include/net/inet_dscp.h

Source file repositories/reference/linux-study-clean/include/net/inet_dscp.h

File Facts

System
Linux kernel
Corpus path
include/net/inet_dscp.h
Extension
.h
Size
1869 bytes
Lines
64
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: implementation source
Status
source implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _INET_DSCP_H
#define _INET_DSCP_H

#include <linux/types.h>

/* Special type for storing DSCP values.
 *
 * A dscp_t variable stores a DS field with the CU (ECN) bits cleared.
 * Using dscp_t allows to strictly separate DSCP and ECN bits, thus avoiding
 * bugs where ECN bits are erroneously taken into account during FIB lookups
 * or policy routing.
 *
 * Note: to get the real DSCP value contained in a dscp_t variable one would
 * have to do a bit shift after calling inet_dscp_to_dsfield(). We could have
 * a helper for that, but there's currently no users.
 */
typedef u8 __bitwise dscp_t;

#define INET_DSCP_MASK 0xfc

/* A few places in the IPv4 code need to ignore the three high order bits of
 * DSCP because of backward compatibility (as these bits used to represent the
 * IPv4 Precedence in RFC 791's TOS field and were ignored).
 */
#define INET_DSCP_LEGACY_TOS_MASK ((__force dscp_t)0x1c)

static inline dscp_t inet_dsfield_to_dscp(__u8 dsfield)
{
	return (__force dscp_t)(dsfield & INET_DSCP_MASK);
}

static inline __u8 inet_dscp_to_dsfield(dscp_t dscp)
{
	return (__force __u8)dscp;
}

static inline bool inet_validate_dscp(__u8 val)
{
	return !(val & ~INET_DSCP_MASK);
}

#endif /* _INET_DSCP_H */

Annotation

Implementation Notes