adns.h

100 病毒源碼,原始碼,無毒 ......

 *  adns_init
 *  adns_submit 1
 *  adns_submit 2
 *  adns_submit 3
 *  adns_wait 1
 *  adns_check 3 -> EAGAIN
 *  adns_wait 2
 *  adns_wait 3
 *  ....
 *  adns_finish
 */

/*
 * Entrypoints for generic asynch io:
 * (these entrypoints are not very useful except in combination with *
 * some of the other I/O model calls which can tell you which fds to
 * be interested in):
 *
 * Note that any adns call may cause adns to open and close fds, so
 * you must call beforeselect or beforepoll again just before
 * blocking, or you may not have an up-to-date list of it's fds.
 */

int adns_processany(adns_state ads);
/* Gives adns flow-of-control for a bit.  This will never block, and
 * can be used with any threading/asynch-io model.  If some error
 * occurred which might cause an event loop to spin then the errno
 * value is returned.
 */

int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
/* Gives adns flow-of-control so that it can process incoming data
 * from, or send outgoing data via, fd.  Very like _processany.  If it
 * returns zero then fd will no longer be readable or writeable
 * (unless of course more data has arrived since).  adns will _only_
 * use that fd and only in the manner specified, regardless of whether
 * adns_if_noautosys was specified.
 *
 * adns_processexceptional should be called when select(2) reports an
 * exceptional condition, or poll(2) reports POLLPRI.
 *
 * It is fine to call _processreabable or _processwriteable when the
 * fd is not ready, or with an fd that doesn't belong to adns; it will
 * then just return 0.
 *
 * If some error occurred which might prevent an event loop to spin
 * then the errno value is returned.
 */

void adns_processtimeouts(adns_state ads, const struct timeval *now);
/* Gives adns flow-of-control so that it can process any timeouts
 * which might have happened.  Very like _processreadable/writeable.
 *
 * now may be 0; if it isn't, *now must be the current time, recently
 * obtained from gettimeofday.
 */

void adns_firsttimeout(adns_state ads,
		       struct timeval **tv_mod, struct timeval *tv_buf,
		       struct timeval now);
/* Asks adns when it would first like the opportunity to time
 * something out.  now must be the current time, from gettimeofday.
 * 
 * If tv_mod points to 0 then tv_buf must be non-null, and
 * _firsttimeout will fill in *tv_buf with the time until the first
 * timeout, and make *tv_mod point to tv_buf.  If adns doesn't have
 * anything that might need timing out it will leave *tv_mod as 0.
 *
 * If *tv_mod is not 0 then tv_buf is not used.  adns will update
 * *tv_mod if it has any earlier timeout, and leave it alone if it
 * doesn't.
 *
 * This call will not actually do any I/O, or change the fds that adns
 * is using.  It always succeeds and never blocks.
 */

void adns_globalsystemfailure(adns_state ads);
/* If serious problem(s) happen which globally affect your ability to
 * interact properly with adns, or adns's ability to function
 * properly, you or adns can call this function.
 *
 * All currently outstanding queries will be made to fail with
 * adns_s_systemfail, and adns will close any stream sockets it has
 * open.
 *
 * This is used by adns, for example, if gettimeofday() fails.
 * Without this the program's event loop might start to spin !
 *
 * This call will never block.
 */

/*
 * Entrypoints for select-loop based asynch io:
 */

void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
		       fd_set *writefds, fd_set *exceptfds,
		       struct timeval **tv_mod, struct timeval *tv_buf,
		       const struct timeval *now);
/* Find out file descriptors adns is interested in, and when it would
 * like the opportunity to time something out.  If you do not plan to
 * block then tv_mod may be 0.  Otherwise, tv_mod and tv_buf are as
 * for adns_firsttimeout.  readfds, writefds, exceptfds and maxfd_io may
 * not be 0.
 *
 * If now is not 0 then this will never actually do any I/O, or change
 * the fds that adns is using or the timeouts it wants.  In any case
 * it won't block, and it will set the timeout to zero if a query
 * finishes in _beforeselect.
 */

void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
		      const fd_set *writefds, const fd_set *exceptfds,
		      const struct timeval *now);
/* Gives adns flow-of-control for a bit; intended for use after
 * select.  This is just a fancy way of calling adns_processreadable/
 * writeable/timeouts as appropriate, as if select had returned the
 * data being passed.  Always succeeds.
 */

/*
 * Example calling sequence:
 *
 *  adns_init _noautosys
 *  loop {
 *   adns_beforeselect
 *   select
 *   adns_afterselect
 *   ...
 *   adns_submit / adns_check
 *   ...
 *  }
 */

/*
 * Entrypoints for poll-loop based asynch io:
 */

struct pollfd;
/* In case your system doesn't have it or you forgot to include
 * <sys/poll.h>, to stop the following declarations from causing
 * problems.  If your system doesn't have poll then the following
 * entrypoints will not be defined in libadns.  Sorry !
 */

int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io,
		    const struct timeval *now);
/* Finds out which fd's adns is interested in, and when it would like
 * to be able to time things out.  This is in a form suitable for use
 * with poll(2).
 * 
 * On entry, usually fds should point to at least *nfds_io structs.
 * adns will fill up to that many structs will information for poll,
 * and record in *nfds_io how many structs it filled.  If it wants to
 * listen for more structs then *nfds_io will be set to the number
 * required and _beforepoll will return ERANGE.
 *
 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
 * adns will fill in the number of fds that it might be interested in
 * in *nfds_io, and always return either 0 (if it is not interested in
 * any fds) or ERANGE (if it is).
 *
 * NOTE that (unless now is 0) adns may acquire additional fds
 * from one call to the next, so you must put adns_beforepoll in a
 * loop, rather than assuming that the second call (with the buffer
 * size requested by the first) will not return ERANGE.
 *
 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
 * structs, and only ever looks at those bits.  POLLPRI is required to
 * detect TCP Urgent Data (which should not be used by a DNS server)
 * so that adns can know that the TCP stream is now useless.
 *
 * In any case, *timeout_io should be a timeout value as for poll(2),
 * which adns will modify downwards as required.  If the caller does
 * not plan to block then *timeout_io should be 0 on entry, or
 * alternatively, timeout_io may be 0.  (Alternatively, the caller may
 * use _beforeselect with timeout_io==0 to find out about file
 * descriptors, and use _firsttimeout is used to find out when adns
 * might want to time something out.)
 *
 * adns_beforepoll will return 0 on success, and will not fail for any
 * reason other than the fds buffer being too small (ERANGE).
 *
 * This call will never actually do any I/O.  If you supply the
 * current time it will not change the fds that adns is using or the
 * timeouts it wants.
 *
 * In any case this call won't block.
 */

#define ADNS_POLLFDS_RECOMMENDED 2
/* If you allocate an fds buf with at least RECOMMENDED entries then
 * you are unlikely to need to enlarge it.  You are recommended to do
 * so if it's convenient.  However, you must be prepared for adns to
 * require more space than this.
 */

void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
		    const struct timeval *now);
/* Gives adns flow-of-control for a bit; intended for use after
 * poll(2).  fds and nfds should be the results from poll().  pollfd
 * structs mentioning fds not belonging to adns will be ignored.
 */


adns_status adns_rr_info(adns_rrtype type,
			 const char **rrtname_r, const char **fmtname_r,
			 int *len_r,
			 const void *datap, char **data_r);
/*
 * Get information about a query type, or convert reply data to a
 * textual form.  type must be specified, and the official name of the
 * corresponding RR type will be returned in *rrtname_r, and
 * information about the processing style in *fmtname_r.  The length
 * of the table entry in an answer for that type will be returned in
 * in *len_r.  Any or all of rrtname_r, fmtname_r and len_r may be 0.
 * If fmtname_r is non-null then *fmtname_r may be null on return,
 * indicating that no special processing is involved.
 *
 * data_r be must be non-null iff datap is.  In this case *data_r will
 * be set to point to a string pointing to a representation of the RR
 * data in master file format.  (The owner name, timeout, class and
 * type will not be present - only the data part of the RR.)  The
 * memory will have been obtained from malloc() and must be freed by
 * the caller.
 *
 * Usually this routine will succeed.  Possible errors include:
 *  adns_s_nomemory
 *  adns_s_rrtypeunknown
 *  adns_s_invaliddata (*datap contained garbage)
 * If an error occurs then no memory has been allocated,
 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
 *
 * There are some adns-invented data formats which are not official
 * master file formats.  These include:
 *
 * Mailboxes if __qtf_mail822: these are just included as-is.
 *
 * Addresses (adns_rr_addr): these may be of pretty much any type.
 * The representation is in two parts: first, a word for the address
 * family (ie, in AF_XXX, the XXX), and then one or more items for the
 * address itself, depending on the format.  For an IPv4 address the
 * syntax is INET followed by the dotted quad (from inet_ntoa).
 * Currently only IPv4 is supported.
 *
 * Text strings (as in adns_rr_txt) appear inside double quotes, and
 * use \" and \\ to represent " and \, and \xHH to represent
 * characters not in the range 32-126.
 *
 * Hostname with addresses (adns_rr_hostaddr): this consists of the
 * hostname, as usual, followed by the adns_status value, as an
 * abbreviation, and then a descriptive string (encoded as if it were
 * a piece of text), for the address lookup, followed by zero or more
 * addresses enclosed in ( and ).  If the result was a temporary
 * failure, then a single ?  appears instead of the ( ).  If the
 * result was a permanent failure then an empty pair of parentheses
 * appears (which a space in between).  For example, one of the NS
 * records for greenend.org.uk comes out like
 *  ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
 * an MX referring to a nonexistent host might come out like:
 *  50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
 * and if nameserver information is not available you might get:
 *  dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
 */

const char *adns_strerror(adns_status st);
const char *adns_errabbrev(adns_status st);
const char *adns_errtypeabbrev(adns_status st);
/* Like strerror but for adns_status values.  adns_errabbrev returns
 * the abbreviation of the error - eg, for adns_s_timeout it returns
 * "timeout".  adns_errtypeabbrev returns the abbreviation of the
 * error class: ie, for values up to adns_s_max_XXX it will return the
 * string XXX.  You MUST NOT call these functions with status values
 * not returned by the same adns library.
 */

#ifdef __cplusplus
} /* end of extern "C" */
#endif
#endif