1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * inet_dscp.h: helpers for handling differentiated services codepoints (DSCP) |
4 | * |
5 | * DSCP is defined in RFC 2474: |
6 | * |
7 | * 0 1 2 3 4 5 6 7 |
8 | * +---+---+---+---+---+---+---+---+ |
9 | * | DSCP | CU | |
10 | * +---+---+---+---+---+---+---+---+ |
11 | * |
12 | * DSCP: differentiated services codepoint |
13 | * CU: currently unused |
14 | * |
15 | * The whole DSCP + CU bits form the DS field. |
16 | * The DS field is also commonly called TOS or Traffic Class (for IPv6). |
17 | * |
18 | * Note: the CU bits are now used for Explicit Congestion Notification |
19 | * (RFC 3168). |
20 | */ |
21 | |
22 | #ifndef _INET_DSCP_H |
23 | #define _INET_DSCP_H |
24 | |
25 | #include <linux/types.h> |
26 | |
27 | /* Special type for storing DSCP values. |
28 | * |
29 | * A dscp_t variable stores a DS field with the CU (ECN) bits cleared. |
30 | * Using dscp_t allows to strictly separate DSCP and ECN bits, thus avoiding |
31 | * bugs where ECN bits are erroneously taken into account during FIB lookups |
32 | * or policy routing. |
33 | * |
34 | * Note: to get the real DSCP value contained in a dscp_t variable one would |
35 | * have to do a bit shift after calling inet_dscp_to_dsfield(). We could have |
36 | * a helper for that, but there's currently no users. |
37 | */ |
38 | typedef u8 __bitwise dscp_t; |
39 | |
40 | #define INET_DSCP_MASK 0xfc |
41 | |
42 | static inline dscp_t inet_dsfield_to_dscp(__u8 dsfield) |
43 | { |
44 | return (__force dscp_t)(dsfield & INET_DSCP_MASK); |
45 | } |
46 | |
47 | static inline __u8 inet_dscp_to_dsfield(dscp_t dscp) |
48 | { |
49 | return (__force __u8)dscp; |
50 | } |
51 | |
52 | static inline bool inet_validate_dscp(__u8 val) |
53 | { |
54 | return !(val & ~INET_DSCP_MASK); |
55 | } |
56 | |
57 | #endif /* _INET_DSCP_H */ |
58 | |