Bug #876 - add missing free_umem_and_xsk function

Missed in merge.

docs/CHANGELOG

@@ -1,4 +1,5 @@
 06/08/2024 Version 4.5.0-beta2
+    - AF_XDP compile issue due to merge issue (#876)
     - memory leak in tcpprep when using include/exclude (#869)
     - memory leak in tcpprep when using RegEx (#867)
     - fix nanosecond timestamp regression bug (#863)
@@ -14,7 +15,7 @@
     - Infinite loop in tcprewrite at get.c (#827 #842)
     - SLL incorrect size and protocol when converted to Ethernet (#826)
     - CVE-2023-43279 add check for empty CIDR (#824 #843)
-    - AF_XDF socket extension (#822 #823)
+    - AF_XDP socket extension (#822 #823)
     - configure.ac: unify search dirs for pcap and add lib32 (#819)
     - tcpreplay-edit recomputes IPv4 checksums unnecessarily (#815 #846)
     - CVE-2023-4256 double free in tcprewrite DLT_JUNIPER_ETHER (#813 #851)

docs/INSTALL

@@ -138,6 +138,7 @@ written to directly.
 This feature requires `libxdp-dev` and `libbpf-dev` packages to be installed.
 For example:
 
+    $ sudo apt install -y libxdp-dev libbpf-dev
     $ ./configure | tail
     Linux/BSD netmap:           no
     Tuntap device support:      yes

src/tcpreplay_api.c

@@ -1400,3 +1400,37 @@ apply_loop_delay(tcpreplay_t *ctx) {
 
     return false;
 }
+
+#ifdef HAVE_LIBXDP
+void
+delete_xsk_socket(struct xsk_socket *xsk)
+{
+    size_t desc_sz = sizeof(struct xdp_desc);
+    struct xdp_mmap_offsets off;
+    socklen_t optlen;
+    int err;
+
+    if (!xsk) {
+        return;
+    }
+
+    optlen = sizeof(off);
+    err = getsockopt(xsk->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);
+    if (!err) {
+        if (xsk->rx) {
+            munmap(xsk->rx->ring - off.rx.desc, off.rx.desc + xsk->config.rx_size * desc_sz);
+        }
+        if (xsk->tx) {
+            munmap(xsk->tx->ring - off.tx.desc, off.tx.desc + xsk->config.tx_size * desc_sz);
+        }
+    }
+    close(xsk->fd);
+}
+
+void
+free_umem_and_xsk(sendpacket_t *sp)
+{
+    xsk_umem__delete(sp->xsk_info->umem->umem);
+    delete_xsk_socket(sp->xsk_info->xsk);
+}
+#endif /*HAVE_LIBXDP*/