/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

#pragma once

/*! \file */

#include <stdbool.h>

#include <isc/buffer.h>
#include <isc/netaddr.h>
#include <isc/types.h>

#include <dns/rdataset.h>
#include <dns/resolver.h>
#include <dns/rpz.h>
#include <dns/types.h>

#include <ns/types.h>

/*% nameserver database version structure */
typedef struct ns_dbversion {
	dns_db_t	*db;
	dns_dbversion_t *version;
	bool		 acl_checked;
	bool		 queryok;
	ISC_LINK(struct ns_dbversion) link;
} ns_dbversion_t;

/*%
 * recursion type; various features can initiate recursion and this enum value
 * allows common code paths to differentiate between them
 */
typedef enum {
	RECTYPE_NORMAL,
	RECTYPE_PREFETCH,
	RECTYPE_RPZ,
	RECTYPE_STALE_REFRESH,
	RECTYPE_HOOK,
	RECTYPE_COUNT,
} ns_query_rectype_t;

/*%
 * Helper macros for accessing isc_nmhandle_t pointers for a specific recursion
 * a given client is associated with.
 */
#define HANDLE_RECTYPE_NORMAL(client) \
	((client)->query.recursions[RECTYPE_NORMAL].handle)
#define HANDLE_RECTYPE_PREFETCH(client) \
	((client)->query.recursions[RECTYPE_PREFETCH].handle)
#define HANDLE_RECTYPE_RPZ(client) \
	((client)->query.recursions[RECTYPE_RPZ].handle)
#define HANDLE_RECTYPE_STALE_REFRESH(client) \
	((client)->query.recursions[RECTYPE_STALE_REFRESH].handle)
#define HANDLE_RECTYPE_HOOK(client) \
	((client)->query.recursions[RECTYPE_HOOK].handle)

/*%
 * Helper macros for accessing dns_fetch_t pointers for a specific recursion a
 * given client is associated with.
 */
#define FETCH_RECTYPE_NORMAL(client) \
	((client)->query.recursions[RECTYPE_NORMAL].fetch)
#define FETCH_RECTYPE_PREFETCH(client) \
	((client)->query.recursions[RECTYPE_PREFETCH].fetch)
#define FETCH_RECTYPE_RPZ(client) \
	((client)->query.recursions[RECTYPE_RPZ].fetch)
#define FETCH_RECTYPE_STALE_REFRESH(client) \
	((client)->query.recursions[RECTYPE_STALE_REFRESH].fetch)
#define FETCH_RECTYPE_HOOK(client) \
	((client)->query.recursions[RECTYPE_HOOK].fetch)

/*%
 * nameserver recursion parameters, to uniquely identify a recursion
 * query; this is used to detect a recursion loop
 */
typedef struct ns_query_recparam {
	dns_rdatatype_t qtype;
	dns_name_t     *qname;
	dns_fixedname_t fqname;
	dns_name_t     *qdomain;
	dns_fixedname_t fqdomain;
} ns_query_recparam_t;

/*% nameserver query structure */
struct ns_query {
	unsigned int	 attributes;
	unsigned int	 restarts;
	bool		 timerset;
	dns_name_t	*qname;
	dns_name_t	*origqname;
	dns_rdatatype_t	 qtype;
	unsigned int	 dboptions;
	unsigned int	 fetchoptions;
	dns_db_t	*gluedb;
	dns_db_t	*authdb;
	dns_zone_t	*authzone;
	bool		 authdbset;
	bool		 isreferral;
	isc_mutex_t	 fetchlock;
	ns_hookasync_t	*hookactx;
	dns_rpz_st_t	*rpz_st;
	isc_bufferlist_t namebufs;
	ISC_LIST(ns_dbversion_t) activeversions;
	ISC_LIST(ns_dbversion_t) freeversions;
	dns_rdataset_t *dns64_aaaa;
	dns_rdataset_t *dns64_sigaaaa;
	bool	       *dns64_aaaaok;
	unsigned int	dns64_aaaaoklen;
	unsigned int	dns64_options;
	unsigned int	dns64_ttl;

	struct {
		dns_db_t       *db;
		dns_zone_t     *zone;
		dns_dbnode_t   *node;
		dns_rdatatype_t qtype;
		dns_name_t     *fname;
		dns_fixedname_t fixed;
		isc_result_t	result;
		dns_rdataset_t *rdataset;
		dns_rdataset_t *sigrdataset;
		bool		authoritative;
		bool		is_zone;
	} redirect;

	struct {
		isc_nmhandle_t *handle;
		dns_fetch_t    *fetch;
	} recursions[RECTYPE_COUNT];

	ns_query_recparam_t recparam;

	dns_keytag_t root_key_sentinel_keyid;
	bool	     root_key_sentinel_is_ta;
	bool	     root_key_sentinel_not_ta;
};

#define NS_QUERYATTR_RECURSIONOK     0x000001
#define NS_QUERYATTR_CACHEOK	     0x000002
#define NS_QUERYATTR_PARTIALANSWER   0x000004
#define NS_QUERYATTR_NAMEBUFUSED     0x000008
#define NS_QUERYATTR_RECURSING	     0x000010
#define NS_QUERYATTR_QUERYOKVALID    0x000040
#define NS_QUERYATTR_QUERYOK	     0x000080
#define NS_QUERYATTR_WANTRECURSION   0x000100
#define NS_QUERYATTR_SECURE	     0x000200
#define NS_QUERYATTR_NOAUTHORITY     0x000400
#define NS_QUERYATTR_NOADDITIONAL    0x000800
#define NS_QUERYATTR_CACHEACLOKVALID 0x001000
#define NS_QUERYATTR_CACHEACLOK	     0x002000
#define NS_QUERYATTR_DNS64	     0x004000
#define NS_QUERYATTR_DNS64EXCLUDE    0x008000
#define NS_QUERYATTR_RRL_CHECKED     0x010000
#define NS_QUERYATTR_REDIRECT	     0x020000
#define NS_QUERYATTR_ANSWERED	     0x040000
#define NS_QUERYATTR_STALEOK	     0x080000

typedef struct query_ctx query_ctx_t;

/* query context structure */
struct query_ctx {
	isc_buffer_t *dbuf;	     /* name buffer */
	dns_name_t   *fname;	     /* found name from DB lookup */
	dns_name_t   *tname;	     /* temporary name, used
				      * when processing ANY
				      * queries */
	dns_rdataset_t *rdataset;    /* found rdataset */
	dns_rdataset_t *sigrdataset; /* found sigrdataset */
	dns_rdataset_t *noqname;     /* rdataset needing
				      * NOQNAME proof */
	dns_rdatatype_t qtype;
	dns_rdatatype_t type;

	unsigned int options; /* DB lookup options */

	bool redirected; /* nxdomain redirected? */
	bool is_zone;	 /* is DB a zone DB? */
	bool is_staticstub_zone;
	bool resuming; /* resumed from recursion? */
	bool dns64, dns64_exclude, rpz;
	bool authoritative;		    /* authoritative query? */
	bool want_restart;		    /* CNAME chain or other
					     * restart needed */
	bool		refresh_rrset;	    /* stale RRset refresh needed */
	bool		need_wildcardproof; /* wildcard proof needed */
	bool		nxrewrite;	    /* negative answer from RPZ */
	bool		findcoveringnsec;   /* lookup covering NSEC */
	bool		answer_has_ns;	    /* NS is in answer */
	dns_fixedname_t wildcardname;	    /* name needing wcard proof */
	dns_fixedname_t dsname;		    /* name needing DS */

	ns_client_t *client;	    /* client object */
	bool	     detach_client; /* client needs detaching */

	dns_fetchresponse_t *fresp; /* recursion response */

	dns_db_t	*db;	  /* zone or cache database */
	dns_dbversion_t *version; /* DB version */
	dns_dbnode_t	*node;	  /* DB node */

	dns_db_t	*zdb;	 /* zone DB values, saved */
	dns_dbnode_t	*znode;	 /* while searching cache */
	dns_name_t	*zfname; /* for a better answer */
	dns_dbversion_t *zversion;
	dns_rdataset_t	*zrdataset;
	dns_rdataset_t	*zsigrdataset;

	dns_rpz_st_t *rpz_st; /* RPZ state */
	dns_zone_t   *zone;   /* zone to search */

	dns_view_t *view; /* client view */

	isc_result_t result; /* query result */
	int	     line;   /* line to report error */
};

typedef isc_result_t (*ns_query_starthookasync_t)(query_ctx_t *qctx,
						  isc_mem_t *mctx, void *arg,
						  isc_loop_t *loop,
						  isc_job_cb cb, void *evarg,
						  ns_hookasync_t **ctxp);

/*
 * The following functions are expected to be used only within query.c
 * and query modules.
 */

isc_result_t
ns_query_done(query_ctx_t *qctx);
/*%<
 * Finalize this phase of the query process:
 *
 * - Clean up.
 * - If we have an answer ready (positive or negative), send it.
 * - If we need to restart for a chaining query, call ns__query_start() again.
 * - If we've started recursion, then just clean up; things will be
 *   restarted via fetch_callback()/query_resume().
 */

isc_result_t
ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
		 dns_name_t *qdomain, dns_rdataset_t *nameservers,
		 bool resuming);
/*%<
 * Prepare client for recursion, then create a resolver fetch, with
 * the event callback set to fetch_callback(). Afterward we terminate
 * this phase of the query, and resume with a new query context when
 * recursion completes.
 */

isc_result_t
ns_query_hookasync(query_ctx_t *qctx, ns_query_starthookasync_t runasync,
		   void *arg);
/*%<
 * Prepare the client for an asynchronous hook action, then call the
 * specified 'runasync' function to start an asynchronous process running
 * in the background.  This function works similarly to ns_query_recurse(),
 * but is expected to be called from a query hook action to support
 * asynchronous event handling in a hook. A typical use case would be for
 * a plugin to initiate recursion, but it may also be used to carry out
 * other time-consuming tasks without blocking the caller or the worker
 * thread.
 *
 * The calling plugin action must pass 'qctx' as passed from the query
 * module.
 *
 * Once a plugin action calls this function, the ownership of 'qctx' is
 * essentially transferred to the query module. Regardless of the return
 * value of this function, the hook must not use 'qctx' anymore.
 *
 * This function must not be called after ns_query_recurse() is called,
 * until the fetch is completed, as it needs resources that
 * ns_query_recurse() would also use.
 *
 * See hooks.h for details about how 'runasync' is supposed to work, and
 * other aspects of hook-triggered asynchronous event handling.
 */

void
ns_query_init(ns_client_t *client);

void
ns_query_free(ns_client_t *client);

void
ns_query_start(ns_client_t *client, isc_nmhandle_t *handle);

void
ns_query_cancel(ns_client_t *client);

/*
 * The following functions are expected to be used only within query.c
 * and query modules.
 */

isc_result_t
ns__query_sfcache(query_ctx_t *qctx);
/*%<
 * (Must not be used outside this module and its associated unit tests.)
 */

isc_result_t
ns__query_start(query_ctx_t *qctx);
/*%<
 * (Must not be used outside this module and its associated unit tests.)
 */
