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

#include "d_udp_lite.h"
#include "rohc_bit_ops.h"
#include "rohc_traces.h"
#include "rohc_debug.h"
#include "rohc_packets.h"
#include "crc.h"

Include dependency graph for d_udp_lite.c:

Functions
int	udp_lite_decode_uo_tail_udp (struct d_generic_context context, const unsigned char packet, unsigned int length, unsigned char *dest)
	Decode the UDP-Lite tail of the UO* ROHC packets.
void *	d_udp_lite_create (void)
	Create the UDP-Lite decompression context.
void	d_udp_lite_destroy (void *context)
	Destroy the context.
int	udp_lite_get_static_part (void)
	Get the size of the static part of an IR packet.
int	d_udp_lite_decode_ir (struct rohc_decomp decomp, struct d_context context, const unsigned char const rohc_packet, const unsigned int rohc_length, int large_cid_len, int is_addcid_used, unsigned char dest)
	Decode one IR packet for the UDP-Lite profile.
unsigned int	udp_lite_detect_ir_size (struct d_context context, unsigned char packet, unsigned int plen, unsigned int large_cid_len)
	Find the length of the IR header.
unsigned int	udp_lite_detect_ir_dyn_size (struct d_context context, unsigned char packet, unsigned int plen, unsigned int large_cid_len)
	Find the length of the IR-DYN header.
int	d_udp_lite_decode (struct rohc_decomp decomp, struct d_context context, const unsigned char const rohc_packet, const unsigned int rohc_length, int second_byte, unsigned char dest)
	Decode one IR-DYN, UO-0, UO-1 or UOR-2 packet, but not IR packet.
int	udp_lite_decode_dynamic_udp (struct d_generic_context context, const unsigned char packet, unsigned int length, unsigned char *dest)
	Decode the UDP-Lite dynamic part of the ROHC packet.
int	udp_lite_build_uncompressed_udp (struct d_generic_context context, struct d_generic_changes active, unsigned char *dest, int payload_size)
	Build an uncompressed UDP-Lite header.
Variables
struct d_profile	d_udplite_profile
	Define the decompression part of the UDP-Lite profile as described in the RFC 4019.

Detailed Description

ROHC decompression context for the UDP-Lite profile.

Author:: Didier Barvaux <didier.barvaux@toulouse.viveris.com>; Didier Barvaux <didier@barvaux.org>; The hackers from ROHC for Linux

Function Documentation

void* d_udp_lite_create ( void )

Create the UDP-Lite decompression context.

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

Returns:: The newly-created UDP-Lite decompression context

int d_udp_lite_decode	(	struct rohc_decomp *	decomp,
		struct d_context *	context,
		const unsigned char *const	rohc_packet,
		const unsigned int	rohc_length,
		int	second_byte,
		unsigned char *	dest
	)

Decode one IR-DYN, UO-0, UO-1 or UOR-2 packet, but not IR packet.

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

Parameters:

decomp	The ROHC decompressor
context	The decompression context
rohc_packet	The ROHC packet to decode
rohc_length	The length of the ROHC packet
second_byte	The offset for the second byte of the ROHC packet (depends on the CID encoding and the packet type)
dest	The decoded IP packet

Returns:: The length of the uncompressed IP packet or ROHC_ERROR if an error occurs

References d_udp_lite_context::cce_packet, d_udp_lite_context::cfi, d_udp_lite_context::cfp, d_generic_decode(), find_packet_type(), PACKET_CCE, PACKET_CCE_OFF, PACKET_IR_DYN, rohc_debugf, ROHC_ERROR, d_context::specific, and d_generic_context::specific.

int d_udp_lite_decode_ir	(	struct rohc_decomp *	decomp,
		struct d_context *	context,
		const unsigned char *const	rohc_packet,
		const unsigned int	rohc_length,
		int	large_cid_len,
		int	is_addcid_used,
		unsigned char *	dest
	)

Decode one IR packet for the UDP-Lite profile.

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

Parameters:

decomp	The ROHC decompressor
context	The decompression context
rohc_packet	The ROHC packet to decode
rohc_length	The length of the ROHC packet to decode
large_cid_len	The length of the large CID field
is_addcid_used	Whether the add-CID field is present or not
dest	The decoded IP packet

Returns:: The length of the uncompressed IP packet or ROHC_OK_NO_DATA if packet is feedback only or ROHC_ERROR if an error occurs

References d_udp_lite_context::cfi, d_udp_lite_context::cfp, d_generic_decode_ir(), d_context::specific, and d_generic_context::specific.

void d_udp_lite_destroy ( void * context )

Destroy 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

References d_generic_context::active1, d_generic_context::active2, d_generic_destroy(), d_generic_context::last1, d_generic_context::last2, d_generic_changes::next_header, and zfree.

int udp_lite_build_uncompressed_udp	(	struct d_generic_context *	context,
		struct d_generic_changes *	active,
		unsigned char *	dest,
		int	payload_size
	)

Build an uncompressed UDP-Lite header.

Parameters:

context	The generic decompression context
active	The UDP-Lite header changes
dest	The buffer to store the UDP-Lite header (MUST be at least of sizeof(struct udphdr) length)
payload_size	The length of the UDP-Lite payload

Returns:: The length of the next header (ie. the UDP-Lite header), -1 in case of error

References d_udp_lite_context::cce_packet, d_udp_lite_context::cfi, d_udp_lite_context::cfp, d_generic_changes::next_header, rohc_debugf, and d_generic_context::specific.

Referenced by d_udp_lite_create().

int udp_lite_decode_dynamic_udp	(	struct d_generic_context *	context,
		const unsigned char *	packet,
		unsigned int	length,
		unsigned char *	dest
	)

Decode the UDP-Lite dynamic part of the ROHC packet.

Parameters:

context	The generic decompression context
packet	The ROHC packet to decode
length	The length of the ROHC packet
dest	The decoded UDP header

Returns:: The number of bytes read in the ROHC packet, -1 in case of failure

References d_udp_lite_context::cfi, d_udp_lite_context::cfp, GET_NEXT_16_BITS, ip_decode_dynamic_ip(), PACKET_IR, PACKET_IR_DYN, d_generic_context::packet_type, rohc_debugf, and d_generic_context::specific.

Referenced by d_udp_lite_create().

int udp_lite_decode_uo_tail_udp	(	struct d_generic_context *	context,
		const unsigned char *	packet,
		unsigned int	length,
		unsigned char *	dest
	)

Decode the UDP-Lite tail of the UO* ROHC packets.

Parameters:

context	The generic decompression context
packet	The ROHC packet to decode
length	The length of the ROHC packet
dest	The decoded UDP-Lite header

Returns:: The number of bytes read in the ROHC packet, -1 in case of failure

References d_udp_lite_context::cfi, d_udp_lite_context::cfp, GET_NEXT_16_BITS, rohc_debugf, and d_generic_context::specific.

Referenced by d_udp_lite_create().

unsigned int udp_lite_detect_ir_dyn_size	(	struct d_context *	context,
		unsigned char *	packet,
		unsigned int	plen,
		unsigned int	large_cid_len
	)

Find the length of the IR-DYN header.

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


 Basic structure of the IR-DYN packet (5.7.7.2):

      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         : if for small CIDs and CID != 0
    +---+---+---+---+---+---+---+---+
 2  | 1   1   1   1   1   0   0   0 | IR-DYN packet type
    +---+---+---+---+---+---+---+---+
    :                               :
 3  /     0-2 octets of CID info    / 1-2 octets if for large CIDs
    :                               :
    +---+---+---+---+---+---+---+---+
 4  |            Profile            | 1 octet
    +---+---+---+---+---+---+---+---+
 5  |              CRC              | 1 octet
    +---+---+---+---+---+---+---+---+
    |                               |
 6  /         Dynamic chain         / variable length
    |                               |
    +---+---+---+---+---+---+---+---+
 7  |             SN                | 2 octets if not RTP
    +---+---+---+---+---+---+---+---+
    :                               :
 8  /           Payload             / variable length
    :                               :
     - - - - - - - - - - - - - - - -

The function computes the length of the fields 2 + 4-8, ie. the first byte, the Profile and CRC fields, the dynamic chains (outer and inner IP headers + UDP-Lite header) and the SN.

Parameters:

context	The decompression context
packet	The IR-DYN packet after the Add-CID byte if present (ie. field 2 in the figure)
plen	The length of the IR-DYN packet minus the Add-CID byte
large_cid_len	The size of the large CID field (ie. field 3 in the figure)

Returns:: The length of the IR-DYN header, 0 if an error occurs

References udp_detect_ir_dyn_size().

unsigned int udp_lite_detect_ir_size	(	struct d_context *	context,
		unsigned char *	packet,
		unsigned int	plen,
		unsigned int	large_cid_len
	)

Find the length of the IR header.

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


 Basic structure of the IR packet (5.7.7.1):

      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  |         Add-CID octet         |  if for small CIDs and CID != 0
    +---+---+---+---+---+---+---+---+
 2  | 1   1   1   1   1   1   0 | D |
    +---+---+---+---+---+---+---+---+
    |                               |
 3  /    0-2 octets of CID info     /  1-2 octets if for large CIDs
    |                               |
    +---+---+---+---+---+---+---+---+
 4  |            Profile            |  1 octet
    +---+---+---+---+---+---+---+---+
 5  |              CRC              |  1 octet
    +---+---+---+---+---+---+---+---+
    |                               |
 6  |         Static chain          |  variable length
    |                               |
    +---+---+---+---+---+---+---+---+
    |                               |
 7  |         Dynamic chain         |  present if D = 1, variable length
    |                               |
    +---+---+---+---+---+---+---+---+
 8  |             SN                |  2 octets if not RTP
    +---+---+---+---+---+---+---+---+
    |                               |
 9  |           Payload             |  variable length
    |                               |
     - - - - - - - - - - - - - - - -

The function computes the length of the fields 2 + 4-8, ie. the first byte, the Profile and CRC fields, the static and dynamic chains (outer and inner IP headers + UDP-Lite header) and the SN.

Parameters:

context	The decompression context
packet	The pointer on the IR packet minus the Add-CID byte (ie. the field 2 in the figure)
plen	The length of the IR packet minus the Add-CID byte
large_cid_len	The size of the large CID field (ie. field 3 in the figure)

Returns:: The length of the IR header, 0 if an error occurs

References GET_BIT_0, and udp_detect_ir_size().

int udp_lite_get_static_part ( void )

Get the size of the static part of an IR packet.

Returns:: the size

Variable Documentation

struct d_profile d_udplite_profile

Initial value:

{
        ROHC_PROFILE_UDPLITE,        
        "UDP-Lite / Decompressor",   
        d_udp_lite_decode,           
        d_udp_lite_decode_ir,
        d_udp_lite_create,
        d_udp_lite_destroy,
        udp_lite_detect_ir_size,
        udp_lite_detect_ir_dyn_size,
        udp_lite_get_static_part,
        d_generic_get_sn,
}

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

Functions

Variables

Detailed Description

Function Documentation

Variable Documentation