/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

#ifndef foosddnshfoo
#define foosddnshfoo

/***
  This file is part of systemd.

  Copyright 2005-2008 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include "_sd-common.h"

_SD_BEGIN_DECLARATIONS;

/** \mainpage
 *
 * \section moo Method of operation
 *
 * To use libasyncns allocate an asyncns_t object with
 * asyncns_new(). This will spawn a number of worker threads (or processes, depending on what is available) which
 * are subsequently used to process the queries the controlling
 * program issues via asyncns_getaddrinfo() and
 * asyncns_getnameinfo(). Use asyncns_free() to shut down the worker
 * threads/processes.
 *
 * Since libasyncns may fork off new processes you have to make sure that
 * your program is not irritated by spurious SIGCHLD signals.
 */

/** An opaque libasyncns session structure */
typedef struct asyncns asyncns_t;

/** An opaque libasyncns query structure */
typedef struct asyncns_query asyncns_query_t;

/** Allocate a new libasyncns session with n_proc worker processes/threads */
asyncns_t* asyncns_new(unsigned n_proc);

/** Free a libasyncns session. This destroys all attached
 * asyncns_query_t objects automatically */
void asyncns_free(asyncns_t *asyncns);

/** Return the UNIX file descriptor to select() for readability
 * on. Use this function to integrate libasyncns with your custom main
 * loop. */
int asyncns_fd(asyncns_t *asyncns);

/** Process pending responses. After this function is called you can
 * get the next completed query object(s) using asyncns_getnext(). If
 * block is non-zero wait until at least one response has been
 * processed. If block is zero, process all pending responses and
 * return. */
int asyncns_wait(asyncns_t *asyncns, int block);

/** Issue a name to address query on the specified session. The
 * arguments are compatible with the ones of libc's
 * getaddrinfo(3). The function returns a new query object. When the
 * query is completed you may retrieve the results using
 * asyncns_getaddrinfo_done().*/
asyncns_query_t* asyncns_getaddrinfo(asyncns_t *asyncns, const char *node, const char *service, const struct addrinfo *hints);

/** Retrieve the results of a preceding asyncns_getaddrinfo()
 * call. Returns a addrinfo structure and a return value compatible
 * with libc's getaddrinfo(3). The query object q is destroyed by this
 * call and may not be used any further. Make sure to free the
 * returned addrinfo structure with asyncns_freeaddrinfo() and not
 * libc's freeaddrinfo(3)! If the query is not completed yet EAI_AGAIN
 * is returned.*/
int asyncns_getaddrinfo_done(asyncns_t *asyncns, asyncns_query_t* q, struct addrinfo **ret_res);

/** Issue an address to name query on the specified session. The
 * arguments are compatible with the ones of libc's
 * getnameinfo(3). The function returns a new query object. When the
 * query is completed you may retrieve the results using
 * asyncns_getnameinfo_done(). Set gethost (resp. getserv) to non-zero
 * if you want to query the hostname (resp. the service name). */
asyncns_query_t* asyncns_getnameinfo(asyncns_t *asyncns, const struct sockaddr *sa, socklen_t salen, int flags, int gethost, int getserv);

/** Retrieve the results of a preceding asyncns_getnameinfo()
 * call. Returns the hostname and the service name in ret_host and
 * ret_serv. The query object q is destroyed by this call and may not
 * be used any further. If the query is not completed yet EAI_AGAIN is
 * returned. */
int asyncns_getnameinfo_done(asyncns_t *asyncns, asyncns_query_t* q, char *ret_host, size_t hostlen, char *ret_serv, size_t servlen);

/** Issue a resolver query on the specified session. The arguments are
 * compatible with the ones of libc's res_query(3). The function returns a new
 * query object. When the query is completed you may retrieve the results using
 * asyncns_res_done().  */
asyncns_query_t* asyncns_res_query(asyncns_t *asyncns, const char *dname, int class, int type);

/** Issue an resolver query on the specified session. The arguments are
 * compatible with the ones of libc's res_search(3). The function returns a new
 * query object. When the query is completed you may retrieve the results using
 * asyncns_res_done().  */
asyncns_query_t* asyncns_res_search(asyncns_t *asyncns, const char *dname, int class, int type);

/** Retrieve the results of a preceding asyncns_res_query() or
 * asyncns_res_search call.  The query object q is destroyed by this
 * call and may not be used any further. Returns a pointer to the
 * answer of the res_query call. If the query is not completed yet
 * -EAGAIN is returned, on failure -errno is returned, otherwise the
 * length of answer is returned. Make sure to free the answer is a
 * call to asyncns_freeanswer(). */
int asyncns_res_done(asyncns_t *asyncns, asyncns_query_t* q, unsigned char **answer);

/** Return the next completed query object. If no query has been
 * completed yet, return NULL. Please note that you need to run
 * asyncns_wait() before this function will return sensible data.  */
asyncns_query_t* asyncns_getnext(asyncns_t *asyncns);

/** Return the number of query objects (completed or not) attached to
 * this session */
int asyncns_getnqueries(asyncns_t *asyncns);

/** Cancel a currently running query. q is is destroyed by this call
 * and may not be used any futher. */
void asyncns_cancel(asyncns_t *asyncns, asyncns_query_t* q);

/** Free the addrinfo structure as returned by
 * asyncns_getaddrinfo_done(). Make sure to use this functions instead
 * of the libc's freeaddrinfo()! */
void asyncns_freeaddrinfo(struct addrinfo *ai);

/** Free the answer data as returned by asyncns_res_done().*/
void asyncns_freeanswer(unsigned char *answer);

/** Returns non-zero when the query operation specified by q has been completed */
int asyncns_isdone(asyncns_t *asyncns, asyncns_query_t*q);

/** Assign some opaque userdata with a query object */
void asyncns_setuserdata(asyncns_t *asyncns, asyncns_query_t *q, void *userdata);

/** Return userdata assigned to a query object. Use
 * asyncns_setuserdata() to set this data. If no data has been set
 * prior to this call it returns NULL. */
void* asyncns_getuserdata(asyncns_t *asyncns, asyncns_query_t *q);

_SD_END_DECLARATIONS;

#endif