c_generic.h File Reference

ROHC generic compression context for IP-only, UDP and UDP Lite profiles. More...

#include <netinet/ip.h>
#include <string.h>
#include "rohc_comp.h"
#include "comp_list.h"

Include dependency graph for c_generic.h:

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Go to the source code of this file.

Classes
struct	ipv4_header_info
	Store information about an IPv4 header between the different compressions of IP packets. More...
struct	ipv6_header_info
	Store information about an IPv6 header between the different compressions of IP packets. More...
struct	ip_header_info
	Store information about an IP (IPv4 or IPv6) header between the different compressions of IP packets. More...
struct	generic_tmp_variables
	Structure that contains variables that are used during one single compression of packet. More...
struct	c_generic_context
	The generic compression context. More...
struct	list_comp
	The list compressor. More...
Defines
#define	IPID_MAX_DELTA   20
	The maximal delta accepted between two consecutive IPv4 ID so that it can be considered as coded in Network Byte Order (NBO)
#define	MAX_ITEM   15
	The number of compression list items.
#define	L   5
Functions
int	c_generic_create (struct c_context *context, const struct ip_packet ip)
	Create a new context and initialize it thanks to the given IP packet.
void	c_generic_destroy (struct c_context *context)
	Destroy the context.
void	change_mode (struct c_context *context, rohc_mode new_mode)
	Change the mode of the context.
void	change_state (struct c_context *context, rohc_c_state new_state)
	Change the state of the context.
void	ip6_c_init_table (struct list_comp *comp)
	Initialize the tables IPv6 extension in compressor.
int	c_algo_list_compress (struct list_comp *comp, const struct ip_packet ip)
	Algorithm of compression list.
int	c_create_current_list (int index, struct list_comp *comp, unsigned char *ext, int index_table)
	Create the current list.
int	decide_type (struct list_comp *comp)
	Decide the encoding type for compression list.
int	encode_list (struct list_comp *comp, unsigned char *dest, int counter, int ps, int size)
	Generique encoding of compressed list.
int	encode_type_0 (struct list_comp *comp, unsigned char *dest, int counter, int ps)
	build Encoding type 0
int	encode_type_1 (struct list_comp *comp, unsigned char *dest, int counter, int ps)
	build Encoding type 1
int	encode_type_3 (struct list_comp *comp, unsigned char *dest, int counter, int ps)
	build Encoding type 3
int	encode_type_2 (struct list_comp *comp, unsigned char *dest, int counter, int ps)
	build Encoding type 2
int	c_generic_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 packet according to a pattern decided by several different factors.
void	c_generic_feedback (struct c_context *context, struct c_feedback *feedback)
	Update the profile when feedback arrives.
void	decide_state (struct c_context *context)
	Decide the state that should be used for the next packet.

---

Detailed Description

ROHC generic compression context for IP-only, UDP and UDP Lite profiles.

Author:

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

The hackers from ROHC for Linux

---

Define Documentation

#define IPID_MAX_DELTA   20

The maximal delta accepted between two consecutive IPv4 ID so that it can be considered as coded in Network Byte Order (NBO)

Referenced by check_ip_identification().

#define L   5

The number of compressed list to send to make the reference list L is the name specified in the RFC

Referenced by c_algo_list_compress(), decode_type_0(), decode_type_1(), decode_type_2(), and decode_type_3().

#define MAX_ITEM   15

The number of compression list items.

Referenced by c_algo_list_compress().

---

Function Documentation

int c_algo_list_compress	(	struct list_comp *	comp,
		const struct ip_packet	ip
	)

Algorithm of compression list.

This function compress a generic extension list

Parameters:

comp	The list compressor which is specific to the extension type
ip	The ip packet to compress

Returns:

1 if a compressed list must be sent, 0 if not and -1 if error

References c_create_current_list(), c_translation::counter, list_comp::counter, list_comp::curr_list, ip_packet::data, delete_elt(), empty_list(), c_list::gen_id, get_elt(), list_comp::get_extension, list_comp::get_index_table, list_elt::index_table, insert_elt(), list_comp::islist, list_elt::item, c_translation::known, L, MAX_ITEM, list_comp::ref_list, rohc_debugf, size_list(), list_comp::trans_table, item::type, and list_comp::update_done.

Referenced by code_ipv6_dynamic_part(), and decide_packet().

int c_create_current_list	(	int	index,
		struct list_comp *	comp,
		unsigned char *	ext,
		int	index_table
	)

Create the current list.

Parameters:

index	the number of the extension
comp	The list compressor which is specific to the extension type
ext	The extension
index_table	The index of the item in the based table

Returns:

1 if successfull, 0 else

References list_comp::based_table, list_comp::compare, c_translation::counter, list_comp::counter, list_comp::create_item, list_comp::curr_list, delete_elt(), elt_index(), get_elt(), list_comp::get_size, list_elt::index_table, insert_elt(), list_elt::item, c_translation::known, item::length, push_back(), rohc_debugf, list_comp::trans_table, and item::type.

Referenced by c_algo_list_compress().

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

Create a new context and initialize it thanks to the given IP 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 packet given to initialize the new context

Returns:

1 if successful, 0 otherwise

References c_create_wlsb(), c_generic_destroy(), c_init_header_info(), c_init_tmp_variables(), C_WINDOW_WIDTH, 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, compute_crc_dynamic(), compute_crc_static(), c_generic_context::compute_crc_static, decide_state(), c_generic_context::decide_state, c_generic_context::fo_count, c_generic_context::go_back_fo_count, c_generic_context::go_back_ir_count, c_profile::id, c_generic_context::init_at_IR, c_generic_context::ip_flags, ip_get_inner_packet(), ip_get_protocol(), c_generic_context::ir_count, c_generic_context::ir_dyn_count, c_generic_context::is_ip2_initialized, c_generic_context::next_header_len, c_generic_context::next_header_proto, c_context::profile, rohc_debugf, ROHC_PROFILE_IP, ROHC_PROFILE_RTP, ROHC_PROFILE_UDP, ROHC_PROFILE_UDPLITE, ROHC_PROFILE_UNCOMPRESSED, c_generic_context::sn, c_generic_context::sn_window, c_generic_context::so_count, c_context::specific, c_generic_context::specific, and c_generic_context::tmp_variables.

Referenced by c_rtp_create(), c_udp_create(), and c_udp_lite_create().

void c_generic_destroy

(

struct c_context *

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 c_destroy_wlsb(), list_comp::curr_list, destroy_list(), ipv6_header_info::ext_comp, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ipv4_header_info::ip_id_window, IPV4, IPV6, c_generic_context::is_ip2_initialized, list_comp::ref_list, c_generic_context::sn_window, c_context::specific, c_generic_context::specific, ip_header_info::v4, ip_header_info::v6, ip_header_info::version, and zfree.

Referenced by c_generic_create(), c_rtp_create(), c_rtp_destroy(), c_udp_create(), and c_udp_lite_create().

int c_generic_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 packet according to a pattern decided by several different factors.

1. Check if we have double IP headers.
2. Check if the IP-ID fields are random and if they are in NBO.
3. Decide in which state to go (IR, FO or SO).
4. Decide how many bits are needed to send the IP-ID and SN fields and more important update the sliding windows.
5. Decide which packet type to send.
6. Code the 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 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_add_ts(), c_init_header_info(), changed_dynamic_both_hdr(), generic_tmp_variables::changed_fields, changed_fields(), generic_tmp_variables::changed_fields2, changed_static_both_hdr(), check_ip_identification(), code_packet(), decide_packet(), c_generic_context::decide_state, c_profile::id, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_hdrlen(), ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), ip_get_total_extension_size(), ip_get_version(), ip_is_fragment(), IPV4, ipv4_get_header(), ipv4_get_id(), ipv6_get_header(), c_generic_context::is_ip2_initialized, generic_tmp_variables::max_size, ipv4_header_info::nbo, c_generic_context::next_header_len, c_generic_context::next_header_proto, generic_tmp_variables::nr_ip_id_bits2, generic_tmp_variables::nr_of_ip_hdr, c_context::num_sent_ir, c_context::num_sent_ir_dyn, ipv4_header_info::old_ip, ipv6_header_info::old_ip, ipv4_header_info::old_nbo, ipv4_header_info::old_rnd, PACKET_IR, PACKET_IR_DYN, generic_tmp_variables::packet_type, c_context::profile, ipv4_header_info::rnd, rohc_debugf, ROHC_PROFILE_RTP, generic_tmp_variables::send_dynamic, generic_tmp_variables::send_static, ip_packet::size, rtphdr::sn, c_generic_context::sn, c_context::specific, c_generic_context::specific, rtp_tmp_variables::timestamp, sc_rtp_context::tmp_variables, c_generic_context::tmp_variables, sc_rtp_context::ts_sc, update_variables(), ip_header_info::v4, and ip_header_info::v6.

Referenced by c_rtp_encode(), c_udp_encode(), and c_udp_lite_encode().

void c_generic_feedback	(	struct c_context *	context,
		struct c_feedback *	feedback
	)

Update the profile when feedback arrives.

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

Parameters:

context	The compression context
feedback	The feedback information including the whole feedback packet

References c_feedback::acktype, c_ack_sn_wlsb(), change_mode(), change_state(), crc_calculate(), CRC_INIT_8, CRC_TYPE_8, c_feedback::data, FO, ip_header_info::info, c_generic_context::ip_flags, ipv4_header_info::ip_id_window, IPV4, IR, c_generic_context::ir_dyn_count, rohc_debugf, c_feedback::size, sn, c_generic_context::sn_window, SO, c_context::specific, c_feedback::specific_offset, c_feedback::specific_size, c_context::state, c_feedback::type, ip_header_info::v4, and ip_header_info::version.

void change_mode	(	struct c_context *	context,
		rohc_mode	new_mode
	)

Change the mode of the context.

Parameters:

context	The compression context
new_mode	The new mode the context must enter in

References change_state(), IR, c_context::mode, and rohc_debugf.

Referenced by c_generic_feedback().

void change_state	(	struct c_context *	context,
		rohc_c_state	new_state
	)

Change the state of the context.

Parameters:

context	The compression context
new_state	The new state the context must enter in

References c_generic_context::fo_count, c_generic_context::ir_count, rohc_debugf, c_generic_context::so_count, c_context::specific, and c_context::state.

Referenced by c_generic_feedback(), change_mode(), decide_state(), periodic_down_transition(), rtp_decide_state(), and udp_decide_state().

void decide_state

(

struct c_context *

context

)

Decide the state that should be used for the next packet.

The three states are:

• Initialization and Refresh (IR),
  
• First Order (FO),
  
• Second Order (SO).

Parameters:

context

The compression context

References change_state(), FO, c_generic_context::fo_count, IR, c_generic_context::ir_count, MAX_FO_COUNT, MAX_IR_COUNT, c_context::mode, periodic_down_transition(), generic_tmp_variables::send_dynamic, generic_tmp_variables::send_static, SO, c_context::specific, c_context::state, c_generic_context::tmp_variables, and U_MODE.

Referenced by c_generic_create(), c_udp_lite_create(), rtp_decide_state(), and udp_decide_state().

int decide_type

(

struct list_comp *

comp

)

Decide the encoding type for compression list.

Parameters:

comp	The list compressor

Returns:

the encoding type

References list_comp::curr_list, get_elt(), list_elt::index_table, list_elt::item, c_translation::known, list_comp::ref_list, size_list(), list_comp::trans_table, and type_is_present().

Referenced by encode_list().

int encode_list	(	struct list_comp *	comp,
		unsigned char *	dest,
		int	counter,
		int	ps,
		int	size
	)

Generique encoding of compressed list.

Parameters:

comp	the list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
ps	the size of the index
size	The number of element in current list

Returns:

The new position

References list_comp::curr_list, decide_type(), encode_type_0(), encode_type_1(), encode_type_2(), encode_type_3(), c_list::first_elt, c_list::gen_id, get_elt(), list_elt::index_table, list_comp::islist, list_comp::list_compress, list_comp::ref_list, and rohc_debugf.

Referenced by code_ipv6_dynamic_part().

int encode_type_0	(	struct list_comp *	comp,
		unsigned char *	dest,
		int	counter,
		int	ps
	)

build Encoding type 0

 
Encoding type 0 (5.8.6.1):

       0   1   2   3   4   5   6   7
      --- --- --- --- --- --- --- ---
     | ET = 0| GP| PS|   CC = m      |  
     +---+---+---+---+---+---+---+---+
     |            gen_id             |
     +---+---+---+---+---+---+---+---+
     |       XI 1, ..., XI m         | m octets, or m * 4 bits
     /               --- --- --- --- /  
     |               :    Padding    : if PS = 0 and m is odd
     +---+---+---+---+---+---+---+---+
     |                               |
     /      item 1, ..., item n      / variable length
     |                               |
     +---+---+---+---+---+---+---+---+
	

Parameters:

comp	the list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
ps	the size of the index

Returns:

The new position

References list_comp::curr_list, item::data, c_list::gen_id, get_elt(), list_elt::index_table, list_elt::item, c_translation::known, item::length, rohc_debugf, size_list(), and list_comp::trans_table.

Referenced by encode_list().

int encode_type_1	(	struct list_comp *	comp,
		unsigned char *	dest,
		int	counter,
		int	ps
	)

build Encoding type 1

Encoding type 1 (5.8.6.2):

	  0   1   2   3   4   5   6   7
	 --- --- --- --- --- --- --- ---
	| ET = 1| GP| PS|     XI 1      |
	+---+---+---+---+---+---+---+---+
	|            gen_id             |
	+---+---+---+---+---+---+---+---+
	|            ref_id             |
	+---+---+---+---+---+---+---+---+
	/       insertion bit mask      /
	+---+---+---+---+---+---+---+---+
	|           XI list             | k octets, or (k-1)*4 bits
	/               --- --- --- --- /
	|               :    Padding    : if PS = 0 and k is even
	+---+---+---+---+---+---+---+---+
	|                               |
	/      item 1, ..., item n      / variable length
	|                               |
	+---+---+---+---+---+---+---+---+

Parameters:

comp	the list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
ps	the size of the index

Returns:

The new position

References list_comp::curr_list, item::data, get_elt(), list_elt::index_table, list_elt::item, c_translation::known, item::length, list_comp::ref_list, size_list(), list_comp::trans_table, and type_is_present().

Referenced by encode_list().

int encode_type_2	(	struct list_comp *	comp,
		unsigned char *	dest,
		int	counter,
		int	ps
	)

build Encoding type 2

Encoding type 2 (5.8.6.3):

	  0   1   2   3   4   5   6   7
	+---+---+---+---+---+---+---+---+
	| ET = 2| GP| PS|    Counter    |
	+---+---+---+---+---+---+---+---+
	|            gen_id             |
	+---+---+---+---+---+---+---+---+
	|            ref_id             |
	+---+---+---+---+---+---+---+---+
	/        removal bit mask       /
	+---+---+---+---+---+---+---+---+
 

Parameters:

comp	the list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
ps	the size of the index

Returns:

The new position

References list_comp::curr_list, get_elt(), list_elt::item, list_comp::ref_list, rohc_debugf, size_list(), and type_is_present().

Referenced by encode_list().

int encode_type_3	(	struct list_comp *	comp,
		unsigned char *	dest,
		int	counter,
		int	ps
	)

build Encoding type 3

Encoding type 3 (5.8.6.4):

	  0   1   2   3   4   5   6   7
	+---+---+---+---+---+---+---+---+
	| ET = 2| GP| PS|     XI 1      |
	+---+---+---+---+---+---+---+---+
	|            gen_id             |
	+---+---+---+---+---+---+---+---+
	|            ref_id             |
	+---+---+---+---+---+---+---+---+
	/        removal bit mask       /
	+---+---+---+---+---+---+---+---+
	/       insertion bit mask      /
        +---+---+---+---+---+---+---+---+
	|           XI list             | k octets, or (k-1)*4 bits
	/               --- --- --- --- /
	|               :    Padding    : if PS = 0 and k is even
	+---+---+---+---+---+---+---+---+
	|                               |
	/      item 1, ..., item n      / variable length
	|                               |
	+---+---+---+---+---+---+---+---+
									

Parameters:

comp	the list compressor
dest	The ROHC packet under build
counter	The current position in the rohc-packet-under-build buffer
ps	the size of the index

Returns:

The new position

References list_comp::curr_list, item::data, GET_BIT_0_2, GET_BIT_3, get_elt(), GET_REAL, list_elt::index_table, list_elt::item, c_translation::known, item::length, list_comp::ref_list, rohc_debugf, size_list(), list_comp::trans_table, and type_is_present().

Referenced by encode_list().

void ip6_c_init_table

(

struct list_comp *

comp

)

Initialize the tables IPv6 extension in compressor.

Parameters:

comp	The list compressor

References AH, item::ahhdr, list_comp::based_table, c_translation::counter, item::data, DEST, item::dest, HBH, item::hbh, item::header, c_translation::item, c_translation::known, item::length, RTHDR, item::rthdr, list_comp::trans_table, and item::type.

Referenced by c_init_header_info().