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 "rohc_comp_rfc3095.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
static bool	c_udp_create (struct rohc_comp_ctxt *const context, const struct net_pkt *const packet)
	Create a new UDP context and initialize it thanks to the given IP/UDP packet. More...
static void	udp_decide_state (struct rohc_comp_ctxt *const context)
	Decide the state that should be used for the next packet compressed with the ROHC UDP profile. More...
static int	c_udp_encode (struct rohc_comp_ctxt *const context, const struct net_pkt *const uncomp_pkt, uint8_t *const rohc_pkt, const size_t rohc_pkt_max_len, rohc_packet_t *const packet_type, size_t *const payload_offset)
	Encode an IP/UDP packet according to a pattern decided by several different factors. More...
static size_t	udp_code_dynamic_udp_part (const struct rohc_comp_ctxt *const context, const uint8_t *const next_header, uint8_t *const dest, const size_t counter)
	Build the dynamic part of the UDP header. More...
static int	udp_changed_udp_dynamic (const struct rohc_comp_ctxt *context, const struct udphdr *udp)
	Check if the dynamic part of the UDP header changed. More...
bool	c_udp_check_profile (const struct rohc_comp *const comp, const struct net_pkt *const packet)
	Check if the given packet corresponds to the UDP profile. More...
bool	c_udp_check_context (const struct rohc_comp_ctxt *const context, const struct net_pkt *const packet, size_t *const cr_score)
	Check if the IP/UDP packet belongs to the context. More...
size_t	udp_code_uo_remainder (const struct rohc_comp_ctxt *const context, const uint8_t *const next_header, uint8_t *const dest, const size_t counter)
	Build UDP-related fields in the tail of the UO packets. More...
size_t	udp_code_static_udp_part (const struct rohc_comp_ctxt *const context, const uint8_t *const next_header, uint8_t *const dest, const size_t counter)
	Build the static part of the UDP header. More...

Variables
const struct rohc_comp_profile	c_udp_profile
	Define the compression part of the UDP profile as described in the RFC 3095. More...

Detailed Description

ROHC compression context for the UDP profile.

Author

Didier Barvaux didie.nosp@m.r.ba.nosp@m.rvaux.nosp@m.@tou.nosp@m.louse.nosp@m..viv.nosp@m.eris..nosp@m.com

Didier Barvaux didie.nosp@m.r@ba.nosp@m.rvaux.nosp@m..org

Function Documentation

c_udp_check_context()

bool c_udp_check_context	(	const struct rohc_comp_ctxt *const	context,
		const struct net_pkt *const	packet,
		size_t *const	cr_score
	)

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
	packet	The IP/UDP packet to check
[out]	cr_score	The score of the context for Context Replication (CR)

Returns

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

c_udp_check_profile()

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

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

rohc_comp_rfc3095_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
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

c_udp_create()

static bool c_udp_create ( struct rohc_comp_ctxt *const  context, const struct net_pkt *const  packet  )

static

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

Returns

true if successful, false otherwise

c_udp_encode()

static int c_udp_encode ( struct rohc_comp_ctxt *const  context, const struct net_pkt *const  uncomp_pkt, uint8_t *const  rohc_pkt, const size_t  rohc_pkt_max_len, rohc_packet_t *const  packet_type, size_t *const  payload_offset  )

static

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

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

udp_changed_udp_dynamic()

static int udp_changed_udp_dynamic ( const struct rohc_comp_ctxt *  context, const struct udphdr *  udp  )

static

Check if the dynamic part of the UDP header changed.

Parameters

context	The compression context
udp	The UDP header

Returns

The number of UDP fields that changed

udp_code_dynamic_udp_part()

static size_t udp_code_dynamic_udp_part ( const struct rohc_comp_ctxt *const  context, const uint8_t *const  next_header, uint8_t *const  dest, const size_t  counter  )

static

Build the dynamic part of the UDP header.

 Dynamic part of UDP header (5.7.7.5):

    +---+---+---+---+---+---+---+---+
 1  /           Checksum            /   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

udp_code_static_udp_part()

size_t udp_code_static_udp_part	(	const struct rohc_comp_ctxt *const	context,
		const uint8_t *const	next_header,
		uint8_t *const	dest,
		const size_t	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

udp_code_uo_remainder()

size_t udp_code_uo_remainder	(	const struct rohc_comp_ctxt *const	context,
		const uint8_t *const	next_header,
		uint8_t *const	dest,
		const size_t	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

udp_decide_state()

static void udp_decide_state ( struct rohc_comp_ctxt *const  context )

static

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

Variable Documentation

c_udp_profile

const struct rohc_comp_profile c_udp_profile

Initial value:

=
{
        .id             = ROHC_PROFILE_UDP, 
        .protocol       = ROHC_IPPROTO_UDP, 
        .create         = c_udp_create,     
        .destroy        = rohc_comp_rfc3095_destroy,
        .check_profile  = c_udp_check_profile,
        .check_context  = c_udp_check_context,
        .encode         = c_udp_encode,
        .feedback       = rohc_comp_rfc3095_feedback,
}

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