c_udp.c File Reference

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

#include "c_udp.h"
#include "c_ip.h"
#include "rohc_traces_internal.h"
#include "rohc_packets.h"
#include "rohc_utils.h"
#include "crc.h"
#include "c_generic.h"
#include "protocols/udp.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

Include dependency graph for c_udp.c:

Data Structures
struct	udp_tmp_vars
	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
bool	c_udp_check_profile (const struct rohc_comp *const comp, const struct ip_packet *const outer_ip, const struct ip_packet *const inner_ip, const uint8_t protocol, rohc_ctxt_key_t *const ctxt_key)
	Check if the given packet corresponds to the UDP profile.
bool	c_udp_check_context (const struct c_context *context, const struct ip_packet *ip)
	Check if the IP/UDP packet belongs to the context.
int	udp_code_uo_remainder (const struct c_context *context, const unsigned char *next_header, unsigned char *const dest, int counter)
	Build UDP-related fields in the tail of the UO packets.
int	udp_code_static_udp_part (const struct c_context *context, const unsigned char *next_header, unsigned char *const dest, int counter)
	Build the static part of the UDP header.
Variables
struct c_profile	c_udp_profile
	Define the compression part of the UDP profile as described in the RFC 3095.

---

Detailed Description

ROHC compression context for the UDP profile.

Author:

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

Didier Barvaux <didier@barvaux.org>

The hackers from ROHC for Linux

---

Function Documentation

bool c_udp_check_context	(	const struct c_context *	context,
		const 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:

true if the IP/UDP packet belongs to the context false if it does not belong to the context

References c_context::compressor, ipv4_hdr::daddr, udphdr::dest, c_profile::id, ip_header_info::info, c_generic_context::ip2_flags, ipv6_hdr::ip6_dst, ipv6_hdr::ip6_src, c_generic_context::ip_flags, ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), ip_get_version(), 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, c_context::profile, ROHC_IPPROTO_IPIP, ROHC_IPPROTO_IPV6, ROHC_IPPROTO_UDP, ROHC_TRACE_COMP, rohc_warning, ipv4_hdr::saddr, udphdr::source, c_generic_context::specific, c_context::specific, ip_header_info::v4, ip_header_info::v6, version, and ip_header_info::version.

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

Check if the given packet corresponds to the UDP profile.

Conditions are:

• the transport protocol is UDP
• the version of the outer IP header is 4 or 6
• 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, the inner IP header is not an IP fragment
• the inner IP payload is at least 8-byte long for UDP header
• the UDP Length field and the UDP payload match

See also:

c_generic_check_profile

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

Parameters:

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

Returns:

Whether the IP packet corresponds to the profile:

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

References c_generic_check_profile(), udphdr::dest, ip_get_next_layer(), ip_get_plen(), udphdr::len, ROHC_IPPROTO_UDP, rohc_ntoh16(), and udphdr::source.

int udp_code_static_udp_part	(	const struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *const	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 udphdr::dest, rohc_comp_debug, and udphdr::source.

int udp_code_uo_remainder	(	const struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *const	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 udphdr::check, and rohc_comp_debug.

---

Variable Documentation

struct c_profile c_udp_profile

Initial value:

{
        ROHC_IPPROTO_UDP,    
        ROHC_PROFILE_UDP,    
        "UDP / Compressor",  
        c_udp_create,        
        c_generic_destroy,
        c_udp_check_profile,
        c_udp_check_context,
        c_udp_encode,
        c_generic_reinit_context,
        c_generic_feedback,
        c_generic_use_udp_port,
}

Define the compression part of the UDP profile as described in the RFC 3095.