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Work around faulty linux rx stats capture filter

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libpcap has a bug on Linux which leads to incorrect BPF generation for our
capture filter. This commit changes the filter expression on Linux such that
correct BPF is generated.

Fixes #354
This commit is contained in:
Srivats P 2023-10-03 10:39:03 +05:30
parent 3bcd31a1ea
commit 5581118e2f
1 changed files with 15 additions and 0 deletions
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15
server/pcaprxstats.cpp
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@ -56,6 +56,20 @@ void PcapRxStats::run()
SignProtocol::magic(), 0, BASE_HEX); SignProtocol::magic(), 0, BASE_HEX);
// XXX: Exclude ICMP packets which contain an embedded signed packet // XXX: Exclude ICMP packets which contain an embedded signed packet
// For now we check upto 4 vlan tags // For now we check upto 4 vlan tags
// XXX: libpcap for Linux has a special bpf vlan check which generates
// incorrect BPF instructions for our capture filter expression,
// so we modify it to work correctly
// See https://srivatsp.com/ostinato/ostinato-rx-stream-stats-zero/
#ifdef Q_OS_LINUX
capture_filter.prepend(
"not ("
"icmp or "
"(vlan and icmp) or "
"(vlan and icmp) or "
"(vlan and icmp) or "
"(vlan and icmp) "
") and ");
#else
capture_filter.append( capture_filter.append(
"and not (" "and not ("
"icmp or " "icmp or "
@ -64,6 +78,7 @@ void PcapRxStats::run()
"(vlan and icmp) or " "(vlan and icmp) or "
"(vlan and icmp) " "(vlan and icmp) "
")"); ")");
#endif
qDebug("In %s", __PRETTY_FUNCTION__); qDebug("In %s", __PRETTY_FUNCTION__);