c_esp.c File Reference

ROHC ESP compression profile. More...

#include "rohc_comp_rfc3095.h"
#include "c_ip.h"
#include "rohc_traces_internal.h"
#include "crc.h"
#include "protocols/esp.h"
#include "rohc_utils.h"
#include <stdbool.h>
#include <string.h>
#include <assert.h>

Include dependency graph for c_esp.c:

Data Structures
struct	sc_esp_context
	Define the ESP part of the profile decompression context. More...

Functions
static bool	c_esp_create (struct rohc_comp_ctxt *const context, const struct net_pkt *const packet)
	Create a new ESP context and initialize it thanks to the given IP/ESP packet. More...
static bool	c_esp_check_profile (const struct rohc_comp *const comp, const struct net_pkt *const packet)
	Check if the given packet corresponds to the ESP profile. More...
static bool	c_esp_check_context (const struct rohc_comp_ctxt *const context, const struct net_pkt *const packet)
	Check if the IP/ESP packet belongs to the context. More...
static int	c_esp_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/ESP packet according to a pattern decided by several different factors. More...
static uint32_t	c_esp_get_next_sn (const struct rohc_comp_ctxt *const context, const struct net_pkt *const uncomp_pkt)
	Determine the SN value for the next packet. More...
static size_t	esp_code_static_esp_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 ESP header. More...
static size_t	esp_code_dynamic_esp_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 ESP header. More...

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

Detailed Description

ROHC ESP compression profile.

Author

FWX rohc_.nosp@m.team.nosp@m.@dial.nosp@m.ine..nosp@m.fr

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

Function Documentation

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

static

Check if the IP/ESP 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 ESP
• the security parameters index of the ESP header must match the one 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

Returns

true if the packet belongs to the context, false if it does not belong to the context

static bool c_esp_check_profile ( const struct rohc_comp *const  comp, const struct net_pkt *const  packet  )

static

Check if the given packet corresponds to the ESP profile.

Conditions are:

• the transport protocol is ESP
• 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

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

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

static

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

Returns

true if successful, false otherwise

static int c_esp_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/ESP 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

static uint32_t c_esp_get_next_sn ( const struct rohc_comp_ctxt *const  context, const struct net_pkt *const  uncomp_pkt  )

static

Determine the SN value for the next packet.

Profile SN is the ESP SN.

Parameters

context	The compression context
uncomp_pkt	The uncompressed packet to encode

Returns

The SN

static size_t esp_code_dynamic_esp_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 ESP header.

 Dynamic part of ESP header (5.7.7.7):

    +---+---+---+---+---+---+---+---+
 1  /       Sequence Number         /   4 octets
    +---+---+---+---+---+---+---+---+

Parameters

context	The compression context
next_header	The ESP 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

static size_t esp_code_static_esp_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 static part of the ESP header.

 Static part of ESP header (5.7.7.7):

    +---+---+---+---+---+---+---+---+
 1  /              SPI              /   4 octets
    +---+---+---+---+---+---+---+---+

 SPI = Security Parameters Index

Parameters

context	The compression context
next_header	The ESP 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

Variable Documentation

const struct rohc_comp_profile c_esp_profile

Initial value:

=
{
        .id             = ROHC_PROFILE_ESP, 
        .protocol       = ROHC_IPPROTO_ESP, 
        .create         = c_esp_create,     
        .destroy        = rohc_comp_rfc3095_destroy,
        .check_profile  = c_esp_check_profile,
        .check_context  = c_esp_check_context,
        .encode         = c_esp_encode,
        .reinit_context = rohc_comp_reinit_context,
        .feedback       = rohc_comp_rfc3095_feedback,
}

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