ROHC compression/decompression library
Defines | Functions
c_generic.c File Reference

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_debug.h"
#include "rohc_packets.h"
#include "rohc_utils.h"
#include "cid.h"
#include "sdvl.h"
#include "crc.h"
#include "config.h"
#include <string.h>
#include <assert.h>
Include dependency graph for c_generic.c:

Defines

#define MOD_TOS   0x0001
#define MOD_TTL   0x0010
#define MOD_PROTOCOL   0x0020

Functions

int code_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the ROHC packet to send.
int code_IR_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the IR packet.
int code_IR_DYN_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the IR-DYN packet.
int code_generic_static_part (const struct c_context *context, struct ip_header_info *const header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the static part of the IR and IR-DYN packets.
int code_ipv4_static_part (const struct c_context *context, struct ip_header_info *const header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the IPv4 static part of the IR and IR-DYN packets.
int code_ipv6_static_part (const struct c_context *context, struct ip_header_info *const header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the IPv6 static part of the IR and IR-DYN packets.
int code_generic_dynamic_part (const struct c_context *context, struct ip_header_info *const header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the dynamic part of the IR and IR-DYN packets.
int code_ipv4_dynamic_part (const struct c_context *const context, struct ip_header_info *header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the IPv4 dynamic part of the IR and IR-DYN packets.
int code_ipv6_dynamic_part (const struct c_context *context, struct ip_header_info *const header_info, const struct ip_packet *ip, unsigned char *const dest, int counter)
 Build the IPv6 dynamic part of the IR and IR-DYN packets.
int code_uo_remainder (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest, int counter)
 Build the tail of the UO packet.
int code_UO0_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the UO-0 packet.
int code_UO1_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the UO-1 packet.
int code_UO2_packet (struct c_context *const context, const struct ip_packet *ip, const struct ip_packet *ip2, const unsigned char *next_header, unsigned char *const dest)
 Build the UO-2 packet.
int code_UOR2_bytes (const struct c_context *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.
int code_UOR2_RTP_bytes (const struct c_context *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.
int code_UOR2_TS_bytes (const struct c_context *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.
int code_UOR2_ID_bytes (const struct c_context *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.
int code_EXT0_packet (const struct c_context *context, unsigned char *const dest, int counter)
 Build the extension 0 of the UO-2 packet.
int code_EXT1_packet (const struct c_context *context, unsigned char *const dest, int counter)
 Build the extension 1 of the UO-2 packet.
int code_EXT2_packet (const struct c_context *context, unsigned char *const dest, int counter)
 Build the extension 2 of the UO-2 packet.
int code_EXT3_packet (const struct c_context *context, const struct ip_packet *ip, const struct ip_packet *ip2, unsigned char *const dest, int counter)
 Build the extension 3 of the UO-2 packet.
int rtp_header_flags_and_fields (const struct c_context *context, const unsigned short changed_f, const struct ip_packet *ip, unsigned char *const dest, int counter)
int header_flags (const struct c_context *context, struct ip_header_info *const header_info, const unsigned short changed_f, const struct ip_packet *ip, const int ip2_or_I2, const size_t nr_ip_id_bits, unsigned char *const dest, int counter)
 Build inner or outer IP header flags.
int header_fields (const struct c_context *context, struct ip_header_info *const header_info, const unsigned short changed_f, const struct ip_packet *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.
int changed_static_both_hdr (const struct c_context *context, const struct ip_packet *ip, const struct ip_packet *ip2)
 Check if the static parts of the context changed in any of the two IP headers.
int changed_static_one_hdr (const struct c_context *const context, const unsigned short changed_fields, struct ip_header_info *const header_info, const struct ip_packet *ip)
 Check if the static part of the context changed in the new IP packet.
int changed_dynamic_both_hdr (const struct c_context *context, const struct ip_packet *ip, const struct ip_packet *ip2)
 Check if the dynamic parts of the context changed in any of the two IP headers.
int changed_dynamic_one_hdr (const struct c_context *const context, const unsigned short changed_fields, struct ip_header_info *const header_info, const struct ip_packet *ip)
 Check if the dynamic part of the context changed in the IP packet.
unsigned short changed_fields (const struct ip_header_info *header_info, const struct ip_packet *ip)
 Find the IP fields that changed between the profile and a new IP packet.
int is_changed (const unsigned short changed_fields, const unsigned short check_field)
 Check if a specified IP field has changed.
int c_init_header_info (struct ip_header_info *header_info, const struct ip_packet *ip, const size_t wlsb_window_width)
 Initialize the inner or outer IP header info stored in the context.
void c_init_tmp_variables (struct generic_tmp_vars *tmp_vars)
 Initialize all temporary variables stored in the context.
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.
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 periodic_down_transition (struct c_context *context)
 Periodically change the context state after a certain number of packets.
void decide_state (struct c_context *const context)
 Decide the state that should be used for the next packet.
rohc_ext_t decide_extension (const struct c_context *context)
 Decide what extension shall be used in the UO-1/UO-2 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, 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>
The hackers from ROHC for Linux

Define Documentation

#define MOD_PROTOCOL   0x0020

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

Referenced by changed_fields(), changed_static_one_hdr(), header_fields(), and header_flags().

#define MOD_TOS   0x0001

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

Referenced by changed_dynamic_one_hdr(), changed_fields(), header_fields(), and header_flags().

#define MOD_TTL   0x0010

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

Referenced by changed_dynamic_one_hdr(), changed_fields(), header_fields(), and header_flags().

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:
contextThe compression context
sn_shiftThe shift parameter (p) to use for encoding SN with W-LSB
ipThe 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:
contextThe 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:
contextThe compression context
ipThe IP packet to encode
packet_sizeThe length of the IP packet to encode
destThe rohc-packet-under-build buffer
dest_sizeThe length of the rohc-packet-under-build buffer
packet_typeOUT: The type of ROHC packet that is created
payload_offsetThe 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:
contextThe compression context
feedbackThe 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.

int c_init_header_info ( struct ip_header_info *  header_info,
const struct ip_packet *  ip,
const size_t  wlsb_window_width 
)

Initialize the inner or outer IP header info stored in the context.

Parameters:
header_infoThe inner or outer IP header info to initialize
ipThe inner or outer IP header
wlsb_window_widthThe width of the W-LSB sliding window for IPv4 IP-ID (must be > 0)
Returns:
1 if successful, 0 otherwise

References c_create_wlsb(), list_comp::changed, list_comp::compare, list_comp::counter, list_comp::create_item, list_comp::curr_list, ipv4_header_info::df_count, ipv6_header_info::ext_comp, c_list::first_elt, list_comp::free_table, c_list::gen_id, list_comp::get_extension, list_comp::get_index_table, list_comp::get_size, ip_header_info::info, ip_get_extension_size(), ip_get_version(), ipv4_header_info::ip_id_window, IPV4, ip_header_info::is_first_header, list_comp::is_present, MAX_FO_COUNT, ipv4_header_info::nbo_count, ip_header_info::protocol_count, list_comp::ref_list, ipv4_header_info::rnd_count, rohc_debugf, ROHC_LSB_SHIFT_IP_ID, ip_header_info::tos_count, ip_header_info::ttl_count, ip_header_info::v4, ip_header_info::v6, and ip_header_info::version.

Referenced by c_generic_create(), and c_generic_encode().

void c_init_tmp_variables ( struct generic_tmp_vars *  tmp_vars)

Initialize all temporary variables stored in the context.

Parameters:
tmp_varsThe temporary variables to initialize

References generic_tmp_vars::changed_fields, generic_tmp_vars::changed_fields2, generic_tmp_vars::max_size, generic_tmp_vars::nr_ip_id_bits, generic_tmp_vars::nr_ip_id_bits2, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, generic_tmp_vars::packet_type, PACKET_UNKNOWN, generic_tmp_vars::send_dynamic, and generic_tmp_vars::send_static.

Referenced by c_generic_create().

void change_mode ( struct c_context *const  context,
const rohc_mode  new_mode 
)

Change the mode of the context.

Parameters:
contextThe compression context
new_modeThe 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:
contextThe compression context
new_stateThe 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().

int changed_dynamic_both_hdr ( const struct c_context *  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2 
)

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

Parameters:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
Returns:
The number of fields that changed

References changed_dynamic_one_hdr(), generic_tmp_vars::changed_fields, generic_tmp_vars::changed_fields2, c_generic_context::ip2_flags, c_generic_context::ip_flags, generic_tmp_vars::nr_of_ip_hdr, rohc_debugf, c_context::specific, and c_generic_context::tmp.

Referenced by c_generic_encode().

int changed_dynamic_one_hdr ( const struct c_context *const  context,
const unsigned short  changed_fields,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip 
)

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 ?
Parameters:
contextThe compression context
changed_fieldsThe fields that changed, created by the function changed_fields
header_infoThe header info stored in the profile
ipThe header of the new IP packet
Returns:
The number of fields that changed

References ipv4_header_info::df_count, c_generic_context::fo_count, ip_header_info::info, ip_get_version(), IPV4, IPV4_GET_DF, ipv4_get_df(), is_changed(), MAX_FO_COUNT, MOD_TOS, MOD_TTL, ipv4_header_info::nbo, ipv4_header_info::nbo_count, ipv4_header_info::old_ip, ipv4_header_info::old_nbo, ipv4_header_info::old_rnd, ipv4_header_info::rnd, ipv4_header_info::rnd_count, rohc_debugf, c_context::specific, ip_header_info::tos_count, ip_header_info::ttl_count, and ip_header_info::v4.

Referenced by changed_dynamic_both_hdr(), and code_EXT3_packet().

unsigned short changed_fields ( const struct ip_header_info *  header_info,
const struct ip_packet *  ip 
)

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:
header_infoThe header info stored in the profile
ipThe header of the new IP packet
Returns:
The bitpattern that indicates which field changed

References ip_header_info::info, ip_get_protocol(), ip_get_tos(), ip_get_ttl(), ip_get_version(), IPV4, IPV6_GET_TC, MOD_PROTOCOL, MOD_TOS, MOD_TTL, ipv4_header_info::old_ip, ipv6_header_info::old_ip, ipv4_hdr::protocol, rohc_debugf, ipv4_hdr::tos, ipv4_hdr::ttl, ip_header_info::v4, and ip_header_info::v6.

Referenced by c_generic_encode().

int changed_static_both_hdr ( const struct c_context *  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2 
)

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

Parameters:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
Returns:
The number of fields that changed

References generic_tmp_vars::changed_fields, generic_tmp_vars::changed_fields2, changed_static_one_hdr(), c_generic_context::ip2_flags, c_generic_context::ip_flags, generic_tmp_vars::nr_of_ip_hdr, c_context::specific, and c_generic_context::tmp.

Referenced by c_generic_encode().

int changed_static_one_hdr ( const struct c_context *const  context,
const unsigned short  changed_fields,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip 
)

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:
contextThe compression context
changed_fieldsThe fields that changed, created by the function changed_fields
header_infoThe header info stored in the profile
ipThe header of the new IP packet
Returns:
The number of fields that changed

References c_generic_context::fo_count, is_changed(), MAX_FO_COUNT, MOD_PROTOCOL, ip_header_info::protocol_count, rohc_debugf, and c_context::specific.

Referenced by changed_static_both_hdr(), and code_EXT3_packet().

int code_EXT0_packet ( const struct c_context *  context,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer if successful, -1 otherwise

References generic_tmp_vars::packet_type, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, rohc_assert, ROHC_IP_HDR_NONE, c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, and rtp_tmp_vars::ts_send.

Referenced by code_UO2_packet().

int code_EXT1_packet ( const struct c_context *  context,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer if successful, -1 otherwise

References generic_tmp_vars::packet_type, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, rohc_assert, ROHC_IP_HDR_NONE, c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, and rtp_tmp_vars::ts_send.

Referenced by code_UO2_packet().

int code_EXT2_packet ( const struct c_context *  context,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer if successful, -1 otherwise

References ipv4_header_info::id_delta, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, IPV4, c_generic_context::is_ip2_initialized, generic_tmp_vars::packet_type, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, ipv4_header_info::rnd, rohc_assert, rohc_debugf, ROHC_IP_HDR_NONE, c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, rtp_tmp_vars::ts_send, ip_header_info::v4, and ip_header_info::version.

Referenced by code_UO2_packet().

int code_EXT3_packet ( const struct c_context *  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
unsigned char *const  dest,
int  counter 
)

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                       / 1-4octets, 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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer if successful, -1 otherwise

References c_bytesSdvl(), c_encodeSdvl(), changed_dynamic_one_hdr(), generic_tmp_vars::changed_fields, generic_tmp_vars::changed_fields2, changed_static_one_hdr(), header_fields(), header_flags(), c_profile::id, ipv4_header_info::id_delta, ip_header_info::info, INIT_STRIDE, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_version(), IPV4, MAX_FO_COUNT, c_context::mode, generic_tmp_vars::nr_ip_id_bits, generic_tmp_vars::nr_ip_id_bits2, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, rtp_tmp_vars::nr_ts_bits, rtp_tmp_vars::nr_ts_bits_ext3, generic_tmp_vars::packet_type, PACKET_UO_1_ID, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, c_context::profile, ipv4_header_info::rnd, ipv4_header_info::rnd_count, rohc_assert, rohc_debugf, ROHC_IP_HDR_FIRST, ROHC_IP_HDR_NONE, ROHC_IP_HDR_SECOND, ROHC_PROFILE_RTP, rtp_header_flags_and_fields(), sc_rtp_context::rtp_pt_change_count, rtp_tmp_vars::rtp_pt_changed, SEND_SCALED, c_generic_context::sn, c_context::specific, c_generic_context::specific, ts_sc_comp::state, sc_rtp_context::tmp, c_generic_context::tmp, sc_rtp_context::ts_sc, rtp_tmp_vars::ts_send, and ip_header_info::v4.

Referenced by code_UO2_packet().

int code_generic_dynamic_part ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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

Parameters:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IP header the dynamic part is built for
destThe rohc-packet-under-build buffer
counterThe 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

References code_ipv4_dynamic_part(), code_ipv6_dynamic_part(), ip_get_version(), and IPV4.

Referenced by code_IR_DYN_packet(), and code_IR_packet().

int code_generic_static_part ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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

Parameters:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IP header the static part is built for
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer

References code_ipv4_static_part(), code_ipv6_static_part(), ip_get_version(), and IPV4.

Referenced by code_IR_packet().

int code_ipv4_dynamic_part ( const struct c_context *const  context,
struct ip_header_info *  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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
    +---+---+---+---+---+---+---+---+
 4  | DF|RND|NBO|         0         |
    +---+---+---+---+---+---+---+---+
 5  / Generic extension header list /  variable length
    +---+---+---+---+---+---+---+---+
Parameters:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IPv4 header the dynamic part is built for
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer

References ipv4_header_info::df_count, ip_header_info::info, ip_get_tos(), ip_get_ttl(), ipv4_get_df(), ipv4_get_id_nbo(), ipv4_header_info::nbo, ipv4_header_info::nbo_count, ipv4_header_info::rnd, ipv4_header_info::rnd_count, rohc_debugf, ip_header_info::tos_count, ip_header_info::ttl_count, and ip_header_info::v4.

Referenced by code_generic_dynamic_part().

int code_ipv4_static_part ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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


 Static part IPv4 (5.7.7.4):

    +---+---+---+---+---+---+---+---+
 1  |  Version = 4  |       0       |
    +---+---+---+---+---+---+---+---+
 2  |           Protocol            |
    +---+---+---+---+---+---+---+---+
 3  /        Source Address         /   4 octets
    +---+---+---+---+---+---+---+---+
 4  /      Destination Address      /   4 octets
    +---+---+---+---+---+---+---+---+
Parameters:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IPv4 header the static part is built for
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer

References ip_get_protocol(), IPV4_ADDR_FORMAT, IPV4_ADDR_RAW, ipv4_get_daddr(), ipv4_get_saddr(), ip_header_info::protocol_count, and rohc_debugf.

Referenced by code_generic_static_part().

int code_ipv6_dynamic_part ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IPv6 header the dynamic part is built for
destThe rohc-packet-under-build buffer
counterThe 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

References list_comp::changed, list_comp::curr_list, ipv6_header_info::ext_comp, ip_header_info::info, ip_get_tos(), ip_get_ttl(), list_comp::is_present, list_get_size(), list_comp::ref_list, rohc_debugf, ip_header_info::tos_count, ip_header_info::ttl_count, and ip_header_info::v6.

Referenced by code_generic_dynamic_part().

int code_ipv6_static_part ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

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


 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:
contextThe compression context
header_infoThe IP header info stored in the profile
ipThe IPv6 header the static part is built for
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer

References ip_get_protocol(), IPV6_ADDR_FORMAT, IPV6_ADDR_IN6, ipv6_get_daddr(), ipv6_get_flow_label(), ipv6_get_saddr(), ip_header_info::protocol_count, and rohc_debugf.

Referenced by code_generic_static_part().

int code_IR_DYN_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header data used to code the dynamic part of the next header for some profiles such as UDP, UDP-Lite, etc.
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer

References c_context::cid, medium::cid_type, code_cid_values(), c_generic_context::code_dynamic_part, code_generic_dynamic_part(), c_generic_context::code_ir_remainder, c_context::compressor, crc_calculate(), CRC_INIT_8, rohc_comp::crc_table_8, c_profile::id, c_generic_context::init_at_IR, c_generic_context::ip2_flags, c_generic_context::ip_flags, generic_tmp_vars::max_size, rohc_comp::medium, generic_tmp_vars::nr_of_ip_hdr, c_context::profile, ROHC_CRC_TYPE_8, rohc_debugf, c_context::specific, and c_generic_context::tmp.

Referenced by code_packet().

int code_IR_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header data used to code the static and dynamic parts of the next header for some profiles such as UDP, UDP-Lite, and so on.
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer

References c_context::cid, medium::cid_type, code_cid_values(), c_generic_context::code_dynamic_part, code_generic_dynamic_part(), code_generic_static_part(), c_generic_context::code_ir_remainder, c_generic_context::code_static_part, c_context::compressor, crc_calculate(), CRC_INIT_8, rohc_comp::crc_table_8, c_profile::id, c_generic_context::init_at_IR, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_version(), IPV4, generic_tmp_vars::max_size, rohc_comp::medium, generic_tmp_vars::nr_ip_id_bits, generic_tmp_vars::nr_ip_id_bits2, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, c_context::profile, ROHC_CRC_TYPE_8, rohc_debugf, c_context::specific, and c_generic_context::tmp.

Referenced by code_packet().

int code_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

Build the ROHC packet to send.

Parameters:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header such as UDP or UDP-Lite
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer if successful, -1 otherwise

References code_IR_DYN_packet(), code_IR_packet(), code_UO0_packet(), code_UO1_packet(), code_UO2_packet(), PACKET_IR, PACKET_IR_DYN, generic_tmp_vars::packet_type, PACKET_UO_0, PACKET_UO_1, PACKET_UO_1_ID, PACKET_UO_1_RTP, PACKET_UO_1_TS, PACKET_UOR_2, PACKET_UOR_2_ID, PACKET_UOR_2_RTP, PACKET_UOR_2_TS, rohc_debugf, c_context::specific, and c_generic_context::tmp.

Referenced by c_generic_encode().

int code_UO0_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header such as UDP or UDP-Lite
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer if successful, -1 otherwise

References c_context::cid, medium::cid_type, code_cid_values(), c_generic_context::code_UO_packet_head, code_uo_remainder(), c_context::compressor, c_generic_context::compute_crc_dynamic, c_generic_context::compute_crc_static, CRC_INIT_3, rohc_comp::crc_table_3, ip_packet::data, ip_get_raw_data(), generic_tmp_vars::max_size, rohc_comp::medium, generic_tmp_vars::nr_of_ip_hdr, ROHC_CRC_TYPE_3, rohc_debugf, c_generic_context::sn, c_context::specific, and c_generic_context::tmp.

Referenced by code_packet().

int code_UO1_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header such as UDP or UDP-Lite
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer if successful, -1 otherwise

References c_context::cid, medium::cid_type, code_cid_values(), c_generic_context::code_UO_packet_head, code_uo_remainder(), c_context::compressor, c_generic_context::compute_crc_dynamic, c_generic_context::compute_crc_static, CRC_INIT_3, rohc_comp::crc_table_3, ip_packet::data, c_profile::id, ipv4_header_info::id_delta, ip_header_info::info, c_generic_context::ip_flags, ip_get_raw_data(), IPV4, rtp_tmp_vars::m_set, generic_tmp_vars::max_size, rohc_comp::medium, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::packet_type, PACKET_UO_1, PACKET_UO_1_ID, PACKET_UO_1_RTP, PACKET_UO_1_TS, c_context::profile, rohc_assert, ROHC_CRC_TYPE_3, rohc_debugf, ROHC_PROFILE_RTP, c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, rtp_tmp_vars::ts_send, ip_header_info::v4, and ip_header_info::version.

Referenced by code_packet().

int code_UO2_packet ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header such as UDP or UDP-Lite
destThe rohc-packet-under-build buffer
Returns:
The position in the rohc-packet-under-build buffer if successful, -1 otherwise

References c_context::cid, medium::cid_type, code_cid_values(), code_EXT0_packet(), code_EXT1_packet(), code_EXT2_packet(), code_EXT3_packet(), c_generic_context::code_UO_packet_head, code_uo_remainder(), code_UOR2_bytes(), code_UOR2_ID_bytes(), code_UOR2_RTP_bytes(), code_UOR2_TS_bytes(), c_context::compressor, c_generic_context::compute_crc_dynamic, c_generic_context::compute_crc_static, CRC_INIT_6, CRC_INIT_7, rohc_comp::crc_table_6, rohc_comp::crc_table_7, ip_packet::data, c_generic_context::decide_extension, extension, c_profile::id, ip_get_raw_data(), generic_tmp_vars::max_size, rohc_comp::medium, generic_tmp_vars::nr_of_ip_hdr, 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_CRC_TYPE_6, ROHC_CRC_TYPE_7, rohc_debugf, rohc_get_ext_descr(), ROHC_PROFILE_RTP, c_context::specific, and c_generic_context::tmp.

Referenced by code_packet().

int code_uo_remainder ( struct c_context *const  context,
const struct ip_packet *  ip,
const struct ip_packet *  ip2,
const unsigned char *  next_header,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
ipThe outer IP header
ip2The inner IP header
next_headerThe next header such as UDP or UDP-Lite
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer

References c_generic_context::code_uo_remainder, ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_version(), IPV4, ipv4_get_id(), generic_tmp_vars::nr_of_ip_hdr, ipv4_header_info::rnd, rohc_debugf, c_context::specific, c_generic_context::tmp, and ip_header_info::v4.

Referenced by code_UO0_packet(), code_UO1_packet(), and code_UO2_packet().

int code_UOR2_bytes ( const struct c_context *  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.

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:
contextThe compression context
extensionThe extension that will be appended to the packet
f_byteIN/OUT: The first byte of the UOR-2 packet
s_byteIN/OUT: Not used by the UOR-2 packet
t_byteIN/OUT: The second byte of the UOR-2 packet
Returns:
1 if successful, 0 otherwise

References generic_tmp_vars::nr_sn_bits, PACKET_EXT_0, PACKET_EXT_1, PACKET_EXT_2, PACKET_EXT_3, PACKET_NOEXT, rohc_debugf, c_generic_context::sn, c_context::specific, and c_generic_context::tmp.

Referenced by code_UO2_packet().

int code_UOR2_ID_bytes ( const struct c_context *  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.

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:
contextThe compression context
extensionThe extension that will be appended to the packet
f_byteIN/OUT: The first byte of the UOR-2-ID packet
s_byteIN/OUT: The second byte of the UOR-2-ID packet
t_byteIN/OUT: The third byte of the UOR-2-ID packet
Returns:
1 if successful, 0 otherwise

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, rtp_tmp_vars::m_set, MAX_FO_COUNT, generic_tmp_vars::nr_sn_bits, rtp_tmp_vars::nr_ts_bits, rtp_tmp_vars::nr_ts_bits_ext3, PACKET_EXT_0, PACKET_EXT_1, PACKET_EXT_2, PACKET_EXT_3, PACKET_NOEXT, ipv4_header_info::rnd_count, rohc_assert, rohc_debugf, ROHC_IP_HDR_FIRST, ROHC_IP_HDR_NONE, sdvl_get_min_len(), c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, rtp_tmp_vars::ts_send, and ip_header_info::v4.

Referenced by code_UO2_packet().

int code_UOR2_RTP_bytes ( const struct c_context *  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.

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:
contextThe compression context
extensionThe extension that will be appended to the packet
f_byteIN/OUT: The first byte of the UOR-2-RTP packet
s_byteIN/OUT: The second byte of the UOR-2-RTP packet
t_byteIN/OUT: The third byte of the UOR-2-RTP packet
Returns:
1 if successful, 0 otherwise

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, IPV4, rtp_tmp_vars::m_set, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, rtp_tmp_vars::nr_ts_bits, rtp_tmp_vars::nr_ts_bits_ext3, PACKET_EXT_0, PACKET_EXT_1, PACKET_EXT_2, PACKET_EXT_3, PACKET_NOEXT, ipv4_header_info::rnd, rohc_assert, rohc_debugf, sdvl_get_min_len(), c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, rtp_tmp_vars::ts_send, ip_header_info::v4, and ip_header_info::version.

Referenced by code_UO2_packet().

int code_UOR2_TS_bytes ( const struct c_context *  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.

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:
contextThe compression context
extensionThe extension that will be appended to the packet
f_byteIN/OUT: The first byte of the UOR-2-TS packet
s_byteIN/OUT: The second byte of the UOR-2-TS packet
t_byteIN/OUT: The third byte of the UOR-2-TS packet
Returns:
1 if successful, 0 otherwise

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, IPV4, rtp_tmp_vars::m_set, generic_tmp_vars::nr_of_ip_hdr, generic_tmp_vars::nr_sn_bits, rtp_tmp_vars::nr_ts_bits, rtp_tmp_vars::nr_ts_bits_ext3, PACKET_EXT_0, PACKET_EXT_1, PACKET_EXT_2, PACKET_EXT_3, PACKET_NOEXT, ipv4_header_info::rnd, rohc_assert, rohc_debugf, rohc_min, sdvl_get_min_len(), c_generic_context::sn, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, c_generic_context::tmp, rtp_tmp_vars::ts_send, ip_header_info::v4, and ip_header_info::version.

Referenced by code_UO2_packet().

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:
contextThe 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:
contextThe 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().

int header_fields ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const unsigned short  changed_f,
const struct ip_packet *  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.

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:
contextThe compression context
header_infoThe header info stored in the profile
changed_fThe fields that changed, created by the function changed_fields
ipOne inner or outer IP header
IThe I flag of the IP header
ip_hdr_posThe position of the IP header
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer
See also:
changed_fields

References ipv4_header_info::id_delta, ip_header_info::info, ip_get_protocol(), ip_get_tos(), ip_get_ttl(), is_changed(), MAX_FO_COUNT, MOD_PROTOCOL, MOD_TOS, MOD_TTL, ip_header_info::protocol_count, rohc_debugf, ROHC_IP_HDR_FIRST, ip_header_info::tos_count, ip_header_info::ttl_count, and ip_header_info::v4.

Referenced by code_EXT3_packet().

int header_flags ( const struct c_context *  context,
struct ip_header_info *const  header_info,
const unsigned short  changed_f,
const struct ip_packet *  ip,
const int  ip2_or_I2,
const size_t  nr_ip_id_bits,
unsigned char *const  dest,
int  counter 
)

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:
contextThe compression context
header_infoThe header info stored in the profile
changed_fThe fields that changed, created by the function changed_fields
ipOne inner or outer IP header
ip2_or_I2Whether the ip2 (inner, RTP only) or I2 (outer) flag is set or not
nr_ip_id_bitsThe number of bits needed to transmit the IP-ID field
destThe rohc-packet-under-build buffer
counterThe current position in the rohc-packet-under-build buffer
Returns:
The new position in the rohc-packet-under-build buffer
See also:
changed_fields

References ipv4_header_info::df_count, ip_header_info::info, IPV4, ipv4_get_df(), is_changed(), MAX_FO_COUNT, MOD_PROTOCOL, MOD_TOS, MOD_TTL, ipv4_header_info::nbo, ipv4_header_info::nbo_count, ip_header_info::protocol_count, ipv4_header_info::rnd, ipv4_header_info::rnd_count, rohc_debugf, ip_header_info::tos_count, ip_header_info::ttl_count, ip_header_info::v4, and ip_header_info::version.

Referenced by code_EXT3_packet().

int is_changed ( const unsigned short  changed_fields,
const unsigned short  check_field 
)

Check if a specified IP field has changed.

Parameters:
changed_fieldsThe fields that changed, created by the function changed_fields
check_fieldThe field for which to check a change
Returns:
1 if the field changed, 0 if not
See also:
changed_fields

Referenced by changed_dynamic_one_hdr(), changed_static_one_hdr(), header_fields(), and header_flags().

void periodic_down_transition ( struct c_context *  context)

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

Parameters:
contextThe compression context

References change_state(), c_context::compressor, FO, c_generic_context::go_back_fo_count, c_generic_context::go_back_ir_count, IR, rohc_comp::periodic_refreshes_fo_timeout, rohc_comp::periodic_refreshes_ir_timeout, rohc_debugf, SO, c_context::specific, and c_context::state.

Referenced by 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:
contextThe compression context
nr_innermost_bitsOUT: the maximum number of IP-ID bits for the innermost IPv4 header
nr_outermost_bitsOUT: 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().

int rtp_header_flags_and_fields ( const struct c_context *  context,
const unsigned short  changed_f,
const struct ip_packet *  ip,
unsigned char *const  dest,
int  counter 
)

References c_bytesSdvl(), c_encodeSdvl(), rtphdr::extension, get_ts_stride(), INIT_STRIDE, ip_get_next_layer(), rtphdr::m, MAX_IR_COUNT, c_context::mode, ts_sc_comp::nr_init_stride_packets, rtphdr::padding, rtphdr::pt, rohc_debugf, ROHC_INIT_TS_STRIDE_MIN, sc_rtp_context::rtp_pt_change_count, rtp_tmp_vars::rtp_pt_changed, SEND_SCALED, c_context::specific, c_generic_context::specific, ts_sc_comp::state, sc_rtp_context::tmp, and sc_rtp_context::ts_sc.

Referenced by code_EXT3_packet().

Generated on Thu Aug 15 2013 21:28:25 for ROHC compression/decompression library by   doxygen 1.7.6.1