IF_GET(9)

IF_GET(9) — Kernel Developer's Manual 💻✨

okay bestie, welcome to the interface-pointer retrieval manual, no cap 🫶

NAME 🎀

if_get, if_unit, if_put — get an interface pointer from an interface index 👑

SYNOPSIS ✨

#include <net/if.h>

struct ifnet *
if_get(unsigned int ifidx);

struct ifnet *
if_unit(const char *name);

void
if_put(struct ifnet *ifp);

DESCRIPTION 💖

Okay so here's the vibe: these functions hand you pointers to interface descriptors, and the reference life cycle is the main character. 🫶

• if_get() — returns a pointer to the interface descriptor corresponding to the unique index ifidx. This descriptor is guaranteed to be valid until if_put() is called on the returned pointer. Slay, but respect the reference. 💅
• The index value 0 is never associated with an interface descriptor and can be used to determine if an interface index is valid or not. Literally a built-in vibe check for index validity. ⭐
• if_unit() — returns a pointer to the interface descriptor corresponding to the unique name name. This descriptor is guaranteed to be valid until if_put() is called on the returned pointer. Same reference rule, bestie. 🎀
• if_put() — releases a reference on the interface descriptor pointed to by ifp. If ifp is a NULL pointer, no action occurs. No drama, no crash, just nothing. 🙈

CONTEXT 🌈

if_get(), if_unit() and if_put() can be called during autoconf, from process context, or from interrupt context. All three contexts, iconic flexibility. 🔥

RETURN VALUES 👑

• if_get() returns a pointer to an interface descriptor if the index is valid, otherwise NULL.
• if_unit() returns a pointer to an interface descriptor if the interface with present name exists, otherwise NULL.

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That's the whole page, bestie. This one came from Debian, dated January 18, 2021, under IF_GET(9). Periodt. 💜