first_packet_length(9)

💖 NAME 💖

first_packet_length — return length of first packet in receive queue. That's the whole vibe, bestie. We're in the Kernel API Manual, and this page is first_packet_length(9). ✨

✨ SYNOPSIS ✨

int first_packet_length (struct sock *sk );

🎀 ARGUMENTS 🎀

• sk — socket. That's it. The one arg. The main character. 🫶

💅 DESCRIPTION 💅

Okay so here's the tea: it drops all bad checksum frames, and keeps going until a valid one is found. No cap. Then it returns the length of the found skb, or -1 if none is found. 😭

🦋 SEE ALSO 🦋

• Kernel file ./net/ipv4/udp.c — plus the rest of the squad: udp_lib_get_port(9), udp4_lib_lookup1(9), udp4_hwcsum(9), udp_poll(9).

Sign-off: this page lives under ./net/ipv4, dated October 2026, and it's literally first_packet_length(9). Mwah 💋✨