udp_lib_get_port(9)

📦 version 7.3.1, in nixpkgs unstable

💅 udp_lib_get_port(9) — like, the UDP port lookup for IPv4 and IPv6 🫶

okay so bestie, welcome to the Kernel API Manual ✨ this one's a little function from ./net/ipv4 that does the whole "is this UDP port free?" thing — except it's iconic and handles both IPv4 and IPv6, no cap 👑

🌸 NAME 🌸

udp_lib_get_port — UDP port lookup for IPv4 and IPv6 💖

✨ SYNOPSIS ✨

int udp_lib_get_port (struct sock *sk , unsigned short snum , unsigned
       int hash2_nulladdr );

that's the whole vibe, three args, one int coming back at you 🎀

🦋 ARGUMENTS 🦋

  • sk — the socket struct in question 💅 like, the actual socket we're doing all this for
  • snum — the port number to look up 🔍 the one we're out here searching for
  • hash2_nulladdr — an AF-dependent hash value in the secondary hash chains, with the NULL address 🌈 yes she's specific, yes she's AF-dependent, and yes she's carrying the NULL address, we love a well-defined parameter

🎀 SEE ALSO 🎀

kernel file ./net/ipv4/udp.c — and while you're in there, go say hi to:

lowkey a whole little friend group of functions in ./net/ipv4 and honestly? we're obsessed 😭

and that's the page, bestie 💜 this cutie lives in ./net/ipv4, it's dated October 2026, and it's brought to you by the Kernel API Manual — stay slaying, go look up those ports responsibly ✨💅👑

📦 where this page comes from