pcap_sendqueue_transmit() return value - sharppcap

Hello.

I'm calling pcap_sendqueue_transmit() with no packets in the queue and seeing 1073741811 returned. I can't figure out the code path in npcap/libpcap that results in this return value. This only occurs for npcap, the test passes on both linux and windows. Using npcap 1.10 in the case where the failure occurs.

I did find PacketSendPackets in pcap-nfp.c but can't find any docs on that function, a google search doesn't turn anything useful up.

If this is a known return value it seems odd, the upper bit isn't set so it doesn't appear to be a negative value. The signatures used for pinvoke look correct.

If I do call pcap_sendqueue_transmit() even with a single packet in the queue I do get the correct value.

You can see the logs from the Azure pipelines issue here, https://dev.azure.com/chmorgan/chmorgan/_build/results?buildId=594&view=logs&j=823afbdf-f891-574b-27d0-2d0231c9608a&t=f870ef66-9f98-5e46-d80f-0a348a0d71b1

Any pointers?

Chris

Start by reviewing pcap_sendqueue_transmit() and the PacketSendPackets path in pcap-nfp.c, then reproduce the empty-queue case with npcap 1.10 and compare it with the one-packet case. Use the linked Azure Pipelines logs to trace the returned value; done means identifying whether 1073741811 is expected and documenting or correcting the behavior.