// This code contributed by Nadi Sarrar.

#include "BitTorrent.h"
#include "TCP_Reassembler.h"

BitTorrent_Analyzer::BitTorrent_Analyzer(Connection* c)
: TCP_ApplicationAnalyzer(AnalyzerTag::BitTorrent, c)
	{
	interp = new binpac::BitTorrent::BitTorrent_Conn(this);
	stop_orig = stop_resp = false;
	stream_len_orig = stream_len_resp = 0;
	}

BitTorrent_Analyzer::~BitTorrent_Analyzer()
	{
	delete interp;
	}

void BitTorrent_Analyzer::Done()
	{
	TCP_ApplicationAnalyzer::Done();

	interp->FlowEOF(true);
	interp->FlowEOF(false);
	}

void BitTorrent_Analyzer::DeliverStream(int len, const u_char* data, bool orig)
	{
	uint64& this_stream_len = orig ? stream_len_orig : stream_len_resp;
	bool& this_stop = orig ? stop_orig : stop_resp;

	TCP_ApplicationAnalyzer::DeliverStream(len, data, orig);

	assert(TCP());

	if ( TCP()->IsPartial() )
		// punt on partial.
		return;

	if ( this_stop )
		return;

	this_stream_len += len;

	try
		{
		interp->NewData(orig, data, data + len);
		}
	catch ( binpac::Exception const &e )
		{
		const char except[] = "binpac exception: invalid handshake";
		if ( ! strncmp(e.c_msg(), except, strlen(except)) )
			// Does not look like bittorrent - silently
			// drop the connection.
			Parent()->RemoveChildAnalyzer(this);
		else
			{
			DeliverWeird(fmt("Stopping BitTorrent analysis: protocol violation (%s)",
					e.c_msg()), orig);
			this_stop = true;
			if ( stop_orig && stop_resp )
				ProtocolViolation("BitTorrent: content gap and/or protocol violation");
			}
		}
	}

void BitTorrent_Analyzer::Undelivered(int seq, int len, bool orig)
	{
	uint64 entry_offset = orig ?
		*interp->upflow()->next_message_offset() :
		*interp->downflow()->next_message_offset();
	uint64& this_stream_len = orig ? stream_len_orig : stream_len_resp;
	bool& this_stop = orig ? stop_orig : stop_resp;

	TCP_ApplicationAnalyzer::Undelivered(seq, len, orig);

	this_stream_len += len;

	if ( entry_offset < this_stream_len )
		{ // entry point is somewhere in the gap
		DeliverWeird("Stopping BitTorrent analysis: cannot recover from content gap", orig);
		this_stop = true;
		if ( stop_orig && stop_resp )
			ProtocolViolation("BitTorrent: content gap and/or protocol violation");
		}
	else
		{ // fill the gap
		try
			{
			u_char gap[len];
			memset(gap, 0, len);
			interp->NewData(orig, gap, gap + len);
			}
		catch ( binpac::Exception const &e )
			{
			DeliverWeird("Stopping BitTorrent analysis: filling content gap failed", orig);
			this_stop = true;
			if ( stop_orig && stop_resp )
				ProtocolViolation("BitTorrent: content gap and/or protocol violation");
			}
		}
	}

void BitTorrent_Analyzer::EndpointEOF(TCP_Reassembler* endp)
	{
	TCP_ApplicationAnalyzer::EndpointEOF(endp);
	interp->FlowEOF(endp->IsOrig());
	}

void BitTorrent_Analyzer::DeliverWeird(const char* msg, bool orig)
	{
	if ( bittorrent_peer_weird )
		{
		val_list* vl = new val_list;
		vl->append(BuildConnVal());
		vl->append(new Val(orig, TYPE_BOOL));
		vl->append(new StringVal(msg));
		ConnectionEvent(bittorrent_peer_weird, vl);
		}
	else
		Weird(msg);
	}