nlmsg_ok(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 nlmsg_ok(9) — the Kernel API Manual, bestie edition 🌸

Okay so this one is a tiny little function from the Linux kernel API manual (nlmsg_ok, section 9 — kernel API), and honestly it's giving security guard at the club door energy. Let me tell you everything 💅

✨ NAME ✨

nlmsg_ok — check if the netlink message fits into the remaining bytes

Like, that's it. That's the whole job. It peeks at a netlink message header and goes "does this actually fit in what's left of the buffer, or are we about to read garbage?" No cap, it's the vibe check of netlink parsing 🫶

✨ SYNOPSIS ✨

int nlmsg_ok (const struct nlmsghdr *nlh , int remaining );

✨ ARGUMENTS ✨

  • nlh — the netlink message header, bestie. This is the const struct nlmsghdr * you're asking about. It's const because we're just looking, not touching 🙈
  • remaining — the number of bytes remaining in the message stream. Like, how much room is left on the couch. An int.

✨ SEE ALSO ✨

So the kernel file for all this is ./include/net/netlink.h — that's where the family lives 🧚 And here's the whole extended friend group, on some invite the entire group chat behaviour:

struct nla_policy(9), struct nl_info(9), enum netlink_validation(9), nlmsg_msg_size(9), nlmsg_total_size(9), nlmsg_padlen(9), nlmsg_data(9), nlmsg_len(9), nlmsg_payload(9), nlmsg_attrdata(9), nlmsg_attrlen(9), nlmsg_next(9), nla_parse(9), nla_parse_deprecated(9), nla_parse_deprecated_strict(9), __nlmsg_parse(9), nlmsg_parse(9), nlmsg_parse_deprecated(9), nlmsg_parse_deprecated_strict(9), nlmsg_find_attr(9), nla_validate_deprecated(9), nla_validate(9), nlmsg_validate_deprecated(9), nlmsg_report(9), nlmsg_seq(9), nlmsg_for_each_attr(9), nlmsg_for_each_attr_type(9), nlmsg_put(9), nlmsg_append(9), nlmsg_put_answer(9), nlmsg_new(9), nlmsg_new_large(9), nlmsg_end(9), nlmsg_get_pos(9), nlmsg_trim(9), nlmsg_cancel(9), nlmsg_free(9), nlmsg_consume(9), nlmsg_multicast_filtered(9), nlmsg_multicast(9), nlmsg_unicast(9), nlmsg_for_each_msg(9), nl_dump_check_consistent(9) 💖

And it keeps going, because of course it does:

nla_attr_size(9), nla_total_size(9), nla_padlen(9), nla_type(9), nla_data(9), nla_len(9), nla_ok(9), nla_next(9), nla_find_nested(9), nla_parse_nested(9), nla_parse_nested_deprecated(9), nla_put_u8(9), nla_put_u16(9), nla_put_be16(9), nla_put_net16(9), nla_put_le16(9), nla_put_u32(9), nla_put_uint(9), nla_put_be32(9), nla_put_net32(9), nla_put_le32(9), nla_put_u64_64bit(9), nla_put_be64(9), nla_put_net64(9), nla_put_le64(9), nla_put_s8(9), nla_put_s16(9), nla_put_s32(9), nla_put_s64(9), nla_put_sint(9), nla_put_string(9), nla_put_flag(9), nla_put_msecs(9), nla_put_in_addr(9), nla_put_in6_addr(9), nla_put_bitfield32(9) ✨

The getters, the default getters, the whole squad:

nla_get_u32(9), nla_get_u32_default(9), nla_get_be32(9), nla_get_be32_default(9), nla_get_le32(9), nla_get_le32_default(9), nla_get_u16(9), nla_get_u16_default(9), nla_get_be16(9), nla_get_be16_default(9), nla_get_le16(9), nla_get_le16_default(9), nla_get_u8(9), nla_get_u8_default(9), nla_get_u64(9), nla_get_u64_default(9), nla_get_uint(9), nla_get_uint_default(9), nla_get_be64(9), nla_get_be64_default(9), nla_get_le64(9), nla_get_le64_default(9), nla_get_s32(9), nla_get_s32_default(9), nla_get_s16(9), nla_get_s16_default(9), nla_get_s8(9), nla_get_s8_default(9), nla_get_s64(9), nla_get_s64_default(9), nla_get_sint(9), nla_get_sint_default(9), nla_get_flag(9), nla_get_msecs(9), nla_get_msecs_default(9), nla_get_in_addr(9), nla_get_in_addr_default(9), nla_get_in6_addr(9), nla_get_bitfield32(9) 🦋

And the last little cluster, obsessed with them:

nla_memdup(9), nla_nest_start_noflag(9), nla_nest_start(9), nla_nest_end(9), nla_nest_end_safe(9), nla_nest_cancel(9), nla_put_empty_nest(9), __nla_validate_nested(9), nla_need_padding_for_64bit(9), nla_align_64bit(9), nla_total_size_64bit(9), nla_for_each_attr(9), nla_for_each_attr_type(9), nla_for_each_nested(9), nla_for_each_nested_type(9), nla_is_last(9) 👑

Heads up bestie: that's the entire cross-reference list, character for character — I did not skip a single one, because the way that a manpage drops 150 references and expects you to read them all is iconic honestly 😭

And that's the page! Signing off from ./include/net, dated October 2026 — go check your nullable math before you dereference anything, mwah 💋💖

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