d_ip.c File Reference

ROHC decompression context for the IP-only profile. More...

#include "d_ip.h"
#include "rohc_bit_ops.h"
#include "rohc_traces.h"
#include "rohc_packets.h"

Include dependency graph for d_ip.c:

Functions
void *	d_ip_create (void)
	Create the IP decompression context.
int	ip_get_static_part (void)
	Get the size of the static part of an IR packet (without IP)
int	ip_decode_dynamic_ip (struct d_generic_context *context, const unsigned char *packet, unsigned int length, unsigned char *dest)
	Decode the IP dynamic part of the ROHC packet.
unsigned int	ip_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	ip_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.
Variables
struct d_profile	d_ip_profile
	Define the decompression part of the IP-only profile as described in the RFC 3843.

---

Detailed Description

ROHC decompression context for the IP-only profile.

Author:

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

The hackers from ROHC for Linux

---

Function Documentation

void* d_ip_create

(

void

)

Create the IP decompression context.

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

Returns:

A fake IP decompression context

References d_generic_create(), d_generic_context::decode_dynamic_next_header, and ip_decode_dynamic_ip().

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

Decode the IP 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	Not used

Returns:

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

References d_generic_context::active1, d_generic_context::active2, d_ip_id_init(), d_lsb_init(), GET_NEXT_16_BITS, d_generic_changes::ip, ip_get_version(), d_generic_context::ip_id1, d_generic_context::ip_id2, IPV4, ipv4_get_id(), d_generic_context::multiple_ip, PACKET_IR, PACKET_IR_DYN, d_generic_context::packet_type, rohc_debugf, sn, and d_generic_context::sn.

Referenced by d_ip_create(), udp_decode_dynamic_udp(), and udp_lite_decode_dynamic_udp().

unsigned int ip_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 + 4-7, ie. the first byte, the Profile and CRC fields, the dynamic chains (outer and inner IP headers) and the SN.

Parameters:

context	The decompression context
packet	The IR-DYN packet after the Add-CID byte if present (ie. the 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 d_generic_detect_ir_dyn_size().

Referenced by udp_detect_ir_dyn_size().

unsigned int ip_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) 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 d_generic_detect_ir_size().

Referenced by udp_detect_ir_size().

int ip_get_static_part

(

void

)

Get the size of the static part of an IR packet (without IP)

Returns:

the size

---

Variable Documentation

struct d_profile d_ip_profile

Initial value:

{
        ROHC_PROFILE_IP,              
        "IP / Decompressor",          
        d_generic_decode,             
        d_generic_decode_ir,
        d_ip_create,
        d_generic_destroy,
        ip_detect_ir_size,
        ip_detect_ir_dyn_size,
        ip_get_static_part,
        d_generic_get_sn,
}

Define the decompression part of the IP-only profile as described in the RFC 3843.