calipso_opt_insert(9)

📦 version 7.3.1, in nixpkgs unstable

✨ calipso_opt_insert(9) ✨

okay bestie, so this one lives in the kernel API manual (section 9, the fancy kernel club 💅), and it's literally all about slipping a CALIPSO option into an IPv6 hop options header. let's get into it 🎀

🌸 NAME 🌸

calipso_opt_insert — the function that inserts a CALIPSO option into an IPv6 hop opt hdr ✨

🦋 SYNOPSIS 🦋

struct ipv6_opt_hdr * calipso_opt_insert (struct ipv6_opt_hdr *hop ,
const struct calipso_doi *doi_def , const struct netlbl_lsm_secattr
*secattr );

💖 ARGUMENTS 💖

  • hop — the original hop options header, like the starting point we're building on 🫶
  • doi_def — the CALIPSO DOI to use, that's the domain-of-interpretation we're rolling with 🔥
  • secattr — the specific security attributes of the socket, i.e. the vibe check info for this socket 👑

🌈 DESCRIPTION 🌈

So basically this function creates a brand new hop options header based on hop, with a CALIPSO option added to it. Iconic behaviour honestly ✨

And here's the tea on how it decides where that option goes:

  • if hop already contains a CALIPSO option, that one gets overwritten 🫣
  • otherwise, the new option is appended after any existing options 💅
  • and if hop is NULL, then the new header will contain just the CALIPSO option and any needed padding 🎀

no cap, that's the whole flow 🌸

🌟 SEE ALSO 🌟

Kernel file ./net/ipv6/calipso.c and honestly the whole calipso bestie squad:

fr fr go read the whole squad, they're all in ./net/ipv6 and they all ate 💀🔥

and that's a wrap bestie 🧚 this page is served up from the ./net/ipv6 source, dated October 2026, and it's the calipso_opt_insert(9) page in the Kernel API Manual — stay hydrated, keep your headers padded, and slay your options 💜🍓

📦 where this page comes from