[bugfix] Fix handling of mock snaplen field in pktHdr for packets smaller than snaplen #86
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fako1024
commented
May 6, 2024
| @@ -121,7 +121,7 @@ func NewSourceFromLink(link *link.Link, options ...Option) (*Source, error) { | |||
| // NextIPPacket() methods (the latter two by calling .Payload() / .IPLayer() on the created buffer). It ensures | |||
| // that a valid packet of appropriate structure / length is created | |||
| func (s *Source) NewPacket() capture.Packet { | |||
| p := make(capture.Packet, 6+s.snapLen) | |||
| p := make(capture.Packet, capture.PacketHdrOffset+s.snapLen) | |||
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Drive-by code cleanup (uses newly introduced const).
fako1024
commented
May 6, 2024
| @@ -141,7 +141,7 @@ func (m *MockSource) addPacket(payload []byte, totalLen uint32, pktType, ipLayer | |||
| block := m.ringBuffer.ring[thisBlock*m.blockSize : thisBlock*m.blockSize+m.blockSize] | |||
|
|
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| *(*tPacketHeaderV3Mock)(unsafe.Pointer(&block[m.curBlockPos+12])) = tPacketHeaderV3Mock{ | |||
| snaplen: min(uint32(m.snapLen), totalLen), // The snaplen is set to the totalLen if a packet is shorter | |||
| snaplen: min(uint32(m.snapLen), uint32(len(payload))), // The snaplen is set to the totalLen if a packet is shorter | |||
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This was incorrect. The totalLen of course is the wrong value to take here, what matters is the actual length of the captured fraction of the packet.
fako1024
changed the title
els0r
approved these changes
May 7, 2024
fako1024
deleted the
84-align-mock-snaplen-handling-for-pkthdr-with-reality-2
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Second attempt - took the wrong default value and found a few other unwanted side-effect / inconsistencies that only occur for the edge case of payloads smaller than the snaplen and situations where it's important that the data length isn't spare.
Closes #84