I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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/*
* Copyright (c) 2013-2021, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/
#ifndef SSU_DATA_H__
#define SSU_DATA_H__
#include <inttypes.h>
#include <string.h>
#include <unordered_map>
#include <vector>
#include <unordered_set>
#include <memory>
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#include <boost/asio.hpp>
#include "I2NPProtocol.h"
#include "Identity.h"
#include "RouterInfo.h"
namespace i2p
{
namespace transport
{
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const size_t SSU_MTU_V4 = 1484;
#ifdef MESHNET
const size_t SSU_MTU_V6 = 1286;
#else
const size_t SSU_MTU_V6 = 1488;
#endif
const size_t IPV4_HEADER_SIZE = 20;
const size_t IPV6_HEADER_SIZE = 40;
const size_t UDP_HEADER_SIZE = 8;
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const size_t SSU_V4_MAX_PACKET_SIZE = SSU_MTU_V4 - IPV4_HEADER_SIZE - UDP_HEADER_SIZE; // 1456
const size_t SSU_V6_MAX_PACKET_SIZE = SSU_MTU_V6 - IPV6_HEADER_SIZE - UDP_HEADER_SIZE; // 1440
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const int RESEND_INTERVAL = 3; // in seconds
const int MAX_NUM_RESENDS = 5;
const int DECAY_INTERVAL = 20; // in seconds
const int INCOMPLETE_MESSAGES_CLEANUP_TIMEOUT = 30; // in seconds
const unsigned int MAX_NUM_RECEIVED_MESSAGES = 1000; // how many msgID we store for duplicates check
const int MAX_OUTGOING_WINDOW_SIZE = 200; // how many unacked message we can store
// data flags
const uint8_t DATA_FLAG_EXTENDED_DATA_INCLUDED = 0x02;
const uint8_t DATA_FLAG_WANT_REPLY = 0x04;
const uint8_t DATA_FLAG_REQUEST_PREVIOUS_ACKS = 0x08;
const uint8_t DATA_FLAG_EXPLICIT_CONGESTION_NOTIFICATION = 0x10;
const uint8_t DATA_FLAG_ACK_BITFIELDS_INCLUDED = 0x40;
const uint8_t DATA_FLAG_EXPLICIT_ACKS_INCLUDED = 0x80;
struct Fragment
{
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int fragmentNum;
size_t len;
bool isLast;
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uint8_t buf[SSU_V4_MAX_PACKET_SIZE + 18]; // use biggest
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Fragment () = default;
Fragment (int n, const uint8_t * b, int l, bool last):
fragmentNum (n), len (l), isLast (last) { memcpy (buf, b, len); };
};
struct FragmentCmp
{
bool operator() (const std::shared_ptr<Fragment>& f1, const std::shared_ptr<Fragment>& f2) const
{
return f1->fragmentNum < f2->fragmentNum;
};
};
struct IncompleteMessage
{
std::shared_ptr<I2NPMessage> msg;
int nextFragmentNum;
uint32_t lastFragmentInsertTime; // in seconds
uint64_t receivedFragmentsBits;
std::set<std::shared_ptr<Fragment>, FragmentCmp> savedFragments;
IncompleteMessage (std::shared_ptr<I2NPMessage> m): msg (m), nextFragmentNum (0),
lastFragmentInsertTime (0), receivedFragmentsBits (0) {};
void AttachNextFragment (const uint8_t * fragment, size_t fragmentSize);
};
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struct SentMessage
{
std::vector<std::shared_ptr<Fragment> > fragments;
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uint32_t nextResendTime; // in seconds
int numResends;
};
class SSUSession;
class SSUData
{
public:
SSUData (SSUSession& session);
~SSUData ();
void Start ();
void Stop ();
void ProcessMessage (uint8_t * buf, size_t len);
void FlushReceivedMessage ();
void Send (std::shared_ptr<i2p::I2NPMessage> msg);
void AdjustPacketSize (std::shared_ptr<const i2p::data::RouterInfo> remoteRouter);
void UpdatePacketSize (const i2p::data::IdentHash& remoteIdent);
private:
void SendMsgAck (uint32_t msgID);
void SendFragmentAck (uint32_t msgID, uint64_t bits);
void ProcessAcks (uint8_t *& buf, uint8_t flag);
void ProcessFragments (uint8_t * buf);
void ProcessSentMessageAck (uint32_t msgID);
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void ScheduleResend ();
void HandleResendTimer (const boost::system::error_code& ecode);
void ScheduleIncompleteMessagesCleanup ();
void HandleIncompleteMessagesCleanupTimer (const boost::system::error_code& ecode);
private:
SSUSession& m_Session;
std::unordered_map<uint32_t, std::shared_ptr<IncompleteMessage> > m_IncompleteMessages;
std::unordered_map<uint32_t, std::shared_ptr<SentMessage> > m_SentMessages;
std::unordered_set<uint32_t> m_ReceivedMessages;
boost::asio::deadline_timer m_ResendTimer, m_IncompleteMessagesCleanupTimer;
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int m_MaxPacketSize, m_PacketSize;
i2p::I2NPMessagesHandler m_Handler;
uint32_t m_LastMessageReceivedTime; // in second
};
}
}
#endif