Via Header
[SIP Headers]

Detailed Description

The Via header indicates the path taken by the request so far.

Via headers can be used to prevent request looping and ensure replies take the same path as the requests. The Via syntax is defined in RFC 3261 as follows:

    Via               =  ( "Via" / "v" ) HCOLON via-parm *(COMMA via-parm)
    via-parm          =  sent-protocol LWS sent-by *( SEMI via-params )
    via-params        =  via-ttl / via-maddr
                         / via-received / via-branch
                         / via-extension
    via-ttl           =  "ttl" EQUAL ttl
    via-maddr         =  "maddr" EQUAL host
    via-received      =  "received" EQUAL (IPv4address / IPv6address)
    via-branch        =  "branch" EQUAL token
    via-extension     =  generic-param
    sent-protocol     =  protocol-name SLASH protocol-version
                         SLASH transport
    protocol-name     =  "SIP" / token
    protocol-version  =  token
    transport         =  "UDP" / "TCP" / "TLS" / "SCTP"
                         / other-transport
    sent-by           =  host [ COLON port ]
    ttl               =  1*3DIGIT ; 0 to 255

Note:: The RFC 2543 syntax allowed <comment>. We accept it, but don't encode it.

In addition to the parameters defined in RFC 3261, RFC 3486 defines a parameter "comp":

     via-compression  =  "comp" EQUAL ("sigcomp" / other-compression)
    via-params      /=  via-compression

RFC 3581 defines a parameter "rport":

    response-port  =  "rport" [EQUAL 1*DIGIT]
    via-params    /=  response-port

The parsed Via header is stored in sip_via_t structure.

Data Structures

struct sip_via_s

Structure for Via header field. More...

Defines

#define sip_via(sip)

Access a SIP Via header structure sip_via_t from sip_t.

#define SIP_VIA_INIT()

Initializer for structure sip_via_t.

#define SIPTAG_VIA(x)

Tag list item for pointer to a Via header structure sip_via_t.

#define SIPTAG_VIA_REF(x)

Tag list item for reference to a Via header pointer.

#define SIPTAG_VIA_STR(s)

Tag list item for string with Via header value.

#define SIPTAG_VIA_STR_REF(x)

Tag list item for reference to a Via header string.

Typedefs

typedef sip_via_s sip_via_t

The structure sip_via_t contains representation of SIP Via header.

Functions

issize_t sip_via_d (su_home_t *, msg_header_t *, char *s, isize_t slen)

Parse a SIP Via header.

issize_t sip_via_e (char b[], isize_t bsiz, msg_header_t const *h, int flags)

Print a SIP Via header.

sip_via_t * sip_via_init (sip_via_t x[1])

Initialize a structure sip_via_t.

int sip_is_via (sip_header_t const *header)

Test if header object is instance of sip_via_t.

sip_via_t * sip_via_dup (su_home_t *home, sip_via_t const *hdr))

Duplicate a list of Via header header structures sip_via_t.

sip_via_t * sip_via_copy (su_home_t *home, sip_via_t const *hdr))

Copy a list of Via header header structures sip_via_t.

sip_via_t * sip_via_make (su_home_t *home, char const *s))

Make a Via header structure sip_via_t.

sip_via_t * sip_via_format (su_home_t *home, char const *fmt,...)))

Make a Via header from formatting result.

int sip_via_add_param (su_home_t *home, sip_via_t *v, char const *param)

Add a parameter to a Via header object.

sip_via_t * sip_via_create (su_home_t *home, char const *host, char const *port, char const *transport,...)

Create a Via object.

char const * sip_via_port (sip_via_t const *v, int *using_rport)

Get port number corresponding to a Via line.

sip_via_t * sip_via_remove (msg_t *msg, sip_t *sip)

Get first via header and remove it from its fragment chain.

Variables

msg_hclass_t sip_via_class []

Header class for Via header.

tag_typedef_t siptag_via

Tag for Via header object.

tag_typedef_t siptag_via_str

Tag for string with Via header value.

Define Documentation

#define SIP_VIA_INIT ( )

Initializer for structure sip_via_t.
A static sip_via_t structure for Via header must be initialized with the SIP_VIA_INIT() macro. For instance,
sip_via_t sip_via = SIP_VIA_INIT;

#define SIPTAG_VIA ( x )

Tag list item for pointer to a Via header structure sip_via_t.
The SIPTAG_VIA() macro is used to include a tag item with a pointer to a sip_via_t structure in a tag list.

Parameters:

x pointer to a sip_via_t structure, or NULL.

The corresponding tag taking reference parameter is SIPTAG_VIA_REF().

#define SIPTAG_VIA_STR ( s )

Tag list item for string with Via header value.
The SIPTAG_VIA_STR() macro is used to include a tag item with a string containing value of a sip_via_t header in a tag list.

Parameters:

s pointer to a string containing Via header value, or NULL.

The string in SIPTAG_VIA_STR() can be converted to a sip_via_t header structure by giving the string s has second argument to function sip_via_make().
The corresponding tag taking reference parameter is SIPTAG_VIA_STR_REF().

Typedef Documentation

typedef struct sip_via_s sip_via_t

The structure sip_via_t contains representation of SIP Via header.
The sip_via_t is defined as follows:
typedef struct sip_via_s { sip_common_t v_common[1]; // Common fragment info sip_via_t *v_next; // Link to next @Via header char const *v_protocol; // Application and transport protocol char const *v_host; // Hostname char const *v_port; // Port number msg_param_t const *v_params; // List of via-params char const *v_comment; // Comment char const *v_ttl; // "ttl" parameter char const *v_maddr; // "maddr" parameter char const *v_received; // "received" parameter char const *v_branch; // "branch" parameter char const *v_comp; // "comp" parameter char const *v_rport; // "rport" parameter } sip_via_t;

Function Documentation

int sip_is_via ( sip_header_t const * header ) [inline]

Test if header object is instance of sip_via_t.
Check if the header class is an instance of Via header object and return true (nonzero), otherwise return false (zero).

Parameters:

header pointer to the header structure to be tested

Return values:

1 (true) if the header is an instance of header via

0 (false) otherwise

int sip_via_add_param ( su_home_t * home,

sip_via_t * v,

char const * param

)

Add a parameter to a Via header object.

Note:
This function does not duplicate param.

Parameters:

home memory home

v sip_via_t object

param parameter string

Return values:

0 when successful

-1 upon an error.

Deprecated:
Use msg_header_replace_param() directly.

sip_via_t * sip_via_copy ( su_home_t * home,

sip_via_t const * hdr

) [inline]

Copy a list of Via header header structures sip_via_t.
The function sip_via_copy() copies a header structure hdr. If the header structure hdr contains a reference (hdr->h_next) to a list of headers, all the headers in that list are copied, too. The function uses given memory home to allocate all the memory areas used to copy the list of header structure hdr.

Parameters:

home memory home used to allocate new structure

hdr pointer to the header structure to be copied

When copying, only the header structure and parameter lists attached to it are duplicated. The new header structure retains all the references to the strings within the old hdr header, including the encoding of the old header, if present.

Example
via = sip_via_copy(home, sip->sip_via);

Returns:
A pointer to newly copied header structure, or NULL upon an error.

sip_via_t* sip_via_create ( su_home_t * home,

char const * host,

char const * port,

char const * transport,

...

)

Create a Via object.
Create a new Via header object with given parameters. If transport is NULL, the default transport "SIP/2.0/UDP" is used. A NULL-terminated list of parameters can be specified after transport.

Parameters:

home memory home

host host name

port protocol port number

transport transport protocol (default is "SIP/2.0/UDP")

... NULL-terminated list of parameters

Returns:
A pointer to newly created Via header object when successful or NULL upon an error.

sip_via_t * sip_via_dup ( su_home_t * home,

sip_via_t const * hdr

) [inline]

Duplicate a list of Via header header structures sip_via_t.
Duplicate a header structure hdr. If the header structure hdr contains a reference (hdr->x_next) to a list of headers, all the headers in the list are duplicated, too.

Parameters:

home memory home used to allocate new structure

hdr header structure to be duplicated

When duplicating, all parameter lists and non-constant strings attached to the header are copied, too. The function uses given memory home to allocate all the memory areas used to copy the header.

Example
via = sip_via_dup(home, sip->sip_via);

Returns:
A pointer to the newly duplicated sip_via_t header structure, or NULL upon an error.

sip_via_t * sip_via_format ( su_home_t * home,

char const * fmt,

...

) [inline]

Make a Via header from formatting result.
Make a new sip_via_t object using formatting result as its value. The function first prints the arguments according to the format fmt specified. Then it allocates a new header structure, and parses the formatting result to the structure sip_via_t.

Parameters:

home memory home used to allocate new header structure.

fmt string used as a printf()-style format

... argument list for format

Returns:
A pointer to newly makes header structure, or NULL upon an error.

sip_via_t* sip_via_init ( sip_via_t x[1] ) [inline]

Initialize a structure sip_via_t.
An sip_via_t structure for Via header can be initialized with the sip_via_init() function/macro. For instance,
sip_via_t sip_via; sip_via_init(&sip_via);

sip_via_t * sip_via_make ( su_home_t * home,

char const * s

) [inline]

Make a Via header structure sip_via_t.
The function sip_via_make() makes a new sip_via_t header structure. It allocates a new header structure, and decodes the string s as the value of the structure.

Parameters:

home memory home used to allocate new header structure.

s string to be decoded as value of the new header structure

Returns:
A pointer to newly maked sip_via_t header structure, or NULL upon an error.

char const* sip_via_port ( sip_via_t const * v,

int * using_rport

)

Get port number corresponding to a Via line.
If using_rport is non-null, try rport. If *using_rport is non-zero, try rport even if <protocol> is not UDP. If <protocol> is UDP, set *using_rport to zero.

Variable Documentation

msg_hclass_t sip_via_class[]

Header class for Via header.
The header class sip_via_class defines how a SIP Via header is parsed and printed. It also contains methods used by SIP parser and other functions to manipulate the sip_via_t header structure.


Data Structures
struct	sip_via_s
	Structure for Via header field. More...
Defines
#define	sip_via(sip)
	Access a SIP Via header structure sip_via_t from sip_t.
#define	SIP_VIA_INIT()
	Initializer for structure sip_via_t.
#define	SIPTAG_VIA(x)
	Tag list item for pointer to a Via header structure sip_via_t.
#define	SIPTAG_VIA_REF(x)
	Tag list item for reference to a Via header pointer.
#define	SIPTAG_VIA_STR(s)
	Tag list item for string with Via header value.
#define	SIPTAG_VIA_STR_REF(x)
	Tag list item for reference to a Via header string.
Typedefs
typedef sip_via_s	sip_via_t
	The structure sip_via_t contains representation of SIP Via header.
Functions
issize_t	sip_via_d (su_home_t , msg_header_t , char *s, isize_t slen)
	Parse a SIP Via header.
issize_t	sip_via_e (char b[], isize_t bsiz, msg_header_t const *h, int flags)
	Print a SIP Via header.
sip_via_t *	sip_via_init (sip_via_t x[1])
	Initialize a structure sip_via_t.
int	sip_is_via (sip_header_t const *header)
	Test if header object is instance of sip_via_t.
sip_via_t *	sip_via_dup (su_home_t home, sip_via_t const hdr))
	Duplicate a list of Via header header structures sip_via_t.
sip_via_t *	sip_via_copy (su_home_t home, sip_via_t const hdr))
	Copy a list of Via header header structures sip_via_t.
sip_via_t *	sip_via_make (su_home_t home, char const s))
	Make a Via header structure sip_via_t.
sip_via_t *	sip_via_format (su_home_t home, char const fmt,...)))
	Make a Via header from formatting result.
int	sip_via_add_param (su_home_t home, sip_via_t v, char const *param)
	Add a parameter to a Via header object.
sip_via_t *	sip_via_create (su_home_t home, char const host, char const port, char const transport,...)
	Create a Via object.
char const *	sip_via_port (sip_via_t const v, int using_rport)
	Get port number corresponding to a Via line.
sip_via_t *	sip_via_remove (msg_t msg, sip_t sip)
	Get first via header and remove it from its fragment chain.
Variables
msg_hclass_t	sip_via_class []
	Header class for Via header.
tag_typedef_t	siptag_via
	Tag for Via header object.
tag_typedef_t	siptag_via_str
	Tag for string with Via header value.

Via Header [SIP Headers]

Detailed Description

Data Structures

Defines

Typedefs

Functions

Variables

Define Documentation

Typedef Documentation

Function Documentation

Variable Documentation

Via Header
[SIP Headers]