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>

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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.
bool	c_generic_check_profile (const struct rohc_comp const comp, const struct ip_packet const outer_ip, const struct ip_packet const inner_ip, const uint8_t protocol, rohc_ctxt_key_t const ctxt_key)
	Check if the given packet corresponds to an IP-based profile.
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 size_t packet_size, unsigned char const dest, const size_t 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.
bool	c_generic_reinit_context (struct c_context *const context)
	Re-initialize the given context.
void	c_generic_feedback (struct c_context const context, const struct c_feedback feedback)
	Update the profile when feedback arrives.
bool	c_generic_use_udp_port (const struct c_context *const context, const unsigned int port)
	Whether the profile uses the given UDP port.
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>; Didier Barvaux <didier@barvaux.org>; 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

bool c_generic_check_profile	(	const struct rohc_comp *const	comp,
		const struct ip_packet *const	outer_ip,
		const struct ip_packet *const	inner_ip,
		const uint8_t	protocol,
		rohc_ctxt_key_t *const	ctxt_key
	)

Check if the given packet corresponds to an IP-based profile.

Conditions are:

the version of the outer IP header is 4 or 6
if the outer IP header is IPv4, it does not contain options
the outer IP header is not an IP fragment
if there are at least 2 IP headers, the version of the inner IP header is 4 or 6
if there are at least 2 IP headers and if the inner IP header is IPv4, it does not contain options
if there are at least 2 IP headers, the inner IP header is not an IP fragment

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

Parameters:

comp	The ROHC compressor
outer_ip	The outer IP header of the IP packet to check
inner_ip	The inner IP header of the IP packet to check if the IP packet contains at least 2 IP headers, NULL if the IP packet to check contains only one IP header
protocol	The transport protocol carried by the IP packet: the protocol carried by the outer IP header if there is only one IP header, the protocol carried by the inner IP header if there are at least two IP headers.
ctxt_key	The key to help finding the context associated with packet

Returns:

Whether the IP packet corresponds to the profile:

true if the IP packet corresponds to the profile,
false if the IP packet does not correspond to the profile

References ipv6_addr::addr, daddr, ip_packet::data, ip_get_hdrlen(), ip_get_version(), ip_is_fragment(), IPV4, ipv4_get_daddr(), ipv4_get_saddr(), IPV6, ipv6_get_daddr(), ipv6_get_saddr(), rohc_debug, ROHC_PROFILE_GENERAL, ROHC_TRACE_COMP, saddr, ipv6_addr::u32, version, and ip_packet::version.

Referenced by c_esp_check_profile(), and c_udp_check_profile().

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

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_generic_context::specific, c_context::specific, ip_header_info::v4, ip_header_info::v6, ip_header_info::version, and zfree.

int c_generic_encode	(	struct c_context *const	context,
		const struct ip_packet *	ip,
		const size_t	packet_size,
		unsigned char *const	dest,
		const size_t	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

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_feedback::cid, c_context::compressor, crc_calculate(), CRC_INIT_8, rohc_comp::crc_table_8, c_feedback::data, FO, c_profile::id, 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, c_context::mode, c_context::profile, rohc_comp_debug, ROHC_CRC_TYPE_8, rohc_info, ROHC_TRACE_COMP, rohc_warning, 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, c_context::used, ip_header_info::v4, and ip_header_info::version.

bool c_generic_reinit_context ( struct c_context *const context )

Re-initialize the given context.

Make the context restart its initialization with decompressor, ie. it goes in the lowest compression state.

Parameters:

context The compression context to re-initialize

Returns:: true in case of success, false otherwise

References change_mode(), change_state(), IR, and U_MODE.

bool c_generic_use_udp_port	(	const struct c_context *const	context,
		const unsigned int	port
	)

Whether the profile uses the given UDP port.

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

Parameters:

context	The compression context
port	The UDP port number to check

Returns:: always return true, it is used by non-RTP profiles

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(), c_context::cid, c_context::compressor, c_profile::id, IR, c_context::mode, c_context::profile, rohc_info, and ROHC_TRACE_COMP.

Referenced by c_generic_feedback(), and c_generic_reinit_context().

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_context::cid, c_context::compressor, c_generic_context::fo_count, c_profile::id, c_generic_context::ir_count, c_context::profile, rohc_info, ROHC_TRACE_COMP, c_generic_context::so_count, c_context::specific, and c_context::state.

Referenced by c_generic_feedback(), c_generic_reinit_context(), change_mode(), decide_state(), and periodic_down_transition().

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 c_context::compressor, c_profile::id, 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, c_context::profile, rohc_assert, rohc_comp_debug, rohc_get_ipid_bits(), ROHC_TRACE_COMP, generic_tmp_vars::send_dynamic, generic_tmp_vars::send_static, c_generic_context::specific, c_context::specific, sc_rtp_context::tmp, and c_generic_context::tmp.

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, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, IPV4, IR, c_generic_context::ir_count, MAX_FO_COUNT, MAX_IR_COUNT, c_context::mode, generic_tmp_vars::nr_of_ip_hdr, periodic_down_transition(), rohc_comp_debug, generic_tmp_vars::send_dynamic, generic_tmp_vars::send_static, ipv4_header_info::sid_count, SO, c_context::specific, c_context::state, c_generic_context::tmp, U_MODE, ip_header_info::v4, and ip_header_info::version.

Referenced by c_generic_create().

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().

Data Structures

Defines

Functions

Detailed Description

Define Documentation

Function Documentation