c_generic.h File Reference

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

#include "rohc_comp_internals.h"
#include "rohc_packets.h"
#include "comp_list.h"
#include "ip.h"
#include "crc.h"
#include <stdlib.h>

Include dependency graph for c_generic.h:

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Go to the source code of this file.

Data Structures
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_vars
	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	MAX_ITEM   15
	The number of compression list items.
#define	L   5
Functions
int	c_generic_create (struct c_context *const context, const rohc_lsb_shift_t sn_shift, 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 *const context)
	Destroy the context.
void	change_mode (struct c_context *const context, const rohc_mode new_mode)
	Change the mode of the context.
void	change_state (struct c_context *const context, const rohc_c_state new_state)
	Change the state of the context.
rohc_ext_t	decide_extension (const struct c_context *context)
	Decide what extension shall be used in the UO-1/UO-2 packet.
int	c_generic_encode (struct c_context *const context, const struct ip_packet *ip, const int packet_size, unsigned char *const dest, const int dest_size, rohc_packet_t *const packet_type, int *const payload_offset)
	Encode an IP packet according to a pattern decided by several different factors.
void	c_generic_feedback (struct c_context *const context, const struct c_feedback *feedback)
	Update the profile when feedback arrives.
void	decide_state (struct c_context *const context)
	Decide the state that should be used for the next packet.
void	rohc_get_ipid_bits (const struct c_context *context, size_t *const nr_innermost_bits, size_t *const nr_outermost_bits)
	Get the number of non-random outer/inner IP-ID bits.

---

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 L   5

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

#define MAX_ITEM   15

The number of compression list items.

---

Function Documentation

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

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

Parameters:

context	The compression context
sn_shift	The shift parameter (p) to use for encoding SN with W-LSB
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_generic_context::code_dynamic_part, c_generic_context::code_static_part, c_generic_context::code_UO_packet_head, c_generic_context::code_uo_remainder, c_context::compressor, c_generic_context::compute_crc_dynamic, compute_crc_dynamic(), compute_crc_static(), c_generic_context::compute_crc_static, c_generic_context::decide_extension, c_generic_context::decide_FO_packet, c_generic_context::decide_SO_packet, c_generic_context::decide_state, decide_state(), c_generic_context::fo_count, c_generic_context::get_next_sn, c_generic_context::go_back_fo_count, c_generic_context::go_back_ir_count, 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::is_ip2_initialized, c_generic_context::next_header_len, c_generic_context::next_header_proto, rohc_debugf, ROHC_IPPROTO_IPIP, ROHC_IPPROTO_IPV6, c_generic_context::sn_window, c_generic_context::so_count, c_context::specific, c_generic_context::specific, c_generic_context::tmp, and rohc_comp::wlsb_window_width.

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

void c_generic_destroy

(

struct c_context *const

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, 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_destroy(), 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 *const	context,
		const struct ip_packet *	ip,
		const int	packet_size,
		unsigned char *const	dest,
		const int	dest_size,
		rohc_packet_t *const	packet_type,
		int *const	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
packet_type	OUT: The type of ROHC packet that is created
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_init_header_info(), changed_dynamic_both_hdr(), generic_tmp_vars::changed_fields, changed_fields(), generic_tmp_vars::changed_fields2, changed_static_both_hdr(), code_packet(), c_context::compressor, c_generic_context::decide_state, c_generic_context::encode_uncomp_fields, c_generic_context::get_next_sn, 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(), IPV4, ipv4_get_header(), ipv4_get_id(), ipv6_get_header(), ip_header_info::is_first_header, c_generic_context::is_ip2_initialized, generic_tmp_vars::max_size, ipv4_header_info::nbo, c_generic_context::next_header_len, generic_tmp_vars::nr_ip_id_bits2, generic_tmp_vars::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_vars::packet_type, PACKET_UNKNOWN, ipv4_header_info::rnd, rohc_debugf, ROHC_IPPROTO_IPIP, ROHC_IPPROTO_IPV6, ROHC_OK, generic_tmp_vars::send_dynamic, generic_tmp_vars::send_static, ip_packet::size, c_generic_context::sn, c_context::specific, c_generic_context::tmp, ip_header_info::v4, ip_header_info::v6, and rohc_comp::wlsb_window_width.

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

void c_generic_feedback	(	struct c_context *const	context,
		const 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(), c_context::compressor, crc_calculate(), CRC_INIT_8, rohc_comp::crc_table_8, c_feedback::data, FO, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ipv4_header_info::ip_id_window, IPV4, IR, c_generic_context::is_ip2_initialized, ROHC_CRC_TYPE_8, 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 *const	context,
		const 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 *const	context,
		const 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().

rohc_ext_t decide_extension

(

const struct c_context *

context

)

Decide what extension shall be used in the UO-1/UO-2 packet.

Extensions 0, 1 & 2 are IPv4 only because of the IP-ID.

Parameters:

context

The compression context

Returns:

The extension code among PACKET_NOEXT, PACKET_EXT_0, PACKET_EXT_1 and PACKET_EXT_3 if successful, PACKET_EXT_UNKNOWN otherwise

References generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, rtp_tmp_vars::nr_ts_bits, PACKET_EXT_0, PACKET_EXT_1, PACKET_EXT_2, PACKET_EXT_3, PACKET_EXT_UNKNOWN, PACKET_NOEXT, generic_tmp_vars::packet_type, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, rohc_assert, rohc_debugf, rohc_get_ipid_bits(), generic_tmp_vars::send_dynamic, generic_tmp_vars::send_static, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, and c_generic_context::tmp.

Referenced by c_udp_create(), and c_udp_lite_create().

void decide_state

(

struct c_context *const

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(), rohc_debugf, generic_tmp_vars::send_dynamic, generic_tmp_vars::send_static, SO, c_context::specific, c_context::state, c_generic_context::tmp, and U_MODE.

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

void rohc_get_ipid_bits	(	const struct c_context *	context,
		size_t *const	nr_innermost_bits,
		size_t *const	nr_outermost_bits
	)

Get the number of non-random outer/inner IP-ID bits.

Parameters:

context	The compression context
nr_innermost_bits	OUT: the maximum number of IP-ID bits for the innermost IPv4 header
nr_outermost_bits	OUT: the maximum number of IP-ID bits for the outermost IP header

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, IPV4, generic_tmp_vars::nr_ip_id_bits, generic_tmp_vars::nr_ip_id_bits2, generic_tmp_vars::nr_of_ip_hdr, ipv4_header_info::rnd, c_context::specific, c_generic_context::tmp, ip_header_info::v4, and ip_header_info::version.

Referenced by decide_extension().