net: introduce proto_ports_offset()
Introduce proto_ports_offset() for getting the position of the ports or
SPI in the message of a protocol.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/in.h b/include/linux/in.h
index 41d88a4..beeb6de 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -250,6 +250,25 @@
#ifdef __KERNEL__
+#include <linux/errno.h>
+
+static inline int proto_ports_offset(int proto)
+{
+ switch (proto) {
+ case IPPROTO_TCP:
+ case IPPROTO_UDP:
+ case IPPROTO_DCCP:
+ case IPPROTO_ESP: /* SPI */
+ case IPPROTO_SCTP:
+ case IPPROTO_UDPLITE:
+ return 0;
+ case IPPROTO_AH: /* SPI */
+ return 4;
+ default:
+ return -EINVAL;
+ }
+}
+
static inline bool ipv4_is_loopback(__be32 addr)
{
return (addr & htonl(0xff000000)) == htonl(0x7f000000);