I2P: End-to-End encrypted and anonymous Internet https://i2pd.website/
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#ifndef SSU_DATA_H__
#define SSU_DATA_H__
#include <inttypes.h>
#include <string.h>
#include <map>
#include <vector>
#include <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;
const size_t SSU_MTU_V6 = 1472;
const size_t IPV4_HEADER_SIZE = 20;
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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; // 1424
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const int RESEND_INTERVAL = 3; // in seconds
const int MAX_NUM_RESENDS = 5;
// 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 Fragment * f1, const Fragment * f2) const
{
return f1->fragmentNum < f2->fragmentNum;
};
};
struct IncompleteMessage
{
I2NPMessage * msg;
int nextFragmentNum;
std::set<Fragment *, FragmentCmp> savedFragments;
IncompleteMessage (I2NPMessage * m): msg (m), nextFragmentNum (0) {};
~IncompleteMessage () { for (auto it: savedFragments) { delete it; }; };
};
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struct SentMessage
{
std::vector<std::unique_ptr<Fragment> > fragments;
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uint32_t nextResendTime; // in seconds
int numResends;
};
class SSUSession;
class SSUData
{
public:
SSUData (SSUSession& session);
~SSUData ();
void ProcessMessage (uint8_t * buf, size_t len);
void Send (i2p::I2NPMessage * msg);
void UpdatePacketSize (const i2p::data::IdentHash& remoteIdent);
private:
void SendMsgAck (uint32_t msgID);
void SendFragmentAck (uint32_t msgID, int fragmentNum);
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 AdjustPacketSize (const i2p::data::RouterInfo& remoteRouter);
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private:
SSUSession& m_Session;
std::map<uint32_t, IncompleteMessage *> m_IncomleteMessages;
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std::map<uint32_t, SentMessage *> m_SentMessages;
std::set<uint32_t> m_ReceivedMessages;
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boost::asio::deadline_timer m_ResendTimer;
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int m_MaxPacketSize, m_PacketSize;
i2p::I2NPMessagesHandler m_Handler;
};
}
}
#endif