Max-Forwards Header [SIP Headers]

The Max-Forwards header is used to limit the number of proxies or gateways that can forward the request. More...

Data Structures
struct	sip_max_forwards_s
	Structure for Max-Forwards header. More...
Defines
#define	sip_max_forwards(sip)
	Access a SIP Max-Forwards header structure sip_max_forwards_t from sip_t.
#define	SIP_MAX_FORWARDS_INIT()
	Initializer for structure sip_max_forwards_t.
#define	SIPTAG_MAX_FORWARDS(x)
	Tag list item for pointer to a Max-Forwards header structure sip_max_forwards_t.
#define	SIPTAG_MAX_FORWARDS_REF(x)
	Tag list item for reference to a Max-Forwards header pointer.
#define	SIPTAG_MAX_FORWARDS_STR(s)
	Tag list item for string with Max-Forwards header value.
#define	SIPTAG_MAX_FORWARDS_STR_REF(x)
	Tag list item for reference to a Max-Forwards header string.
Typedefs
typedef struct sip_max_forwards_s	sip_max_forwards_t
	The structure sip_max_forwards_t contains representation of SIP Max-Forwards header.
Functions
issize_t	sip_max_forwards_d (su_home_t *, msg_header_t *, char *s, isize_t slen)
	Parse a SIP Max-Forwards header.
issize_t	sip_max_forwards_e (char b[], isize_t bsiz, msg_header_t const *h, int flags)
	Print a SIP Max-Forwards header.
sip_max_forwards_t *	sip_max_forwards_init (sip_max_forwards_t x[1])
	Initialize a structure sip_max_forwards_t.
int	sip_is_max_forwards (sip_header_t const *header)
	Test if header object is instance of sip_max_forwards_t.
sip_max_forwards_t *	sip_max_forwards_dup (su_home_t *home, sip_max_forwards_t const *hdr))
	Duplicate a list of Max-Forwards header header structures sip_max_forwards_t.
sip_max_forwards_t *	sip_max_forwards_copy (su_home_t *home, sip_max_forwards_t const *hdr))
	Copy a list of Max-Forwards header header structures sip_max_forwards_t.
sip_max_forwards_t *	sip_max_forwards_make (su_home_t *home, char const *s))
	Make a Max-Forwards header structure sip_max_forwards_t.
sip_max_forwards_t *	sip_max_forwards_format (su_home_t *home, char const *fmt,...)))
	Make a Max-Forwards header from formatting result.
Variables
msg_hclass_t	sip_max_forwards_class []
	Header class for Max-Forwards header.
tag_typedef_t	siptag_max_forwards
	Tag for Max-Forwards header object.
tag_typedef_t	siptag_max_forwards_str
	Tag for string with Max-Forwards header value.

---

Detailed Description

The Max-Forwards header is used to limit the number of proxies or gateways that can forward the request.

The Max-Forwards syntax is defined in RFC 3261 as follows:

    Max-Forwards  =  "Max-Forwards" HCOLON 1*DIGIT

The parsed Max-Forwards header is stored in sip_max_forwards_t structure.

---

Define Documentation

#define SIP_MAX_FORWARDS_INIT

(

)

Initializer for structure sip_max_forwards_t.

A static sip_max_forwards_t structure for Max-Forwards header must be initialized with the SIP_MAX_FORWARDS_INIT() macro. For instance,

  sip_max_forwards_t sip_max_forwards = SIP_MAX_FORWARDS_INIT;

#define SIPTAG_MAX_FORWARDS

(

x

)

Tag list item for pointer to a Max-Forwards header structure sip_max_forwards_t.

The SIPTAG_MAX_FORWARDS() macro is used to include a tag item with a pointer to a sip_max_forwards_t structure in a tag list.

Parameters:

x

pointer to a sip_max_forwards_t structure, or NULL.

The corresponding tag taking reference parameter is SIPTAG_MAX_FORWARDS_REF().

#define SIPTAG_MAX_FORWARDS_STR

(

s

)

Tag list item for string with Max-Forwards header value.

The SIPTAG_MAX_FORWARDS_STR() macro is used to include a tag item with a string containing value of a sip_max_forwards_t header in a tag list.

Parameters:

s

pointer to a string containing Max-Forwards header value, or NULL.

The string in SIPTAG_MAX_FORWARDS_STR() can be converted to a sip_max_forwards_t header structure by giving the string s has second argument to function sip_max_forwards_make().

The corresponding tag taking reference parameter is SIPTAG_MAX_FORWARDS_STR_REF().

---

Typedef Documentation

typedef struct sip_max_forwards_s sip_max_forwards_t

The structure sip_max_forwards_t contains representation of SIP Max-Forwards header.

The sip_max_forwards_t is defined as follows:

 typedef struct sip_max_forwards_s {
   sip_common_t        mf_common[1];  // Common fragment info
   sip_error_t        *mf_next;       // Link to next (dummy)
   unsigned long       mf_count;      // Digits
 } sip_max_forwards_t;

---

Function Documentation

int sip_is_max_forwards

(

sip_header_t const *

header

)

[inline]

Test if header object is instance of sip_max_forwards_t.

Check if the header class is an instance of Max-Forwards 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 max_forwards
	0	(false) otherwise

sip_max_forwards_t * sip_max_forwards_copy	(	su_home_t *	home,
		sip_max_forwards_t const *	hdr
	)			[inline]

Copy a list of Max-Forwards header header structures sip_max_forwards_t.

The function sip_max_forwards_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

   max_forwards = sip_max_forwards_copy(home, sip->sip_max_forwards);

Returns:

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

sip_max_forwards_t * sip_max_forwards_dup	(	su_home_t *	home,
		sip_max_forwards_t const *	hdr
	)			[inline]

Duplicate a list of Max-Forwards header header structures sip_max_forwards_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

   max_forwards = sip_max_forwards_dup(home, sip->sip_max_forwards);

Returns:

A pointer to the newly duplicated sip_max_forwards_t header structure, or NULL upon an error.

sip_max_forwards_t * sip_max_forwards_format	(	su_home_t *	home,
		char const *	fmt,
			...
	)			[inline]

Make a Max-Forwards header from formatting result.

Make a new sip_max_forwards_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_max_forwards_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_max_forwards_t* sip_max_forwards_init

(

sip_max_forwards_t

x[1]

)

[inline]

Initialize a structure sip_max_forwards_t.

An sip_max_forwards_t structure for Max-Forwards header can be initialized with the sip_max_forwards_init() function/macro. For instance,

  sip_max_forwards_t sip_max_forwards;

  sip_max_forwards_init(&sip_max_forwards);

sip_max_forwards_t * sip_max_forwards_make	(	su_home_t *	home,
		char const *	s
	)			[inline]

Make a Max-Forwards header structure sip_max_forwards_t.

The function sip_max_forwards_make() makes a new sip_max_forwards_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_max_forwards_t header structure, or NULL upon an error.

---

Variable Documentation

msg_hclass_t sip_max_forwards_class[]

Header class for Max-Forwards header.

The header class sip_max_forwards_class defines how a SIP Max-Forwards header is parsed and printed. It also contains methods used by SIP parser and other functions to manipulate the sip_max_forwards_t header structure.