ipv4_pktinfo_prepare(9)

ipv4_pktinfo_prepare(9) 💅✨

okay so this is a Kernel API Manual page, and it's literally about transferring some info from rtable to skb. bestie, it's giving low-level kernel realness 🫶

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🌸 NAME 🌸

ipv4_pktinfo_prepare — transfer some info from rtable to skb 💖

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✨ SYNOPSIS ✨

the whole mood, signature-wise:

void ipv4_pktinfo_prepare (const struct sock *sk , struct sk_buff *skb ,
       bool drop_dst );

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🎀 ARGUMENTS 🎀

• sk — socket. that's the socket bestie, no cap 🧚
• skb — buffer. the packet buffer, the little carry-on 🦋
• drop_dst — if true, drops skb dst. yes literally: true means the skb dst gets dropped 💀

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💜 DESCRIPTION 💜

okay so to support the IP_CMSG_PKTINFO option, we store rt_iif and the specific destination in skb->cb[] before dst drop. that's the whole move ✨

the way this slays: the receiver doesn't make cache line misses to read rtable. no cap, it's a whole performance vibe 🔥

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🦋 SEE ALSO 🦋

go look at the kernel file ./net/ipv4/ip_sockglue.c — that's the reference, iykyk 👑

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xoxo kernel bestie 💖 sourced from ./net/ipv4, dated October 2026, page ipv4_pktinfo_prepare(9) — periodt. 🌈