ARES_SET_LOCAL_DEV(3)

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✨ ARES_SET_LOCAL_DEV ✨

okay bestie, welcome to page 3 of the Library Functions Manual — yes this is ARES_SET_LOCAL_DEV, and yes it's about to be your new fave 🎀

💖 NAME 💖

ares_set_local_dev — bind to a specific network device when creating sockets 🫶

🌸 SYNOPSIS 🌸

#include <ares.h>

void ares_set_local_dev(ares_channel_t *channel, const char* local_dev_name)

🦋 DESCRIPTION 🦋

so like, the way that ares_set_local_dev works is: it makes all future sockets get bound to this device with SO_BINDTODEVICE. literally every socket from here on out, no cap 💅

which means it forces your communications to go over a certain interface — and that's highkey useful on multi-homed machines where you've got options and you need to pick one 🧚

⚠️ okay but listen — this option is only supported on Linux, and there are two lil conditions: the interface must not already be bound to the socket, or the current effective user must have CAP_NET_RAW capability in the current network namespace for the option to work. both of those, real talk. 👑

and if SO_BINDTODEVICE isn't supported at all, or the setsockopt call just... fails (probably because of permissions 🙈), then the error is silently ignored. like, no screaming, no warning, nothing. it's giving "we don't talk about it." 💀

🔥 SEE ALSO 🔥

👑 NOTES 👑

this function was added in c-ares 1.7.4 — so she's been iconic for a minute ⭐

and that's the whole page, bestie! this one's from the Library Functions Manual, dated 23 September 2024, and it's serving ARES_SET_LOCAL_DEV(3) realness. slay, go bind some sockets responsibly 💖✨🎀

📦 where this page comes from