mirror of
https://github.com/PurpleI2P/i2pd
synced 2024-11-08 23:40:12 +03:00
241 lines
7.7 KiB
C++
241 lines
7.7 KiB
C++
/*
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* Copyright (c) 2013-2024, 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 <string.h>
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#include "Crypto.h"
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#include "I2PEndian.h"
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#include "Log.h"
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#include "RouterContext.h"
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#include "Transports.h"
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#include "TunnelGateway.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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TunnelGatewayBuffer::TunnelGatewayBuffer ():
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m_CurrentTunnelDataMsg (nullptr), m_RemainingSize (0), m_NonZeroRandomBuffer (nullptr)
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{
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}
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TunnelGatewayBuffer::~TunnelGatewayBuffer ()
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{
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ClearTunnelDataMsgs ();
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if (m_NonZeroRandomBuffer) delete[] m_NonZeroRandomBuffer;
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}
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void TunnelGatewayBuffer::PutI2NPMsg (const TunnelMessageBlock& block)
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{
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bool messageCreated = false;
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if (!m_CurrentTunnelDataMsg)
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{
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CreateCurrentTunnelDataMessage ();
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if (block.data && block.data->onDrop)
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{
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// onDrop is called for the first fragment in tunnel message
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// that's usually true for short TBMs or lookups
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m_CurrentTunnelDataMsg->onDrop = block.data->onDrop;
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block.data->onDrop = nullptr;
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}
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messageCreated = true;
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}
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// create delivery instructions
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uint8_t di[43]; // max delivery instruction length is 43 for tunnel
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size_t diLen = 1;// flag
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if (block.deliveryType != eDeliveryTypeLocal) // tunnel or router
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{
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if (block.deliveryType == eDeliveryTypeTunnel)
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{
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htobe32buf (di + diLen, block.tunnelID);
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diLen += 4; // tunnelID
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}
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memcpy (di + diLen, block.hash, 32);
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diLen += 32; //len
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}
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di[0] = block.deliveryType << 5; // set delivery type
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// create fragments
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const std::shared_ptr<I2NPMessage> & msg = block.data;
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size_t fullMsgLen = diLen + msg->GetLength () + 2; // delivery instructions + payload + 2 bytes length
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if (!messageCreated && fullMsgLen > m_RemainingSize) // check if we should complete previous message
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{
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size_t numFollowOnFragments = fullMsgLen / TUNNEL_DATA_MAX_PAYLOAD_SIZE;
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// length of bytes doesn't fit full tunnel message
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// every follow-on fragment adds 7 bytes
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size_t nonFit = (fullMsgLen + numFollowOnFragments*7) % TUNNEL_DATA_MAX_PAYLOAD_SIZE;
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if (!nonFit || nonFit > m_RemainingSize || m_RemainingSize < fullMsgLen/5)
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{
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CompleteCurrentTunnelDataMessage ();
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CreateCurrentTunnelDataMessage ();
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}
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}
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if (fullMsgLen <= m_RemainingSize)
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{
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// message fits. First and last fragment
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htobe16buf (di + diLen, msg->GetLength ());
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diLen += 2; // size
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memcpy (m_CurrentTunnelDataMsg->buf + m_CurrentTunnelDataMsg->len, di, diLen);
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memcpy (m_CurrentTunnelDataMsg->buf + m_CurrentTunnelDataMsg->len + diLen, msg->GetBuffer (), msg->GetLength ());
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m_CurrentTunnelDataMsg->len += diLen + msg->GetLength ();
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m_RemainingSize -= diLen + msg->GetLength ();
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if (!m_RemainingSize)
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CompleteCurrentTunnelDataMessage ();
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}
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else
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{
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if (diLen + 6 <= m_RemainingSize)
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{
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// delivery instructions fit
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uint32_t msgID;
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memcpy (&msgID, msg->GetHeader () + I2NP_HEADER_MSGID_OFFSET, 4); // in network bytes order
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size_t size = m_RemainingSize - diLen - 6; // 6 = 4 (msgID) + 2 (size)
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// first fragment
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di[0] |= 0x08; // fragmented
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htobuf32 (di + diLen, msgID);
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diLen += 4; // Message ID
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htobe16buf (di + diLen, size);
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diLen += 2; // size
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memcpy (m_CurrentTunnelDataMsg->buf + m_CurrentTunnelDataMsg->len, di, diLen);
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memcpy (m_CurrentTunnelDataMsg->buf + m_CurrentTunnelDataMsg->len + diLen, msg->GetBuffer (), size);
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m_CurrentTunnelDataMsg->len += diLen + size;
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CompleteCurrentTunnelDataMessage ();
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// follow on fragments
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int fragmentNumber = 1;
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while (size < msg->GetLength ())
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{
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CreateCurrentTunnelDataMessage ();
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uint8_t * buf = m_CurrentTunnelDataMsg->GetBuffer ();
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buf[0] = 0x80 | (fragmentNumber << 1); // frag
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bool isLastFragment = false;
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size_t s = msg->GetLength () - size;
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if (s > TUNNEL_DATA_MAX_PAYLOAD_SIZE - 7) // 7 follow on instructions
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s = TUNNEL_DATA_MAX_PAYLOAD_SIZE - 7;
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else // last fragment
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{
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buf[0] |= 0x01;
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isLastFragment = true;
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}
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htobuf32 (buf + 1, msgID); //Message ID
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htobe16buf (buf + 5, s); // size
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memcpy (buf + 7, msg->GetBuffer () + size, s);
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m_CurrentTunnelDataMsg->len += s+7;
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if (isLastFragment)
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{
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if(m_RemainingSize < (s+7)) {
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LogPrint (eLogError, "TunnelGateway: remaining size overflow: ", m_RemainingSize, " < ", s+7);
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} else {
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m_RemainingSize -= s+7;
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if (m_RemainingSize == 0)
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CompleteCurrentTunnelDataMessage ();
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}
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}
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else
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CompleteCurrentTunnelDataMessage ();
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size += s;
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fragmentNumber++;
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}
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}
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else
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{
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// delivery instructions don't fit. Create new message
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CompleteCurrentTunnelDataMessage ();
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PutI2NPMsg (block);
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// don't delete msg because it's taken care inside
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}
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}
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}
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void TunnelGatewayBuffer::ClearTunnelDataMsgs ()
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{
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m_TunnelDataMsgs.clear ();
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m_CurrentTunnelDataMsg = nullptr;
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}
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void TunnelGatewayBuffer::CreateCurrentTunnelDataMessage ()
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{
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m_CurrentTunnelDataMsg = NewI2NPTunnelMessage (true); // tunnel endpoint is at least of two tunnel messages size
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// we reserve space for padding
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m_CurrentTunnelDataMsg->offset += TUNNEL_DATA_MSG_SIZE + I2NP_HEADER_SIZE;
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m_CurrentTunnelDataMsg->len = m_CurrentTunnelDataMsg->offset;
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m_RemainingSize = TUNNEL_DATA_MAX_PAYLOAD_SIZE;
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}
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void TunnelGatewayBuffer::CompleteCurrentTunnelDataMessage ()
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{
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if (!m_CurrentTunnelDataMsg) return;
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uint8_t * payload = m_CurrentTunnelDataMsg->GetBuffer ();
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size_t size = m_CurrentTunnelDataMsg->len - m_CurrentTunnelDataMsg->offset;
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m_CurrentTunnelDataMsg->offset = m_CurrentTunnelDataMsg->len - TUNNEL_DATA_MSG_SIZE - I2NP_HEADER_SIZE;
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uint8_t * buf = m_CurrentTunnelDataMsg->GetPayload ();
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RAND_bytes (buf + 4, 16); // original IV
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memcpy (payload + size, buf + 4, 16); // copy IV for checksum
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uint8_t hash[32];
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SHA256(payload, size+16, hash);
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memcpy (buf+20, hash, 4); // checksum
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payload[-1] = 0; // zero
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ptrdiff_t paddingSize = payload - buf - 25; // 25 = 24 + 1
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if (paddingSize > 0)
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{
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// non-zero padding
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if (!m_NonZeroRandomBuffer) // first time?
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{
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m_NonZeroRandomBuffer = new uint8_t[TUNNEL_DATA_MAX_PAYLOAD_SIZE];
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RAND_bytes (m_NonZeroRandomBuffer, TUNNEL_DATA_MAX_PAYLOAD_SIZE);
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for (size_t i = 0; i < TUNNEL_DATA_MAX_PAYLOAD_SIZE; i++)
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if (!m_NonZeroRandomBuffer[i]) m_NonZeroRandomBuffer[i] = 1;
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}
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auto randomOffset = rand () % (TUNNEL_DATA_MAX_PAYLOAD_SIZE - paddingSize + 1);
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memcpy (buf + 24, m_NonZeroRandomBuffer + randomOffset, paddingSize);
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}
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// we can't fill message header yet because encryption is required
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m_TunnelDataMsgs.push_back (m_CurrentTunnelDataMsg);
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m_CurrentTunnelDataMsg = nullptr;
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}
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void TunnelGateway::SendTunnelDataMsg (const TunnelMessageBlock& block)
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{
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if (block.data)
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{
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PutTunnelDataMsg (block);
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SendBuffer ();
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}
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}
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void TunnelGateway::PutTunnelDataMsg (const TunnelMessageBlock& block)
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{
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if (block.data)
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m_Buffer.PutI2NPMsg (block);
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}
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void TunnelGateway::SendBuffer ()
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{
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m_Buffer.CompleteCurrentTunnelDataMessage ();
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std::list<std::shared_ptr<I2NPMessage> > newTunnelMsgs;
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const auto& tunnelDataMsgs = m_Buffer.GetTunnelDataMsgs ();
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for (auto& tunnelMsg : tunnelDataMsgs)
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{
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auto newMsg = CreateEmptyTunnelDataMsg (false);
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m_Tunnel->EncryptTunnelMsg (tunnelMsg, newMsg);
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htobe32buf (newMsg->GetPayload (), m_Tunnel->GetNextTunnelID ());
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newMsg->FillI2NPMessageHeader (eI2NPTunnelData);
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if (tunnelMsg->onDrop) newMsg->onDrop = tunnelMsg->onDrop;
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newTunnelMsgs.push_back (newMsg);
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m_NumSentBytes += TUNNEL_DATA_MSG_SIZE;
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}
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m_Buffer.ClearTunnelDataMsgs ();
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i2p::transport::transports.SendMessages (m_Tunnel->GetNextIdentHash (), std::move (newTunnelMsgs));
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}
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}
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}
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