58 lines
1.6 KiB
C
58 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* inet_dscp.h: helpers for handling differentiated services codepoints (DSCP)
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*
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* DSCP is defined in RFC 2474:
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*
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* 0 1 2 3 4 5 6 7
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* +---+---+---+---+---+---+---+---+
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* | DSCP | CU |
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* +---+---+---+---+---+---+---+---+
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*
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* DSCP: differentiated services codepoint
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* CU: currently unused
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*
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* The whole DSCP + CU bits form the DS field.
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* The DS field is also commonly called TOS or Traffic Class (for IPv6).
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*
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* Note: the CU bits are now used for Explicit Congestion Notification
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* (RFC 3168).
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*/
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#ifndef _INET_DSCP_H
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#define _INET_DSCP_H
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#include <linux/types.h>
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/* Special type for storing DSCP values.
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*
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* A dscp_t variable stores a DS field with the CU (ECN) bits cleared.
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* Using dscp_t allows to strictly separate DSCP and ECN bits, thus avoiding
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* bugs where ECN bits are erroneously taken into account during FIB lookups
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* or policy routing.
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*
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* Note: to get the real DSCP value contained in a dscp_t variable one would
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* have to do a bit shift after calling inet_dscp_to_dsfield(). We could have
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* a helper for that, but there's currently no users.
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*/
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typedef u8 __bitwise dscp_t;
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#define INET_DSCP_MASK 0xfc
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static inline dscp_t inet_dsfield_to_dscp(__u8 dsfield)
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{
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return (__force dscp_t)(dsfield & INET_DSCP_MASK);
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}
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static inline __u8 inet_dscp_to_dsfield(dscp_t dscp)
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{
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return (__force __u8)dscp;
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}
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static inline bool inet_validate_dscp(__u8 val)
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{
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return !(val & ~INET_DSCP_MASK);
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}
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#endif /* _INET_DSCP_H */
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