rewrite sit tunnel creation to use libc rather than bindings

3 files changed, 101 insertions, 19 deletions

diff --git a/Cargo.lock b/Cargo.lock
index d434422..e3ef295 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -45,6 +45,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "bitfield"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d7e60934ceec538daadb9d8432424ed043a904d8e0243f3c6446bce549a46ac"
+
+[[package]]
 name = "bitflags"
 version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -269,9 +275,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.147"
+version = "0.2.149"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
+checksum = "a08173bc88b7955d1b3145aa561539096c421ac8debde8cbc3612ec635fee29b"
 
 [[package]]
 name = "log"
@@ -477,9 +483,11 @@ dependencies = [
 name = "rsdsl_netlinkd"
 version = "0.7.0-dev"
 dependencies = [
+ "bitfield",
  "futures",
  "futures-util",
  "ipnet",
+ "libc",
  "netlink-packet-route",
  "notify",
  "rsdsl_ip_config",
diff --git a/Cargo.toml b/Cargo.toml
index af4256a..5760f2a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,9 +6,11 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+bitfield = "0.14.0"
 futures = "0.3.28"
 futures-util = "0.3.27"
 ipnet = "2.8.0"
+libc = "0.2.149"
 netlink-packet-route = "0.17.0"
 notify = "5.1.0"
 rsdsl_ip_config = { git = "https://github.com/rsdsl/ip_config.git", version = "0.2.2" }
diff --git a/src/tunnel.rs b/src/tunnel.rs
index 240e5fb..ac5d074 100644
--- a/src/tunnel.rs
+++ b/src/tunnel.rs
@@ -4,6 +4,10 @@ use std::ffi::CString;
 use std::io;
 use std::net::{Ipv4Addr, Ipv6Addr};
 
+use bitfield::bitfield;
+
+const SIOCADDTUNNEL: u64 = 0x89F0 + 1;
+
 /// A handle to a 6in4 tunnel. The interface is automatically deleted on drop.
 #[derive(Debug)]
 pub struct Sit {
@@ -18,28 +22,53 @@ impl Drop for Sit {
 
 impl Sit {
     pub fn new(name: &str, master: &str, laddr: Ipv4Addr, raddr: Ipv4Addr) -> Result<Self> {
-        let tnlname = CString::new(name)?.into_raw();
-        let ifmaster = CString::new(master)?.into_raw();
+        let mut vihl = VerIhl::default();
+
+        vihl.set_version(4);
+        vihl.set_ihl(5);
+
+        let p = IpTunnelParm {
+            name: CString::new(name)?,
+            link: libc::if_nametoindex(CString::new(master)?.as_ptr()),
+            i_flags: 0,
+            o_flags: 0,
+            i_key: 0,
+            o_key: 0,
+            iph: IpHdr {
+                vihl,
+                tos: 0,
+                tot_len: 0,
+                id: 0,
+                frag_off: 0,
+                check: 0,
+                ttl: 64,
+                protocol: libc::IPPROTO_IPV6 as u8,
+                saddr: laddr,
+                daddr: raddr,
+            },
+        };
 
-        let err = unsafe {
-            internal::netlinkd_create_6in4(
-                tnlname,
-                ifmaster,
-                u32::from(laddr).to_be(),
-                u32::from(raddr).to_be(),
-            )
+        if p.link == 0 {
+            return Err(Error::LinkNotFound(master.to_owned()));
+        }
+
+        let ifr = IfReq {
+            name: CString::new("sit0")?,
+            ifru_data: &p,
         };
 
-        let _ = unsafe { CString::from_raw(tnlname) };
-        let _ = unsafe { CString::from_raw(ifmaster) };
+        let fd = libc::socket(libc::AF_INET, libc::SOCK_DGRAM, libc::IPPROTO_IP);
+        if fd < 0 {
+            return Err(io::Error::last_os_error().into());
+        }
 
-        if err < 0 {
-            Err(Error::Io(io::Error::last_os_error()))
-        } else {
-            Ok(Self {
-                name: name.to_owned(),
-            })
+        if libc::ioctl(fd, SIOCADDTUNNEL, &ifr) < 0 {
+            return Err(io::Error::last_os_error().into());
         }
+
+        Ok(Self {
+            name: name.to_owned(),
+        })
     }
 
     fn do_delete(&self) -> Result<()> {
@@ -105,3 +134,46 @@ impl IpIp6 {
         }
     }
 }
+
+bitfield! {
+    #[derive(Default)]
+    struct VerIhl(u8);
+    impl Debug;
+
+    version, set_version: 7, 4;
+    ihl, set_ihl: 3, 0;
+}
+
+#[derive(Debug)]
+#[repr(C)]
+struct IpHdr {
+    vihl: VerIhl,
+    tos: u8,
+    tot_len: u16,
+    id: u16,
+    frag_off: u16,
+    ttl: u8,
+    protocol: u8,
+    check: u16,
+    saddr: Ipv4Addr,
+    daddr: Ipv4Addr,
+}
+
+#[derive(Debug)]
+#[repr(C)]
+struct IpTunnelParm {
+    name: CString,
+    link: u32,
+    i_flags: u16,
+    o_flags: u16,
+    i_key: u32,
+    o_key: u32,
+    iph: IpHdr,
+}
+
+#[derive(Debug)]
+#[repr(C)]
+struct IfReq {
+    name: CString,
+    ifru_data: *const IpTunnelParm,
+}