c_udp.h File Reference

ROHC compression context for the UDP profile. More...

#include "rohc_comp_internals.h"
#include <stdint.h>
#include <stdbool.h>

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Functions
bool	c_udp_check_profile (const struct rohc_comp *const comp, const struct net_pkt *const packet)
	Check if the given packet corresponds to the UDP profile.
bool	c_udp_check_context (const struct rohc_comp_ctxt *context, const struct net_pkt *const packet)
	Check if the IP/UDP packet belongs to the context.
size_t	udp_code_uo_remainder (const struct rohc_comp_ctxt *context, const unsigned char *next_header, unsigned char *const dest, const size_t counter)
	Build UDP-related fields in the tail of the UO packets.
size_t	udp_code_static_udp_part (const struct rohc_comp_ctxt *const context, const unsigned char *const next_header, unsigned char *const dest, const size_t counter)
	Build the static part of the UDP header.

---

Detailed Description

ROHC compression context for the UDP profile.

Author:

Didier Barvaux <didier.barvaux@toulouse.viveris.com>

---

Function Documentation

bool c_udp_check_context	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	packet
	)

Check if the IP/UDP packet belongs to the context.

Conditions are:

• the number of IP headers must be the same as in context
• IP version of the two IP headers must be the same as in context
• IP packets must not be fragmented
• the source and destination addresses of the two IP headers must match the ones in the context
• the transport protocol must be UDP
• the source and destination ports of the UDP header must match the ones in the context
• IPv6 only: the Flow Label of the two IP headers must match the ones the context

This function is one of the functions that must exist in one profile for the framework to work.

Parameters:

context	The compression context
packet	The IP/UDP packet to check

Returns:

true if the IP/UDP packet belongs to the context false if it does not belong to the context

bool c_udp_check_profile	(	const struct rohc_comp *const	comp,
		const struct net_pkt *const	packet
	)

Check if the given packet corresponds to the UDP profile.

Conditions are:

• the transport protocol is UDP
• the version of the outer IP header is 4 or 6
• the outer IP header is not an IP fragment
• if there are at least 2 IP headers, the version of the inner IP header is 4 or 6
• if there are at least 2 IP headers, the inner IP header is not an IP fragment
• the inner IP payload is at least 8-byte long for UDP header
• the UDP Length field and the UDP payload match

See also:

c_generic_check_profile

This function is one of the functions that must exist in one profile for the framework to work.

Parameters:

comp	The ROHC compressor
packet	The packet to check

Returns:

Whether the IP packet corresponds to the profile:

• true if the IP packet corresponds to the profile,
• false if the IP packet does not correspond to the profile

size_t udp_code_static_udp_part	(	const struct rohc_comp_ctxt *const	context,
		const unsigned char *const	next_header,
		unsigned char *const	dest,
		const size_t	counter
	)

Build the static part of the UDP header.

 Static part of UDP header (5.7.7.5):

    +---+---+---+---+---+---+---+---+
 1  /          Source Port          /   2 octets
    +---+---+---+---+---+---+---+---+
 2  /       Destination Port        /   2 octets
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
next_header	The UDP header
dest	The rohc-packet-under-build buffer
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer

size_t udp_code_uo_remainder	(	const struct rohc_comp_ctxt *const	context,
		const unsigned char *const	next_header,
		unsigned char *const	dest,
		const size_t	counter
	)

Build UDP-related fields in the tail of the UO packets.

     --- --- --- --- --- --- --- ---
    :                               :
 13 +         UDP Checksum          +  2 octets,
    :                               :  if context(UDP Checksum) != 0
     --- --- --- --- --- --- --- ---

Parameters:

context	The compression context
next_header	The UDP header
dest	The rohc-packet-under-build buffer
counter	The current position in the rohc-packet-under-build buffer

Returns:

The new position in the rohc-packet-under-build buffer