mirror of
https://github.com/PurpleI2P/i2pd.git
synced 2024-11-04 06:00:37 +00:00
306 lines
9.5 KiB
C++
306 lines
9.5 KiB
C++
/*
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* Copyright (c) 2013-2020, 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 "I2PEndian.h"
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#include <string.h>
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#include "Crypto.h"
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#include "Log.h"
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#include "NetDb.hpp"
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#include "I2NPProtocol.h"
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#include "Transports.h"
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#include "RouterContext.h"
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#include "Timestamp.h"
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#include "TunnelEndpoint.h"
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namespace i2p
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{
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namespace tunnel
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{
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TunnelEndpoint::~TunnelEndpoint ()
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{
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}
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void TunnelEndpoint::HandleDecryptedTunnelDataMsg (std::shared_ptr<I2NPMessage> msg)
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{
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m_NumReceivedBytes += TUNNEL_DATA_MSG_SIZE;
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uint8_t * decrypted = msg->GetPayload () + 20; // 4 + 16
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uint8_t * zero = (uint8_t *)memchr (decrypted + 4, 0, TUNNEL_DATA_ENCRYPTED_SIZE - 4); // witout 4-byte checksum
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if (zero)
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{
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uint8_t * fragment = zero + 1;
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// verify checksum
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memcpy (msg->GetPayload () + TUNNEL_DATA_MSG_SIZE, msg->GetPayload () + 4, 16); // copy iv to the end
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uint8_t hash[32];
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SHA256(fragment, TUNNEL_DATA_MSG_SIZE -(fragment - msg->GetPayload ()) + 16, hash); // payload + iv
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if (memcmp (hash, decrypted, 4))
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{
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LogPrint (eLogError, "TunnelMessage: checksum verification failed");
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return;
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}
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// process fragments
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while (fragment < decrypted + TUNNEL_DATA_ENCRYPTED_SIZE)
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{
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uint8_t flag = fragment[0];
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fragment++;
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bool isFollowOnFragment = flag & 0x80, isLastFragment = true;
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uint32_t msgID = 0;
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int fragmentNum = 0;
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TunnelMessageBlockEx m;
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if (!isFollowOnFragment)
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{
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// first fragment
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m.deliveryType = (TunnelDeliveryType)((flag >> 5) & 0x03);
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switch (m.deliveryType)
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{
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case eDeliveryTypeLocal: // 0
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break;
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case eDeliveryTypeTunnel: // 1
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m.tunnelID = bufbe32toh (fragment);
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fragment += 4; // tunnelID
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m.hash = i2p::data::IdentHash (fragment);
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fragment += 32; // hash
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break;
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case eDeliveryTypeRouter: // 2
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m.hash = i2p::data::IdentHash (fragment);
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fragment += 32; // to hash
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break;
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default: ;
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}
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bool isFragmented = flag & 0x08;
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if (isFragmented)
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{
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// Message ID
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msgID = bufbe32toh (fragment);
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fragment += 4;
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isLastFragment = false;
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}
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}
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else
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{
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// follow on
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msgID = bufbe32toh (fragment); // MessageID
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fragment += 4;
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fragmentNum = (flag >> 1) & 0x3F; // 6 bits
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isLastFragment = flag & 0x01;
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}
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uint16_t size = bufbe16toh (fragment);
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fragment += 2;
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msg->offset = fragment - msg->buf;
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msg->len = msg->offset + size;
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if (msg->len > msg->maxLen)
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{
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LogPrint (eLogError, "TunnelMessage: fragment is too long ", (int)size);
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return;
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}
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if (fragment + size < decrypted + TUNNEL_DATA_ENCRYPTED_SIZE)
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{
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// this is not last message. we have to copy it
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m.data = NewI2NPTunnelMessage ();
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m.data->offset += TUNNEL_GATEWAY_HEADER_SIZE; // reserve room for TunnelGateway header
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m.data->len += TUNNEL_GATEWAY_HEADER_SIZE;
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*(m.data) = *msg;
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}
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else
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m.data = msg;
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if (!isFollowOnFragment && isLastFragment)
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HandleNextMessage (m);
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else
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{
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if (msgID) // msgID is presented, assume message is fragmented
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{
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if (!isFollowOnFragment) // create new incomlete message
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{
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m.nextFragmentNum = 1;
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m.receiveTime = i2p::util::GetMillisecondsSinceEpoch ();
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auto ret = m_IncompleteMessages.insert (std::pair<uint32_t, TunnelMessageBlockEx>(msgID, m));
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if (ret.second)
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HandleOutOfSequenceFragments (msgID, ret.first->second);
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else
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LogPrint (eLogError, "TunnelMessage: Incomplete message ", msgID, " already exists");
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}
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else
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{
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m.nextFragmentNum = fragmentNum;
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HandleFollowOnFragment (msgID, isLastFragment, m);
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}
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}
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else
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LogPrint (eLogError, "TunnelMessage: Message is fragmented, but msgID is not presented");
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}
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fragment += size;
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}
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}
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else
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LogPrint (eLogError, "TunnelMessage: zero not found");
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}
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void TunnelEndpoint::HandleFollowOnFragment (uint32_t msgID, bool isLastFragment, const TunnelMessageBlockEx& m)
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{
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auto fragment = m.data->GetBuffer ();
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auto size = m.data->GetLength ();
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auto it = m_IncompleteMessages.find (msgID);
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if (it != m_IncompleteMessages.end())
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{
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auto& msg = it->second;
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if (m.nextFragmentNum == msg.nextFragmentNum)
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{
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if (msg.data->len + size < I2NP_MAX_MESSAGE_SIZE) // check if message is not too long
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{
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if (msg.data->len + size > msg.data->maxLen)
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{
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// LogPrint (eLogWarning, "TunnelMessage: I2NP message size ", msg.data->maxLen, " is not enough");
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auto newMsg = NewI2NPMessage ();
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*newMsg = *(msg.data);
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msg.data = newMsg;
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}
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if (msg.data->Concat (fragment, size) < size) // concatenate fragment
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LogPrint (eLogError, "TunnelMessage: I2NP buffer overflow ", msg.data->maxLen);
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if (isLastFragment)
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{
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// message complete
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HandleNextMessage (msg);
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m_IncompleteMessages.erase (it);
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}
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else
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{
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msg.nextFragmentNum++;
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HandleOutOfSequenceFragments (msgID, msg);
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}
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}
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else
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{
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LogPrint (eLogError, "TunnelMessage: Fragment ", m.nextFragmentNum, " of message ", msgID, "exceeds max I2NP message size, message dropped");
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m_IncompleteMessages.erase (it);
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}
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}
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else
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{
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LogPrint (eLogWarning, "TunnelMessage: Unexpected fragment ", (int)m.nextFragmentNum, " instead ", (int)msg.nextFragmentNum, " of message ", msgID, ", saved");
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AddOutOfSequenceFragment (msgID, m.nextFragmentNum, isLastFragment, m.data);
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}
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}
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else
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{
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LogPrint (eLogWarning, "TunnelMessage: First fragment of message ", msgID, " not found, saved");
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AddOutOfSequenceFragment (msgID, m.nextFragmentNum, isLastFragment, m.data);
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}
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}
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void TunnelEndpoint::AddOutOfSequenceFragment (uint32_t msgID, uint8_t fragmentNum, bool isLastFragment, std::shared_ptr<I2NPMessage> data)
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{
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if (!m_OutOfSequenceFragments.insert ({{msgID, fragmentNum}, {isLastFragment, data, i2p::util::GetMillisecondsSinceEpoch () }}).second)
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LogPrint (eLogInfo, "TunnelMessage: duplicate out-of-sequence fragment ", fragmentNum, " of message ", msgID);
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}
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void TunnelEndpoint::HandleOutOfSequenceFragments (uint32_t msgID, TunnelMessageBlockEx& msg)
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{
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while (ConcatNextOutOfSequenceFragment (msgID, msg))
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{
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if (!msg.nextFragmentNum) // message complete
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{
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HandleNextMessage (msg);
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m_IncompleteMessages.erase (msgID);
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break;
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}
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}
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}
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bool TunnelEndpoint::ConcatNextOutOfSequenceFragment (uint32_t msgID, TunnelMessageBlockEx& msg)
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{
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auto it = m_OutOfSequenceFragments.find ({msgID, msg.nextFragmentNum});
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if (it != m_OutOfSequenceFragments.end ())
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{
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LogPrint (eLogDebug, "TunnelMessage: Out-of-sequence fragment ", (int)msg.nextFragmentNum, " of message ", msgID, " found");
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size_t size = it->second.data->GetLength ();
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if (msg.data->len + size > msg.data->maxLen)
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{
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LogPrint (eLogWarning, "TunnelMessage: Tunnel endpoint I2NP message size ", msg.data->maxLen, " is not enough");
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auto newMsg = NewI2NPMessage ();
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*newMsg = *(msg.data);
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msg.data = newMsg;
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}
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if (msg.data->Concat (it->second.data->GetBuffer (), size) < size) // concatenate out-of-sync fragment
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LogPrint (eLogError, "TunnelMessage: Tunnel endpoint I2NP buffer overflow ", msg.data->maxLen);
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if (it->second.isLastFragment)
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// message complete
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msg.nextFragmentNum = 0;
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else
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msg.nextFragmentNum++;
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m_OutOfSequenceFragments.erase (it);
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return true;
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}
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return false;
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}
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void TunnelEndpoint::HandleNextMessage (const TunnelMessageBlock& msg)
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{
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if (!m_IsInbound && msg.data->IsExpired ())
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{
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LogPrint (eLogInfo, "TunnelMessage: message expired");
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return;
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}
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uint8_t typeID = msg.data->GetTypeID ();
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LogPrint (eLogDebug, "TunnelMessage: handle fragment of ", msg.data->GetLength (), " bytes, msg type ", (int)typeID);
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// catch RI or reply with new list of routers
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if ((IsRouterInfoMsg (msg.data) || typeID == eI2NPDatabaseSearchReply) &&
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!m_IsInbound && msg.deliveryType != eDeliveryTypeLocal)
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i2p::data::netdb.PostI2NPMsg (CopyI2NPMessage (msg.data));
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switch (msg.deliveryType)
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{
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case eDeliveryTypeLocal:
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i2p::HandleI2NPMessage (msg.data);
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break;
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case eDeliveryTypeTunnel:
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if (!m_IsInbound) // outbound transit tunnel
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i2p::transport::transports.SendMessage (msg.hash, i2p::CreateTunnelGatewayMsg (msg.tunnelID, msg.data));
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else
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LogPrint (eLogError, "TunnelMessage: Delivery type 'tunnel' arrived from an inbound tunnel, dropped");
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break;
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case eDeliveryTypeRouter:
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if (!m_IsInbound) // outbound transit tunnel
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i2p::transport::transports.SendMessage (msg.hash, msg.data);
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else // we shouldn't send this message. possible leakage
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LogPrint (eLogError, "TunnelMessage: Delivery type 'router' arrived from an inbound tunnel, dropped");
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break;
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default:
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LogPrint (eLogError, "TunnelMessage: Unknown delivery type ", (int)msg.deliveryType);
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};
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}
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void TunnelEndpoint::Cleanup ()
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{
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auto ts = i2p::util::GetMillisecondsSinceEpoch ();
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// out-of-sequence fragments
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for (auto it = m_OutOfSequenceFragments.begin (); it != m_OutOfSequenceFragments.end ();)
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{
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if (ts > it->second.receiveTime + i2p::I2NP_MESSAGE_EXPIRATION_TIMEOUT)
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it = m_OutOfSequenceFragments.erase (it);
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else
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++it;
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}
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// incomplete messages
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for (auto it = m_IncompleteMessages.begin (); it != m_IncompleteMessages.end ();)
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{
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if (ts > it->second.receiveTime + i2p::I2NP_MESSAGE_EXPIRATION_TIMEOUT)
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it = m_IncompleteMessages.erase (it);
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else
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++it;
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}
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}
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}
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}
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