net: sync some IP headers with glibc

Solution:
=========

- Synchronize linux's `include/uapi/linux/in6.h'
  with glibc's `inet/netinet/in.h'.
- Synchronize glibc's `inet/netinet/in.h with linux's
  `include/uapi/linux/in6.h'.
- Allow including the headers in either other.
- First header included defines the structures and macros.

Details:
========

The kernel promises not to break the UAPI ABI so I don't
see why we can't just have the two userspace headers
coordinate?

If you include the kernel headers first you get those,
and if you include the glibc headers first you get those,
and the following patch arranges a coordination and
synchronization between the two.

Let's handle `include/uapi/linux/in6.h' from linux,
and `inet/netinet/in.h' from glibc and ensure they compile
in any order and preserve the required ABI.

These two patches pass the following compile tests:

cat >> test1.c <<EOF
int main (void) {
  return 0;
}
EOF
gcc -c test1.c

cat >> test2.c <<EOF
int main (void) {
  return 0;
}
EOF
gcc -c test2.c

One wrinkle is that the kernel has a different name for one of
the members in ipv6_mreq. In the kernel patch we create a macro
to cover the uses of the old name, and while that's not entirely
clean it's one of the best solutions (aside from an anonymous
union which has other issues).

I've reviewed the code and it looks to me like the ABI is
assured and everything matches on both sides.

Notes:
- You want netinet/in.h to include bits/in.h as early as possible,
  but it needs in_addr so define in_addr early.
- You want bits/in.h included as early as possible so you can use
  the linux specific code to define __USE_KERNEL_DEFS based on
  the _UAPI_* macro definition and use those to cull in.h.
- glibc was missing IPPROTO_MH, added here.

Compile tested and inspected.

Reported-by: Thomas Backlund <tmb@mageia.org>
Cc: Thomas Backlund <tmb@mageia.org>
Cc: libc-alpha@sourceware.org
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: David S. Miller <davem@davemloft.net>
Tested-by: Cong Wang <amwang@redhat.com>
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/in.h

@@ -24,30 +24,53 @@
 /* Standard well-defined IP protocols.  */
 enum {
   IPPROTO_IP = 0,		/* Dummy protocol for TCP		*/
+#define IPPROTO_IP		IPPROTO_IP
   IPPROTO_ICMP = 1,		/* Internet Control Message Protocol	*/
+#define IPPROTO_ICMP		IPPROTO_ICMP
   IPPROTO_IGMP = 2,		/* Internet Group Management Protocol	*/
+#define IPPROTO_IGMP		IPPROTO_IGMP
   IPPROTO_IPIP = 4,		/* IPIP tunnels (older KA9Q tunnels use 94) */
+#define IPPROTO_IPIP		IPPROTO_IPIP
   IPPROTO_TCP = 6,		/* Transmission Control Protocol	*/
+#define IPPROTO_TCP		IPPROTO_TCP
   IPPROTO_EGP = 8,		/* Exterior Gateway Protocol		*/
+#define IPPROTO_EGP		IPPROTO_EGP
   IPPROTO_PUP = 12,		/* PUP protocol				*/
+#define IPPROTO_PUP		IPPROTO_PUP
   IPPROTO_UDP = 17,		/* User Datagram Protocol		*/
+#define IPPROTO_UDP		IPPROTO_UDP
   IPPROTO_IDP = 22,		/* XNS IDP protocol			*/
+#define IPPROTO_IDP		IPPROTO_IDP
+  IPPROTO_TP = 29,		/* SO Transport Protocol Class 4	*/
+#define IPPROTO_TP		IPPROTO_TP
   IPPROTO_DCCP = 33,		/* Datagram Congestion Control Protocol */
-  IPPROTO_RSVP = 46,		/* RSVP protocol			*/
+#define IPPROTO_DCCP		IPPROTO_DCCP
+  IPPROTO_IPV6 = 41,		/* IPv6-in-IPv4 tunnelling		*/
+#define IPPROTO_IPV6		IPPROTO_IPV6
+  IPPROTO_RSVP = 46,		/* RSVP Protocol			*/
+#define IPPROTO_RSVP		IPPROTO_RSVP
   IPPROTO_GRE = 47,		/* Cisco GRE tunnels (rfc 1701,1702)	*/
-
-  IPPROTO_IPV6	 = 41,		/* IPv6-in-IPv4 tunnelling		*/
-
-  IPPROTO_ESP = 50,            /* Encapsulation Security Payload protocol */
-  IPPROTO_AH = 51,             /* Authentication Header protocol       */
-  IPPROTO_BEETPH = 94,	       /* IP option pseudo header for BEET */
-  IPPROTO_PIM    = 103,		/* Protocol Independent Multicast	*/
-
-  IPPROTO_COMP   = 108,                /* Compression Header protocol */
-  IPPROTO_SCTP   = 132,		/* Stream Control Transport Protocol	*/
+#define IPPROTO_GRE		IPPROTO_GRE
+  IPPROTO_ESP = 50,		/* Encapsulation Security Payload protocol */
+#define IPPROTO_ESP		IPPROTO_ESP
+  IPPROTO_AH = 51,		/* Authentication Header protocol	*/
+#define IPPROTO_AH		IPPROTO_AH
+  IPPROTO_MTP = 92,		/* Multicast Transport Protocol		*/
+#define IPPROTO_MTP		IPPROTO_MTP
+  IPPROTO_BEETPH = 94,		/* IP option pseudo header for BEET	*/
+#define IPPROTO_BEETPH		IPPROTO_BEETPH
+  IPPROTO_ENCAP = 98,		/* Encapsulation Header			*/
+#define IPPROTO_ENCAP		IPPROTO_ENCAP
+  IPPROTO_PIM = 103,		/* Protocol Independent Multicast	*/
+#define IPPROTO_PIM		IPPROTO_PIM
+  IPPROTO_COMP = 108,		/* Compression Header Protocol		*/
+#define IPPROTO_COMP		IPPROTO_COMP
+  IPPROTO_SCTP = 132,		/* Stream Control Transport Protocol	*/
+#define IPPROTO_SCTP		IPPROTO_SCTP
   IPPROTO_UDPLITE = 136,	/* UDP-Lite (RFC 3828)			*/
-
-  IPPROTO_RAW	 = 255,		/* Raw IP packets			*/
+#define IPPROTO_UDPLITE		IPPROTO_UDPLITE
+  IPPROTO_RAW = 255,		/* Raw IP packets			*/
+#define IPPROTO_RAW		IPPROTO_RAW
   IPPROTO_MAX
 };