cipso_v4_optptr(9)

🌸 cipso_v4_optptr(9) — the "where's the CIPSO option bestie" finder 🌸

okay so real talk, this is a page out of the Kernel API Manual (cipso_v4_optptr(9)), and it's genuinely one of the shorter ones, so we can absolutely get through this together 🫶

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✨ NAME ✨

cipso_v4_optptr — Find the CIPSO option in the packet

like... that's the whole job. it finds things. it's giving search-and-rescue but for IP options 💅

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🎀 SYNOPSIS 🎀

unsigned char * cipso_v4_optptr (const struct sk_buff *skb );

look at that signature. so clean. so unsigned char *. we love a pointer return type that could also be NULL 😭

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🦋 ARGUMENTS 🦋

• skb — the packet

that's it. that's the argument. one (1) packet, no cap. it's the const struct sk_buff * and we are not touching it, hence the const — respectful king behavior 👑

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💖 DESCRIPTION 💖

so what it does is: parse the packet's IP header looking for a CIPSO option. 🔍✨

and then — the payoff — it returns a pointer to the start of the CIPSO option on success, or NULL if one is not found. that's it! that's the entire vibe check. found it → you get a pointer to the goods; not found → NULL, go home, there's nothing for you here 🙈

heads up: NULL here means "not found", not "something exploded". lowkey important distinction iykyk 💀

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🌈 SEE ALSO 🌈

okay bestie this part is long, and i mean iconic long. it's all the CIPSO friends living in ./net/ipv4/cipso_ipv4.c, and we're listing every single one because they all deserve their moment ⭐

• cipso_v4_cache_entry_free(9)
• cipso_v4_map_cache_hash(9)
• cipso_v4_cache_init(9)
• cipso_v4_cache_invalidate(9)
• cipso_v4_cache_check(9)
• cipso_v4_cache_add(9)
• cipso_v4_doi_search(9)
• cipso_v4_doi_add(9)
• cipso_v4_doi_free(9)
• cipso_v4_doi_free_rcu(9)
• cipso_v4_doi_remove(9)
• cipso_v4_doi_getdef(9)
• cipso_v4_doi_putdef(9)
• cipso_v4_doi_walk(9)
• cipso_v4_map_lvl_valid(9)
• cipso_v4_map_lvl_hton(9)
• cipso_v4_map_lvl_ntoh(9)
• cipso_v4_map_cat_rbm_valid(9)
• cipso_v4_map_cat_rbm_hton(9)
• cipso_v4_map_cat_rbm_ntoh(9)
• cipso_v4_map_cat_enum_valid(9)
• cipso_v4_map_cat_enum_hton(9)
• cipso_v4_map_cat_enum_ntoh(9)
• cipso_v4_map_cat_rng_valid(9)
• cipso_v4_map_cat_rng_hton(9)
• cipso_v4_map_cat_rng_ntoh(9)
• cipso_v4_gentag_hdr(9)
• cipso_v4_gentag_rbm(9)
• cipso_v4_parsetag_rbm(9)
• cipso_v4_gentag_enum(9)
• cipso_v4_parsetag_enum(9)
• cipso_v4_gentag_rng(9)
• cipso_v4_parsetag_rng(9)
• cipso_v4_gentag_loc(9)
• cipso_v4_parsetag_loc(9)
• cipso_v4_validate(9)
• cipso_v4_error(9)
• cipso_v4_genopt(9)
• cipso_v4_sock_setattr(9)
• cipso_v4_req_setattr(9)
• cipso_v4_delopt(9)
• cipso_v4_sock_delattr(9)
• cipso_v4_req_delattr(9)
• cipso_v4_getattr(9)
• cipso_v4_sock_getattr(9)
• cipso_v4_skbuff_setattr(9)
• cipso_v4_skbuff_delattr(9)
• cipso_v4_init(9)

the way that list just goes. ate and left no crumbs 🔥 all of them live in the kernel file ./net/ipv4/cipso_ipv4.c, so if you ever get lost, that's the address, bestie 🌸

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that's the whole page!! short, sweet, and to the point 🧚💜 this one came out of ./net/ipv4 and it's dated October 2026 — so mark your calendar, screenshot it, frame it, whatever, it's a whole era 💅✨👑