/* Find public key in DNS
 * Copyright (C) 2000-2002  D. Hugh Redelmeier.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program 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 General Public License
 * for more details.
 */

#ifndef _DNSKEY_H_

#include <resolv.h>
#include "adns.h"       /* needs <resolv.h> */

extern int
	adns_qfd,                       /* file descriptor for sending queries to adns */
	adns_afd;                       /* file descriptor for receiving answers from adns */
extern const char *pluto_adns_option;   /* path from --pluto_adns */

extern bool adns_reapchild(pid_t pid, int status);
extern void init_adns(void);
extern void stop_adns(void);
extern void handle_adns_answer(void);

extern bool unsent_ADNS_queries;
extern void send_unsent_ADNS_queries(void);

/* The asynchronouse DNS continuation structure
 *
 * Pluto is an event-driven transaction system.
 * Each transaction must take a very small slice of time.
 * Those that cannot, must be broken into multiple
 * transactions and the state carried between them
 * cannot be on the stack or in simple global variables.
 * A continuation is used to hold such state.
 *
 * NOTE: this struct is the used in an twisted way to implement
 * something like specialization in object-oriented languages.
 *
 * In particular, struct adns_continuation appears as the first field
 * several other structs.  Thus a pointer to one of those structs is
 * also a pointer to a struct adns_continuation
 * (of course the types must be finessed).
 *
 * The routines that appear to deal with struct adns_continuation
 * objects are in fact dealing generically with either of those
 * two specializations of it.
 *
 * (common prefix of) stuff remembered between async DNS query and answer.
 * Filled in by start_adns_query.
 * Freed by call to release_adns_continuation.
 */

struct adns_continuation;       /* forward declaration (not far!) */

typedef void (*cont_fn_t)(struct adns_continuation *cr, err_t ugh);

struct adns_continuation {
	unsigned long qtid;                     /* query transaction id number */
	int type;                               /* T_TXT or T_KEY, selecting rr type of interest */
	cont_fn_t cont_fn;                      /* function to carry on suspended work */
	struct id id;                           /* subject of query */
	bool sgw_specified;
	struct id sgw_id;                       /* peer, if constrained */
	lset_t debugging;
	struct gw_info *gateways_from_dns;      /* answer, if looking for our TXT rrs */
#ifdef USE_KEYRR
	struct pubkey_list *keys_from_dns;      /* answer, if looking for KEY rrs */
#endif
	struct adns_continuation *previous, *next;
	struct pubkey *last_info; /* the last structure we accumulated */
	struct adns_query query;
};

extern err_t start_adns_query(const struct id *id,      /* domain to query */
			      const struct id *sgw_id,  /* if non-null, any accepted gw_info must match */
			      int type,                 /* T_TXT or T_KEY, selecting rr type of interest */
			      cont_fn_t cont_fn,        /* continuation function */
			      struct adns_continuation *cr);

/* Gateway info gleaned from reverse DNS of client */
struct gw_info {
	unsigned refcnt;        /* reference counted! */
	unsigned pref;          /* preference: lower is better */
	struct id client_id;    /* id of client of peer */
	struct id gw_id;        /* id of peer (if id_is_ipaddr, .ip_addr is address) */
	bool gw_key_present;
	struct pubkey *key;
	struct gw_info *next;
};

extern void gw_addref(struct gw_info *gw),
gw_delref(struct gw_info **gwp);

extern void reset_adns_restart_count(void);

#define _DNSKEY_H_
#endif /* _DNSKEY_H_ */