IPv6 Support about rust-tun

[DebianArch64]

Hey, just wanted to let you guys know that I'm currently working on PR for IPV6 support.

I got it working on Mac, need to work on the other platforms you guys support and make sure the coding style matches. Don't worry about it saying 'broadcast' in the screenshot, IPv6 doesn't support it so I just skip over it.

[ssrlive]

Welcome your PR. Thanks.

[DebianArch64]

Sorry for the long response, I ended up going with making a Apple TunnelProvider and using the 'createUDPSession' to connect to my rust socket, but here is what I had:

Since my ipv6 implementation is pretty badly formatted, I'll let the owner make changes to it:
[1] Add 'ifaddr_in6' structures mostly from libc.

//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//                    Version 2, December 2004
//
// Copyleft (ↄ) meh. <[email protected]> | http://meh.schizofreni.co
//
// Everyone is permitted to copy and distribute verbatim or modified
// copies of this license document, and changing it is allowed as long
// as the name is changed.
//
//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
//
//  0. You just DO WHAT THE FUCK YOU WANT TO.

//! Bindings to internal macOS stuff.

use libc::{c_char, c_uint, ifreq, sockaddr, sockaddr_in6, IFNAMSIZ};
use nix::{ioctl_readwrite, ioctl_write_ptr};

pub const UTUN_CONTROL_NAME: &str = "com.apple.net.utun_control";
pub const IN6_IFF_NODAD: i32 = 0x0020;
pub const IN6_IFF_SECURED: i32 = 0x0400;

#[allow(non_camel_case_types)]
#[repr(C)]
#[derive(Copy, Clone)]
pub struct ctl_info {
    pub ctl_id: c_uint,
    pub ctl_name: [c_char; 96],
}

#[allow(non_camel_case_types)]
#[repr(C)]
#[derive(Copy, Clone)]
pub struct ifaliasreq {
    pub ifra_name: [c_char; IFNAMSIZ],
    pub ifra_addr: sockaddr,
    pub ifra_broadaddr: sockaddr,
    pub ifra_mask: sockaddr,
}

#[allow(non_camel_case_types)]
#[repr(C)]
pub struct in6_ifaliasreq {
    pub ifra_name: [c_char; IFNAMSIZ],
    pub ifra_addr: sockaddr_in6,
    pub ifra_dstaddr: sockaddr_in6,
    pub ifra_prefixmask: sockaddr_in6,
    pub ifra_flags: libc::c_int,
    pub in6_addrlifetime: libc::in6_addrlifetime,
}

ioctl_readwrite!(ctliocginfo, b'N', 3, ctl_info);

ioctl_write_ptr!(siocsifflags, b'i', 16, ifreq);
ioctl_readwrite!(siocgifflags, b'i', 17, ifreq);

ioctl_write_ptr!(siocsifaddr, b'i', 12, ifreq);
ioctl_readwrite!(siocgifaddr, b'i', 33, ifreq);

ioctl_write_ptr!(siocsifdstaddr, b'i', 14, ifreq);
ioctl_readwrite!(siocgifdstaddr, b'i', 34, ifreq);

ioctl_write_ptr!(siocsifbrdaddr, b'i', 19, ifreq);
ioctl_readwrite!(siocgifbrdaddr, b'i', 35, ifreq);

ioctl_write_ptr!(siocsifnetmask, b'i', 22, ifreq);
ioctl_readwrite!(siocgifnetmask, b'i', 37, ifreq);

ioctl_write_ptr!(siocsifmtu, b'i', 52, ifreq);
ioctl_readwrite!(siocgifmtu, b'i', 51, ifreq);

ioctl_write_ptr!(siocaifaddr, b'i', 26, ifaliasreq);
ioctl_write_ptr!(siocdifaddr, b'i', 25, ifreq);

// basing off: https://opensource.apple.com/source/xnu/xnu-1504.15.3/bsd/netinet6/in6_var.h
ioctl_write_ptr!(siocaifaddr_in6, b'i', 26, in6_ifaliasreq);

ioctl_write_ptr!(siocsifaddr_in6, b'i', 12, libc::in6_ifreq);
ioctl_readwrite!(siocgifaddr_in6, b'i', 33, libc::in6_ifreq);

[2]
In 'set_alias' function is where we set IP address and do pretty much everything for IPV6.
'set_destination' and 'broadaddr' is useless for IPV6 and in Device::new() there needs to be a way to set family dynamically

let ctl = Some(posix::Fd::new(
                libc::socket(
                    /*AF_INET*/ AF_INET6,
                    SOCK_DGRAM, 0,
                ),
                true,
            )?);

fn set_alias(&mut self, addr: IpAddr, broadaddr: IpAddr, mask: IpAddr) -> Result<()> {
        let tun_name = self.tun_name.as_ref().ok_or(Error::InvalidConfig)?;
        let ctl = self.ctl.as_ref().ok_or(Error::InvalidConfig)?;
        match addr {
            IpAddr::V4(addr) => unsafe {
                let mut req: ifaliasreq = mem::zeroed();
                ptr::copy_nonoverlapping(
                    tun_name.as_ptr() as *const c_char,
                    req.ifra_name.as_mut_ptr(),
                    tun_name.len(),
                );

                req.ifra_addr = sockaddr_union::from((addr, 0)).addr;
                req.ifra_broadaddr = sockaddr_union::from((broadaddr, 0)).addr;
                req.ifra_mask = sockaddr_union::from((mask, 0)).addr;

                if let Err(err) = siocaifaddr(ctl.as_raw_fd(), &req) {
                    return Err(io::Error::from(err).into());
                }
                let route = Route {
                    addr: std::net::IpAddr::V4(addr),
                    netmask: mask,
                    dest: broadaddr,
                };
                if let Err(e) = self.set_route(route) {
                    log::warn!("{e:?}");
                }
                Ok(())
            },
            IpAddr::V6(_addr) => unsafe {
                let mut req: in6_ifaliasreq = mem::zeroed();
                ptr::copy_nonoverlapping(
                    tun_name.as_ptr() as *const c_char,
                    req.ifra_name.as_mut_ptr(),
                    tun_name.len(),
                );

                req.ifra_addr = sockaddr_union::from((addr, 0)).addr6;
                req.ifra_prefixmask = sockaddr_union::from((mask, 0)).addr6;
                req.in6_addrlifetime.ia6t_vltime = 0xffffffff_u32;
                req.in6_addrlifetime.ia6t_pltime = 0xffffffff_u32;

                // https://opensource.apple.com/source/xnu/xnu-6153.61.1/bsd/netinet6/in6_var.h.auto.html
                req.ifra_flags = IN6_IFF_NODAD;
                if let Err(err) = siocaifaddr_in6(ctl.as_raw_fd(), &req) {
                    return Err(io::Error::from(err).into());
                }

                let route = Route {
                    addr,
                    netmask: mask,
                    dest: broadaddr,
                };
                if let Err(e) = self.set_route(route) {
                    log::warn!("{e:?}");
                }
                Ok(())
            },
        }
    }