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use std::fs::File;
use std::io;
use std::net::{Ipv6Addr, SocketAddr};
use std::path::Path;
use std::thread;
use std::time::Duration;
use hickory_resolver::config::{NameServerConfig, Protocol, ResolverConfig, ResolverOpts};
use hickory_resolver::Resolver;
use ipnet::Ipv6Net;
use rsdsl_netlinklib::tunnel::IpIp6;
use rsdsl_pd_config::PdConfig;
use signal_hook::{consts::SIGUSR1, iterator::Signals};
use sysinfo::{ProcessExt, Signal, System, SystemExt};
use thiserror::Error;
const MAX_ATTEMPTS: usize = 3;
const BACKOFF: u64 = 30;
#[derive(Debug, Error)]
pub enum Error {
#[error("no address associated with aftr name")]
NoDnsRecord,
#[error("not enough ipv6 subnets")]
NotEnoughIpv6Subnets,
#[error("io error: {0}")]
Io(#[from] io::Error),
#[error("invalid prefix length: {0}")]
IpnetPrefixLen(#[from] ipnet::PrefixLenError),
#[error("netlinklib error: {0}")]
Netlinklib(#[from] rsdsl_netlinklib::Error),
#[error("serde_json error: {0}")]
SerdeJson(#[from] serde_json::Error),
#[error("hickory_resolver resolve error: {0}")]
HickoryResolverResolve(#[from] hickory_resolver::error::ResolveError),
}
pub type Result<T> = std::result::Result<T, Error>;
fn main() -> Result<()> {
println!("[info] init");
let mut tnl = None;
let mut last = None;
logic(&mut tnl, &mut last)?;
let mut signals = Signals::new([SIGUSR1])?;
for _ in signals.forever() {
logic(&mut tnl, &mut last)?;
}
unreachable!()
}
fn logic(tnl: &mut Option<IpIp6>, last: &mut Option<(Ipv6Addr, Ipv6Addr)>) -> Result<()> {
if !Path::new(rsdsl_pd_config::LOCATION).exists() {
println!("[info] no lease");
*tnl = None; // Delete tunnel.
for netlinkd in System::new_all().processes_by_exact_name("rsdsl_netlinkd") {
netlinkd.kill_with(Signal::User1);
}
return Ok(());
}
let mut file = File::open(rsdsl_pd_config::LOCATION)?;
let pdconfig: PdConfig = serde_json::from_reader(&mut file)?;
if let Some(ref aftr) = pdconfig.aftr {
let local = local_address(&pdconfig)?;
let remote = multitry_resolve6(&pdconfig, aftr)?;
if unchanged(local, remote, last) {
println!("[info] no change");
return Ok(());
}
*tnl = None; // Delete tunnel first, otherwise creation fails with "file exists".
*tnl = Some(IpIp6::new(
"dslite0".to_string(),
"ppp0".to_string(),
local,
remote,
)?);
for netlinkd in System::new_all().processes_by_exact_name("rsdsl_netlinkd") {
netlinkd.kill_with(Signal::User1);
}
println!("[info] init ds-lite tunnel {} <=> {}", local, remote);
} else {
*tnl = None; // Delete tunnel (if any).
for netlinkd in System::new_all().processes_by_exact_name("rsdsl_netlinkd") {
netlinkd.kill_with(Signal::User1);
}
println!("[info] no aftr");
}
Ok(())
}
fn local_address(pdconfig: &PdConfig) -> Result<Ipv6Addr> {
let prefix = Ipv6Net::new(pdconfig.prefix, pdconfig.len)?.trunc();
let mut subnets = prefix.subnets(64)?;
let addr = next_ifid1(&mut subnets)?;
Ok(addr)
}
fn next_ifid1<T: Iterator<Item = Ipv6Net>>(subnets: &mut T) -> Result<Ipv6Addr> {
Ok((u128::from(subnets.next().ok_or(Error::NotEnoughIpv6Subnets)?.addr()) + 1).into())
}
fn resolve6(pdconfig: &PdConfig, fqdn: &str) -> Result<Ipv6Addr> {
let mut cfg = ResolverConfig::new();
cfg.add_name_server(NameServerConfig::new(
SocketAddr::new(pdconfig.dns1.into(), 53),
Protocol::Udp,
));
cfg.add_name_server(NameServerConfig::new(
SocketAddr::new(pdconfig.dns2.into(), 53),
Protocol::Udp,
));
let resolver = Resolver::new(cfg, ResolverOpts::default())?;
let response = resolver.ipv6_lookup(fqdn)?;
let addr = response.iter().next().ok_or(Error::NoDnsRecord)?;
Ok(**addr)
}
fn multitry_resolve6(pdconfig: &PdConfig, fqdn: &str) -> Result<Ipv6Addr> {
for i in 0..MAX_ATTEMPTS {
match resolve6(pdconfig, fqdn) {
Ok(v) => return Ok(v),
Err(e) => {
if i >= MAX_ATTEMPTS - 1 {
return Err(e);
} else {
println!(
"[warn] resolve aftr {}: {} (attempt {}/{})",
fqdn, e, i, MAX_ATTEMPTS
)
}
}
}
thread::sleep(Duration::from_secs(BACKOFF));
}
unreachable!()
}
fn unchanged(local: Ipv6Addr, remote: Ipv6Addr, last: &mut Option<(Ipv6Addr, Ipv6Addr)>) -> bool {
let unchanged = if let Some(last) = last {
local == last.0 && remote == last.1
} else {
false
};
*last = Some((local, remote));
unchanged
}
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