Implement the rest of clat packet translation

src/protomask-clat.rs

@@ -9,9 +9,10 @@ use easy_tun::Tun;
 use interproto::protocols::ip::{translate_ipv4_to_ipv6, translate_ipv6_to_ipv4};
 use ipnet::Ipv6Net;
 use nix::unistd::Uid;
+use rfc6052::{embed_ipv4_addr_unchecked, extract_ipv4_addr_unchecked};
 use std::{
  io::{Read, Write},
- net::Ipv4Addr,
+ net::{Ipv4Addr, Ipv6Addr},
 };
 
 mod common;
@@ -61,28 +62,37 @@ pub async fn main() {
  log::trace!("New packet with layer 3 protocol: {}", layer_3_proto);
  let output = match layer_3_proto {
  // IPv4
- 4 => {
- // Get the IPv4 source and destination addresses
- let ipv4_source =
- u32::from_be_bytes([buffer[12], buffer[13], buffer[14], buffer[15]]);
- let ipv4_destination =
- u32::from_be_bytes([buffer[16], buffer[17], buffer[18], buffer[19]]);
-
- // Create a new IPv6 source and destination address by embedding the IPv4 addresses into the clat prefix
- let new_source = u128::from(args.embed_prefix.addr()) | (ipv4_source as u128);
- let new_destination =
- u128::from(args.embed_prefix.addr()) | (ipv4_destination as u128);
-
- translate_ipv4_to_ipv6(&buffer[..len], new_source.into(), new_destination.into())
- }
+ 4 => translate_ipv4_to_ipv6(
+ &buffer[..len],
+ unsafe {
+ embed_ipv4_addr_unchecked(
+ Ipv4Addr::from(u32::from_be_bytes(buffer[12..16].try_into().unwrap())),
+ args.embed_prefix,
+ )
+ },
+ unsafe {
+ embed_ipv4_addr_unchecked(
+ Ipv4Addr::from(u32::from_be_bytes(buffer[16..20].try_into().unwrap())),
+ args.embed_prefix,
+ )
+ },
+ ),
 
  // IPv6
  6 => translate_ipv6_to_ipv4(
  &buffer[..len],
- // NOTE: The new source and destination addresses are just the last
- // 4 octets of the IPv6 source and destination addresses
- Ipv4Addr::new(buffer[20], buffer[21], buffer[22], buffer[23]),
- Ipv4Addr::new(buffer[36], buffer[37], buffer[38], buffer[39]),
+ unsafe {
+ extract_ipv4_addr_unchecked(
+ Ipv6Addr::from(u128::from_be_bytes(buffer[8..24].try_into().unwrap())),
+ args.embed_prefix.prefix_len(),
+ )
+ },
+ unsafe {
+ extract_ipv4_addr_unchecked(
+ Ipv6Addr::from(u128::from_be_bytes(buffer[24..40].try_into().unwrap())),
+ args.embed_prefix.prefix_len(),
+ )
+ },
  ),
  // Unknown
  proto => {
@@ -91,5 +101,8 @@ pub async fn main() {
  }
  }
  .unwrap();
+
+ // Write the translated packet back to the TUN interface
+ tun.write(&output).unwrap();
  }
 }