add: replace support for xdp

Signed-off-by: yogaraj.s <[email protected]>

libbpf-rs/src/xdp.rs

@@ -1,5 +1,6 @@
 use bitflags::bitflags;
 use std::mem::size_of;
+use std::os::fd::RawFd;
 use std::os::unix::io::AsRawFd;
 use std::os::unix::io::BorrowedFd;
 
@@ -91,4 +92,14 @@ impl<'fd> Xdp<'fd> {
             unsafe { libbpf_sys::bpf_xdp_query_id(ifindex, flags.bits() as i32, &mut prog_id) };
         util::parse_ret(err).map(|()| prog_id)
     }
+
+    /// Replace an existing xdp program (identified by old_prog_fd) with this xdp program
+    pub fn replace(&self, ifindex: i32, old_prog_fd: RawFd, flags: XdpFlags) -> Result<()> {
+        let mut opts = self.attach_opts;
+        opts.old_prog_fd = old_prog_fd;
+        let ret = unsafe {
+            libbpf_sys::bpf_xdp_attach(ifindex, self.fd.as_raw_fd(), flags.bits(), &opts)
+        };
+        util::parse_ret(ret)
+    }
 }

libbpf-rs/tests/test_xdp.rs

@@ -1,4 +1,5 @@
 use std::os::fd::AsFd;
+use std::os::fd::AsRawFd;
 
 use scopeguard::defer;
 
@@ -18,7 +19,11 @@ fn test_sudo_xdp() {
     let obj = get_test_object("xdp.bpf.o");
     let fd = obj.prog("xdp_filter").unwrap().as_fd();
 
+    let obj1 = get_test_object("xdp.bpf.o");
+    let fd1 = obj1.prog("xdp_filter").unwrap().as_fd();
+
     let xdp_prog = Xdp::new(fd);
+    let xdp_prog1 = Xdp::new(fd1);
 
     defer! {
         xdp_prog.detach(LO_IFINDEX, XdpFlags::UPDATE_IF_NOEXIST).unwrap();
@@ -41,6 +46,10 @@ fn test_sudo_xdp() {
         .query(LO_IFINDEX, XdpFlags::UPDATE_IF_NOEXIST)
         .is_ok());
 
+    assert!(xdp_prog1
+        .replace(LO_IFINDEX, fd.as_raw_fd(), XdpFlags::REPLACE)
+        .is_ok());
+
     assert!(xdp_prog
         .detach(LO_IFINDEX, XdpFlags::UPDATE_IF_NOEXIST)
         .is_ok());