no comment info in pcpa file

[wangzhankun]

Describe the bug

When the output is stdout, ptcpdump can show the comment info. But when try to output to pcap file, I cannnot find comment info in wireshark.

 ./ptcpdump -i eth0 -v # stdout
 ./ptcpdump -i eth0 -v -w test.pcap # to pcap file

Environment

• ptcpdump version: ptcpdump version 0.24.0 libpcap version 1.10.5 (with TPACKET_V3)

• OS: PRETTY_NAME="Debian GNU/Linux 10 (buster)" NAME="Debian GNU/Linux" VERSION_ID="10" VERSION="10 (buster)" VERSION_CODENAME=buster ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/"

• Kernel: 5.4.250-4-velinux1u1-amd64

Additional context

[mozillazg]

@wangzhankun Thanks for reporting. Only the pcapng format support comment. Please try again with pcapng file:

 ./ptcpdump -i eth0 -v -w test.pcapng