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I2P: End-to-End encrypted and anonymous Internet
https://i2pd.website/
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344 lines
12 KiB
344 lines
12 KiB
/* |
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* Copyright (c) 2022, The PurpleI2P Project |
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* |
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* This file is part of Purple i2pd project and licensed under BSD3 |
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* |
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* See full license text in LICENSE file at top of project tree |
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*/ |
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#include <string.h> |
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#include <openssl/rand.h> |
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#include "Log.h" |
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#include "RouterContext.h" |
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#include "Transports.h" |
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#include "Config.h" |
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#include "SSU2.h" |
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namespace i2p |
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{ |
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namespace transport |
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{ |
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static uint64_t CreateHeaderMask (const uint8_t * kh, const uint8_t * nonce) |
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{ |
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uint64_t data = 0; |
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i2p::crypto::ChaCha20 ((uint8_t *)&data, 8, kh, nonce, (uint8_t *)&data); |
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return data; |
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} |
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SSU2Session::SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter, |
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std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool peerTest): |
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TransportSession (in_RemoteRouter, SSU2_TERMINATION_TIMEOUT), |
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m_Server (server), m_Address (addr), m_DestConnID (0), m_SourceConnID (0) |
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{ |
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m_NoiseState.reset (new i2p::crypto::NoiseSymmetricState); |
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if (in_RemoteRouter && m_Address) |
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{ |
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// outgoing |
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InitNoiseXKState1 (*m_NoiseState, m_Address->s); |
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m_RemoteEndpoint = boost::asio::ip::udp::endpoint (m_Address->host, m_Address->port); |
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} |
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else |
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{ |
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// incoming |
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InitNoiseXKState1 (*m_NoiseState, i2p::context.GetSSU2StaticPublicKey ()); |
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} |
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} |
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SSU2Session::~SSU2Session () |
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{ |
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} |
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void SSU2Session::SendSessionRequest () |
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{ |
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// we are Alice |
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m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair (); |
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Header header; |
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uint8_t headerX[48], payload[1200]; // TODO: correct payload size |
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size_t payloadSize = 8; |
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// fill packet |
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RAND_bytes ((uint8_t *)&m_DestConnID, 8); |
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header.h.connID = m_DestConnID; // dest id |
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memset (header.h.packetNum, 0, 4); |
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header.h.type = eSSU2SessionRequest; |
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header.h.flags[0] = 2; // ver |
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header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID |
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header.h.flags[2] = 0; // flag |
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RAND_bytes ((uint8_t *)&m_SourceConnID, 8); |
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memcpy (headerX, &m_SourceConnID, 8); // source id |
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RAND_bytes (headerX + 8, 8); // token |
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memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // X |
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m_Server.AddPendingOutgoingSession (boost::asio::ip::udp::endpoint (m_Address->host, m_Address->port), shared_from_this ()); |
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// KDF for session request |
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m_NoiseState->MixHash ({ {header.buf, 16}, {headerX, 16} }); // h = SHA256(h || header) |
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m_NoiseState->MixHash (m_EphemeralKeys->GetPublicKey (), 32); // h = SHA256(h || aepk); |
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uint8_t sharedSecret[32]; |
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m_EphemeralKeys->Agree (m_Address->s, sharedSecret); |
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m_NoiseState->MixKey (sharedSecret); |
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// encrypt |
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const uint8_t nonce[12] = {0}; |
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i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true); |
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payloadSize += 16; |
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header.ll[0] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 24)); |
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header.ll[1] ^= CreateHeaderMask (m_Address->i, payload + (payloadSize - 12)); |
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i2p::crypto::ChaCha20 (headerX, 48, m_Address->i, nonce, headerX); |
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m_NoiseState->MixHash (payload, 32); // h = SHA256(h || 32 byte encrypted payload from Session Request) for SessionCreated |
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// send |
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m_Server.Send (header.buf, 16, headerX, 48, payload, payloadSize, m_RemoteEndpoint); |
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} |
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void SSU2Session::ProcessSessionRequest (uint64_t connID, uint8_t * buf, size_t len) |
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{ |
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// we are Bob |
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m_SourceConnID = connID; |
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Header header; |
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header.h.connID = connID; |
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memcpy (header.buf + 8, buf + 8, 8); |
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header.ll[1] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 12)); |
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if (header.h.type != eSSU2SessionRequest) |
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{ |
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LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type); |
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return; |
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} |
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const uint8_t nonce[12] = {0}; |
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uint8_t headerX[48]; |
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i2p::crypto::ChaCha20 (buf + 16, 48, i2p::context.GetSSU2IntroKey (), nonce, headerX); |
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memcpy (&m_DestConnID, headerX, 8); |
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// KDF for session request |
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m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header) |
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m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || aepk); |
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uint8_t sharedSecret[32]; |
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i2p::context.GetSSU2StaticKeys ().Agree (headerX + 16, sharedSecret); |
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m_NoiseState->MixKey (sharedSecret); |
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// decrypt |
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uint8_t * payload = buf + 64; |
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if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, len - 80, false)) |
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{ |
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LogPrint (eLogWarning, "SSU2: SessionRequest AEAD verification failed "); |
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return; |
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} |
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// process payload |
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m_Server.AddSession (m_SourceConnID, shared_from_this ()); |
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SendSessionCreated (headerX + 16); |
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} |
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void SSU2Session::SendSessionCreated (const uint8_t * X) |
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{ |
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// we are Bob |
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m_EphemeralKeys = i2p::transport::transports.GetNextX25519KeysPair (); |
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// fill packet |
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Header header; |
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uint8_t headerX[48], payload[1200]; // TODO: correct payload size |
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size_t payloadSize = 8; |
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header.h.connID = m_DestConnID; // dest id |
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memset (header.h.packetNum, 0, 4); |
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header.h.type = eSSU2SessionCreated; |
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header.h.flags[0] = 2; // ver |
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header.h.flags[1] = (uint8_t)i2p::context.GetNetID (); // netID |
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header.h.flags[2] = 0; // flag |
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memcpy (headerX, &m_SourceConnID, 8); // source id |
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RAND_bytes (headerX + 8, 8); // token |
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memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // Y |
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// KDF for SessionCreated |
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m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header) |
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m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || bepk); |
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uint8_t sharedSecret[32]; |
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m_EphemeralKeys->Agree (X, sharedSecret); |
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m_NoiseState->MixKey (sharedSecret); |
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// encrypt |
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const uint8_t nonce[12] = {0}; |
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i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true); |
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payloadSize += 16; |
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header.ll[0] ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), payload + (payloadSize - 24)); |
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uint8_t kh2[32]; |
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i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessCreateHeader", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessCreateHeader", 32) |
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header.ll[1] ^= CreateHeaderMask (kh2, payload + (payloadSize - 12)); |
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i2p::crypto::ChaCha20 (headerX, 48, kh2, nonce, headerX); |
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// send |
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m_Server.Send (header.buf, 16, headerX, 48, payload, payloadSize, m_RemoteEndpoint); |
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} |
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bool SSU2Session::ProcessSessionCreated (uint8_t * buf, size_t len) |
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{ |
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// we are Alice |
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Header header; |
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header.h.connID = m_SourceConnID; |
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memcpy (header.buf + 8, buf + 8, 8); |
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uint8_t kh2[32]; |
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i2p::crypto::HKDF (m_NoiseState->m_CK, nullptr, 0, "SessCreateHeader", kh2, 32); // k_header_2 = HKDF(chainKey, ZEROLEN, "SessCreateHeader", 32) |
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header.ll[1] ^= CreateHeaderMask (kh2, buf + (len - 12)); |
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if (header.h.type != eSSU2SessionCreated) |
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{ |
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LogPrint (eLogWarning, "SSU2: Unexpected message type ", (int)header.h.type); |
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return false; |
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} |
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const uint8_t nonce[12] = {0}; |
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uint8_t headerX[48]; |
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i2p::crypto::ChaCha20 (buf + 16, 48, kh2, nonce, headerX); |
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// KDF for SessionCreated |
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m_NoiseState->MixHash ( { {header.buf, 16}, {headerX, 16} } ); // h = SHA256(h || header) |
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m_NoiseState->MixHash (headerX + 16, 32); // h = SHA256(h || bepk); |
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uint8_t sharedSecret[32]; |
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m_EphemeralKeys->Agree (headerX + 16, sharedSecret); |
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m_NoiseState->MixKey (sharedSecret); |
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// decrypt |
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uint8_t * payload = buf + 64; |
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if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len - 80, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, len - 80, false)) |
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{ |
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LogPrint (eLogWarning, "SSU2: SessionCreated AEAD verification failed "); |
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return false; |
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} |
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// process payload |
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m_Server.AddSession (m_SourceConnID, shared_from_this ()); |
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return true; |
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} |
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SSU2Server::SSU2Server (): |
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RunnableServiceWithWork ("SSU2"), m_Socket (GetService ()) |
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{ |
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} |
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void SSU2Server::Start () |
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{ |
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if (!IsRunning ()) |
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{ |
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StartIOService (); |
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auto& addresses = i2p::context.GetRouterInfo ().GetAddresses (); |
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for (const auto& address: addresses) |
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{ |
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if (!address) continue; |
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if (address->transportStyle == i2p::data::RouterInfo::eTransportSSU2) |
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{ |
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auto port = address->port; |
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if (!port) |
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{ |
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uint16_t ssu2Port; i2p::config::GetOption ("ssu2.port", ssu2Port); |
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if (ssu2Port) port = ssu2Port; |
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else |
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{ |
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uint16_t p; i2p::config::GetOption ("port", p); |
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if (p) port = p; |
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} |
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} |
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if (port) |
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{ |
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OpenSocket (port); |
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Receive (); |
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} |
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else |
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LogPrint (eLogError, "SSU2: Can't start server because port not specified "); |
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break; |
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} |
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} |
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} |
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} |
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void SSU2Server::Stop () |
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{ |
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StopIOService (); |
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} |
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void SSU2Server::OpenSocket (int port) |
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{ |
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try |
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{ |
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m_Socket.open (boost::asio::ip::udp::v6()); |
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m_Socket.set_option (boost::asio::socket_base::receive_buffer_size (SSU2_SOCKET_RECEIVE_BUFFER_SIZE)); |
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m_Socket.set_option (boost::asio::socket_base::send_buffer_size (SSU2_SOCKET_SEND_BUFFER_SIZE)); |
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m_Socket.bind (boost::asio::ip::udp::endpoint (boost::asio::ip::udp::v6(), port)); |
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LogPrint (eLogInfo, "SSU2: Start listening port ", port); |
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} |
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catch (std::exception& ex ) |
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{ |
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LogPrint (eLogError, "SSU2: Failed to bind to port ", port, ": ", ex.what()); |
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ThrowFatal ("Unable to start SSU2 transport at port ", port, ": ", ex.what ()); |
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} |
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} |
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void SSU2Server::Receive () |
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{ |
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Packet * packet = m_PacketsPool.AcquireMt (); |
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m_Socket.async_receive_from (boost::asio::buffer (packet->buf, SSU2_MTU), packet->from, |
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std::bind (&SSU2Server::HandleReceivedFrom, this, std::placeholders::_1, std::placeholders::_2, packet)); |
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} |
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void SSU2Server::HandleReceivedFrom (const boost::system::error_code& ecode, size_t bytes_transferred, Packet * packet) |
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{ |
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if (!ecode) |
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{ |
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packet->len = bytes_transferred; |
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ProcessNextPacket (packet->buf, packet->len, packet->from); |
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m_PacketsPool.ReleaseMt (packet); |
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Receive (); |
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} |
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else |
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{ |
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m_PacketsPool.ReleaseMt (packet); |
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if (ecode != boost::asio::error::operation_aborted) |
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{ |
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LogPrint (eLogError, "SSU2: Receive error: code ", ecode.value(), ": ", ecode.message ()); |
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auto port = m_Socket.local_endpoint ().port (); |
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m_Socket.close (); |
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OpenSocket (port); |
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Receive (); |
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} |
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} |
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} |
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void SSU2Server::AddSession (uint64_t connID, std::shared_ptr<SSU2Session> session) |
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{ |
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m_Sessions.emplace (connID, session); |
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} |
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void SSU2Server::AddPendingOutgoingSession (const boost::asio::ip::udp::endpoint& ep, std::shared_ptr<SSU2Session> session) |
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{ |
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m_PendingOutgoingSessions.emplace (ep, session); |
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} |
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void SSU2Server::ProcessNextPacket (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint) |
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{ |
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uint64_t connID; |
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memcpy (&connID, buf, 8); |
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connID ^= CreateHeaderMask (i2p::context.GetSSU2IntroKey (), buf + (len - 24)); |
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auto it = m_Sessions.find (connID); |
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if (it != m_Sessions.end ()) |
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{ |
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} |
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else |
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{ |
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// check pending sessions if it's SessionCreated |
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auto it1 = m_PendingOutgoingSessions.find (senderEndpoint); |
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if (it1 != m_PendingOutgoingSessions.end ()) |
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{ |
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if (it1->second->ProcessSessionCreated (buf, len)) |
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m_PendingOutgoingSessions.erase (it1); |
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} |
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else |
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{ |
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// assume new incoming session |
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auto session = std::make_shared<SSU2Session> (*this); |
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session->SetRemoteEndpoint (senderEndpoint); |
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session->ProcessSessionRequest (connID, buf, len); |
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} |
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} |
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} |
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void SSU2Server::Send (const uint8_t * header, size_t headerLen, const uint8_t * headerX, size_t headerXLen, |
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const uint8_t * payload, size_t payloadLen, const boost::asio::ip::udp::endpoint& to) |
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{ |
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std::vector<boost::asio::const_buffer> bufs |
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{ |
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boost::asio::buffer (header, headerLen), |
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boost::asio::buffer (headerX, headerXLen), |
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boost::asio::buffer (payload, payloadLen) |
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}; |
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boost::system::error_code ec; |
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m_Socket.send_to (bufs, to, 0, ec); |
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} |
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} |
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}
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