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

#include "c_udp_lite.h"
#include "rohc_traces.h"

Include dependency graph for c_udp_lite.c:

Functions
int	udp_lite_code_dynamic_udp_lite_part (struct c_context context, const unsigned char next_header, unsigned char *dest, int counter)
	Build the dynamic part of the UDP-Lite header.
int	udp_lite_build_cce_packet (struct c_context context, const unsigned char next_header, unsigned char dest, int counter, int first_position)
	Build the Checksum Coverage Extension (CCE) packet.
boolean	udp_lite_send_cce_packet (struct c_context context, const struct udphdr udp_lite)
	Check whether a Checksum Coverage Extension (CCE) packet must be sent or not in order to compress the given UDP-Lite header.
int	udp_lite_code_UO_packet_tail (struct c_context context, const unsigned char next_header, unsigned char *dest, int counter)
	Build UDP-Lite-related fields in the tail of the UO packets.
void	udp_lite_init_cc (struct c_context context, const unsigned char next_header)
	Initialize checksum coverage in the compression context with the given UDP-Lite header.
int	c_udp_lite_create (struct c_context *context, const struct ip_packet ip)
	Create a new UDP-Lite context and initialize it thanks to the given IP/UDP-Lite packet.
int	c_udp_lite_check_context (struct c_context *context, struct ip_packet ip)
	Check if the IP/UDP-Lite packet belongs to the context.
int	c_udp_lite_encode (struct c_context context, const struct ip_packet ip, int packet_size, unsigned char dest, int dest_size, int *payload_offset)
	Encode an IP/UDP-lite packet according to a pattern decided by several different factors.
Variables
struct c_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>; The hackers from ROHC for Linux

Function Documentation

int c_udp_lite_check_context	(	struct c_context *	context,
		struct ip_packet	ip
	)

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
ip	The IP/UDP-Lite packet to check

Returns:: 1 if the IP/UDP-Lite packet belongs to the context, 0 if it does not belong to the context and -1 if the profile cannot compress it or an error occurs

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), ip_get_version(), ip_is_fragment(), IPPROTO_UDPLITE, IPV4, ipv4_get_daddr(), ipv4_get_saddr(), IPV6, IPV6_ADDR_CMP, ipv6_get_daddr(), IPV6_GET_FLOW_LABEL, ipv6_get_flow_label(), ipv6_get_saddr(), c_generic_context::is_ip2_initialized, ipv4_header_info::old_ip, ipv6_header_info::old_ip, sc_udp_lite_context::old_udp_lite, rohc_debugf, c_context::specific, c_generic_context::specific, ip_header_info::v4, ip_header_info::v6, version, and ip_header_info::version.

int c_udp_lite_create	(	struct c_context *	context,
		const struct ip_packet	ip
	)

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
ip	The IP/UDP-Lite packet given to initialize the new context

Returns:: 1 if successful, 0 otherwise

References c_generic_create(), c_generic_destroy(), sc_udp_lite_context::cfi, sc_udp_lite_context::cfp, c_generic_context::code_dynamic_part, c_generic_context::code_static_part, c_generic_context::code_UO_packet_head, c_generic_context::code_UO_packet_tail, c_generic_context::compute_crc_dynamic, c_generic_context::compute_crc_static, sc_udp_lite_context::coverage_equal_count, sc_udp_lite_context::coverage_inferred_count, decide_state(), c_generic_context::decide_state, sc_udp_lite_context::FK, c_generic_context::init_at_IR, ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), IPPROTO_UDPLITE, MAX_IR_COUNT, c_generic_context::next_header_len, c_generic_context::next_header_proto, sc_udp_lite_context::old_udp_lite, rohc_debugf, sc_udp_lite_context::sent_cce_off_count, sc_udp_lite_context::sent_cce_on_count, sc_udp_lite_context::sent_cce_only_count, c_context::specific, c_generic_context::specific, sc_udp_lite_context::tmp_variables, udp_code_static_udp_part(), udp_compute_crc_dynamic(), udp_compute_crc_static(), udp_lite_build_cce_packet(), udp_lite_code_dynamic_udp_lite_part(), udp_lite_code_UO_packet_tail(), udp_lite_init_cc(), and udp_lite_tmp_variables::udp_size.

int c_udp_lite_encode	(	struct c_context *	context,
		const struct ip_packet	ip,
		int	packet_size,
		unsigned char *	dest,
		int	dest_size,
		int *	payload_offset
	)

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

Parameters:

context	The compression context
ip	The IP packet to encode
packet_size	The length of the IP packet to encode
dest	The rohc-packet-under-build buffer
dest_size	The length of the rohc-packet-under-build buffer
payload_offset	The offset for the payload in the IP packet

Returns:: The length of the created ROHC packet or -1 in case of failure

References c_generic_encode(), ip_get_hdrlen(), ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), IPPROTO_UDPLITE, sc_udp_lite_context::old_udp_lite, PACKET_IR, PACKET_IR_DYN, generic_tmp_variables::packet_type, rohc_debugf, c_context::specific, c_generic_context::specific, sc_udp_lite_context::tmp_variables, c_generic_context::tmp_variables, and udp_lite_tmp_variables::udp_size.

int udp_lite_build_cce_packet	(	struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *	dest,
		int	counter,
		int *	first_position
	)

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

References sc_udp_lite_context::FK, rohc_debugf, c_context::specific, c_generic_context::specific, and udp_lite_send_cce_packet().

Referenced by c_udp_lite_create().

int udp_lite_code_dynamic_udp_lite_part	(	struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *	dest,
		int	counter
	)

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

References rohc_debugf.

Referenced by c_udp_lite_create().

int udp_lite_code_UO_packet_tail	(	struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *	dest,
		int	counter
	)

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

References sc_udp_lite_context::cfp, rohc_debugf, c_context::specific, c_generic_context::specific, and udp_lite_send_cce_packet().

Referenced by c_udp_lite_create().

void udp_lite_init_cc	(	struct c_context *	context,
		const unsigned char *	next_header
	)

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

Parameters:

context	The compression context
next_header	The UDP-Lite header

References sc_udp_lite_context::cfi, sc_udp_lite_context::cfp, c_generic_context::ir_count, sc_udp_lite_context::old_udp_lite, rohc_debugf, c_context::specific, c_generic_context::specific, sc_udp_lite_context::tmp_coverage, sc_udp_lite_context::tmp_variables, and udp_lite_tmp_variables::udp_size.

Referenced by c_udp_lite_create().

boolean udp_lite_send_cce_packet	(	struct c_context *	context,
		const struct udphdr *	udp_lite
	)

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:: Whether a CCE packet must be sent

Referenced by udp_lite_build_cce_packet(), and udp_lite_code_UO_packet_tail().

Variable Documentation

struct c_profile c_udp_lite_profile

Initial value:

{
        IPPROTO_UDPLITE,          
        NULL,                     
        ROHC_PROFILE_UDPLITE,     
        "1.0b",                   
        "UDP-Lite / Compressor",  
        c_udp_lite_create,        
        c_generic_destroy,
        c_udp_lite_check_context,
        c_udp_lite_encode,
        c_generic_feedback,
}

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

Functions

Variables

Detailed Description

Function Documentation

Variable Documentation