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handle SSU2 SessionConfirmed

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orignal 2022-03-23 14:06:55 -04:00
parent 77c5dde320
commit 2440ffbfc9
4 changed files with 118 additions and 2 deletions
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10
libi2pd/RouterInfo.cpp
View File

@ -895,6 +895,16 @@ namespace data
});
}
std::shared_ptr<const RouterInfo::Address> RouterInfo::GetSSU2AddressWithStaticKey (const uint8_t * key) const
{
if (!key) return nullptr;
return GetAddress (
[key](std::shared_ptr<const RouterInfo::Address> address)->bool
{
return address->IsSSU2 () && !memcmp (address->s, key, 32);
});
}
std::shared_ptr<const RouterInfo::Address> RouterInfo::GetPublishedNTCP2V4Address () const
{
return GetAddress (

1
libi2pd/RouterInfo.h
View File

@ -183,6 +183,7 @@ namespace data
virtual void ClearProperties () {};
Addresses& GetAddresses () { return *m_Addresses; }; // should be called for local RI only, otherwise must return shared_ptr
std::shared_ptr<const Address> GetNTCP2AddressWithStaticKey (const uint8_t * key) const;
std::shared_ptr<const Address> GetSSU2AddressWithStaticKey (const uint8_t * key) const;
std::shared_ptr<const Address> GetPublishedNTCP2V4Address () const;
std::shared_ptr<const Address> GetPublishedNTCP2V6Address () const;
std::shared_ptr<const Address> GetSSUAddress (bool v4only = true) const;

107
libi2pd/SSU2.cpp
View File

@ -13,6 +13,7 @@
#include "Transports.h"
#include "Config.h"
#include "Gzip.h"
#include "NetDb.hpp"
#include "SSU2.h"
namespace i2p
@ -239,7 +240,7 @@ namespace transport
// fill packet
Header header;
header.h.connID = m_DestConnID; // dest id
header.h.packetNum = htobe32 (1);
header.h.packetNum = 0;
header.h.type = eSSU2SessionConfirmed;
header.h.flags[0] = 2; // ver
header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID
@ -293,6 +294,79 @@ namespace transport
// send
m_Server.Send (header.buf, 16, part1, 48, payload, payloadSize, m_RemoteEndpoint);
}
bool SSU2Session::ProcessSessionConfirmed (uint8_t * buf, size_t len)
{
// we are Bob
Header header;
memcpy (header.buf, buf, 16);
header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 24));
uint8_t kh2[32];
i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessionConfirmed", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessionConfirmed", 32)
header.ll[1] ^= CreateHeaderMask (kh2, buf + (len - 12));
if (header.h.type != eSSU2SessionConfirmed)
{
LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type);
return false;
}
// KDF for Session Confirmed part 1
m_NoiseState->MixHash (header.buf, 16); // h = SHA256(h || header)
// decrypt part1
uint8_t nonce[12];
CreateNonce (1, nonce);
uint8_t S[32];
if (!i2p::crypto::AEADChaCha20Poly1305 (buf + 16, 32, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, S, 32, false))
{
LogPrint (eLogWarning, "SSU2: SessionConfirmed part 1 AEAD verification failed ");
return false;
}
m_NoiseState->MixHash (buf + 16, 48); // h = SHA256(h || ciphertext);
// KDF for Session Confirmed part 2
uint8_t sharedSecret[32];
m_EphemeralKeys->Agree (S, sharedSecret);
m_NoiseState->MixKey (sharedSecret);
// decrypt part2
uint8_t * payload = buf + 64;
std::vector<uint8_t> decryptedPayload(len - 80);
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32,
m_NoiseState->m_CK + 32, nonce, decryptedPayload.data (), decryptedPayload.size (), false))
{
LogPrint (eLogWarning, "SSU2: SessionConfirmed part 2 AEAD verification failed ");
return false;
}
m_NoiseState->MixHash (payload, len - 64); // h = SHA256(h || ciphertext);
// payload
// handle RouterInfo block that must be first
if (decryptedPayload[0] != eSSU2BlkRouterInfo)
{
LogPrint (eLogError, "SSU2: SessionConfirmed unexpected first block type ", (int)decryptedPayload[0]);
return false;
}
size_t riSize = bufbe16toh (decryptedPayload.data () + 1);
if (riSize + 3 > decryptedPayload.size ())
{
LogPrint (eLogError, "SSU2: SessionConfirmed RouterInfo block is too long ", riSize);
return false;
}
LogPrint (eLogDebug, "SSU2: RouterInfo in SessionConfirmed");
auto ri = ExtractRouterInfo (decryptedPayload.data () + 3, riSize);
if (!ri)
{
LogPrint (eLogError, "SSU2: SessionConfirmed malformed RouterInfo block");
return false;
}
if (!ri->GetSSU2AddressWithStaticKey (S))
{
LogPrint (eLogError, "SSU2: No SSU2 address with static key found in SessionConfirmed");
return false;
}
i2p::data::netdb.PostI2NPMsg (CreateI2NPMessage (eI2NPDummyMsg, ri->GetBuffer (), ri->GetBufferLen ())); // TODO: should insert ri
// handle other blocks
HandlePayload (decryptedPayload.data () + riSize + 3, decryptedPayload.size () - riSize - 3);
return true;
}
bool SSU2Session::ProcessRetry (uint8_t * buf, size_t len)
{
@ -339,7 +413,14 @@ namespace transport
LogPrint (eLogDebug, "SSU2: Options");
break;
case eSSU2BlkRouterInfo:
break;
{
// not from SessionConfirmed
LogPrint (eLogDebug, "SSU2: RouterInfo");
auto ri = ExtractRouterInfo (buf + offset, size);
if (ri)
i2p::data::netdb.PostI2NPMsg (CreateI2NPMessage (eI2NPDummyMsg, ri->GetBuffer (), ri->GetBufferLen ())); // TODO: should insert ri
break;
}
case eSSU2BlkI2NPMessage:
break;
case eSSU2BlkFirstFragment:
@ -445,6 +526,26 @@ namespace transport
return size + 3;
}
std::shared_ptr<const i2p::data::RouterInfo> SSU2Session::ExtractRouterInfo (const uint8_t * buf, size_t size)
{
if (size < 2) return nullptr;
// TODO: handle frag
std::shared_ptr<const i2p::data::RouterInfo> ri;
if (buf[0] & SSU2_ROUTER_INFO_FLAG_GZIP)
{
i2p::data::GzipInflator inflator;
uint8_t uncompressed[i2p::data::MAX_RI_BUFFER_SIZE];
size_t uncompressedSize = inflator.Inflate (buf + 2, size - 2, uncompressed, i2p::data::MAX_RI_BUFFER_SIZE);
if (uncompressedSize && uncompressedSize < i2p::data::MAX_RI_BUFFER_SIZE)
ri = std::make_shared<i2p::data::RouterInfo>(uncompressed, uncompressedSize);
else
LogPrint (eLogInfo, "SSU2: RouterInfo decompression failed ", uncompressedSize);
}
else
ri = std::make_shared<i2p::data::RouterInfo>(buf + 2, size - 2);
return ri;
}
void SSU2Session::CreateNonce (uint64_t seqn, uint8_t * nonce)
{
memset (nonce, 0, 4);
@ -572,6 +673,8 @@ namespace transport
auto it = m_Sessions.find (connID);
if (it != m_Sessions.end ())
{
// TODO: check state
it->second->ProcessSessionConfirmed (buf, len);
}
else
{

2
libi2pd/SSU2.h
View File

@ -96,6 +96,7 @@ namespace transport
void ProcessSessionRequest (uint64_t connID, uint8_t * buf, size_t len);
bool ProcessSessionCreated (uint8_t * buf, size_t len);
bool ProcessSessionConfirmed (uint8_t * buf, size_t len);
bool ProcessRetry (uint8_t * buf, size_t len);
private:
@ -107,6 +108,7 @@ namespace transport
void HandlePayload (const uint8_t * buf, size_t len);
bool ExtractEndpoint (const uint8_t * buf, size_t size, boost::asio::ip::udp::endpoint& ep);
size_t CreateAddressBlock (const boost::asio::ip::udp::endpoint& ep, uint8_t * buf, size_t len);
std::shared_ptr<const i2p::data::RouterInfo> ExtractRouterInfo (const uint8_t * buf, size_t size);
void CreateNonce (uint64_t seqn, uint8_t * nonce);
private: