mirror of
https://github.com/PurpleI2P/i2pd.git
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375 lines
12 KiB
C++
375 lines
12 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); // without 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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if (!isFollowOnFragment)
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{
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// first fragment
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if (m_CurrentMsgID)
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AddIncompleteCurrentMessage (); // we have got a new message while previous is not complete
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m_CurrentMessage.deliveryType = (TunnelDeliveryType)((flag >> 5) & 0x03);
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switch (m_CurrentMessage.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_CurrentMessage.tunnelID = bufbe32toh (fragment);
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fragment += 4; // tunnelID
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m_CurrentMessage.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_CurrentMessage.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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m_CurrentMsgID = msgID;
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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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// handle fragment
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if (isFollowOnFragment)
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{
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// existing message
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if (m_CurrentMsgID && m_CurrentMsgID == msgID && m_CurrentMessage.nextFragmentNum == fragmentNum)
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HandleCurrenMessageFollowOnFragment (fragment, size, isLastFragment); // previous
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else
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{
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HandleFollowOnFragment (msgID, isLastFragment, fragmentNum, fragment, size); // another
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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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}
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}
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else
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{
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// new message
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msg->offset = fragment - msg->buf;
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msg->len = msg->offset + size;
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// check message 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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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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return;
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}
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// create new or assign I2NP message
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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_CurrentMessage.data = NewI2NPTunnelMessage (true);
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*(m_CurrentMessage.data) = *msg;
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}
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else
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m_CurrentMessage.data = msg;
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if (isLastFragment)
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{
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// single message
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HandleNextMessage (m_CurrentMessage);
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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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}
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else if (msgID)
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{
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// first fragment of a new message
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m_CurrentMessage.nextFragmentNum = 1;
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m_CurrentMessage.receiveTime = i2p::util::GetMillisecondsSinceEpoch ();
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HandleOutOfSequenceFragments (msgID, m_CurrentMessage);
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}
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else
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{
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LogPrint (eLogError, "TunnelMessage: Message is fragmented, but msgID is not presented");
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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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}
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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,
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uint8_t fragmentNum, const uint8_t * fragment, size_t size)
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{
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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 (fragmentNum == msg.nextFragmentNum)
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{
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if (ConcatFollowOnFragment (msg, fragment, size))
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{
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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 ", fragmentNum, " 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)fragmentNum, " instead ", (int)msg.nextFragmentNum, " of message ", msgID, ", saved");
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AddOutOfSequenceFragment (msgID, fragmentNum, isLastFragment, fragment, size);
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}
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}
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else
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{
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LogPrint (eLogDebug, "TunnelMessage: First fragment of message ", msgID, " not found, saved");
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AddOutOfSequenceFragment (msgID, fragmentNum, isLastFragment, fragment, size);
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}
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}
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bool TunnelEndpoint::ConcatFollowOnFragment (TunnelMessageBlockEx& msg, const uint8_t * fragment, size_t size) const
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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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{
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LogPrint (eLogError, "TunnelMessage: I2NP buffer overflow ", msg.data->maxLen);
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return false;
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}
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}
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else
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return false;
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return true;
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}
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void TunnelEndpoint::HandleCurrenMessageFollowOnFragment (const uint8_t * fragment, size_t size, bool isLastFragment)
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{
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if (ConcatFollowOnFragment (m_CurrentMessage, fragment, size))
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{
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if (isLastFragment)
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{
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// message complete
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HandleNextMessage (m_CurrentMessage);
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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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}
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else
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{
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m_CurrentMessage.nextFragmentNum++;
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HandleOutOfSequenceFragments (m_CurrentMsgID, m_CurrentMessage);
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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_CurrentMessage.nextFragmentNum, " of message ", m_CurrentMsgID, " exceeds max I2NP message size, message dropped");
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m_CurrentMsgID = 0; m_CurrentMessage.data = nullptr;
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}
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}
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void TunnelEndpoint::AddIncompleteCurrentMessage ()
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{
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if (m_CurrentMsgID)
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{
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auto ret = m_IncompleteMessages.emplace (m_CurrentMsgID, m_CurrentMessage);
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if (!ret.second)
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LogPrint (eLogError, "TunnelMessage: Incomplete message ", m_CurrentMsgID, " already exists");
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m_CurrentMessage.data = nullptr;
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m_CurrentMsgID = 0;
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}
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}
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void TunnelEndpoint::AddOutOfSequenceFragment (uint32_t msgID, uint8_t fragmentNum,
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bool isLastFragment, const uint8_t * fragment, size_t size)
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{
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std::unique_ptr<Fragment> f(new Fragment (isLastFragment, i2p::util::GetMillisecondsSinceEpoch (), size));
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memcpy (f->data.data (), fragment, size);
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if (!m_OutOfSequenceFragments.emplace ((uint64_t)msgID << 32 | fragmentNum, std::move (f)).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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if (&msg == &m_CurrentMessage)
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{
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m_CurrentMsgID = 0;
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m_CurrentMessage.data = nullptr;
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}
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else
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m_IncompleteMessages.erase (msgID);
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LogPrint (eLogDebug, "TunnelMessage: All fragments of message ", msgID, " found");
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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 ((uint64_t)msgID << 32 | 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.size ();
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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.data (), 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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