Hello wireguard@, I recently found out that in-Linux wireguard has, since its inception, set its v6 sockets to v6-only (https://github.com/torvalds/linux/blob/e7096c131e5161fa3b8e52a650d7719d2857adfd/drivers/net/wireguard/socket.c#L381) and it keys only off the address family to decide which socket to use (https://github.com/torvalds/linux/blob/e7096c131e5161fa3b8e52a650d7719d2857adfd/drivers/net/wireguard/socket.c#L188). This means that v4-mapped v6 addresses (::ffff:a.b.c.d) can be registered as peer endpoints, but the kernel very silently won't try to reach out. Is that deliberate for some reason that eludes me? If it is, could the userspace tooling be educated about v4-mapped addresses and translate them accordingly before handing them up to the kernel; if it isn't, could we drop the v6-only flag on the kernel socket?
Thanks for any input, --nwf;
