linux: Add definitions for Multipath TCP

Author: george-hopkins

libc-test/build.rs

@@ -2645,6 +2645,10 @@ fn test_linux(target: &str) {
             // Require Linux kernel 5.6:
             "VMADDR_CID_LOCAL" => true,
 
+            // IPPROTO_MAX was increased in 5.6 for IPPROTO_MPTCP:
+            | "IPPROTO_MAX"
+            | "IPPROTO_MPTCP" => true,
+
             // Defined in kernel headers but musl removes it; need musl 1.2 for definition in musl
             // headers.
             "P_PIDFD" => true,

src/unix/linux_like/linux/mod.rs

@@ -1228,6 +1228,7 @@ pub const RTLD_NOW: ::c_int = 0x2;
 pub const AT_EACCESS: ::c_int = 0x200;
 
 pub const TCP_MD5SIG: ::c_int = 14;
+pub const TCP_ULP: ::c_int = 31;
 
 align_const! {
     pub const PTHREAD_MUTEX_INITIALIZER: pthread_mutex_t = pthread_mutex_t {
@@ -1316,7 +1317,9 @@ pub const IPPROTO_UDPLITE: ::c_int = 136;
 pub const IPPROTO_MPLS: ::c_int = 137;
 /// raw IP packet
 pub const IPPROTO_RAW: ::c_int = 255;
-pub const IPPROTO_MAX: ::c_int = 256;
+/// Multipath TCP
+pub const IPPROTO_MPTCP: ::c_int = 262;
+pub const IPPROTO_MAX: ::c_int = 263;
 
 pub const IP_MSFILTER: ::c_int = 41;
 pub const MCAST_JOIN_GROUP: ::c_int = 42;