Add bpf constant on macOS

libc-test/build.rs

@@ -183,6 +183,7 @@ fn main() {
         cfg.header("sys/event.h");
         cfg.header("net/if_dl.h");
         if freebsd {
+            cfg.header("net/bpf.h");
             cfg.header("libutil.h");
         } else {
             cfg.header("util.h");

src/unix/bsd/apple/mod.rs

@@ -2167,6 +2167,26 @@ pub const MH_MAGIC_64: u32 = 0xfeedfacf;
 pub const UTUN_OPT_FLAGS: ::c_int = 1;
 pub const UTUN_OPT_IFNAME: ::c_int = 2;
 
+// net/bpf.h
+pub const DLT_NULL: ::c_uint = 0;         // no link-layer encapsulation
+pub const DLT_EN10MB: ::c_uint = 1;       // Ethernet (10Mb)
+pub const DLT_EN3MB: ::c_uint = 2;        // Experimental Ethernet (3Mb)
+pub const DLT_AX25: ::c_uint = 3;         // Amateur Radio AX.25
+pub const DLT_PRONET: ::c_uint = 4;       // Proteon ProNET Token Ring
+pub const DLT_CHAOS: ::c_uint = 5;        // Chaos
+pub const DLT_IEEE802: ::c_uint = 6;      // IEEE 802 Networks
+pub const DLT_ARCNET: ::c_uint = 7;       // ARCNET
+pub const DLT_SLIP: ::c_uint = 8;         // Serial Line IP
+pub const DLT_PPP: ::c_uint = 9;          // Point-to-point Protocol
+pub const DLT_FDDI: ::c_uint = 10;        // FDDI
+pub const DLT_ATM_RFC1483: ::c_uint = 11; // LLC/SNAP encapsulated atm
+pub const DLT_RAW: ::c_uint = 12;         // raw IP
+pub const DLT_LOOP: ::c_uint = 108;
+
+// https://github.com/apple/darwin-xnu/blob/master/bsd/net/bpf.h#L100
+// sizeof(int32_t)
+pub const BPF_ALIGNMENT: ::c_int = 4;
+
 f! {
     pub fn WSTOPSIG(status: ::c_int) -> ::c_int {
         status >> 8

src/unix/bsd/freebsdlike/mod.rs

@@ -956,6 +956,10 @@ pub const ONLRET: ::tcflag_t = 0x40;
 
 pub const CMGROUP_MAX: usize = 16;
 
+// https://github.com/freebsd/freebsd/blob/master/sys/net/bpf.h
+// sizeof(long)
+pub const BPF_ALIGNMENT: ::c_int = 8;
+
 f! {
     pub fn WIFCONTINUED(status: ::c_int) -> bool {
         status == 0x13