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Encrypt/Decrypt/Validate SSU packet

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pull/15/head
orignal 10 years ago
parent f69965f168
commit 58386bb88e
2 changed files with 130 additions and 11 deletions
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116
SSU.cpp
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@ -1,5 +1,7 @@
#include <string.h>
#include <boost/bind.hpp>
#include "Log.h"
#include "RouterContext.h"
#include "hmac.h"
#include "SSU.h"
@ -8,22 +10,94 @@ namespace i2p
namespace ssu
{
SSUSession::SSUSession (): m_State (eSessionStateUnknown)
SSUSession::SSUSession (SSUServer * server, const boost::asio::ip::udp::endpoint& remoteEndpoint,
i2p::data::RouterInfo * router): m_Server (server), m_RemoteEndpoint (remoteEndpoint),
m_State (eSessionStateUnknown)
{
}
void SSUSession::ProcessNextMessage (uint8_t * buf, std::size_t len)
void SSUSession::ProcessNextMessage (uint8_t * buf, size_t len)
{
switch (m_State)
{
case eSessionStateUnknown:
// we assume session request
ProcessSessionRequest (buf, len);
break;
default:
LogPrint ("SSU state not implemented yet");
}
}
void SSUSession::Authenticate (uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey)
void SSUSession::ProcessSessionRequest (uint8_t * buf, size_t len)
{
auto address = i2p::context.GetRouterInfo ().GetSSUAddress ();
if (address)
{
// use intro key for verification and decryption
if (Validate (buf, len, address->key))
{
m_State = eSessionStateRequestReceived;
LogPrint ("Session request received");
Decrypt (buf, len, address->key);
// TODO:
}
else
LogPrint ("MAC verifcation failed");
}
else
LogPrint ("SSU is not supported");
}
void SSUSession::Encrypt (uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint ("Unexpected SSU packet length ", len);
return;
}
SSUHeader * header = (SSUHeader *)buf;
memcpy (header->iv, iv, 16);
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
m_Encryption.SetKeyWithIV (aesKey, 32, iv);
m_Encryption.ProcessData (encrypted, encrypted, encryptedLen);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, iv, 16);
*(uint16_t *)(buf + len + 16) = htobe16 (encryptedLen);
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, header->mac);
}
void SSUSession::Decrypt (uint8_t * buf, size_t len, uint8_t * aesKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint ("Unexpected SSU packet length ", len);
return;
}
SSUHeader * header = (SSUHeader *)buf;
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
m_Decryption.SetKeyWithIV (aesKey, 32, header->iv);
m_Decryption.ProcessData (encrypted, encrypted, encryptedLen);
}
bool SSUSession::Validate (uint8_t * buf, size_t len, uint8_t * macKey)
{
if (len < sizeof (SSUHeader))
{
LogPrint ("Unexpected SSU packet length ", len);
return false;
}
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);
*(uint16_t *)(buf + len + 16) = htobe16 (encryptedLen);
uint8_t digest[16];
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, digest);
return !memcmp (header->mac, digest, 16);
}
SSUServer::SSUServer (boost::asio::io_service& service, int port):
@ -47,6 +121,11 @@ namespace ssu
m_Socket.close ();
}
void SSUServer::Send (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& to)
{
m_Socket.send_to (boost::asio::buffer (buf, len), to);
}
void SSUServer::Receive ()
{
m_Socket.async_receive_from (boost::asio::buffer (m_ReceiveBuffer, SSU_MTU), m_SenderEndpoint,
@ -62,9 +141,9 @@ namespace ssu
auto it = m_Sessions.find (m_SenderEndpoint);
if (it != m_Sessions.end ())
session = it->second;
if (session)
if (!session)
{
session = new SSUSession ();
session = new SSUSession (this, m_SenderEndpoint);
m_Sessions[m_SenderEndpoint] = session;
LogPrint ("New SSU session from ", m_SenderEndpoint.address ().to_string (), ":", m_SenderEndpoint.port (), " created");
}
@ -74,6 +153,33 @@ namespace ssu
else
LogPrint ("SSU receive error: ", ecode.message ());
}
SSUSession * SSUServer::GetSession (i2p::data::RouterInfo * router)
{
SSUSession * session = nullptr;
if (router)
{
auto address = router->GetSSUAddress ();
if (address)
{
boost::asio::ip::udp::endpoint remoteEndpoint (address->host, address->port);
auto it = m_Sessions.find (remoteEndpoint);
if (it != m_Sessions.end ())
session = it->second;
else
{
// otherwise create new session
session = new SSUSession (this, remoteEndpoint, router);
m_Sessions[remoteEndpoint] = session;
LogPrint ("New SSU session to [", router->GetIdentHashAbbreviation (), "] ",
remoteEndpoint.address ().to_string (), ":", remoteEndpoint.port (), " created");
}
}
else
LogPrint ("Router ", router->GetIdentHashAbbreviation (), " doesn't have SSU address");
}
return session;
}
}
}

25
SSU.h
Unescape Escape View File

@ -7,6 +7,7 @@
#include <cryptopp/modes.h>
#include <cryptopp/aes.h>
#include "I2PEndian.h"
#include "RouterInfo.h"
namespace i2p
{
@ -46,21 +47,30 @@ namespace ssu
eSessionStateEstablised
};
class SSUServer;
class SSUSession
{
public:
SSUSession ();
void ProcessNextMessage (uint8_t * buf, size_t len);
SSUSession (SSUServer * server, const boost::asio::ip::udp::endpoint& remoteEndpoint,
i2p::data::RouterInfo * router = nullptr);
void ProcessNextMessage (uint8_t * buf, size_t len);
private:
void Authenticate (uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey);
void ProcessSessionRequest (uint8_t * buf, size_t len);
void Encrypt (uint8_t * buf, size_t len, uint8_t * aesKey, uint8_t * iv, uint8_t * macKey);
void Decrypt (uint8_t * buf, size_t len, uint8_t * aesKey);
bool Validate (uint8_t * buf, size_t len, uint8_t * macKey);
private:
SSUServer * m_Server;
boost::asio::ip::udp::endpoint m_RemoteEndpoint;
SessionState m_State;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption;
CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption m_Decryption;
};
class SSUServer
@ -71,6 +81,9 @@ namespace ssu
~SSUServer ();
void Start ();
void Stop ();
SSUSession * GetSession (i2p::data::RouterInfo * router);
void Send (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& to);
private:
@ -81,7 +94,7 @@ namespace ssu
boost::asio::ip::udp::socket m_Socket;
boost::asio::ip::udp::endpoint m_SenderEndpoint;
uint8_t m_ReceiveBuffer[SSU_MTU];
uint8_t m_ReceiveBuffer[2*SSU_MTU];
std::map<boost::asio::ip::udp::endpoint, SSUSession *> m_Sessions;
};
}

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