Add if_packet.h headers

Some structs for implementing af_packet(7)

Author: Alexander Danilov

src/unix/notbsd/linux/mod.rs

@@ -229,6 +229,13 @@ s! {
         pad: [::c_long; 4],
     }
 
+    pub struct packet_mreq {
+        pub mr_ifindex: ::c_int,
+        pub mr_type: ::c_ushort,
+        pub mr_alen: ::c_ushort,
+        pub mr_address: [::c_char; 8],
+    }
+
     pub struct cpu_set_t {
         #[cfg(all(target_pointer_width = "32",
                   not(target_arch = "x86_64")))]
@@ -1300,6 +1307,17 @@ pub const CTRL_ATTR_MCAST_GRP_UNSPEC: ::c_int = 0;
 pub const CTRL_ATTR_MCAST_GRP_NAME: ::c_int = 1;
 pub const CTRL_ATTR_MCAST_GRP_ID: ::c_int = 2;
 
+
+// linux/if_packet.h
+pub const PACKET_ADD_MEMBERSHIP: ::c_int = 1;
+pub const PACKET_DROP_MEMBERSHIP: ::c_int = 2;
+
+pub const PACKET_MR_MULTICAST: ::c_int = 0;
+pub const PACKET_MR_PROMISC: ::c_int = 1;
+pub const PACKET_MR_ALLMULTI: ::c_int = 2;
+pub const PACKET_MR_UNICAST: ::c_int = 3;
+
+
 // linux/netfilter.h
 pub const NF_DROP: ::c_int = 0;
 pub const NF_ACCEPT: ::c_int =  1;