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@ -1,5 +1,11 @@
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#include <string.h>
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#include <boost/bind.hpp>
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#include <cryptopp/dh.h>
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#include <cryptopp/secblock.h>
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#include "CryptoConst.h"
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#include "Log.h"
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#include "Timestamp.h"
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#include "RouterContext.h"
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#include "hmac.h"
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#include "SSU.h"
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@ -8,16 +14,244 @@ namespace i2p
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namespace ssu
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{
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SSUSession::SSUSession (): m_State (eSessionStateUnknown)
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SSUSession::SSUSession (SSUServer * server, const boost::asio::ip::udp::endpoint& remoteEndpoint,
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i2p::data::RouterInfo * router): m_Server (server), m_RemoteEndpoint (remoteEndpoint),
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m_RemoteRouter (router), m_State (eSessionStateUnknown)
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{
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}
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void SSUSession::ProcessNextMessage (uint8_t * buf, std::size_t len)
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void SSUSession::CreateAESKey (uint8_t * pubKey, uint8_t * aesKey) // TODO: move it to base class for NTCP and SSU
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{
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CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
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CryptoPP::SecByteBlock secretKey(dh.AgreedValueLength());
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if (!dh.Agree (secretKey, i2p::context.GetPrivateKey (), pubKey))
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{
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LogPrint ("Couldn't create shared key");
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return;
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};
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if (secretKey[0] & 0x80)
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{
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aesKey[0] = 0;
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memcpy (aesKey + 1, secretKey, 31);
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}
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else
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memcpy (aesKey, secretKey, 32);
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}
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void SSUSession::ProcessNextMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
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{
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switch (m_State)
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{
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case eSessionStateUnknown:
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// session request
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ProcessSessionRequest (buf, len, senderEndpoint);
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break;
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case eSessionStateRequestSent:
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// session created
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ProcessSessionCreated (buf, len);
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break;
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default:
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LogPrint ("SSU state not implemented yet");
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}
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}
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void SSUSession::ProcessSessionRequest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
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{
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LogPrint ("Process session request");
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// use our intro key
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if (ProcessIntroKeyEncryptedMessage (PAYLOAD_TYPE_SESSION_REQUEST,
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i2p::context.GetRouterInfo (), buf, len))
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{
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m_State = eSessionStateRequestReceived;
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LogPrint ("Session request received");
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m_RemoteEndpoint = senderEndpoint;
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SendSessionCreated (buf + sizeof (SSUHeader));
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}
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}
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void SSUSession::ProcessSessionCreated (uint8_t * buf, size_t len)
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{
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LogPrint ("Process session created");
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if (!m_RemoteRouter)
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{
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LogPrint ("Unsolicited session created message");
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return;
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}
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// use remote intro key
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if (ProcessIntroKeyEncryptedMessage (PAYLOAD_TYPE_SESSION_CREATED, *m_RemoteRouter, buf, len))
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{
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m_State = eSessionStateCreatedReceived;
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LogPrint ("Session created received");
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boost::asio::ip::address_v4 ourAddress (be32toh (*(uint32_t* )(buf + sizeof (SSUHeader) + 257)));
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uint16_t ourPort = be16toh (*(uint16_t *)(buf + sizeof (SSUHeader) + 261));
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LogPrint ("Our external address is ", ourAddress.to_string (), ":", ourPort);
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}
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}
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void SSUSession::SendSessionRequest ()
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{
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auto address = m_RemoteRouter ? m_RemoteRouter->GetSSUAddress () : nullptr;
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if (!address)
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{
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LogPrint ("Missing remote SSU address");
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return;
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}
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uint8_t buf[304 + 18]; // 304 bytes for ipv4 (320 for ipv6)
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uint8_t * payload = buf + sizeof (SSUHeader);
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memcpy (payload, i2p::context.GetRouterIdentity ().publicKey, 256);
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payload[256] = 4; // we assume ipv4
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*(uint32_t *)(payload + 257) = htobe32 (address->host.to_v4 ().to_ulong ());
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uint8_t iv[16];
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CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
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rnd.GenerateBlock (iv, 16); // random iv
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FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_REQUEST, buf, 304, address->key, iv, address->key);
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m_State = eSessionStateRequestSent;
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m_Server->Send (buf, 304, m_RemoteEndpoint);
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}
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void SSUSession::SendSessionCreated (const uint8_t * x)
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{
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auto address = m_RemoteRouter ? m_RemoteRouter->GetSSUAddress () : nullptr;
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if (!address)
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{
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LogPrint ("Missing remote SSU address");
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return;
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}
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uint8_t signedData[532]; // x,y, remote IP, remote port, our IP, our port, relayTag, signed on time
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memcpy (signedData, x, 256); // x
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uint8_t buf[368 + 18];
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uint8_t * payload = buf + sizeof (SSUHeader);
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memcpy (payload, i2p::context.GetRouterIdentity ().publicKey, 256);
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memcpy (signedData + 256, payload, 256); // y
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payload += 256;
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*payload = 4; // we assume ipv4
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payload++;
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*(uint32_t *)(payload) = htobe32 (m_RemoteEndpoint.address ().to_v4 ().to_ulong ());
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payload += 4;
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*(uint16_t *)(payload) = htobe16 (m_RemoteEndpoint.port ());
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payload += 2;
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memcpy (signedData + 512, payload - 6, 6); // remote endpoint IP and port
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*(uint32_t *)(signedData + 518) = m_Server->GetEndpoint ().address ().to_v4 ().to_ulong (); // our IP
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*(uint16_t *)(signedData + 522) = htobe16 (m_Server->GetEndpoint ().port ()); // our port
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*(uint32_t *)(payload) = 0; // relay tag, always 0 for now
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payload += 4;
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*(uint32_t *)(payload) = htobe32 (i2p::util::GetSecondsSinceEpoch ()); // signed on time
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payload += 4;
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memcpy (signedData + 524, payload - 8, 8); // relayTag and signed on time
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i2p::context.Sign (signedData, 532, payload); // DSA signature
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// TODO: fill padding with random data
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uint8_t iv[16];
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CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
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rnd.GenerateBlock (iv, 16); // random iv
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// encrypt signature and 8 bytes padding with newly created session key
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m_Encryption.SetKeyWithIV (m_SessionKey, 32, iv);
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m_Encryption.ProcessData (payload, payload, 48);
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// encrypt message with intro key
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FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_CREATED, buf, 368, address->key, iv, address->key);
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m_State = eSessionStateRequestSent;
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m_Server->Send (buf, 368, m_RemoteEndpoint);
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}
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bool SSUSession::ProcessIntroKeyEncryptedMessage (uint8_t expectedPayloadType, i2p::data::RouterInfo& r, uint8_t * buf, size_t len)
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{
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auto address = r.GetSSUAddress ();
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if (address)
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{
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// use intro key for verification and decryption
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if (Validate (buf, len, address->key))
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{
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Decrypt (buf, len, address->key);
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SSUHeader * header = (SSUHeader *)buf;
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if ((header->flag >> 4) == expectedPayloadType)
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{
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CreateAESKey (buf + sizeof (SSUHeader), m_SessionKey);
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return true;
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}
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else
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LogPrint ("Unexpected payload type ", (int)(header->flag >> 4));
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}
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else
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LogPrint ("MAC verifcation failed");
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}
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else
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LogPrint ("SSU is not supported by ", r.GetIdentHashAbbreviation ());
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return false;
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}
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void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey)
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{
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if (len < sizeof (SSUHeader))
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{
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LogPrint ("Unexpected SSU packet length ", len);
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return;
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}
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SSUHeader * header = (SSUHeader *)buf;
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memcpy (header->iv, iv, 16);
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header->flag = payloadType << 4; // MSB is 0
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header->time = htobe32 (i2p::util::GetSecondsSinceEpoch ());
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uint8_t * encrypted = &header->flag;
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uint16_t encryptedLen = len - (encrypted - buf);
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m_Encryption.SetKeyWithIV (aesKey, 32, iv);
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m_Encryption.ProcessData (encrypted, encrypted, encryptedLen);
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// assume actual buffer size is 18 (16 + 2) bytes more
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memcpy (buf + len, iv, 16);
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*(uint16_t *)(buf + len + 16) = htobe16 (encryptedLen);
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i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, header->mac);
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}
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void SSUSession::Decrypt (uint8_t * buf, size_t len, uint8_t * aesKey)
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{
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if (len < sizeof (SSUHeader))
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{
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LogPrint ("Unexpected SSU packet length ", len);
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return;
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}
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SSUHeader * header = (SSUHeader *)buf;
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uint8_t * encrypted = &header->flag;
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uint16_t encryptedLen = len - (encrypted - buf);
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m_Decryption.SetKeyWithIV (aesKey, 32, header->iv);
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encryptedLen = (encryptedLen/16)*16; // make sure 16 bytes boundary
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m_Decryption.ProcessData (encrypted, encrypted, encryptedLen);
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}
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bool SSUSession::Validate (uint8_t * buf, size_t len, uint8_t * macKey)
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{
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if (len < sizeof (SSUHeader))
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{
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LogPrint ("Unexpected SSU packet length ", len);
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return false;
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}
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SSUHeader * header = (SSUHeader *)buf;
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uint8_t * encrypted = &header->flag;
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uint16_t encryptedLen = len - (encrypted - buf);
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// assume actual buffer size is 18 (16 + 2) bytes more
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memcpy (buf + len, header->iv, 16);
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*(uint16_t *)(buf + len + 16) = htobe16 (encryptedLen);
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uint8_t digest[16];
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i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, digest);
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return !memcmp (header->mac, digest, 16);
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}
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void SSUSession::Connect ()
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{
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SendSessionRequest ();
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}
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void SSUSession::SendI2NPMessage (I2NPMessage * msg)
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{
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// TODO:
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}
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SSUServer::SSUServer (boost::asio::io_service& service, int port):
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m_Socket (service, boost::asio::ip::udp::v4 (), port)
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m_Endpoint (boost::asio::ip::udp::v4 (), port), m_Socket (service, m_Endpoint)
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{
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}
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@ -37,6 +271,11 @@ namespace ssu
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m_Socket.close ();
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}
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void SSUServer::Send (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& to)
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{
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m_Socket.send_to (boost::asio::buffer (buf, len), to);
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}
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void SSUServer::Receive ()
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{
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m_Socket.async_receive_from (boost::asio::buffer (m_ReceiveBuffer, SSU_MTU), m_SenderEndpoint,
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@ -52,18 +291,46 @@ namespace ssu
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auto it = m_Sessions.find (m_SenderEndpoint);
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if (it != m_Sessions.end ())
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session = it->second;
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if (session)
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if (!session)
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{
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session = new SSUSession ();
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session = new SSUSession (this, m_SenderEndpoint);
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m_Sessions[m_SenderEndpoint] = session;
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LogPrint ("New SSU session from ", m_SenderEndpoint.address ().to_string (), ":", m_SenderEndpoint.port (), " created");
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}
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session->ProcessNextMessage (m_ReceiveBuffer, bytes_transferred);
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session->ProcessNextMessage (m_ReceiveBuffer, bytes_transferred, m_SenderEndpoint);
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Receive ();
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}
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else
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LogPrint ("SSU receive error: ", ecode.message ());
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}
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SSUSession * SSUServer::GetSession (i2p::data::RouterInfo * router)
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{
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SSUSession * session = nullptr;
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if (router)
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{
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auto address = router->GetSSUAddress ();
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if (address)
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{
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boost::asio::ip::udp::endpoint remoteEndpoint (address->host, address->port);
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auto it = m_Sessions.find (remoteEndpoint);
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if (it != m_Sessions.end ())
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session = it->second;
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else
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{
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// otherwise create new session
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session = new SSUSession (this, remoteEndpoint, router);
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m_Sessions[remoteEndpoint] = session;
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LogPrint ("New SSU session to [", router->GetIdentHashAbbreviation (), "] ",
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remoteEndpoint.address ().to_string (), ":", remoteEndpoint.port (), " created");
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session->Connect ();
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}
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}
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else
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LogPrint ("Router ", router->GetIdentHashAbbreviation (), " doesn't have SSU address");
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}
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return session;
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}
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}
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}
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chertov
11 years ago