Fix PacketCapture pcapng file issue on macOS #6804
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By default, gopacket will write snap length=0 in the pcapng file header, means unlimited snaplen. tcpdump on osx(libpcap version 1.10.1) cannot recognize this and will report error. This patch will set a default value(524288) for it. Signed-off-by: Hang Yan <[email protected]>
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Signed-off-by: Hang Yan <[email protected]>
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| // 0 and means unlimited, but tcpdump on Mac OSX will complain: | ||
| // 'tcpdump: pcap_loop: invalid packet capture length <len>, bigger than snaplen of 524288' | ||
| ngInterface := pcapgo.DefaultNgInterface | ||
| ngInterface.SnapLength = 65536 |
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do you think the snapshot length could be a parameter to the Capture interface method, after which snapLength could be defined as a constant in this file, and we could use the constant here, as well as when invoking Capture?
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| defer func() { | ||
| defer file.Close() | ||
| defer os.Remove(dstFileName) | ||
| }() |
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what is the point of having 2 defer statements in a deferred function?
Couldn't the code be like this:
require.NoError(t, data.copyPodFiles(antreaPodName, "antrea-agent", "kube-system", packetFile, os.TempDir()))
defer os.Remove(dstFileName)
file, err := os.Open(dstFileName)
require.NoError(t, err)
defer file.Close()this would close the file first, then remove it (reversed order of execution for deferred statements)
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By default, gopacket will write snap length=0 in the pcapng file header, means unlimited snaplen. tcpdump on osx(libpcap version 1.10.1) cannot recognize this and will report error. This patch will set a default value(524288) for it. This patch also add packets file verification in e2e tests.
origin error message:
pcapng format ref: https://pcapng.com/