* @{ */SIP_DLL extern msg_hclass_t sip_X_class[];enum {  /** Hash of X. @internal */ sip_X_hash = hash };/** Parse a X. @internal */msg_parse_f sip_X_d;/** Print a X. @internal */msg_print_f sip_X_e;/**Initializer for structure sip_X_t. *  * A static sip_X_t structure must be initialized * with the SIP_X_INIT() macro. For instance, * @code  *  *  sip_X_t sip_X = SIP_X_INIT; *  * @endcode * @HI */#define SIP_X_INIT() SIP_HDR_INIT(X)/**Initialize a structure sip_X_t. *  * An sip_X_t structure can be initialized with the * sip_X_init() function/macro. For instance, * @code *  *  sip_X_t sip_X; *  *  sip_X_init(&sip_X); *  * @endcode * @HI */#if SU_HAVE_INLINEsu_inline sip_X_t *sip_X_init(sip_X_t x[1]){  return SIP_HEADER_INIT(x, sip_X_class, sizeof(sip_X_t));}#else#define sip_X_init(x) \  SIP_HEADER_INIT(x, sip_X_class, sizeof(sip_X_t))#endif/**Test if header object is instance of sip_X_t. *  * The function sip_is_X() returns true (nonzero) if * the header class is an instance of X * object and false (zero) otherwise. *  * @param header pointer to the header structure to be tested *  * @return * The function sip_is_X() returns true (nonzero) if * the header object is an instance of header X and * false (zero) otherwise. */#if SU_HAVE_INLINEsu_inline int sip_is_X(sip_header_t const *header){  return header && header->sh_class->hc_id == sip_hdr_X;}#elseint sip_is_X(sip_header_t const *header);#endif#define sip_X_p(h) sip_is_X((h))/**Duplicate (deep copy) @c sip_X_t. *  * The function sip_X_dup() duplicates a header * structure @a hdr.  If the header structure @a hdr * contains a reference (@c hdr->x_next) to a list of * headers, all the headers in the list are duplicated, too. *  * @param home  memory home used to allocate new structure * @param 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 @a home to allocate all the * memory areas used to copy the header. *  * @par Example * @code *  *   X = sip_X_dup(home, sip->sip_X); *  * @endcode *  * @return * The function sip_X_dup() returns a pointer to the * newly duplicated sip_X_t header structure, or NULL * upon an error. */sip_X_t *sip_X_dup(su_home_t *home, sip_X_t const *hdr);/**Copy a sip_X_t header structure. *  * The function sip_X_copy() copies a header structure @a * hdr.  If the header structure @a hdr contains a reference (@c * hdr->h_next) to a list of headers, all the headers in that * list are copied, too. The function uses given memory @a home * to allocate all the memory areas used to copy the header * structure @a hdr. *  * @param home    memory home used to allocate new structure * @param hdr     pointer to the header structure to be duplicated *  * 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 @a * header, including the encoding of the old header, if present. *  * @par Example * @code *  *   X = sip_X_copy(home, sip->sip_X); *  * @endcode *  * @return * The function sip_X_copy() returns a pointer to * newly copied header structure, or NULL upon an error. */sip_X_t *sip_X_copy(su_home_t *home, 				  sip_X_t const *hdr);/**Make a header structure sip_X_t. *  * The function sip_X_make() makes a new * sip_X_t header structure.  It allocates a new * header structure, and decodes the string @a s as the * value of the structure. *  * @param home memory home used to allocate new header structure. * @param s    string to be decoded as value of the new header structure *  * @note This function is usually implemented as a macro calling * sip_header_make(). *  * @return * The function sip_X_make() returns a pointer to * newly maked sip_X_t header structure, or NULL upon * an error. */#if SU_HAVE_INLINEsu_inline sip_X_t *sip_X_make(su_home_t *home, char const *s){  return sip_header_make(home, sip_X_class, s)->sh_X;}#elsesip_X_t *sip_X_make(su_home_t *home, char const *s);#endif/**Make a X from formatting result. *  * The function sip_X_format() makes a new * X object using formatting result as its * value.  The function first prints the arguments according to * the format @a fmt specified.  Then it allocates a new header * structure, and uses the formatting result as the header * value. *  * @param home   memory home used to allocate new header structure. * @param fmt    string used as a printf()-style format * @param ...    argument list for format *  * @note This function is usually implemented as a macro calling * msg_header_format(). *  * @return * The function sip_X_format() returns a pointer to newly * makes header structure, or NULL upon an error. *  * @HIDE */#if SU_HAVE_INLINEsu_inline#endifsip_X_t *sip_X_format(su_home_t *home, char const *fmt, ...)     __attribute__((format (printf, 2, 3)));#if SU_HAVE_INLINEsu_inline sip_X_t *sip_X_format(su_home_t *home, char const *fmt, ...){  sip_header_t *h;  va_list ap;    va_start(ap, fmt);  h = sip_header_vformat(home, sip_X_class, fmt, ap);  va_end(ap);   return h->sh_X;}#endif/**Decode a header X. * * The function sip_X_d() decodes value of the header X in the preallocated * header structure @a h.  The string @a s to be decoded should not contain * the header name or colon. The decoding function also expects that the * leading and trailing whitespace has been removed from the string @a s. * * @param home   memory home used to allocate new header structure. * @param h      sip_X_t header structure  * @param s      string to be decoded * @param bsiz   length of string @a s * * @return * The function sip_X_d() returns non-negative value when successful, or * -1 upon an error. */int sip_X_d(su_home_t *home, sip_header_t *h, char *s, int bsiz);/**Encode a header X. * * The function sip_X_e() encodes a header structure @a h to the given * buffer @a buf.  Even if the given buffer @a buf is NULL or its size @a * bufsiz is too small to fit the encoding result, the function returns the * number of characters required for the encoding. * * @param buf    buffer to store the encoding result * @param bsiz   size of the encoding buffer * @param h      header to be encoded. * @param flags  flags controlling the encoding *  * @note  * The encoding buffer size @b must be @b bigger than, not equal to, * the actual encoding result. * * @return * The function sip_X_e() returns the number of characters required for the * encoding. */int sip_X_e(char buf[], int bsiz, sip_header_t const *h, int flags);/**@}*//**@nodefgroup sip SIP Headers and Messages - "sip" * * SIP headers and messages. *//**@defgroup sip_status_codes SIP Status Codes and Reason Phrases * * The macros and variables for the standard SIP status codes and reason * phrases are defined in <sip_status.h>. *//**@defgroup sip_tag SIP Tags * * SIP headers in tag item lists and tagged argument lists.  * * The include file <sip_tag.h> defines tags and tag items for including SIP * headers in tag item lists or tagged argument lists. For each header, * there is a tag for pointer to header object and an another tag for string * containing header value. For example, @b From header has tags * SIPTAG_FROM() and SIPTAG_FROM_STR(). * * It is also possible to include user-defined headers or non-standard * headers using SIPTAG_HEADER_STR(). * * A function taking SIP headers as arguments could be called like this: * @code * sip_payload_t *payload; * ... * sip_add_tl(msg, sip,  *            SIPTAG_CONTENT_TYPE_STR("text/plain"), *            SIPTAG_USER_AGENT(agent->user_agent), *            SIPTAG_PAYLOAD(payload), *            SIPTAG_HEADER_STR("X-Header: contents\nP-Header: bar"), *            TAG_END()); * ... * @endcode * * In the above fragment, the function sip_add_tl() will add @b Content-Type * and @b User-Agent headers along with message payload to the SIP message. * The @b Content-Type header is made with value "text/plain". * */