zeek/src/file_analysis/File.cc

// See the file "COPYING" in the main distribution directory for copyright.

#include <string>

#include "File.h"
#include "FileTimer.h"
#include "Analyzer.h"
#include "Manager.h"
#include "Reporter.h"
#include "Val.h"
#include "Type.h"
#include "Event.h"
#include "RuleMatcher.h"

#include "analyzer/Analyzer.h"
#include "analyzer/Manager.h"

#include "analyzer/extract/Extract.h"

using namespace file_analysis;

static Val* empty_connection_table()
	{
	TypeList* tbl_index = new TypeList(conn_id);
	tbl_index->Append(conn_id->Ref());
	TableType* tbl_type = new TableType(tbl_index, connection_type->Ref());
	Val* rval = new TableVal(tbl_type);
	Unref(tbl_type);
	return rval;
	}

static RecordVal* get_conn_id_val(const Connection* conn)
	{
	RecordVal* v = new RecordVal(conn_id);
	v->Assign(0, new AddrVal(conn->OrigAddr()));
	v->Assign(1, new PortVal(ntohs(conn->OrigPort()), conn->ConnTransport()));
	v->Assign(2, new AddrVal(conn->RespAddr()));
	v->Assign(3, new PortVal(ntohs(conn->RespPort()), conn->ConnTransport()));
	return v;
	}

int File::id_idx = -1;
int File::parent_id_idx = -1;
int File::source_idx = -1;
int File::is_orig_idx = -1;
int File::conns_idx = -1;
int File::last_active_idx = -1;
int File::seen_bytes_idx = -1;
int File::total_bytes_idx = -1;
int File::missing_bytes_idx = -1;
int File::overflow_bytes_idx = -1;
int File::timeout_interval_idx = -1;
int File::bof_buffer_size_idx = -1;
int File::bof_buffer_idx = -1;
int File::mime_type_idx = -1;
int File::mime_types_idx = -1;

void File::StaticInit()
	{
	if ( id_idx != -1 )
		return;

	id_idx = Idx("id");
	parent_id_idx = Idx("parent_id");
	source_idx = Idx("source");
	is_orig_idx = Idx("is_orig");
	conns_idx = Idx("conns");
	last_active_idx = Idx("last_active");
	seen_bytes_idx = Idx("seen_bytes");
	total_bytes_idx = Idx("total_bytes");
	missing_bytes_idx = Idx("missing_bytes");
	overflow_bytes_idx = Idx("overflow_bytes");
	timeout_interval_idx = Idx("timeout_interval");
	bof_buffer_size_idx = Idx("bof_buffer_size");
	bof_buffer_idx = Idx("bof_buffer");
	mime_type_idx = Idx("mime_type");
	mime_types_idx = Idx("mime_types");
	}

File::File(const string& file_id, Connection* conn, analyzer::Tag tag,
           bool is_orig)
	: id(file_id), val(0), stream_offset(0), reassembly_max_buffer(0), 
	  reassembly_enabled(false), postpone_timeout(false), done(false), 
	  did_file_new_event(false), analyzers(this)
	{
	StaticInit();

	DBG_LOG(DBG_FILE_ANALYSIS, "Creating new File object %s", file_id.c_str());

	val = new RecordVal(fa_file_type);
	val->Assign(id_idx, new StringVal(file_id.c_str()));

	file_reassembler = 0;
	if ( conn )
		{
		// add source, connection, is_orig fields
		SetSource(analyzer_mgr->GetComponentName(tag));
		val->Assign(is_orig_idx, new Val(is_orig, TYPE_BOOL));
		UpdateConnectionFields(conn, is_orig);
		}

	UpdateLastActivityTime();
	}

File::~File()
	{
	DBG_LOG(DBG_FILE_ANALYSIS, "Destroying File object %s", id.c_str());
	Unref(val);

	while ( ! fonc_queue.empty() )
		{
		delete_vals(fonc_queue.front().second);
		fonc_queue.pop();
		}

	if ( file_reassembler )
		delete file_reassembler;
	}

void File::UpdateLastActivityTime()
	{
	val->Assign(last_active_idx, new Val(network_time, TYPE_TIME));
	}

double File::GetLastActivityTime() const
	{
	return val->Lookup(last_active_idx)->AsTime();
	}

void File::UpdateConnectionFields(Connection* conn, bool is_orig)
	{
	if ( ! conn )
		return;

	Val* conns = val->Lookup(conns_idx);

	if ( ! conns )
		{
		conns = empty_connection_table();
		val->Assign(conns_idx, conns);
		}

	Val* idx = get_conn_id_val(conn);
	if ( ! conns->AsTableVal()->Lookup(idx) )
		{
		Val* conn_val = conn->BuildConnVal();
		conns->AsTableVal()->Assign(idx, conn_val);

		if ( FileEventAvailable(file_over_new_connection) )
			{
			val_list* vl = new val_list();
			vl->append(val->Ref());
			vl->append(conn_val->Ref());
			vl->append(new Val(is_orig, TYPE_BOOL));

			if ( did_file_new_event )
				FileEvent(file_over_new_connection, vl);
			else
				fonc_queue.push(pair<EventHandlerPtr, val_list*>(
				        file_over_new_connection, vl));
			}
		}

	Unref(idx);
	}

uint64 File::LookupFieldDefaultCount(int idx) const
	{
	Val* v = val->LookupWithDefault(idx);
	uint64 rval = v->AsCount();
	Unref(v);
	return rval;
	}

double File::LookupFieldDefaultInterval(int idx) const
	{
	Val* v = val->LookupWithDefault(idx);
	double rval = v->AsInterval();
	Unref(v);
	return rval;
	}

int File::Idx(const string& field)
	{
	int rval = fa_file_type->FieldOffset(field.c_str());
	if ( rval < 0 )
		reporter->InternalError("Unknown fa_file field: %s", field.c_str());

	return rval;
	}

string File::GetSource() const
	{
	Val* v = val->Lookup(source_idx);

	return v ? v->AsString()->CheckString() : string();
	}

void File::SetSource(const string& source)
	{
	val->Assign(source_idx, new StringVal(source.c_str()));
	}

double File::GetTimeoutInterval() const
	{
	return LookupFieldDefaultInterval(timeout_interval_idx);
	}

void File::SetTimeoutInterval(double interval)
	{
	val->Assign(timeout_interval_idx, new Val(interval, TYPE_INTERVAL));
	}

bool File::SetExtractionLimit(RecordVal* args, uint64 bytes)
	{
	Analyzer* a = analyzers.Find(file_mgr->GetComponentTag("EXTRACT"), args);

	if ( ! a )
		return false;

	Extract* e = dynamic_cast<Extract*>(a);

	if ( ! e )
		return false;

	e->SetLimit(bytes);
	return true;
	}

void File::IncrementByteCount(uint64 size, int field_idx)
	{
	uint64 old = LookupFieldDefaultCount(field_idx);
	val->Assign(field_idx, new Val(old + size, TYPE_COUNT));
	}

void File::SetTotalBytes(uint64 size)
	{
	val->Assign(total_bytes_idx, new Val(size, TYPE_COUNT));
	}

bool File::IsComplete() const
	{
	Val* total = val->Lookup(total_bytes_idx);
	if ( ! total )
		return false;

	if ( stream_offset >= total->AsCount() )
		return true;

	return false;
	}

void File::ScheduleInactivityTimer() const
	{
	timer_mgr->Add(new FileTimer(network_time, id, GetTimeoutInterval()));
	}

bool File::AddAnalyzer(file_analysis::Tag tag, RecordVal* args)
	{
	return done ? false : analyzers.QueueAdd(tag, args);
	}

bool File::RemoveAnalyzer(file_analysis::Tag tag, RecordVal* args)
	{
	return done ? false : analyzers.QueueRemove(tag, args);
	}

bool File::BufferBOF(const u_char* data, uint64 len)
	{
	if ( bof_buffer.full || bof_buffer.replayed )
		return false;

	uint64 desired_size = LookupFieldDefaultCount(bof_buffer_size_idx);

	bof_buffer.chunks.push_back(new BroString(data, len, 0));
	bof_buffer.size += len;

	if ( bof_buffer.size >= desired_size )
		{
		bof_buffer.full = true;
		ReplayBOF();
		}

	return true;
	}

bool File::DetectMIME(const u_char* data, uint64 len)
	{
	RuleMatcher::MIME_Matches matches;
	len = min(len, LookupFieldDefaultCount(bof_buffer_size_idx));
	file_mgr->DetectMIME(data, len, &matches);

	if ( matches.empty() )
		return false;

	val->Assign(mime_type_idx,
	            new StringVal(*(matches.begin()->second.begin())));
	val->Assign(mime_types_idx, file_analysis::GenMIMEMatchesVal(matches));

	return true;
	}

void File::EnableReassembly()
	{
	reassembly_enabled = true;
	}

void File::DisableReassembly()
	{
	reassembly_enabled = false;
	if ( file_reassembler )
		{
		delete file_reassembler;
		file_reassembler = NULL;
		}
	}

void File::SetReassemblyBuffer(uint64 max)
	{
	reassembly_max_buffer = max;
	}

void File::ReplayBOF()
	{
	if ( bof_buffer.replayed )
		return;

	bof_buffer.replayed = true;

	if ( bof_buffer.chunks.empty() )
		{
		// We definitely can't do anything if we don't have any chunks.
		return;
		}

	BroString* bs = concatenate(bof_buffer.chunks);
	val->Assign(bof_buffer_idx, new StringVal(bs));

	for ( size_t i = 0; i < bof_buffer.chunks.size(); ++i )
		DataIn(bof_buffer.chunks[i]->Bytes(), bof_buffer.chunks[i]->Len());
	}

void File::DeliverStream(const u_char* data, uint64 len)
	{
	// Buffer enough data send to libmagic.
	if ( BufferBOF(data, len) )
		return;

	if ( stream_offset == 0 )
		{
		DetectMIME(data, len);
		FileEvent(file_new);
		}

	file_analysis::Analyzer* a = 0;
	IterCookie* c = analyzers.InitForIteration();
	while ( (a = analyzers.NextEntry(c)) )
		{
		if ( !a->DeliverStream(data, len) )
			{
			analyzers.QueueRemove(a->Tag(), a->Args());
			}
		}

	stream_offset += len;
	IncrementByteCount(len, seen_bytes_idx);
	}

void File::DeliverChunk(const u_char* data, uint64 len, uint64 offset)
	{
	// Potentially handle reassembly and deliver to the stream analyzers.
	if ( file_reassembler )
		{
		if ( reassembly_max_buffer > 0 &&
		     reassembly_max_buffer < file_reassembler->TotalSize() ) 
			{
			uint64 first_offset = file_reassembler->GetFirstBlockOffset();
			int gap_bytes = file_reassembler->TrimToSeq(first_offset);
			
			if ( FileEventAvailable(file_reassembly_buffer_overflow) )
				{
				val_list* vl = new val_list();
				vl->append(val->Ref());
				vl->append(new Val(stream_offset, TYPE_COUNT));
				vl->append(new Val(gap_bytes, TYPE_COUNT));
				FileEvent(file_reassembly_buffer_overflow, vl);
				}

			Gap(stream_offset, gap_bytes);
			}

		// Forward data to the reassembler.
		file_reassembler->NewBlock(network_time, offset, len, data);
		}
	else if ( stream_offset == offset )
		{
		// This is the normal case where a file is transferred linearly.
		// Nothing special should be done here.
		DeliverStream(data, len);
		}
	else if ( reassembly_enabled )
		{
		// This is data that doesn't match the offset and the reassembler 
		// needs to be enabled.
		file_reassembler = new FileReassembler(this, stream_offset);
		file_reassembler->NewBlock(network_time, offset, len, data);
		}
	else
		{
		// We can't reassemble so we throw out the data for streaming.
		IncrementByteCount(len, overflow_bytes_idx);
		}

	// Deliver to the chunk analyzers.
	file_analysis::Analyzer* a = 0;
	IterCookie* c = analyzers.InitForIteration();
	while ( (a = analyzers.NextEntry(c)) )
		{
		if ( !a->DeliverChunk(data, len, offset) )
			{
			analyzers.QueueRemove(a->Tag(), a->Args());
			}
		}

	if ( IsComplete() )
		{
		// If the file is complete we can automatically go and close out the file from here.
		EndOfFile();
		}
	}


void File::DataIn(const u_char* data, uint64 len, uint64 offset)
	{
	analyzers.DrainModifications();
	DeliverChunk(data, len, offset);
	analyzers.DrainModifications();
	}

void File::DataIn(const u_char* data, uint64 len)
	{
	analyzers.DrainModifications();
	
	uint64 offset = LookupFieldDefaultCount(seen_bytes_idx) +
	                LookupFieldDefaultCount(missing_bytes_idx);
	DeliverChunk(data, len, offset);
	analyzers.DrainModifications();
	}

void File::EndOfFile()
	{
	if ( done )
		return;

	analyzers.DrainModifications();

	// Send along anything that's been buffered, but never flushed.
	ReplayBOF();

	done = true;

	file_analysis::Analyzer* a = 0;
	IterCookie* c = analyzers.InitForIteration();

	while ( (a = analyzers.NextEntry(c)) )
		{
		if ( ! a->EndOfFile() )
			analyzers.QueueRemove(a->Tag(), a->Args());
		}

	FileEvent(file_state_remove);

	analyzers.DrainModifications();
	}

void File::Gap(uint64 offset, uint64 len)
	{
	analyzers.DrainModifications();

	// If we were buffering the beginning of the file, a gap means we've got
	// as much contiguous stuff at the beginning as possible, so work with that.
	ReplayBOF();

	file_analysis::Analyzer* a = 0;
	IterCookie* c = analyzers.InitForIteration();

	while ( (a = analyzers.NextEntry(c)) )
		{
		if ( ! a->Undelivered(offset, len) )
			analyzers.QueueRemove(a->Tag(), a->Args());
		}

	if ( FileEventAvailable(file_gap) )
		{
		val_list* vl = new val_list();
		vl->append(val->Ref());
		vl->append(new Val(offset, TYPE_COUNT));
		vl->append(new Val(len, TYPE_COUNT));
		FileEvent(file_gap, vl);
		}

	analyzers.DrainModifications();

	stream_offset += len;
	IncrementByteCount(len, missing_bytes_idx);
	}

bool File::FileEventAvailable(EventHandlerPtr h)
	{
	return h && ! file_mgr->IsIgnored(id);
	}

void File::FileEvent(EventHandlerPtr h)
	{
	if ( ! FileEventAvailable(h) )
		return;

	val_list* vl = new val_list();
	vl->append(val->Ref());
	FileEvent(h, vl);
	}

static void flush_file_event_queue(queue<pair<EventHandlerPtr, val_list*> >& q)
	{
	while ( ! q.empty() )
		{
		pair<EventHandlerPtr, val_list*> p = q.front();
		mgr.QueueEvent(p.first, p.second);
		q.pop();
		}
	}

void File::FileEvent(EventHandlerPtr h, val_list* vl)
	{
	if ( h == file_state_remove )
		flush_file_event_queue(fonc_queue);

	mgr.QueueEvent(h, vl);

	if ( h == file_new )
		{
		did_file_new_event = true;
		flush_file_event_queue(fonc_queue);
		}

	if ( h == file_new || h == file_timeout || h == file_extraction_limit )
		{
		// immediate feedback is required for these events.
		mgr.Drain();
		analyzers.DrainModifications();
		}
	}