[PATCH net-next 1/2] net: add IP_DSCP_MASK

[Hangbin Liu <liuhangbin@gmail.com>]

In RFC1349 it defined TOS field like

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |   PRECEDENCE    |          TOS          | MBZ |
    +-----+-----+-----+-----+-----+-----+-----+-----+

But this has been obsoleted by RFC2474, and updated by RFC3168 later.
Now the DS Field should be like

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |          DS FIELD, DSCP           | ECN FIELD |
    +-----+-----+-----+-----+-----+-----+-----+-----+

      DSCP: differentiated services codepoint
      ECN:  Explicit Congestion Notification

So the old IPTOS_TOS_MASK 0x1E should be updated. But since
changed the value will break UAPI, let's add a new value
IP_DSCP_MASK 0xFC as a replacement.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 include/uapi/linux/in_route.h | 1 +
 include/uapi/linux/ip.h       | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/include/uapi/linux/in_route.h b/include/uapi/linux/in_route.h
index 0cc2c23b47f8..26ba4efb054d 100644
--- a/include/uapi/linux/in_route.h
+++ b/include/uapi/linux/in_route.h
@@ -29,5 +29,6 @@
 #define RTCF_NAT	(RTCF_DNAT|RTCF_SNAT)
 
 #define RT_TOS(tos)	((tos)&IPTOS_TOS_MASK)
+#define RT_DSCP(tos)	((tos)&IP_DSCP_MASK)
 
 #endif /* _LINUX_IN_ROUTE_H */
diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
index e42d13b55cf3..62e4169277eb 100644
--- a/include/uapi/linux/ip.h
+++ b/include/uapi/linux/ip.h
@@ -22,6 +22,8 @@
 
 #define IPTOS_TOS_MASK		0x1E
 #define IPTOS_TOS(tos)		((tos)&IPTOS_TOS_MASK)
+#define IP_DSCP_MASK		0xFC
+#define IP_DSCP(tos)		((tos)&IP_DSCP_MASK)
 #define	IPTOS_LOWDELAY		0x10
 #define	IPTOS_THROUGHPUT	0x08
 #define	IPTOS_RELIABILITY	0x04
-- 
2.25.4