Method Negotiate

src/EncryptedStreamSocket.cpp:434–691

}

int CEncryptedStreamSocket::Negotiate(const uint8* pBuffer, uint32 nLen)
{
	uint32_t nRead = 0;
	// Hitting Negotiate() with m_nReceiveBytesWanted == 0 means the
	// negotiation state machine has consumed everything it was expecting
	// for the current step but somebody (the kernel buffer flushing on
	// a teardown, late bytes from a server we're switching away from,
	// etc.) still posted a Read on this socket while it's stuck in
	// ECS_NEGOTIATING. wxASSERT used to abort debug builds and silently
	// UB in release (entering the while loop below with bogus byte
	// math). wxCHECK_MSG returns the same -1 sentinel both call sites
	// already check for (see Read() at the ECS_NEGOTIATING case and the
	// "non-normal header" branch), so the caller cleanly aborts the
	// connection instead. #778.
	wxCHECK_MSG(m_nReceiveBytesWanted > 0, -1,
		"CEncryptedStreamSocket::Negotiate: called with m_nReceiveBytesWanted == 0");

	//DumpMem(pBuffer, nLen, "Negotiate buffer: ");

	try {
		while (m_NegotiatingState != ONS_COMPLETE && m_nReceiveBytesWanted > 0) {
			if (m_nReceiveBytesWanted > 512) {
				wxFAIL;
				return 0;
			}

			const uint32_t nToRead =  std::min(nLen - nRead, m_nReceiveBytesWanted);
			//printf("Reading %i bytes, add from %i position on %i position\n",nToRead, nRead, (int)m_pfiReceiveBuffer.GetPosition());
			//DumpMem(pBuffer + nRead, nToRead, "Recv Buffer: ");
			m_pfiReceiveBuffer.Write(pBuffer + nRead, nToRead);
			nRead += nToRead;
			m_nReceiveBytesWanted -= nToRead;
			if (m_nReceiveBytesWanted > 0)  {
				return nRead;
			}

			if (m_NegotiatingState != ONS_BASIC_CLIENTA_RANDOMPART && m_NegotiatingState != ONS_BASIC_SERVER_DHANSWER) {
				// We have the keys, decrypt
				//printf("We have the keys, so decrypt away on %s\n", (const char*) unicode2char(GetPeer()));
				m_pfiReceiveBuffer.Encrypt();
			}

			m_pfiReceiveBuffer.Seek(0);

			switch (m_NegotiatingState) {
				case ONS_NONE: // would be a bug
					wxFAIL;
					return 0;
				case ONS_BASIC_CLIENTA_RANDOMPART: {
					//printf("We are on ONS_BASIC_CLIENTA_RANDOMPART, create the keys on %s\n", (const char*) unicode2char(GetPeer()));
					// This creates the send/receive keys.

					uint8_t achKeyData[21];
					md4cpy(achKeyData, thePrefs::GetUserHash().GetHash());
					m_pfiReceiveBuffer.Read(achKeyData + 17, 4);

					achKeyData[16] = MAGICVALUE_REQUESTER;