c_udp.h File Reference

ROHC compression context for the UDP profile. More...

#include <netinet/ip.h>
#include <netinet/udp.h>
#include "c_generic.h"

Include dependency graph for c_udp.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Classes
struct	udp_tmp_variables
	Define the UDP-specific temporary variables in the profile compression context. More...
struct	sc_udp_context
	Define the UDP part of the profile decompression context. More...
Functions
int	c_udp_create (struct c_context *context, const struct ip_packet ip)
	Create a new UDP context and initialize it thanks to the given IP/UDP packet.
int	c_udp_check_context (struct c_context *context, const struct ip_packet ip)
	Check if the IP/UDP packet belongs to the context.
int	c_udp_encode (struct c_context *context, const struct ip_packet ip, int packet_size, unsigned char *dest, int dest_size, int *payload_offset)
	Encode an IP/UDP packet according to a pattern decided by several different factors.
void	udp_decide_state (struct c_context *context)
	Decide the state that should be used for the next packet compressed with the ROHC UDP profile.
int	udp_code_UO_packet_tail (struct c_context *context, const unsigned char *next_header, unsigned char *dest, int counter)
	Build UDP-related fields in the tail of the UO packets.
int	udp_code_static_udp_part (struct c_context *context, const unsigned char *next_header, unsigned char *dest, int counter)
	Build the static part of the UDP header.

---

Detailed Description

ROHC compression context for the UDP profile.

Author:

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

The hackers from ROHC for Linux

---

Function Documentation

int c_udp_check_context	(	struct c_context *	context,
		struct ip_packet	ip
	)

Check if the IP/UDP packet belongs to the context.

Conditions are:

• the number of IP headers must be the same as in context
• IP version of the two IP headers must be the same as in context
• IP packets must not be fragmented
• the source and destination addresses of the two IP headers must match the ones in the context
• the transport protocol must be UDP
• the source and destination ports of the UDP header must match the ones in the context
• IPv6 only: the Flow Label of the two IP headers must match the ones 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
ip	The IP/UDP packet to check

Returns:

1 if the IP/UDP packet belongs to the context, 0 if it does not belong to the context and -1 if the profile cannot compress it or an error occurs

References ip_header_info::info, c_generic_context::ip2_flags, c_generic_context::ip_flags, ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), ip_get_version(), ip_is_fragment(), IPV4, ipv4_get_daddr(), ipv4_get_saddr(), IPV6, IPV6_ADDR_CMP, ipv6_get_daddr(), IPV6_GET_FLOW_LABEL, ipv6_get_flow_label(), ipv6_get_saddr(), c_generic_context::is_ip2_initialized, ipv4_header_info::old_ip, ipv6_header_info::old_ip, sc_udp_context::old_udp, rohc_debugf, c_context::specific, c_generic_context::specific, ip_header_info::v4, ip_header_info::v6, version, and ip_header_info::version.

Referenced by c_rtp_check_context().

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

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

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

Parameters:

context	The compression context
ip	The IP/UDP packet given to initialize the new context

Returns:

1 if successful, 0 otherwise

References c_generic_create(), c_generic_destroy(), c_generic_context::code_dynamic_part, c_generic_context::code_static_part, c_generic_context::code_UO_packet_head, c_generic_context::code_UO_packet_tail, c_generic_context::compute_crc_dynamic, c_generic_context::compute_crc_static, c_generic_context::decide_state, c_generic_context::init_at_IR, ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), c_generic_context::next_header_len, c_generic_context::next_header_proto, sc_udp_context::old_udp, rohc_debugf, udp_tmp_variables::send_udp_dynamic, c_context::specific, c_generic_context::specific, sc_udp_context::tmp_variables, sc_udp_context::udp_checksum_change_count, udp_code_dynamic_udp_part(), udp_code_static_udp_part(), udp_code_UO_packet_tail(), udp_compute_crc_dynamic(), udp_compute_crc_static(), and udp_decide_state().

int c_udp_encode	(	struct c_context *	context,
		const struct ip_packet	ip,
		int	packet_size,
		unsigned char *	dest,
		int	dest_size,
		int *	payload_offset
	)

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

Parameters:

context	The compression context
ip	The IP packet to encode
packet_size	The length of the IP packet to encode
dest	The rohc-packet-under-build buffer
dest_size	The length of the rohc-packet-under-build buffer
payload_offset	The offset for the payload in the IP packet

Returns:

The length of the created ROHC packet or -1 in case of failure

References c_generic_encode(), ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), sc_udp_context::old_udp, PACKET_IR, PACKET_IR_DYN, generic_tmp_variables::packet_type, rohc_debugf, udp_tmp_variables::send_udp_dynamic, c_context::specific, c_generic_context::specific, sc_udp_context::tmp_variables, c_generic_context::tmp_variables, and udp_changed_udp_dynamic().

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

Build the static part of the UDP header.

 Static part of UDP header (5.7.7.5):
 
    +---+---+---+---+---+---+---+---+
 1  /          Source Port          /   2 octets
    +---+---+---+---+---+---+---+---+
 2  /       Destination Port        /   2 octets
    +---+---+---+---+---+---+---+---+

Parameters:

context	The compression context
next_header	The UDP 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

References rohc_debugf.

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

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

Build UDP-related fields in the tail of the UO packets.

     --- --- --- --- --- --- --- ---
    :                               :
 13 +         UDP Checksum          +  2 octets,
    :                               :  if context(UDP Checksum) != 0
     --- --- --- --- --- --- --- ---

Parameters:

context	The compression context
next_header	The UDP 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

References rohc_debugf.

Referenced by c_rtp_create(), and c_udp_create().

void udp_decide_state

(

struct c_context *

context

)

Decide the state that should be used for the next packet compressed with the ROHC UDP profile.

The three states are:

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

Parameters:

context

The compression context

References change_state(), decide_state(), IR, rohc_debugf, udp_tmp_variables::send_udp_dynamic, c_context::specific, c_generic_context::specific, and sc_udp_context::tmp_variables.

Referenced by c_udp_create().