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simplify tcp flag checks, fix stream_follower (#334)

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* simplify tcp flag checks, fix stream_follower

On various places was used simple comparison for checking state of flags.

tcp.flags() == (TCP::SYN | TCP::ACK)

This is not what you want usually, because this check is false
in case that another flag is set also. Correct check for syn-ack
packet should be:

(tcp.flags() & (TCP::SYN | TCP::ACK)) == (TCP::SYN | TCP::ACK)

To simplify this kind of check, add new has_flags method:

bool TCP::has_flags(small_uint<12> check_flags) const

* remove duplicate TCP::SYN flag check
This commit is contained in:
Lukáš Karas
2019-03-15 02:18:12 +01:00
committed by Matias Fontanini
parent 74e3d909e6
commit 22b4435c81
8 changed files with 32 additions and 11 deletions
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5
src/tcp_ip/stream_follower.cpp
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@@ -84,7 +84,8 @@ void StreamFollower::process_packet(PDU& packet, const timestamp_type& ts) {
if (iter == streams_.end()) {
// Start tracking if they're either SYNs or they contain data (attach
// to an already running flow).
if (tcp->flags() == TCP::SYN || (attach_to_flows_ && tcp->find_pdu<RawPDU>() != 0)) {
const bool is_syn = tcp->has_flags(TCP::SYN);
if (is_syn || (attach_to_flows_ && tcp->find_pdu<RawPDU>() != 0)) {
iter = streams_.insert(make_pair(identifier, Stream(packet, ts))).first;
iter->second.setup_flows_callbacks();
if (on_new_connection_) {
@@ -93,7 +94,7 @@ void StreamFollower::process_packet(PDU& packet, const timestamp_type& ts) {
else {
throw callback_not_set();
}
if (tcp->flags() != TCP::SYN) {
if (!is_syn) {
// assume the connection is established
iter->second.client_flow().state(Flow::ESTABLISHED);
iter->second.server_flow().state(Flow::ESTABLISHED);