Getting details of sockets from Linux kernel

1
votes

I have a user space application that creates several raw sockets (of AF_INET & AF_PACKET families with different protocols). To aid in debugging, I need to programmatically display details of these sockets (e.g. the number of bytes/packets queued at these sockets).

I tried using the FIONREAD ioctl, and recv with MSG_PEEK flag, but both these give me only the number of bytes of the first packet queued in a socket.

So it appears that I need to read the "/proc/PID/net/raw" file to get the details I need. Q1: is there a better way?

The Linux kernel only adds sockets of the AF_INET family to its raw sockets hash table, but not sockets of the AF_PACKET family. As a result, only sockets of the AF_INET family are listed in the "/proc/PID/net/raw" file. Q2: is there any way to get details of sockets of the AF_PACKET family?

By reading the "/proc/PID/net/raw" file, I can get the number of bytes in the kernel's send & receive queues. Q3: Can I somehow get the number of packets queued?

Any help would be highly appreciated.

p.s: my program is in C, but I'll be happy to look at snippets of code in other languages as well.

1
socketslinux-kernel

1 Answers

0
votes

This is in response to question # 2.

No, it is not possible to get details of the sockets of the AF_PACKET family (at least not through the Linux kernel). This is because for sockets of the AF_PACKET family, the entire protocol stack in the Kernel is skipped and the packets are delivered directly to the user space application that created the socket.