_IsSessionKey = true;
m_SessionKeyEncryption.SetKey (m_SessionKey);
m_SessionKeyDecryption.SetKey (m_SessionKey);
}
void SSUSession::ProcessNextMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
{
m_NumReceivedBytes += len;
if (m_State == eSessionStateIntroduced)
{
// HolePunch received
LogPrint ("SSU HolePunch of ", len, " bytes received");
m_State = eSessionStateUnknown;
Connect ();
}
else
{
if (!len) return; // ignore zero-length packets
if (m_State == eSessionStateEstablished)
ScheduleTermination ();
if (m_IsSessionKey && Validate (buf, len, m_MacKey)) // try session key first
DecryptSessionKey (buf, len);
else
{
// try intro key depending on side
auto introKey = GetIntroKey ();
if (introKey && Validate (buf, len, introKey))
Decrypt (buf, len, introKey);
else
{
// try own intro key
auto address = i2p::context.GetRouterInfo ().GetSSUAddress ();
if (!address)
{
LogPrint (eLogError, "SSU is not supported");
return;
}
if (Validate (buf, len, address->key))
Decrypt (buf, len, address->key);
else
{
LogPrint (eLogError, "MAC verification failed ", len, " bytes from ", senderEndpoint);
m_Server.DeleteSession (shared_from_this ());
return;
}
}
}
// successfully decrypted
ProcessMessage (buf, len, senderEndpoint);
}
}
void SSUSession::ProcessMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
{
//TODO: since we are accessing a uint8_t this is unlikely to crash due to alignment but should be improved
SSUHeader * header = (SSUHeader *)buf;
switch (header->GetPayloadType ())
{
case PAYLOAD_TYPE_DATA:
ProcessData (buf + sizeof (SSUHeader), len - sizeof (SSUHeader));
break;
case PAYLOAD_TYPE_SESSION_REQUEST:
ProcessSessionRequest (buf, len, senderEndpoint);
break;
case PAYLOAD_TYPE_SESSION_CREATED:
ProcessSessionCreated (buf, len);
break;
case PAYLOAD_TYPE_SESSION_CONFIRMED:
ProcessSessionConfirmed (buf, len);
break;
case PAYLOAD_TYPE_PEER_TEST:
LogPrint (eLogDebug, "SSU peer test received");
ProcessPeerTest (buf + sizeof (SSUHeader), len - sizeof (SSUHeader), senderEndpoint);
break;
case PAYLOAD_TYPE_SESSION_DESTROYED:
{
LogPrint (eLogDebug, "SSU session destroy received");
m_Server.DeleteSession (shared_from_this ());
break;
}
case PAYLOAD_TYPE_RELAY_RESPONSE:
ProcessRelayResponse (buf, len);
if (m_State != eSessionStateEstablished)
m_Server.DeleteSession (shared_from_this ());
break;
case PAYLOAD_TYPE_RELAY_REQUEST:
LogPrint (eLogDebug, "SSU relay request received");
ProcessRelayRequest (buf + sizeof (SSUHeader), len - sizeof (SSUHeader), senderEndpoint);
break;
case PAYLOAD_TYPE_RELAY_INTRO:
LogPrint (eLogDebug, "SSU relay intro received");
ProcessRelayIntro (buf + sizeof (SSUHeader), len - sizeof (SSUHeader));
break;
default:
LogPrint (eLogWarning, "Unexpected SSU payload type ", (int)header->GetPayloadType ());
}
}
void SSUSession::ProcessSessionRequest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
{
LogPrint (eLogDebug, "Session request received");
m_RemoteEndpoint = senderEndpoint;
if (!m_DHKeysPair)
m_DHKeysPair = transports.GetNextDHKeysPair ();
CreateAESandMacKey (buf + sizeof (SSUHeader));
SendSessionCreated (buf + sizeof (SSUHeader));
}
void SSUSession::ProcessSessionCreated (uint8_t * buf, size_t len)
{
if (!m_RemoteRouter || !m_DHKeysPair)
{
LogPrint (eLogWarning, "Unsolicited session created message");
return;
}
LogPrint (eLogDebug, "Session created received");
m_Timer.cancel (); // connect timer
SignedData s; // x,y, our IP, our port, remote IP, remote port, relayTag, signed on time
uint8_t * payload = buf + sizeof (SSUHeader);
uint8_t * y = payload;
CreateAESandMacKey (y);
s.Insert (m_DHKeysPair->publicKey, 256); // x
s.Insert (y, 256); // y
payload += 256;
uint8_t addressSize = *payload;
payload += 1; // size
uint8_t * ourAddress = payload;
boost::asio::ip::address ourIP;
if (addressSize == 4) // v4
{
boost::asio::ip::address_v4::bytes_type bytes;
memcpy (bytes.data (), ourAddress, 4);
ourIP = boost::asio::ip::address_v4 (bytes);
}
else // v6
{
boost::asio::ip::address_v6::bytes_type bytes;
memcpy (bytes.data (), ourAddress, 16);
ourIP = boost::asio::ip::address_v6 (bytes);
}
s.Insert (ourAddress, addressSize); // our IP
payload += addressSize; // address
uint16_t ourPort = bufbe16toh (payload);
s.Insert (payload, 2); // our port
payload += 2; // port
LogPrint ("Our external address is ", ourIP.to_string (), ":", ourPort);
i2p::context.UpdateAddress (ourIP);
if (m_RemoteEndpoint.address ().is_v4 ())
s.Insert (m_RemoteEndpoint.address ().to_v4 ().to_bytes ().data (), 4); // remote IP v4
else
s.Insert (m_RemoteEndpoint.address ().to_v6 ().to_bytes ().data (), 16); // remote IP v6
s.Insert (htobe16 (m_RemoteEndpoint.port ())); // remote port
s.Insert (payload, 8); // relayTag and signed on time
m_RelayTag = bufbe32toh (payload);
payload += 4; // relayTag
payload += 4; // signed on time
// decrypt signature
size_t signatureLen = m_RemoteIdentity.GetSignatureLen ();
size_t paddingSize = signatureLen & 0x0F; // %16
if (paddingSize > 0) signatureLen += (16 - paddingSize);
//TODO: since we are accessing a uint8_t this is unlikely to crash due to alignment but should be improved
m_SessionKeyDecryption.SetIV (((SSUHeader *)buf)->iv);
m_SessionKeyDecryption.Decrypt (payload, signatureLen, payload);
// verify
if (!s.Verify (m_RemoteIdentity, payload))
LogPrint (eLogError, "SSU signature verification failed");
SendSessionConfirmed (y, ourAddress, addressSize + 2);
}
void SSUSession::ProcessSessionConfirmed (uint8_t * buf, size_t len)
{
LogPrint (eLogDebug, "Session confirmed received");
uint8_t * payload = buf + sizeof (SSUHeader);
payload++; // identity fragment info
uint16_t identitySize = bufbe16toh (payload);
payload += 2; // size of identity fragment
m_RemoteIdentity.FromBuffer (payload, identitySize);
m_Data.UpdatePacketSize (m_RemoteIdentity.GetIdentHash ());
payload += identitySize; // identity
payload += 4; // signed-on time
size_t paddingSize = (payload - buf) + m_RemoteIdentity.GetSignatureLen ();
paddingSize &= 0x0F; // %16
if (paddingSize > 0) paddingSize = 16 - paddingSize;
payload += paddingSize;
// TODO: verify signature (need data from session request), payload points to signature
m_Data.Send (CreateDeliveryStatusMsg (0));
Established ();
}
void SSUSession::SendSessionRequest ()
{
auto introKey = GetIntroKey ();
if (!introKey)
{
LogPrint (eLogError, "SSU is not supported");
return;
}
uint8_t buf[320 + 18]; // 304 bytes for ipv4, 320 for ipv6
uint8_t * payload = buf + sizeof (SSUHeader);
memcpy (payload, m_DHKeysPair->publicKey, 256); // x
bool isV4 = m_RemoteEndpoint.address ().is_v4 ();
if (isV4)
{
payload[256] = 4;
memcpy (payload + 257, m_RemoteEndpoint.address ().to_v4 ().to_bytes ().data(), 4);
}
else
{
payload[256] = 16;
memcpy (payload + 257, m_RemoteEndpoint.address ().to_v6 ().to_bytes ().data(), 16);
}
uint8_t iv[16];
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_REQUEST, buf, isV4 ? 304 : 320, introKey, iv, introKey);
m_Server.Send (buf, isV4 ? 304 : 320, m_RemoteEndpoint);
}
void SSUSession::SendRelayRequest (uint32_t iTag, const uint8_t * iKey)
{
auto address = i2p::context.GetRouterInfo ().GetSSUAddress ();
if (!address)
{
LogPrint (eLogError, "SSU is not supported");
return;
}
uint8_t buf[96 + 18];
uint8_t * payload = buf + sizeof (SSUHeader);
htobe32buf (payload, iTag);
payload += 4;
*payload = 0; // no address
payload++;
htobuf16(payload, 0); // port = 0
payload += 2;
*payload = 0; // challenge
payload++;
memcpy (payload, (const uint8_t *)address->key, 32);
payload += 32;
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
htobe32buf (payload, rnd.GenerateWord32 ()); // nonce
uint8_t iv[16];
rnd.GenerateBlock (iv, 16); // random iv
if (m_State == eSessionStateEstablished)
FillHeaderAndEncrypt (PAYLOAD_TYPE_RELAY_REQUEST, buf, 96, m_SessionKey, iv, m_MacKey);
else
FillHeaderAndEncrypt (PAYLOAD_TYPE_RELAY_REQUEST, buf, 96, iKey, iv, iKey);
m_Server.Send (buf, 96, m_RemoteEndpoint);
}
void SSUSession::SendSessionCreated (const uint8_t * x)
{
auto introKey = GetIntroKey ();
auto address = IsV6 () ? i2p::context.GetRouterInfo ().GetSSUV6Address () :
i2p::context.GetRouterInfo ().GetSSUAddress (true); //v4 only
if (!introKey || !address)
{
LogPrint (eLogError, "SSU is not supported");
return;
}
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
SignedData s; // x,y, remote IP, remote port, our IP, our port, relayTag, signed on time
s.Insert (x, 256); // x
uint8_t buf[384 + 18];
uint8_t * payload = buf + sizeof (SSUHeader);
memcpy (payload, m_DHKeysPair->publicKey, 256);
s.Insert (payload, 256); // y
payload += 256;
if (m_RemoteEndpoint.address ().is_v4 ())
{
// ipv4
*payload = 4;
payload++;
memcpy (payload, m_RemoteEndpoint.address ().to_v4 ().to_bytes ().data(), 4);
s.Insert (payload, 4); // remote endpoint IP V4
payload += 4;
}
else
{
// ipv6
*payload = 16;
payload++;
memcpy (payload, m_RemoteEndpoint.address ().to_v6 ().to_bytes ().data(), 16);
s.Insert (payload, 16); // remote endpoint IP V6
payload += 16;
}
htobe16buf (payload, m_RemoteEndpoint.port ());
s.Insert (payload, 2); // remote port
payload += 2;
if (address->host.is_v4 ())
s.Insert (address->host.to_v4 ().to_bytes ().data (), 4); // our IP V4
else
s.Insert (address->host.to_v6 ().to_bytes ().data (), 16); // our IP V6
s.Insert (htobe16 (address->port)); // our port
uint32_t relayTag = 0;
if (i2p::context.GetRouterInfo ().IsIntroducer ())
{
relayTag = rnd.GenerateWord32 ();
if (!relayTag) relayTag = 1;
m_Server.AddRelay (relayTag, m_RemoteEndpoint);
}
htobe32buf (payload, relayTag);
payload += 4; // relay tag
htobe32buf (payload, i2p::util::GetSecondsSinceEpoch ()); // signed on time
payload += 4;
s.Insert (payload - 8, 8); // relayTag and signed on time
s.Sign (i2p::context.GetPrivateKeys (), payload); // DSA signature
// TODO: fill padding with random data
uint8_t iv[16];
rnd.GenerateBlock (iv, 16); // random iv
// encrypt signature and padding with newly created session key
size_t signatureLen = i2p::context.GetIdentity ().GetSignatureLen ();
size_t paddingSize = signatureLen & 0x0F; // %16
if (paddingSize > 0) signatureLen += (16 - paddingSize);
m_SessionKeyEncryption.SetIV (iv);
m_SessionKeyEncryption.Encrypt (payload, signatureLen, payload);
payload += signatureLen;
size_t msgLen = payload - buf;
// encrypt message with intro key
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_CREATED, buf, msgLen, introKey, iv, introKey);
Send (buf, msgLen);
}
void SSUSession::SendSessionConfirmed (const uint8_t * y, const uint8_t * ourAddress, size_t ourAddressLen)
{
uint8_t buf[512 + 18];
uint8_t * payload = buf + sizeof (SSUHeader);
*payload = 1; // 1 fragment
payload++; // info
size_t identLen = i2p::context.GetIdentity ().GetFullLen (); // 387+ bytes
htobe16buf (payload, identLen);
payload += 2; // cursize
i2p::context.GetIdentity ().ToBuffer (payload, identLen);
payload += identLen;
uint32_t signedOnTime = i2p::util::GetSecondsSinceEpoch ();
htobe32buf (payload, signedOnTime); // signed on time
payload += 4;
auto signatureLen = i2p::context.GetIdentity ().GetSignatureLen ();
size_t paddingSize = ((payload - buf) + signatureLen)%16;
if (paddingSize > 0) paddingSize = 16 - paddingSize;
// TODO: fill padding
payload += paddingSize; // padding size
// signature
SignedData s; // x,y, our IP, our port, remote IP, remote port, relayTag, our signed on time
s.Insert (m_DHKeysPair->publicKey, 256); // x
s.Insert (y, 256); // y
s.Insert (ourAddress, ourAddressLen); // our address/port as seem by party
if (m_RemoteEndpoint.address ().is_v4 ())
s.Insert (m_RemoteEndpoint.address ().to_v4 ().to_bytes ().data (), 4); // remote IP V4
else
s.Insert (m_RemoteEndpoint.address ().to_v6 ().to_bytes ().data (), 16); // remote IP V6
s.Insert (htobe16 (m_RemoteEndpoint.port ())); // remote port
s.Insert (htobe32 (m_RelayTag)); // relay tag
s.Insert (htobe32 (signedOnTime)); // signed on time
s.Sign (i2p::context.GetPrivateKeys (), payload); // DSA signature
payload += signatureLen;
size_t msgLen = payload - buf;
uint8_t iv[16];
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_CONFIRMED, buf, msgLen, m_SessionKey, iv, m_MacKey);
Send (buf, msgLen);
}
void SSUSession::ProcessRelayRequest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& from)
{
uint32_t relayTag = bufbe32toh (buf);
auto session = m_Server.FindRelaySession (relayTag);
if (session)
{
buf += 4; // relay tag
uint8_t size = *buf;
buf++; // size
buf += size; // address
buf += 2; // port
uint8_t challengeSize = *buf;
buf++; // challenge size
buf += challengeSize;
uint8_t * introKey = buf;
buf += 32; // introkey
uint32_t nonce = bufbe32toh (buf);
SendRelayResponse (nonce, from, introKey, session->m_RemoteEndpoint);
SendRelayIntro (session.get (), from);
}
}
void SSUSession::SendRelayResponse (uint32_t nonce, const boost::asio::ip::udp::endpoint& from,
const uint8_t * introKey, const boost::asio::ip::udp::endpoint& to)
{
uint8_t buf[80 + 18]; // 64 Alice's ipv4 and 80 Alice's ipv6
uint8_t * payload = buf + sizeof (SSUHeader);
// Charlie's address always v4
if (!to.address ().is_v4 ())
{
LogPrint (eLogError, "Charlie's IP must be v4");
return;
}
*payload = 4;
payload++; // size
htobe32buf (payload, to.address ().to_v4 ().to_ulong ()); // Charlie's IP
payload += 4; // address
htobe16buf (payload, to.port ()); // Charlie's port
payload += 2; // port
// Alice
bool isV4 = from.address ().is_v4 (); // Alice's
if (isV4)
{
*payload = 4;
payload++; // size
memcpy (payload, from.address ().to_v4 ().to_bytes ().data (), 4); // Alice's IP V4
payload += 4; // address
}
else
{
*payload = 16;
payload++; // size
memcpy (payload, from.address ().to_v6 ().to_bytes ().data (), 16); // Alice's IP V6
payload += 16; // address
}
htobe16buf (payload, from.port ()); // Alice's port
payload += 2; // port
htobe32buf (payload, nonce);
if (m_State == eSessionStateEstablished)
{
// encrypt with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_RELAY_RESPONSE, buf, isV4 ? 64 : 80);
Send (buf, isV4 ? 64 : 80);
}
else
{
// ecrypt with Alice's intro key
uint8_t iv[16];
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
FillHeaderAndEncrypt (PAYLOAD_TYPE_RELAY_RESPONSE, buf, isV4 ? 64 : 80, introKey, iv, introKey);
m_Server.Send (buf, isV4 ? 64 : 80, from);
}
LogPrint (eLogDebug, "SSU relay response sent");
}
void SSUSession::SendRelayIntro (SSUSession * session, const boost::asio::ip::udp::endpoint& from)
{
if (!session) return;
// Alice's address always v4
if (!from.address ().is_v4 ())
{
LogPrint (eLogError, "Alice's IP must be v4");
return;
}
uint8_t buf[48 + 18];
uint8_t * payload = buf + sizeof (SSUHeader);
*payload = 4;
payload++; // size
htobe32buf (payload, from.address ().to_v4 ().to_ulong ()); // Alice's IP
payload += 4; // address
htobe16buf (payload, from.port ()); // Alice's port
payload += 2; // port
*payload = 0; // challenge size
uint8_t iv[16];
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
FillHeaderAndEncrypt (PAYLOAD_TYPE_RELAY_INTRO, buf, 48, session->m_SessionKey, iv, session->m_MacKey);
m_Server.Send (buf, 48, session->m_RemoteEndpoint);
LogPrint (eLogDebug, "SSU relay intro sent");
}
void SSUSession::ProcessRelayResponse (uint8_t * buf, size_t len)
{
LogPrint (eLogDebug, "Relay response received");
uint8_t * payload = buf + sizeof (SSUHeader);
uint8_t remoteSize = *payload;
payload++; // remote size
//boost::asio::ip::address_v4 remoteIP (bufbe32toh (payload));
payload += remoteSize; // remote address
//uint16_t remotePort = bufbe16toh (payload);
payload += 2; // remote port
uint8_t ourSize = *payload;
payload++; // our size
boost::asio::ip::address ourIP;
if (ourSize == 4)
{
boost::asio::ip::address_v4::bytes_type bytes;
memcpy (bytes.data (), payload, 4);
ourIP = boost::asio::ip::address_v4 (bytes);
}
else
{
boost::asio::ip::address_v6::bytes_type bytes;
memcpy (bytes.data (), payload, 16);
ourIP = boost::asio::ip::address_v6 (bytes);
}
payload += ourSize; // our address
uint16_t ourPort = bufbe16toh (payload);
payload += 2; // our port
LogPrint ("Our external address is ", ourIP.to_string (), ":", ourPort);
i2p::context.UpdateAddress (ourIP);
}
void SSUSession::ProcessRelayIntro (uint8_t * buf, size_t len)
{
uint8_t size = *buf;
if (size == 4)
{
buf++; // size
boost::asio::ip::address_v4 address (bufbe32toh (buf));
buf += 4; // address
uint16_t port = bufbe16toh (buf);
// send hole punch of 1 byte
m_Server.Send (buf, 0, boost::asio::ip::udp::endpoint (address, port));
}
else
LogPrint (eLogWarning, "Address size ", size, " is not supported");
}
void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len,
const uint8_t * aesKey, const uint8_t * iv, const uint8_t * macKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "Unexpected SSU packet length ", len);
return;
}
//TODO: we are using a dirty solution here but should work for now
SSUHeader * header = (SSUHeader *)buf;
memcpy (header->iv, iv, 16);
header->flag = payloadType << 4; // MSB is 0
htobe32buf (&(header->time), i2p::util::GetSecondsSinceEpoch ());
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
i2p::crypto::CBCEncryption encryption;
encryption.SetKey (aesKey);
encryption.SetIV (iv);
encryption.Encrypt (encrypted, encryptedLen, encrypted);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, iv, 16);
htobe16buf (buf + len + 16, encryptedLen);
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, header->mac);
}
void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "Unexpected SSU packet length ", len);
return;
}
//TODO: we are using a dirty solution here but should work for now
SSUHeader * header = (SSUHeader *)buf;
i2p::context.GetRandomNumberGenerator ().GenerateBlock (header->iv, 16); // random iv
m_SessionKeyEncryption.SetIV (header->iv);
header->flag = payloadType << 4; // MSB is 0
htobe32buf (&(header->time), i2p::util::GetSecondsSinceEpoch ());
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
m_SessionKeyEncryption.Encrypt (encrypted, encryptedLen, encrypted);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, header->iv, 16);
htobe16buf (buf + len + 16, encryptedLen);
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, m_MacKey, header->mac);
}
void SSUSession::Decrypt (uint8_t * buf, size_t len, const uint8_t * aesKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "Unexpected SSU packet length ", len);
return;
}
//TODO: since we are accessing a uint8_t this is unlikely to crash due to alignment but should be improved
SSUHeader * header = (SSUHeader *)buf;
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
i2p::crypto::CBCDecryption decryption;
decryption.SetKey (aesKey);
decryption.SetIV (header->iv);
decryption.Decrypt (encrypted, encryptedLen, encrypted);
}
void SSUSession::DecryptSessionKey (uint8_t * buf, size_t len)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "Unexpected SSU packet length ", len);
return;
}
//TODO: since we are accessing a uint8_t this is unlikely to crash due to alignment but should be improved
SSUHeader * header = (SSUHeader *)buf;
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
if (encryptedLen > 0)
{
m_SessionKeyDecryption.SetIV (header->iv);
m_SessionKeyDecryption.Decrypt (encrypted, encryptedLen, encrypted);
}
}
bool SSUSession::Validate (uint8_t * buf, size_t len, const uint8_t * macKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint (eLogError, "Unexpected SSU packet length ", len);
return false;
}
//TODO: since we are accessing a uint8_t this is unlikely to crash due to alignment but should be improved
SSUHeader * header = (SSUHeader *)buf;
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, header->iv, 16);
htobe16buf (buf + len + 16, encryptedLen);
uint8_t digest[16];
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, digest);
return !memcmp (header->mac, digest, 16);
}
void SSUSession::Connect ()
{
if (m_State == eSessionStateUnknown)
{
// set connect timer
ScheduleConnectTimer ();
m_DHKeysPair = transports.GetNextDHKeysPair ();
SendSessionRequest ();
}
}
void SSUSession::WaitForConnect ()
{
if (!m_RemoteRouter) // incoming session
ScheduleConnectTimer ();
else
LogPrint (eLogError, "SSU wait for connect for outgoing session");
}
void SSUSession::ScheduleConnectTimer ()
{
m_Timer.cancel ();
m_Timer.expires_from_now (boost::posix_time::seconds(SSU_CONNECT_TIMEOUT));
m_Timer.async_wait (std::bind (&SSUSession::HandleConnectTimer,
shared_from_this (), std::placeholders::_1));
}
void SSUSession::HandleConnectTimer (const boost::system::error_code& ecode)
{
if (!ecode)
{
// timeout expired
LogPrint ("SSU session was not established after ", SSU_CONNECT_TIMEOUT, " second");
Failed ();
}
}
void SSUSession::Introduce (uint32_t iTag, const uint8_t * iKey)
{
if (m_State == eSessionStateUnknown)
{
// set connect timer
m_Timer.expires_from_now (boost::posix_time::seconds(SSU_CONNECT_TIMEOUT));
m_Timer.async_wait (std::bind (&SSUSession::HandleConnectTimer,
shared_from_this (), std::placeholders::_1));
}
SendRelayRequest (iTag, iKey);
}
void SSUSession::WaitForIntroduction ()
{
m_State = eSessionStateIntroduced;
// set connect timer
m_Timer.expires_from_now (boost::posix_time::seconds(SSU_CONNECT_TIMEOUT));
m_Timer.async_wait (std::bind (&SSUSession::HandleConnectTimer,
shared_from_this (), std::placeholders::_1));
}
void SSUSession::Close ()
{
m_State = eSessionStateClosed;
SendSesionDestroyed ();
transports.PeerDisconnected (shared_from_this ());
m_Data.Stop ();
m_Timer.cancel ();
}
void SSUSession::Done ()
{
GetService ().post (std::bind (&SSUSession::Failed, shared_from_this ()));
}
void SSUSession::Established ()
{
m_State = eSessionStateEstablished;
if (m_DHKeysPair)
{
delete m_DHKeysPair;
m_DHKeysPair = nullptr;
}
m_Data.Start ();
m_Data.Send (CreateDatabaseStoreMsg ());
transports.PeerConnected (shared_from_this ());
if (m_PeerTest && (m_RemoteRouter && m_RemoteRouter->IsPeerTesting ()))
SendPeerTest ();
ScheduleTermination ();
}
void SSUSession::Failed ()
{
if (m_State != eSessionStateFailed)
{
m_State = eSessionStateFailed;
m_Server.DeleteSession (shared_from_this ());
}
}
void SSUSession::ScheduleTermination ()
{
m_Timer.cancel ();
m_Timer.expires_from_now (boost::posix_time::seconds(SSU_TERMINATION_TIMEOUT));
m_Timer.async_wait (std::bind (&SSUSession::HandleTerminationTimer,
shared_from_this (), std::placeholders::_1));
}
void SSUSession::HandleTerminationTimer (const boost::system::error_code& ecode)
{
if (ecode != boost::asio::error::operation_aborted)
{
LogPrint ("SSU no activity fo ", SSU_TERMINATION_TIMEOUT, " seconds");
Failed ();
}
}
const uint8_t * SSUSession::GetIntroKey () const
{
if (m_RemoteRouter)
{
// we are client
auto address = m_RemoteRouter->GetSSUAddress ();
return address ? (const uint8_t *)address->key : nullptr;
}
else
{
// we are server
auto address = i2p::context.GetRouterInfo ().GetSSUAddress ();
return address ? (const uint8_t *)address->key : nullptr;
}
}
void SSUSession::SendI2NPMessage (I2NPMessage * msg)
{
GetService ().post (std::bind (&SSUSession::PostI2NPMessage, shared_from_this (), msg));
}
void SSUSession::PostI2NPMessage (I2NPMessage * msg)
{
if (msg)
m_Data.Send (msg);
}
void SSUSession::SendI2NPMessages (const std::vector<I2NPMessage *>& msgs)
{
GetService ().post (std::bind (&SSUSession::PostI2NPMessages, shared_from_this (), msgs));
}
void SSUSession::PostI2NPMessages (std::vector<I2NPMessage *> msgs)
{
for (auto it: msgs)
if (it) m_Data.Send (it);
}
void SSUSession::ProcessData (uint8_t * buf, size_t len)
{
m_Data.ProcessMessage (buf, len);
}
void SSUSession::ProcessPeerTest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
{
uint8_t * buf1 = buf;
uint32_t nonce = bufbe32toh (buf);
buf += 4; // nonce
uint8_t size = *buf;
buf++; // size
uint32_t address = (size == 4) ? buf32toh(buf) : 0; // use it as is
buf += size; // address
uint16_t port = buf16toh(buf); // use it as is
buf += 2; // port
uint8_t * introKey = buf;
if (port && !address)
{
LogPrint (eLogWarning, "Address of ", size, " bytes not supported");
return;
}
if (m_PeerTestNonces.count (nonce) > 0)
{
// existing test
if (m_PeerTest)
{
LogPrint (eLogDebug, "SSU peer test from Bob. We are Alice");
m_PeerTestNonces.erase (nonce);
m_PeerTest = false;
}
else if (port)
{
LogPrint (eLogDebug, "SSU peer test from Charlie. We are Bob");
boost::asio::ip::udp::endpoint ep (boost::asio::ip::address_v4 (be32toh (address)), be16toh (port)); // Alice's address/port
auto session = m_Server.FindSession (ep); // find session with Alice
if (session)
session->Send (PAYLOAD_TYPE_PEER_TEST, buf1, len); // back to Alice
}
else
{
LogPrint (eLogDebug, "SSU peer test from Alice. We are Charlie");
SendPeerTest (nonce, senderEndpoint.address ().to_v4 ().to_ulong (),
senderEndpoint.port (), introKey); // to Alice
}
}
else
{
if (m_State == eSessionStateEstablished)
{
// new test
m_PeerTestNonces.insert (nonce);
if (port)
{
LogPrint (eLogDebug, "SSU peer test from Bob. We are Charlie");
Send (PAYLOAD_TYPE_PEER_TEST, buf1, len); // back to Bob
SendPeerTest (nonce, be32toh (address), be16toh (port), introKey); // to Alice
}
else
{
LogPrint (eLogDebug, "SSU peer test from Alice. We are Bob");
auto session = m_Server.GetRandomEstablishedSession (shared_from_this ()); // charlie
if (session)
session->SendPeerTest (nonce, senderEndpoint.address ().to_v4 ().to_ulong (),
senderEndpoint.port (), introKey, false);
}
}
else
LogPrint (eLogDebug, "SSU peer test from Charlie. We are Alice");
}
}
void SSUSession::SendPeerTest (uint32_t nonce, uint32_t address, uint16_t port,
const uint8_t * introKey, bool toAddress)
{
uint8_t buf[80 + 18];
uint8_t iv[16];
uint8_t * payload = buf + sizeof (SSUHeader);
htobe32buf (payload, nonce);
payload += 4; // nonce
if (address)
{
*payload = 4;
payload++; // size
htobe32buf (payload, address);
payload += 4; // address
}
else
{
*payload = 0;
payload++; //size
}
htobe16buf (payload, port);
payload += 2; // port
memcpy (payload, introKey, 32); // intro key
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
if (toAddress)
{
// encrypt message with specified intro key
FillHeaderAndEncrypt (PAYLOAD_TYPE_PEER_TEST, buf, 80, introKey, iv, introKey);
boost::asio::ip::udp::endpoint e (boost::asio::ip::address_v4 (address), port);
m_Server.Send (buf, 80, e);
}
else
{
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_PEER_TEST, buf, 80);
Send (buf, 80);
}
}
void SSUSession::SendPeerTest ()
{
LogPrint (eLogDebug, "SSU sending peer test");
auto address = i2p::context.GetRouterInfo ().GetSSUAddress ();
if (!address)
{
LogPrint (eLogError, "SSU is not supported. Can't send peer test");
return;
}
uint32_t nonce = i2p::context.GetRandomNumberGenerator ().GenerateWord32 ();
if (!nonce) nonce = 1;
m_PeerTestNonces.insert (nonce);
SendPeerTest (nonce, 0, 0, address->key, false); // address and port always zero for Alice
}
void SSUSession::SendKeepAlive ()
{
if (m_State == eSessionStateEstablished)
{
uint8_t buf[48 + 18];
uint8_t * payload = buf + sizeof (SSUHeader);
*payload = 0; // flags
payload++;
*payload = 0; // num fragments
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_DATA, buf, 48);
Send (buf, 48);
LogPrint (eLogDebug, "SSU keep-alive sent");
ScheduleTermination ();
}
}
void SSUSession::SendSesionDestroyed ()
{
if (m_IsSessionKey)
{
uint8_t buf[48 + 18];
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_DESTROYED, buf, 48);
Send (buf, 48);
LogPrint (eLogDebug, "SSU session destroyed sent");
}
}
void SSUSession::Send (uint8_t type, const uint8_t * payload, size_t len)
{
uint8_t buf[SSU_MTU_V4 + 18];
size_t msgSize = len + sizeof (SSUHeader);
if (msgSize > SSU_MTU_V4)
{
LogPrint (eLogWarning, "SSU payload size ", msgSize, " exceeds MTU");
return;
}
memcpy (buf + sizeof (SSUHeader), payload, len);
// encrypt message with session key
FillHeaderAndEncrypt (type, buf, msgSize);
Send (buf, msgSize);
}
void SSUSession::Send (const uint8_t * buf, size_t size)
{
m_NumSentBytes += size;
m_Server.Send (buf, size, m_RemoteEndpoint);
}
}
}
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