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

#include "c_udp.h"
#include "c_ip.h"
#include "rohc_traces_internal.h"
#include "rohc_packets.h"
#include "rohc_utils.h"
#include "crc.h"
#include "c_generic.h"
#include "protocols/udp_lite.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

Include dependency graph for c_udp_lite.c:

Data Structures
struct	udp_lite_tmp_vars
	Define the UDP-Lite-specific temporary variables in the profile compression context. More...
struct	sc_udp_lite_context
	Define the UDP-Lite part of the profile compression context. More...
Defines
#define	MAX_LITE_COUNT 2
	The maximal number of times the checksum coverage dit not change or may be inferred.
Functions
static bool	c_udp_lite_create (struct rohc_comp_ctxt const context, const struct net_pkt const packet)
	Create a new UDP-Lite context and initialize it thanks to the given IP/UDP-Lite packet.
static bool	c_udp_lite_check_profile (const struct rohc_comp const comp, const struct net_pkt const packet)
	Check if the given packet corresponds to the UDP-Lite profile.
static bool	c_udp_lite_check_context (const struct rohc_comp_ctxt const context, const struct net_pkt const packet)
	Check if the IP/UDP-Lite packet belongs to the context.
static int	c_udp_lite_encode (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char const rohc_pkt, const size_t rohc_pkt_max_len, rohc_packet_t const packet_type, size_t *const payload_offset)
	Encode an IP/UDP-lite packet according to a pattern decided by several different factors.
static size_t	udp_lite_code_dynamic_udplite_part (const struct rohc_comp_ctxt const context, const unsigned char const next_header, unsigned char *const dest, const size_t counter)
	Build the dynamic part of the UDP-Lite header.
static size_t	udp_lite_build_cce_packet (const struct rohc_comp_ctxt const context, const unsigned char const next_header, unsigned char const dest, const size_t counter, size_t const first_position)
	Build the Checksum Coverage Extension (CCE) packet.
static bool	udp_lite_send_cce_packet (const struct rohc_comp_ctxt const context, const struct udphdr const udp_lite)
	Check whether a Checksum Coverage Extension (CCE) packet must be sent or not in order to compress the given UDP-Lite header.
static size_t	udp_lite_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-Lite-related fields in the tail of the UO packets.
static void	udp_lite_init_cc (const struct rohc_comp_ctxt context, const unsigned char next_header)
	Initialize checksum coverage in the compression context with the given UDP-Lite header.
Variables
struct rohc_comp_profile	c_udp_lite_profile
	Define the compression part of the UDP-Lite profile as described in the RFC 4019.

Detailed Description

ROHC compression context for the UDP-Lite profile.

Author:: Didier Barvaux <didier.barvaux@toulouse.viveris.com>; Didier Barvaux <didier@barvaux.org>

Define Documentation

#define MAX_LITE_COUNT 2

The maximal number of times the checksum coverage dit not change or may be inferred.

Function Documentation

static bool c_udp_lite_check_context	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	packet
	)		`[static]`

Check if the IP/UDP-Lite 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-Lite
the source and destination ports of the UDP-Lite 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-Lite packet to check

Returns:: true if the IP/UDP-Lite packet belongs to the context, false if it does not belong to the context

static bool c_udp_lite_check_profile	(	const struct rohc_comp *const	comp,
		const struct net_pkt *const	packet
	)		`[static]`

Check if the given packet corresponds to the UDP-Lite profile.

Conditions are:

the transport protocol is UDP-Lite
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

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

static bool c_udp_lite_create	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	packet
	)		`[static]`

Create a new UDP-Lite context and initialize it thanks to the given IP/UDP-Lite packet.

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-Lite packet given to initialize the new context

Returns:: true if successful, false otherwise

static int c_udp_lite_encode	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len,
		rohc_packet_t *const	packet_type,
		size_t *const	payload_offset
	)		`[static]`

Encode an IP/UDP-lite packet according to a pattern decided by several different factors.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet
packet_type	OUT: The type of ROHC packet that is created
payload_offset	OUT: The offset for the payload in the IP packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static size_t udp_lite_build_cce_packet	(	const struct rohc_comp_ctxt *const	context,
		const unsigned char *const	next_header,
		unsigned char *const	dest,
		const size_t	counter,
		size_t *const	first_position
	)		`[static]`

Build the Checksum Coverage Extension (CCE) packet.

The Checksum Coverage Extension is located at the very start of the UO packet (part 2 in the following figure).


     0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         :  If for small CIDs and CID 1 - 15
    +---+---+---+---+---+---+---+---+
 2  | 1   1   1   1   1   0   F | K |  Outer packet type identifier
    +---+---+---+---+---+---+---+---+
    :                               :
 3  /   0, 1, or 2 octets of CID    /  1 - 2 octets if large CIDs
    :                               :
    +---+---+---+---+---+---+---+---+
    :                               :
 4  /   UO-0, UO-1 or UO-2 packet   /
    :                               :
    +---+---+---+---+---+---+---+---+

Parts 1, 3 and 4 are coded by the generic code_UO0_packet, code_UO1_packet and code_UO2_packet functions. These functions call the code_UO_packet_head function which in case of UDP-Lite profile is the udp_lite_build_cce_packet function.

When the udp_lite_build_cce_packet is called, the parameter first_position points on the part 2 and the parameter counter points on the beginning of the part 4.

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
first_position	The position to place the first byte of packet

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

static size_t udp_lite_code_dynamic_udplite_part	(	const struct rohc_comp_ctxt *const	context,
		const unsigned char *const	next_header,
		unsigned char *const	dest,
		const size_t	counter
	)		`[static]`

Build the dynamic part of the UDP-Lite header.


 Dynamic part of UDP-Lite header (5.2.1 of RFC 4019):

    +---+---+---+---+---+---+---+---+
 1  /       Checksum Coverage       /   2 octets
    +---+---+---+---+---+---+---+---+
 2  /           Checksum            /   2 octets
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
next_header	The UDP-Lite 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

static size_t udp_lite_code_uo_remainder	(	const struct rohc_comp_ctxt *const	context,
		const unsigned char *const	next_header,
		unsigned char *const	dest,
		const size_t	counter
	)		`[static]`

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


     --- --- --- --- --- --- --- ---
    :                               :  2 octets,
 1  +  UDP-Lite Checksum Coverage   +  if context(CFP) = 1 or
    :                               :  if packet type = CCE
     --- --- --- --- --- --- --- ---
    :                               :
 2  +       UDP-Lite Checksum       +  2 octets
    :                               :
     --- --- --- --- --- --- --- ---

Parameters:

context	The compression context
next_header	The UDP-Lite 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

static void udp_lite_init_cc	(	const struct rohc_comp_ctxt *	context,
		const unsigned char *	next_header
	)		`[static]`

Initialize checksum coverage in the compression context with the given UDP-Lite header.

Parameters:

context	The compression context
next_header	The UDP-Lite header

static bool udp_lite_send_cce_packet	(	const struct rohc_comp_ctxt *const	context,
		const struct udphdr *const	udp_lite
	)		`[static]`

Check whether a Checksum Coverage Extension (CCE) packet must be sent or not in order to compress the given UDP-Lite header.

The function also updates the FK variable stored in the UDP-Lite context.

Parameters:

context	The compression context
udp_lite	The UDP-Lite header

Returns:: true if a CCE packet must be sent, false if not

Variable Documentation

struct rohc_comp_profile c_udp_lite_profile

Initial value:

{
        .id             = ROHC_PROFILE_UDPLITE, 
        .protocol       = ROHC_IPPROTO_UDPLITE, 
        .create         = c_udp_lite_create,    
        .destroy        = c_generic_destroy,
        .check_profile  = c_udp_lite_check_profile,
        .check_context  = c_udp_lite_check_context,
        .encode         = c_udp_lite_encode,
        .reinit_context = c_generic_reinit_context,
        .feedback       = c_generic_feedback,
        .use_udp_port   = c_generic_use_udp_port,
}

Define the compression part of the UDP-Lite profile as described in the RFC 4019.

Data Structures

Defines

Functions

Variables

Detailed Description

Define Documentation

Function Documentation

Variable Documentation