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

#include "c_generic.h"
#include "c_rtp.h"
#include "rohc_traces.h"
#include "rohc_traces_internal.h"
#include "rohc_debug.h"
#include "rohc_packets.h"
#include "rohc_utils.h"
#include "schemes/cid.h"
#include "schemes/list_ipv6.h"
#include "sdvl.h"
#include "crc.h"
#include <string.h>
#include <assert.h>
#include "config.h"

Include dependency graph for c_generic.c:

Defines
#define	MOD_TOS 0x0001
#define	MOD_TTL 0x0010
#define	MOD_PROTOCOL 0x0020
#define	MOD_IPV6_EXT_LIST_STRUCT 0x0002
#define	MOD_IPV6_EXT_LIST_CONTENT 0x0004
#define	MOD_ERROR 0x0008
Functions
static bool	ip_header_info_new (struct ip_header_info const header_info, const struct ip_packet const ip, const size_t list_trans_nr, const size_t wlsb_window_width, rohc_trace_callback_t trace_cb, rohc_trace_callback2_t trace_cb2, void *const trace_cb_priv, const int profile_id)
	Initialize the IP header info stored in the context.
static void	ip_header_info_free (struct ip_header_info *const header_info)
	Reset the given IP header info.
static void	c_init_tmp_variables (struct generic_tmp_vars *const tmp_vars)
	Initialize all temporary variables stored in the context.
static void	change_mode (struct rohc_comp_ctxt *const context, const rohc_mode_t new_mode)
	Change the mode of the context.
static rohc_packet_t	decide_packet (const struct rohc_comp_ctxt *const context)
	Decide which packet to send when in the different states.
static int	code_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the ROHC packet to send.
static int	code_IR_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the IR packet.
static int	code_IR_DYN_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the IR-DYN packet.
static int	rohc_code_static_part (const struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, int counter)
	Build the static part of the IR packet.
static int	rohc_code_static_ip_part (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the static part of one IP header for the IR packet.
static int	code_ipv4_static_part (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the IPv4 static part of the IR packet.
static int	code_ipv6_static_part (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the IPv6 static part of the IR packet.
static int	rohc_code_dynamic_part (const struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, int counter)
	Build the dynamic part of the IR and IR-DYN packets.
static int	rohc_code_dynamic_ip_part (const struct rohc_comp_ctxt const context, const unsigned int hdr_pos, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the dynamic part of one IP header for the IR/IR-DYN packets.
static int	code_ipv4_dynamic_part (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the IPv4 dynamic part of the IR and IR-DYN packets.
static int	code_ipv6_dynamic_part (const struct rohc_comp_ctxt const context, const unsigned int hdr_pos, struct ip_header_info const header_info, const struct ip_packet const ip, unsigned char const dest, int counter)
	Build the IPv6 dynamic part of the IR and IR-DYN packets.
static int	code_uo_remainder (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const dest, int counter)
	Build the tail of the UO packet.
static int	code_UO0_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the UO-0 packet.
static int	code_UO1_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the UO-1 packet.
static int	code_UO2_packet (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const rohc_pkt, const size_t rohc_pkt_max_len)
	Build the UO-2 packet.
static int	code_UOR2_bytes (const struct rohc_comp_ctxt const context, const rohc_ext_t extension, unsigned char const f_byte, unsigned char const s_byte, unsigned char const t_byte)
	Code some fields of the UOR-2 packet.
static int	code_UOR2_RTP_bytes (const struct rohc_comp_ctxt const context, const rohc_ext_t extension, unsigned char const f_byte, unsigned char const s_byte, unsigned char const t_byte)
	Code some fields of the UOR-2-RTP packet.
static int	code_UOR2_TS_bytes (const struct rohc_comp_ctxt const context, const rohc_ext_t extension, unsigned char const f_byte, unsigned char const s_byte, unsigned char const t_byte)
	Code some fields of the UOR-2-TS packet.
static int	code_UOR2_ID_bytes (const struct rohc_comp_ctxt const context, const rohc_ext_t extension, unsigned char const f_byte, unsigned char const s_byte, unsigned char const t_byte)
	Code some fields of the UOR-2-ID packet.
static int	code_EXT0_packet (const struct rohc_comp_ctxt const context, unsigned char const dest, int counter)
	Build the extension 0 of the UO-2 packet.
static int	code_EXT1_packet (const struct rohc_comp_ctxt const context, unsigned char const dest, int counter)
	Build the extension 1 of the UO-2 packet.
static int	code_EXT2_packet (const struct rohc_comp_ctxt const context, unsigned char const dest, int counter)
	Build the extension 2 of the UO-2 packet.
static int	code_EXT3_packet (const struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char *const dest, int counter)
	Build the extension 3 of the UO-2 packet.
static int	rtp_header_flags_and_fields (const struct rohc_comp_ctxt const context, const struct ip_packet const ip, unsigned char *const dest, int counter)
static int	header_flags (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const unsigned short changed_f, const struct ip_packet const ip, const int ip2_or_I2, unsigned char const dest, int counter)
	Build inner or outer IP header flags.
static int	header_fields (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const unsigned short changed_f, const struct ip_packet const ip, const int I, const ip_header_pos_t ip_hdr_pos, unsigned char const dest, int counter)
	Build inner or outer IP header fields.
static uint8_t	compute_uo_crc (const struct c_generic_context g_context, const struct net_pkt const uncomp_pkt, const rohc_crc_type_t crc_type, const uint8_t crc_init, const unsigned char *const crc_table)
	Compute the CRC for a UO* packet.
static void	periodic_down_transition (struct rohc_comp_ctxt *const context)
	Periodically change the context state after a certain number of packets.
static void	update_context (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Update the compression context with the successfully compressed packet.
static void	update_context_ip_hdr (struct ip_header_info const ip_flags, const struct ip_packet const ip)
	Update the IP information with the IP header.
static bool	c_generic_detect_changes (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Detect changes between packet and context.
static int	changed_static_both_hdr (const struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Check if the static parts of the context changed in any of the two IP headers.
static int	changed_static_one_hdr (const struct rohc_comp_ctxt const context, const unsigned short changed_fields, struct ip_header_info const header_info)
	Check if the static part of the context changed in the new IP packet.
static int	changed_dynamic_both_hdr (const struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Check if the dynamic parts of the context changed in any of the two IP headers.
static int	changed_dynamic_one_hdr (const struct rohc_comp_ctxt const context, const unsigned short changed_fields, struct ip_header_info const header_info, const struct ip_packet *const ip)
	Check if the dynamic part of the context changed in the IP packet.
static unsigned short	detect_changed_fields (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info,const struct ip_packet *const ip)
	Find the IP fields that changed between the profile and a new IP packet.
static bool	is_field_changed (const unsigned short changed_fields, const unsigned short check_field)
	Check if a specified IP field has changed.
static void	detect_ip_id_behaviours (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Detect the behaviour of the IP-ID fields of the IPv4 headers.
static void	detect_ip_id_behaviour (const struct rohc_comp_ctxt const context, struct ip_header_info const header_info, const struct ip_packet *const ip)
	Detect the behaviour of the IP-ID field of the given IPv4 header.
static bool	is_ip_id_increasing (const uint16_t old_id, const uint16_t new_id)
	Whether the new IP-ID is increasing.
static bool	encode_uncomp_fields (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt)
	Encode uncompressed fields with the corresponding encoding scheme.
static void	rohc_get_innermost_ipv4_non_rnd (const struct rohc_comp_ctxt const context, ip_header_pos_t const pos, size_t const nr_bits, uint16_t const offset)
	Determine the number of IP-ID bits and the IP-ID offset of the innermost IPv4 header with non-random IP-ID.
static bool	c_generic_feedback_2 (struct rohc_comp_ctxt const context, const struct c_feedback const feedback)
	Update the profile when FEEDBACK-2 is received.
bool	c_generic_create (struct rohc_comp_ctxt const context, const rohc_lsb_shift_t sn_shift, const struct net_pkt const packet)
	Create a new context and initialize it thanks to the given IP packet.
void	c_generic_destroy (struct rohc_comp_ctxt *const context)
	Destroy the context.
bool	c_generic_check_profile (const struct rohc_comp const comp, const struct net_pkt const packet)
	Check if the given packet corresponds to an IP-based profile.
void	change_state (struct rohc_comp_ctxt *const context, const rohc_comp_state_t new_state)
	Change the state of the context.
int	c_generic_encode (struct rohc_comp_ctxt const context, const struct net_pkt const uncomp_pkt, unsigned char const rohc_pkt, const size_t rohc_pkt_max_len, rohc_packet_t const packet_type, size_t *const payload_offset)
	Encode an IP packet according to a pattern decided by several different factors.
bool	c_generic_reinit_context (struct rohc_comp_ctxt *const context)
	Re-initialize the given context.
bool	c_generic_feedback (struct rohc_comp_ctxt const context, const struct c_feedback const feedback)
	Update the profile when feedback is received.
bool	c_generic_use_udp_port (const struct rohc_comp_ctxt *const context, const unsigned int port)
	Whether the profile uses the given UDP port.
void	decide_state (struct rohc_comp_ctxt *const context)
	Decide the state that should be used for the next packet.
rohc_ext_t	decide_extension (const struct rohc_comp_ctxt *const context)
	Decide what extension shall be used in the UO-1-ID/UOR-2 packet.
void	rohc_get_ipid_bits (const struct rohc_comp_ctxt const 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, UDP-Lite, ESP, and RTP profiles.

Author:: Didier Barvaux <didier.barvaux@toulouse.viveris.com>; Didier Barvaux <didier@barvaux.org>; David Moreau from TAS; Emmanuelle Pechereau <epechereau@toulouse.viveris.com>

Define Documentation

#define MOD_ERROR 0x0008

A flag to indicate that an errror occurred

#define MOD_IPV6_EXT_LIST_CONTENT 0x0004

A flag to indicate that the content of the IPv6 extension headers list changed in IP header

#define MOD_IPV6_EXT_LIST_STRUCT 0x0002

A flag to indicate that the structure of the IPv6 extension headers list changed in IP header

#define MOD_PROTOCOL 0x0020

A flag to indicate that the IPv4 Protocol field changed in IP header

#define MOD_TOS 0x0001

A flag to indicate that IPv4 Type Of Service field changed in IP header

#define MOD_TTL 0x0010

A flag to indicate that IPv4 Time To Live field changed in IP header

Function Documentation

bool c_generic_check_profile	(	const struct rohc_comp *const	comp,
		const struct net_pkt *const	packet
	)

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
packet	The packet to check

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

bool c_generic_create	(	struct rohc_comp_ctxt *const	context,
		const rohc_lsb_shift_t	sn_shift,
		const struct net_pkt *const	packet
	)

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
packet	The packet given to initialize the new context

Returns:: bool if successful, false otherwise

void c_generic_destroy ( struct rohc_comp_ctxt *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

static bool c_generic_detect_changes	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Detect changes between packet and context.

Parameters:

context	The compression context to compare
uncomp_pkt	The uncompressed packet to compare

Returns:: true if changes were successfully detected, false if a problem occurred

int c_generic_encode	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len,
		rohc_packet_t *const	packet_type,
		size_t *const	payload_offset
	)

Encode an IP packet according to a pattern decided by several different factors.

1. parse uncompressed packet (done in rohc_compress3)
2. detect changes between the new uncompressed packet and the context
3. decide new compressor state
4. determine how many bytes are required for every field
5. decide which packet to send
6. code the ROHC header
7. copy the packet payload (done in rohc_compress3)
8. update the context with the new headers

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

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet
packet_type	OUT: The type of ROHC packet that is created
payload_offset	OUT: The offset for the payload in the IP packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

bool c_generic_feedback	(	struct rohc_comp_ctxt *const	context,
		const struct c_feedback *const	feedback
	)

Update the profile when feedback is received.

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

Returns:: true if the feedback was successfully handled, false if the feedback could not be taken into account

static bool c_generic_feedback_2	(	struct rohc_comp_ctxt *const	context,
		const struct c_feedback *const	feedback
	)		`[static]`

Update the profile when FEEDBACK-2 is received.

Parameters:

context	The compression context
feedback	The feedback information

Returns:: true if the feedback was successfully handled, false if the feedback could not be taken into account

bool c_generic_reinit_context ( struct rohc_comp_ctxt *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

bool c_generic_use_udp_port	(	const struct rohc_comp_ctxt *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

static void c_init_tmp_variables ( struct generic_tmp_vars *const tmp_vars ) [static]

Initialize all temporary variables stored in the context.

Parameters:

tmp_vars The temporary variables to initialize

static void change_mode	(	struct rohc_comp_ctxt *const	context,
		const rohc_mode_t	new_mode
	)		`[static]`

Change the mode of the context.

Parameters:

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

void change_state	(	struct rohc_comp_ctxt *const	context,
		const rohc_comp_state_t	new_state
	)

Change the state of the context.

Parameters:

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

static int changed_dynamic_both_hdr	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Check if the dynamic parts of the context changed in any of the two IP headers.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet

Returns:: The number of dynamic fields that changed

static int changed_dynamic_one_hdr	(	const struct rohc_comp_ctxt *const	context,
		const unsigned short	changed_fields,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip
	)		`[static]`

Check if the dynamic part of the context changed in the IP packet.

The fields classified as CHANGING by RFC need to be checked for change. The fields are:

the TOS, IP-ID and TTL fields for IPv4,
the TC and HL fields for IPv6.

The IP-ID changes are managed outside of this function.

Althought classified as STATIC, the IPv4 Don't Fragment flag is not part of the static initialization, but of the dynamic initialization. It needs to be checked for change.

Other flags are checked for change for IPv4. There are IP-ID related flags:

RND: is the IP-ID random?
NBO: is the IP-ID in Network Byte Order?
SID: is the IP-ID static?

Parameters:

context	The compression context
changed_fields	The fields that changed, created by the function changed_fields
header_info	The header info stored in the profile
ip	The header of the new IP packet

Returns:: The number of fields that changed

static int changed_static_both_hdr	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Check if the static parts of the context changed in any of the two IP headers.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet

Returns:: The number of static fields that changed

static int changed_static_one_hdr	(	const struct rohc_comp_ctxt *const	context,
		const unsigned short	changed_fields,
		struct ip_header_info *const	header_info
	)		`[static]`

Check if the static part of the context changed in the new IP packet.

The fields classified as STATIC-DEF by RFC do not need to be checked for change. These fields are constant for all packets in a stream (ie. a profile context). So, the Source Address and Destination Address fields are not checked for change for both IPv4 and IPv6. The Flow Label is not checked for IPv6.

Althought not classified as STATIC-DEF, the Version field is the same for all packets in a stream (ie. a profile context) and therefore does not need to be checked for change neither for IPv4 nor IPv6.

Althought classified as STATIC, the IPv4 Don't Fragment flag is not part of the static initialization, but of the dynamic initialization.

Summary:

For IPv4, check the Protocol field for change.
For IPv6, check the Next Header field for change.

Parameters:

context	The compression context
changed_fields	The fields that changed, created by the function changed_fields
header_info	The header info stored in the profile

Returns:: The number of fields that changed

static int code_EXT0_packet	(	const struct rohc_comp_ctxt *const	context,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the extension 0 of the UO-2 packet.


 Extension 0 for non-RTP profiles (5.11.4):

    +---+---+---+---+---+---+---+---+
 1  | 0   0 |    SN     |   IP-ID   |
    +---+---+---+---+---+---+---+---+

 Extension 0 for RTP profile (5.7.5):

    +---+---+---+---+---+---+---+---+
 1  | 0   0 |    SN     |    +T     |
    +---+---+---+---+---+---+---+---+

 if T = 0 -> +T = IP-ID
          -> -T = TS

 if T = 1 -> +T = TS
          -> -T = IP-ID

 no T bit -> +T = -T = TS

Parameters:

context	The compression context
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 if successful, -1 otherwise

static int code_EXT1_packet	(	const struct rohc_comp_ctxt *const	context,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the extension 1 of the UO-2 packet.


 Extension 1 for non-RTP profiles (5.11.4):

    +---+---+---+---+---+---+---+---+
 1  | 0   1 |    SN     |   IP-ID   |
    +---+---+---+---+---+---+---+---+
 2  |             IP-ID             |
    +---+---+---+---+---+---+---+---+

 Extension 1 for RTP profile (5.7.5):

    +---+---+---+---+---+---+---+---+
 1  | 0   1 |    SN     |    +T     |
    +---+---+---+---+---+---+---+---+
 2  |               -T              |
    +---+---+---+---+---+---+---+---+

 if T = 0 -> +T = IP-ID
          -> -T = TS

 if T = 1 -> +T = TS
          -> -T = IP-ID

 no T bit -> +T = -T = TS

Parameters:

context	The compression context
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 if successful, -1 otherwise

static int code_EXT2_packet	(	const struct rohc_comp_ctxt *const	context,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the extension 2 of the UO-2 packet.


 Extension 2 for non-RTP profiles (5.11.4):

    +---+---+---+---+---+---+---+---+
 1  | 1   0 |    SN     |   IP-ID2  |
    +---+---+---+---+---+---+---+---+
 2  |            IP-ID2             |
    +---+---+---+---+---+---+---+---+
 3  |             IP-ID             |
    +---+---+---+---+---+---+---+---+

 IP-ID2 is for outer IP-ID field

 Extension 2 for RTP profile (5.7.5):

    +---+---+---+---+---+---+---+---+
 1  | 1   0 |    SN     |     +T    |
    +---+---+---+---+---+---+---+---+
 2  |               +T              |
    +---+---+---+---+---+---+---+---+
 3  |               -T              |
    +---+---+---+---+---+---+---+---+

 if T = 0 -> +T = IP-ID
          -> -T = TS

 if T = 1 -> +T = TS
          -> -T = IP-ID

 no T bit -> +T = -T = TS

Parameters:

context	The compression context
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 if successful, -1 otherwise

static int code_EXT3_packet	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the extension 3 of the UO-2 packet.


 Extension 3 for non-RTP profiles (5.7.5 & 5.11.4):

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
 1  |  1     1  |  S  |   Mode    |  I  | ip  | ip2 |
    +-----+-----+-----+-----+-----+-----+-----+-----+
 2  |            Inner IP header flags        |     |  if ip = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 3  |            Outer IP header flags              |  if ip2 = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 4  |                      SN                       |  if S = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |
 5  /            Inner IP header fields             /  variable,
    |                                               |  if ip = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 6  |                     IP-ID                     |  2 octets, if I = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |
 7  /            Outer IP header fields             /  variable,
    |                                               |  if ip2 = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+

 Extension 3 for RTP profile (5.7.5):

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
 1  |  1     1  |  S  |R-TS | Tsc |  I  | ip  | rtp |
    +-----+-----+-----+-----+-----+-----+-----+-----+
 2  |            Inner IP header flags        | ip2 |  if ip = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 3  |            Outer IP header flags              |  if ip2 = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 4  |                      SN                       |  if S = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |
4.1 /                      TS                       / 1-4 octets, if R-TS = 1
    |                                               |
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |
 5  /            Inner IP header fields             /  variable,
    |                                               |  if ip = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
 6  |                     IP-ID                     |  2 octets, if I = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |
 7  /            Outer IP header fields             /  variable,
    |                                               |  if ip2 = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                                               |  variable,
 8  /          RTP Header flags and fields          /  if rtp = 1
    |                                               |
    +-----+-----+-----+-----+-----+-----+-----+-----+

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
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 if successful, -1 otherwise

static int code_ipv4_dynamic_part	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the IPv4 dynamic part of the IR and IR-DYN packets.


 Dynamic part IPv4 (5.7.7.4):

    +---+---+---+---+---+---+---+---+
 1  |        Type of Service        |
   +---+---+---+---+---+---+---+---+
 2  |         Time to Live          |
    +---+---+---+---+---+---+---+---+
 3  /        Identification         /   2 octets, sent verbatim
    +---+---+---+---+---+---+---+---+
 4  | DF|RND|NBO|SID|       0       |
    +---+---+---+---+---+---+---+---+
 5  / Generic extension header list /  variable length
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
header_info	The IP header info stored in the profile
ip	The IPv4 header the dynamic part is built for
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

static int code_ipv4_static_part	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the IPv4 static part of the IR packet.


 Static part IPv4 (5.7.7.4):

    +---+---+---+---+---+---+---+---+
 1  |  Version = 4  |       0       |
    +---+---+---+---+---+---+---+---+
 2  |           Protocol            |
    +---+---+---+---+---+---+---+---+
 3  /        Source Address         /   4 octets
    +---+---+---+---+---+---+---+---+
 4  /      Destination Address      /   4 octets
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
header_info	The IP header info stored in the profile
ip	The IPv4 header the static part is built for
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

static int code_ipv6_dynamic_part	(	const struct rohc_comp_ctxt *const	context,
		const unsigned int	hdr_pos,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the IPv6 dynamic part of the IR and IR-DYN packets.


 Dynamic part IPv6 (5.7.7.3):

    +---+---+---+---+---+---+---+---+
 1  |         Traffic Class         |   1 octet
    +---+---+---+---+---+---+---+---+
 2  |           Hop Limit           |   1 octet
    +---+---+---+---+---+---+---+---+
 3  / Generic extension header list /   variable length
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
hdr_pos	The position of the IP header: 1 for the outer header or 2 for the inner IP header
header_info	The IP header info stored in the profile
ip	The IPv6 header the dynamic part is built for
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, -1 in case of error

static int code_ipv6_static_part	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the IPv6 static part of the IR packet.


 Static part IPv6 (5.7.7.3):

    +---+---+---+---+---+---+---+---+
 1  |  Version = 6  |Flow Label(msb)|   1 octet
    +---+---+---+---+---+---+---+---+
 2  /        Flow Label (lsb)       /   2 octets
    +---+---+---+---+---+---+---+---+
 3  |          Next Header          |   1 octet
    +---+---+---+---+---+---+---+---+
 4  /        Source Address         /   16 octets
    +---+---+---+---+---+---+---+---+
 5  /      Destination Address      /   16 octets
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
header_info	The IP header info stored in the profile
ip	The IPv6 header the static part is built for
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

static int code_IR_DYN_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the IR-DYN packet.


 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 nor ESP
    +---+---+---+---+---+---+---+---+
    :                               :
    /           Payload             / variable length
    :                               :
     - - - - - - - - - - - - - - - -

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static int code_IR_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the IR packet.


 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 nor ESP
    +---+---+---+---+---+---+---+---+
    |                               |
    |           Payload             |  variable length
    |                               |
     - - - - - - - - - - - - - - - -

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

int code_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the ROHC packet to send.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static int code_UO0_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the UO-0 packet.


      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         :
    +---+---+---+---+---+---+---+---+
 2  |   first octet of base header  |
    +---+---+---+---+---+---+---+---+
    :                               :
 3  /   0, 1, or 2 octets of CID    /
    :                               :
    +---+---+---+---+---+---+---+---+

 UO-0 (5.7.1)

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 0 |      SN       |    CRC    |
    +===+===+===+===+===+===+===+===+

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static int code_UO1_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the UO-1 packet.

UO-1 and UO-1-ID cannot be used if there is no IPv4 header in the context or if value(RND) and value(RND2) are both 1.

Todo:: Handle extension (X bit) for UO-1-ID packet


      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         :
    +---+---+---+---+---+---+---+---+
 2  |   first octet of base header  |
    +---+---+---+---+---+---+---+---+
    :                               :
 3  /   0, 1, or 2 octets of CID    /
    :                               :
    +---+---+---+---+---+---+---+---+

 UO-1 (5.11.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   0 |         IP-ID         |
    +===+===+===+===+===+===+===+===+
 4  |        SN         |    CRC    |
    +---+---+---+---+---+---+---+---+

 UO-1-RTP (5.7.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   0 |          TS           |
    +===+===+===+===+===+===+===+===+
 4  | M |      SN       |    CRC    |
    +---+---+---+---+---+---+---+---+

 UO-1-ID (5.7.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   0 |T=0|      IP-ID        |
    +===+===+===+===+===+===+===+===+
 4  | X |      SN       |    CRC    |
    +---+---+---+---+---+---+---+---+

 UO-1-TS (5.7.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   0 |T=1|        TS         |
    +===+===+===+===+===+===+===+===+
 4  | M |      SN       |    CRC    |
    +---+---+---+---+---+---+---+---+

 X: X = 0 indicates that no extension is present;
    X = 1 indicates that an extension is present.

 T: T = 0 indicates format UO-1-ID;
    T = 1 indicates format UO-1-TS.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static int code_UO2_packet	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		const size_t	rohc_pkt_max_len
	)		`[static]`

Build the UO-2 packet.


      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         :
    +---+---+---+---+---+---+---+---+
 2  |   first octet of base header  |
    +---+---+---+---+---+---+---+---+
    :                               :
 3  /   0, 1, or 2 octets of CID    /
    :                               :
    +---+---+---+---+---+---+---+---+

 UOR-2 (5.11.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        SN         |
    +===+===+===+===+===+===+===+===+
 5  | X |            CRC            |
    +---+---+---+---+---+---+---+---+

 UOR-2-RTP (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        TS         |
    +===+===+===+===+===+===+===+===+
 4  | TS| M |       SN              |
    +---+---+---+---+---+---+---+---+
 5  | X |            CRC            |
    +---+---+---+---+---+---+---+---+

 UOR-2-TS (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        TS         |
    +===+===+===+===+===+===+===+===+
 4  |T=1| M |          SN           |
    +---+---+---+---+---+---+---+---+
 5  | X |           CRC             |
    +---+---+---+---+---+---+---+---+

 UOR-2-ID (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |      IP-ID        |
    +===+===+===+===+===+===+===+===+
 4  |T=0| M |          SN           |
    +---+---+---+---+---+---+---+---+
 5  | X |           CRC             |
    +---+---+---+---+---+---+---+---+

    +---+---+---+---+---+---+---+---+
    :                               :
 6  /           Extension           /
    :                               :
     --- --- --- --- --- --- --- ---

 X: X = 0 indicates that no extension is present;
    X = 1 indicates that an extension is present.

 T: T = 0 indicates format UOR-2-ID;
    T = 1 indicates format UOR-2-TS.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet

Returns:: The length of the ROHC packet if successful, -1 otherwise

static int code_uo_remainder	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the tail of the UO packet.


 The general format for the UO packets is:

      0   1   2   3   4   5   6   7
     --- --- --- --- --- --- --- ---
 1  :         Add-CID octet         :                    |
    +---+---+---+---+---+---+---+---+                    |
 2  |   first octet of base header  |                    |
    +---+---+---+---+---+---+---+---+                    |
    :                               :                    |
 3  /   0, 1, or 2 octets of CID    /                    |
    :                               :                    |
    +---+---+---+---+---+---+---+---+                    |
 4  /   remainder of base header    /                    |
    +---+---+---+---+---+---+---+---+                    |
    :                               :                    |
 5  /           Extension           /                    |
    :                               :                    |
     --- --- --- --- --- --- --- ---                     |
    :                               :                    |
 6  +   IP-ID of outer IPv4 header  +
    :                               :     (see section 5.7 or [RFC-3095])
     --- --- --- --- --- --- --- ---
 7  /    AH data for outer list     /                    |
     --- --- --- --- --- --- --- ---                     |
    :                               :                    |
 8  +         GRE checksum          +                    |
    :                               :                    |
     --- --- --- --- --- --- --- ---                     |
    :                               :                    |
 9  +   IP-ID of inner IPv4 header  +                    |
    :                               :                    |
     --- --- --- --- --- --- --- ---                     |
 10 /    AH data for inner list     /                    |
     --- --- --- --- --- --- --- ---                     |
    :                               :                    |
 11 +         GRE checksum          +                    |
    :                               :                    |
     --- --- --- --- --- --- --- ---
    :            List of            :
 12 /        Dynamic chains         /  variable, given by static chain
    :   for additional IP headers   :  (includes no SN)
     --- --- --- --- --- --- --- ---

     --- --- --- --- --- --- --- ---
    :                               :  RTP/UDP profiles only [RFC-3095]
 13 +         UDP Checksum          +  2 octets,
    :                               :  if context(UDP Checksum) != 0
     --- --- --- --- --- --- --- ---

Parts 7, 8, 10, 11 and 12 are not supported. Parts 1, 2, 3, 4 and 5 are built in packet-specific functions. Parts 6 and 9 are built in this function. Part 13 is built in profile-specific function.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
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

static int code_UOR2_bytes	(	const struct rohc_comp_ctxt *const	context,
		const rohc_ext_t	extension,
		unsigned char *const	f_byte,
		unsigned char *const	s_byte,
		unsigned char *const	t_byte
	)		`[static]`

Code some fields of the UOR-2 packet.

This function is called by code_UO2_packet. It should not be called directly.

See also:: code_UO2_packet


 UOR-2 (5.11.3):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        SN         |
    +===+===+===+===+===+===+===+===+
 5  | X |            CRC            |
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
extension	The extension that will be appended to the packet
f_byte	IN/OUT: The first byte of the UOR-2 packet
s_byte	IN/OUT: Not used by the UOR-2 packet
t_byte	IN/OUT: The second byte of the UOR-2 packet

Returns:: 1 if successful, 0 otherwise

static int code_UOR2_ID_bytes	(	const struct rohc_comp_ctxt *const	context,
		const rohc_ext_t	extension,
		unsigned char *const	f_byte,
		unsigned char *const	s_byte,
		unsigned char *const	t_byte
	)		`[static]`

Code some fields of the UOR-2-ID packet.

This function is called by code_UO2_packet. It should not be called directly.

See also:: code_UO2_packet


 UOR-2-ID (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |      IP-ID        |
    +===+===+===+===+===+===+===+===+
 4  |T=0| M |          SN           |
    +---+---+---+---+---+---+---+---+
 5  | X |           CRC             |
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
extension	The extension that will be appended to the packet
f_byte	IN/OUT: The first byte of the UOR-2-ID packet
s_byte	IN/OUT: The second byte of the UOR-2-ID packet
t_byte	IN/OUT: The third byte of the UOR-2-ID packet

Returns:: 1 if successful, 0 otherwise

static int code_UOR2_RTP_bytes	(	const struct rohc_comp_ctxt *const	context,
		const rohc_ext_t	extension,
		unsigned char *const	f_byte,
		unsigned char *const	s_byte,
		unsigned char *const	t_byte
	)		`[static]`

Code some fields of the UOR-2-RTP packet.

This function is called by code_UO2_packet. It should not be called directly.

See also:: code_UO2_packet


 UOR-2-RTP (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        TS         |
    +===+===+===+===+===+===+===+===+
 4  | TS| M |       SN              |
    +---+---+---+---+---+---+---+---+
 5  | X |            CRC            |
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
extension	The extension that will be appended to the packet
f_byte	IN/OUT: The first byte of the UOR-2-RTP packet
s_byte	IN/OUT: The second byte of the UOR-2-RTP packet
t_byte	IN/OUT: The third byte of the UOR-2-RTP packet

Returns:: 1 if successful, 0 otherwise

static int code_UOR2_TS_bytes	(	const struct rohc_comp_ctxt *const	context,
		const rohc_ext_t	extension,
		unsigned char *const	f_byte,
		unsigned char *const	s_byte,
		unsigned char *const	t_byte
	)		`[static]`

Code some fields of the UOR-2-TS packet.

This function is called by code_UO2_packet. It should not be called directly.

See also:: code_UO2_packet


 UOR-2-TS (5.7.4):

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
 2  | 1   1   0 |        TS         |
    +===+===+===+===+===+===+===+===+
 4  |T=1| M |          SN           |
    +---+---+---+---+---+---+---+---+
 5  | X |           CRC             |
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
extension	The extension that will be appended to the packet
f_byte	IN/OUT: The first byte of the UOR-2-TS packet
s_byte	IN/OUT: The second byte of the UOR-2-TS packet
t_byte	IN/OUT: The third byte of the UOR-2-TS packet

Returns:: 1 if successful, 0 otherwise

static uint8_t compute_uo_crc	(	const struct c_generic_context *	g_context,
		const struct net_pkt *const	uncomp_pkt,
		const rohc_crc_type_t	crc_type,
		const uint8_t	crc_init,
		const unsigned char *const	crc_table
	)		`[static]`

Compute the CRC for a UO* packet.

Parameters:

g_context	The generic compression context
uncomp_pkt	The uncompressed packet to encode
crc_type	The type of CRC to compute
crc_init	The initial value of the CRC
crc_table	The table of pre-computed CRC

Returns:: The computed CRC

rohc_ext_t decide_extension ( const struct rohc_comp_ctxt *const context )

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

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

Parameters:

context The compression context

Returns:: The extension code among ROHC_EXT_NONE, ROHC_EXT_0, ROHC_EXT_1 and ROHC_EXT_3 if successful, ROHC_EXT_UNKNOWN otherwise

static rohc_packet_t decide_packet ( const struct rohc_comp_ctxt *const context ) [static]

Decide which packet to send when in the different states.

In IR state, IR packets are used. In FO and SO, the profile-specific functions are called if they are defined, otherwise IR packets are used.

Parameters:

context The compression context

Returns:

The packet type among ROHC_PACKET_IR, ROHC_PACKET_IR_DYN, ROHC_PACKET_UO_0, ROHC_PACKET_UO_1* and ROHC_PACKET_UOR_2* in case of success
ROHC_PACKET_UNKNOWN in case of failure

void decide_state ( struct rohc_comp_ctxt *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

static unsigned short detect_changed_fields	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip
	)		`[static]`

Find the IP fields that changed between the profile and a new IP packet.

Only some fields are checked for change in the compression process, so only check these ones to avoid useless work. The fields to check are: TOS/TC, TTL/HL and Protocol/Next Header.

Parameters:

context	The compression context
header_info	The header info stored in the profile
ip	The header of the new IP packet

Returns:: The bitpattern that indicates which field changed

static void detect_ip_id_behaviour	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip
	)		`[static]`

Detect the behaviour of the IP-ID field of the given IPv4 header.

Detect how the IP-ID field behave:

constant,
increase in Network Bit Order (NBO),
increase in Little Endian,
randomly.

Parameters:

context	The compression context
header_info	The header info stored in the profile
ip	One IPv4 header

static void detect_ip_id_behaviours	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Detect the behaviour of the IP-ID fields of the IPv4 headers.

Detect how the IP-ID fields behave:

constant (not handled yet),
increase in Network Bit Order (NBO),
increase in Little Endian,
randomly.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet

static bool encode_uncomp_fields	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Encode uncompressed fields with the corresponding encoding scheme.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode

Returns:: true in case of success, false otherwise

static int header_fields	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const unsigned short	changed_f,
		const struct ip_packet *const	ip,
		const int	I,
		const ip_header_pos_t	ip_hdr_pos,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build inner or outer IP header fields.

This function is used to code the IP header fields of the extension 3 of the UO-2 packet. The function is called twice (one for inner IP header and one for outer IP header) with different arguments.

See also:: code_EXT3_packet


    +-----+-----+-----+-----+-----+-----+-----+-----+
 1  |         Type of Service/Traffic Class         |  if TOS = 1
     ..... ..... ..... ..... ..... ..... ..... .....
 2  |         Time to Live/Hop Limit                |  if TTL = 1
     ..... ..... ..... ..... ..... ..... ..... .....
 3  |         Protocol/Next Header                  |  if PR = 1
     ..... ..... ..... ..... ..... ..... ..... .....
 4  /         IP extension headers                  /  variable, if IPX = 1
     ..... ..... ..... ..... ..... ..... ..... .....

 For outer IP-ID:
     ..... ..... ..... ..... ..... ..... ..... .....
 5  |                  IP-ID                        |  2 octets,
     ..... ..... ..... ..... ..... ..... ..... .....    if I2 = 1

Part 4 is not supported.

Parameters:

context	The compression context
header_info	The header info stored in the profile
changed_f	The fields that changed, created by the function changed_fields
ip	One inner or outer IP header
I	The I flag of the IP header
ip_hdr_pos	The position of the IP 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

See also:: changed_fields

static int header_flags	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const unsigned short	changed_f,
		const struct ip_packet *const	ip,
		const int	ip2_or_I2,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build inner or outer IP header flags.

This function is used to code the IP header fields of the extension 3 of the UO-2 packet. The function is called twice (one for inner IP header and one for outer IP header) with different arguments.

See also:: code_EXT3_packet


 Header flags for IP and UDP profiles (5.11.4):

 For inner flags:

    +-----+-----+-----+-----+-----+-----+-----+-----+
 1  |            Inner IP header flags        |     |  if ip = 1
    | TOS | TTL | DF  | PR  | IPX | NBO | RND | ip2 |  ip2 = 0 if non-RTP
    +-----+-----+-----+-----+-----+-----+-----+-----+

 or for outer flags:

    +-----+-----+-----+-----+-----+-----+-----+-----+
 2  |            Outer IP header flags              |
    | TOS2| TTL2| DF2 | PR2 |IPX2 |NBO2 |RND2 |  I2 |  if ip2 = 1
    +-----+-----+-----+-----+-----+-----+-----+-----+

Parameters:

context	The compression context
header_info	The header info stored in the profile
changed_f	The fields that changed, created by the function changed_fields
ip	One inner or outer IP header
ip2_or_I2	Whether the ip2 (inner, RTP only) or I2 (outer) flag is set or not
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

See also:: changed_fields

static void ip_header_info_free ( struct ip_header_info *const header_info ) [static]

Reset the given IP header info.

Parameters:

header_info The IP header info to reset

static bool ip_header_info_new	(	struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		const size_t	list_trans_nr,
		const size_t	wlsb_window_width,
		rohc_trace_callback_t	trace_cb,
		rohc_trace_callback2_t	trace_cb2,
		void *const	trace_cb_priv,
		const int	profile_id
	)		`[static]`

Initialize the IP header info stored in the context.

Parameters:

header_info	The IP header info to initialize
ip	The IP header
list_trans_nr	The number of uncompressed transmissions for list compression (L)
wlsb_window_width	The width of the W-LSB sliding window for IPv4 IP-ID (must be > 0)
trace_cb	The old function to call for printing traces
trace_cb2	The new function to call for printing traces
trace_cb_priv	An optional private context, may be NULL
profile_id	The ID of the associated compression profile

Returns:: true if successful, false otherwise

static bool is_field_changed	(	const unsigned short	changed_fields,
		const unsigned short	check_field
	)		`[static]`

Check if a specified IP field has changed.

Parameters:

changed_fields	The fields that changed, created by the function changed_fields
check_field	The field for which to check a change

Returns:: 1 if the field changed, 0 if not

See also:: changed_fields

static bool is_ip_id_increasing	(	const uint16_t	old_id,
		const uint16_t	new_id
	)		`[static]`

Whether the new IP-ID is increasing.

The new IP-ID is considered as increasing if the new value is greater by a small delta then the previous IP-ID. Wraparound shall be taken into account.

Parameters:

old_id	The IP-ID of the previous IPv4 header
new_id	The IP-ID of the current IPv4 header

Returns:: Whether the IP-ID is increasing

static void periodic_down_transition ( struct rohc_comp_ctxt *const context ) [static]

Periodically change the context state after a certain number of packets.

Parameters:

context The compression context

static int rohc_code_dynamic_ip_part	(	const struct rohc_comp_ctxt *const	context,
		const unsigned int	hdr_pos,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the dynamic part of one IP header for the IR/IR-DYN packets.

Parameters:

context	The compression context
hdr_pos	The position of the IP header: 1 for the outer header or 2 for the inner IP header
header_info	The IP header info stored in the profile
ip	The IP header the dynamic part is built for
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, -1 in case of error

static int rohc_code_dynamic_part	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		int	counter
	)		`[static]`

Build the dynamic part of the IR and IR-DYN packets.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	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

static int rohc_code_static_ip_part	(	const struct rohc_comp_ctxt *const	context,
		struct ip_header_info *const	header_info,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

Build the static part of one IP header for the IR packet.

Parameters:

context	The compression context
header_info	The IP header info stored in the profile
ip	The IP header the static part is built for
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

static int rohc_code_static_part	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt,
		unsigned char *const	rohc_pkt,
		int	counter
	)		`[static]`

Build the static part of the IR packet.

Parameters:

context	The compression context
uncomp_pkt	The uncompressed packet to encode
rohc_pkt	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

static void rohc_get_innermost_ipv4_non_rnd	(	const struct rohc_comp_ctxt *const	context,
		ip_header_pos_t *const	pos,
		size_t *const	nr_bits,
		uint16_t *const	offset
	)		`[static]`

Determine the number of IP-ID bits and the IP-ID offset of the innermost IPv4 header with non-random IP-ID.

Parameters:

context	The compression context
pos	OUT: The position of the header
nr_bits	OUT: the number of IP-ID bits of the found header
offset	OUT: the IP-ID offset of the found header

void rohc_get_ipid_bits	(	const struct rohc_comp_ctxt *const	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

static int rtp_header_flags_and_fields	(	const struct rohc_comp_ctxt *const	context,
		const struct ip_packet *const	ip,
		unsigned char *const	dest,
		int	counter
	)		`[static]`

static void update_context	(	struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	uncomp_pkt
	)		`[static]`

Update the compression context with the successfully compressed packet.

Parameters:

context	The compression context to update
uncomp_pkt	The uncompressed packet that updates the context

static void update_context_ip_hdr	(	struct ip_header_info *const	ip_flags,
		const struct ip_packet *const	ip
	)		`[static]`

Update the IP information with the IP header.

Parameters:

ip_flags	The IP context to update
ip	The uncompressed IP header that updates the context

Defines

Functions

Detailed Description

Define Documentation

Function Documentation