/*
 * 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

/* Add -DDNS_RPZ_TRACE=1 to CFLAGS for detailed reference tracing */

#include <inttypes.h>
#include <stdbool.h>

#include <isc/deprecated.h>
#include <isc/event.h>
#include <isc/ht.h>
#include <isc/lang.h>
#include <isc/refcount.h>
#include <isc/rwlock.h>
#include <isc/time.h>
#include <isc/timer.h>

#include <dns/fixedname.h>
#include <dns/rdata.h>
#include <dns/types.h>

ISC_LANG_BEGINDECLS

#define DNS_RPZ_PREFIX "rpz-"
/*
 * Sub-zones of various trigger types.
 */
#define DNS_RPZ_CLIENT_IP_ZONE DNS_RPZ_PREFIX "client-ip"
#define DNS_RPZ_IP_ZONE	       DNS_RPZ_PREFIX "ip"
#define DNS_RPZ_NSIP_ZONE      DNS_RPZ_PREFIX "nsip"
#define DNS_RPZ_NSDNAME_ZONE   DNS_RPZ_PREFIX "nsdname"
/*
 * Special policies.
 */
#define DNS_RPZ_PASSTHRU_NAME DNS_RPZ_PREFIX "passthru"
#define DNS_RPZ_DROP_NAME     DNS_RPZ_PREFIX "drop"
#define DNS_RPZ_TCP_ONLY_NAME DNS_RPZ_PREFIX "tcp-only"

typedef uint8_t dns_rpz_prefix_t;

typedef enum {
	DNS_RPZ_TYPE_BAD,
	DNS_RPZ_TYPE_CLIENT_IP,
	DNS_RPZ_TYPE_QNAME,
	DNS_RPZ_TYPE_IP,
	DNS_RPZ_TYPE_NSDNAME,
	DNS_RPZ_TYPE_NSIP
} dns_rpz_type_t;

/*
 * Require DNS_RPZ_POLICY_PASSTHRU < DNS_RPZ_POLICY_DROP
 * < DNS_RPZ_POLICY_TCP_ONLY DNS_RPZ_POLICY_NXDOMAIN < DNS_RPZ_POLICY_NODATA
 * < DNS_RPZ_POLICY_CNAME to choose among competing policies.
 */
typedef enum {
	DNS_RPZ_POLICY_GIVEN = 0,    /* 'given': what policy record says */
	DNS_RPZ_POLICY_DISABLED = 1, /* log what would have happened */
	DNS_RPZ_POLICY_PASSTHRU = 2, /* 'passthru': do not rewrite */
	DNS_RPZ_POLICY_DROP = 3,     /* 'drop': do not respond */
	DNS_RPZ_POLICY_TCP_ONLY = 4, /* 'tcp-only': answer UDP with TC=1 */
	DNS_RPZ_POLICY_NXDOMAIN = 5, /* 'nxdomain': answer with NXDOMAIN */
	DNS_RPZ_POLICY_NODATA = 6,   /* 'nodata': answer with ANCOUNT=0 */
	DNS_RPZ_POLICY_CNAME = 7,    /* 'cname x': answer with x's rrsets */
	DNS_RPZ_POLICY_DNS64,	     /* Apply DN64 to the A rewrite */
	DNS_RPZ_POLICY_RECORD,
	DNS_RPZ_POLICY_WILDCNAME,
	DNS_RPZ_POLICY_MISS,
	DNS_RPZ_POLICY_ERROR
} dns_rpz_policy_t;

typedef uint8_t dns_rpz_num_t;

#define DNS_RPZ_MAX_ZONES 64
/*
 * Type dns_rpz_zbits_t must be an unsigned int wide enough to contain
 * at least DNS_RPZ_MAX_ZONES bits.
 */
typedef uint64_t dns_rpz_zbits_t;

#define DNS_RPZ_ALL_ZBITS ((dns_rpz_zbits_t)-1)

#define DNS_RPZ_INVALID_NUM DNS_RPZ_MAX_ZONES

#define DNS_RPZ_ZBIT(n) (((dns_rpz_zbits_t)1) << (dns_rpz_num_t)(n))

/*
 * Mask of the specified and higher numbered policy zones
 * Avoid hassles with (1<<33) or (1<<65)
 */
#define DNS_RPZ_ZMASK(n)                                     \
	((dns_rpz_zbits_t)((((n) >= DNS_RPZ_MAX_ZONES - 1)   \
				    ? 0                      \
				    : (1ULL << ((n) + 1))) - \
			   1))

/*
 * The trigger counter type.
 */
typedef size_t dns_rpz_trigger_counter_t;

/*
 * The number of triggers of each type in a response policy zone.
 */
typedef struct dns_rpz_triggers dns_rpz_triggers_t;
struct dns_rpz_triggers {
	dns_rpz_trigger_counter_t client_ipv4;
	dns_rpz_trigger_counter_t client_ipv6;
	dns_rpz_trigger_counter_t qname;
	dns_rpz_trigger_counter_t ipv4;
	dns_rpz_trigger_counter_t ipv6;
	dns_rpz_trigger_counter_t nsdname;
	dns_rpz_trigger_counter_t nsipv4;
	dns_rpz_trigger_counter_t nsipv6;
};

/*
 * A single response policy zone.
 */
typedef struct dns_rpz_zone  dns_rpz_zone_t;
typedef struct dns_rpz_zones dns_rpz_zones_t;

struct dns_rpz_zone {
	unsigned int magic;

	dns_rpz_num_t	 num;	    /* ordinal in list of policy zones */
	dns_name_t	 origin;    /* Policy zone name */
	dns_name_t	 client_ip; /* DNS_RPZ_CLIENT_IP_ZONE.origin. */
	dns_name_t	 ip;	    /* DNS_RPZ_IP_ZONE.origin. */
	dns_name_t	 nsdname;   /* DNS_RPZ_NSDNAME_ZONE.origin */
	dns_name_t	 nsip;	    /* DNS_RPZ_NSIP_ZONE.origin. */
	dns_name_t	 passthru;  /* DNS_RPZ_PASSTHRU_NAME. */
	dns_name_t	 drop;	    /* DNS_RPZ_DROP_NAME. */
	dns_name_t	 tcp_only;  /* DNS_RPZ_TCP_ONLY_NAME. */
	dns_name_t	 cname;	    /* override value for ..._CNAME */
	dns_ttl_t	 max_policy_ttl;
	dns_rpz_policy_t policy; /* DNS_RPZ_POLICY_GIVEN or override */

	uint32_t  min_update_interval;	/* minimal interval between updates */
	isc_ht_t *nodes;		/* entries in zone */
	dns_rpz_zones_t *rpzs;		/* owner */
	isc_time_t	 lastupdated;	/* last time the zone was processed */
	bool		 updatepending; /* there is an update pending */
	bool		 updaterunning; /* there is an update running */
	isc_result_t	 updateresult;	/* result from the offloaded work */
	dns_db_t	*db;		/* zones database */
	dns_dbversion_t *dbversion;	/* version we will be updating to */
	dns_db_t	*updb;		/* zones database we're working on */
	dns_dbversion_t *updbversion;	/* version we're working on */
	bool		 addsoa;	/* add soa to the additional section */
	isc_timer_t	*updatetimer;
	isc_event_t	 updateevent;
};

/*
 * Radix tree node for response policy IP addresses
 */
typedef struct dns_rpz_cidr_node dns_rpz_cidr_node_t;

/*
 * Bitfields indicating which policy zones have policies of
 * which type.
 */
typedef struct dns_rpz_have dns_rpz_have_t;
struct dns_rpz_have {
	dns_rpz_zbits_t client_ipv4;
	dns_rpz_zbits_t client_ipv6;
	dns_rpz_zbits_t client_ip;
	dns_rpz_zbits_t qname;
	dns_rpz_zbits_t ipv4;
	dns_rpz_zbits_t ipv6;
	dns_rpz_zbits_t ip;
	dns_rpz_zbits_t nsdname;
	dns_rpz_zbits_t nsipv4;
	dns_rpz_zbits_t nsipv6;
	dns_rpz_zbits_t nsip;
	dns_rpz_zbits_t qname_skip_recurse;
};

/*
 * Policy options
 */
typedef struct dns_rpz_popt dns_rpz_popt_t;
struct dns_rpz_popt {
	dns_rpz_zbits_t no_rd_ok;
	dns_rpz_zbits_t no_log;
	dns_rpz_zbits_t nsip_on;
	dns_rpz_zbits_t nsdname_on;
	bool		dnsrps_enabled;
	bool		break_dnssec;
	bool		qname_wait_recurse;
	bool		nsip_wait_recurse;
	bool		nsdname_wait_recurse;
	unsigned int	min_ns_labels;
	dns_rpz_num_t	num_zones;
};

/*
 * Response policy zones known to a view.
 */
struct dns_rpz_zones {
	unsigned int	magic;
	isc_refcount_t	references;
	isc_mem_t      *mctx;
	isc_taskmgr_t  *taskmgr;
	isc_timermgr_t *timermgr;
	isc_task_t     *updater;

	dns_rpz_popt_t	   p;
	dns_rpz_zone_t	  *zones[DNS_RPZ_MAX_ZONES];
	dns_rpz_triggers_t triggers[DNS_RPZ_MAX_ZONES];

	/*
	 * RPZ policy version number.
	 * It is initially 0 and it increases whenever the server is
	 * reconfigured with new zones or policy.
	 */
	int rpz_ver;

	dns_rpz_zbits_t defined;

	/*
	 * The set of records for a policy zone are in one of these states:
	 *	never loaded		    load_begun=0  have=0
	 *	during initial loading	    load_begun=1  have=0
	 *				and rbtdb->rpzsp == rbtdb->load_rpzsp
	 *	after good load		    load_begun=1  have!=0
	 *	after failed initial load   load_begun=1  have=0
	 *				and rbtdb->load_rpzsp == NULL
	 *	reloading after failure	    load_begun=1  have=0
	 *	reloading after success
	 *		main rpzs	    load_begun=1  have!=0
	 *		load rpzs	    load_begun=1  have=0
	 */
	dns_rpz_zbits_t load_begun;
	dns_rpz_have_t	have;

	/*
	 * total_triggers maintains the total number of triggers in all
	 * policy zones in the view. It is only used to print summary
	 * statistics after a zone load of how the trigger counts
	 * changed.
	 */
	dns_rpz_triggers_t total_triggers;

	/*
	 * One lock for short term read-only search that guarantees the
	 * consistency of the pointers.
	 * A second lock for maintenance that guarantees no other thread
	 * is adding or deleting nodes.
	 */
	isc_rwlock_t search_lock;
	isc_mutex_t  maint_lock;

	bool shuttingdown;

	dns_rpz_cidr_node_t *cidr;
	dns_rbt_t	    *rbt;

	/*
	 * DNSRPZ librpz configuration string and handle on librpz connection
	 */
	char		     *rps_cstr;
	size_t		      rps_cstr_size;
	struct librpz_client *rps_client;
};

/*
 * context for finding the best policy
 */
typedef struct {
	unsigned int state;
#define DNS_RPZ_REWRITTEN      0x0001
#define DNS_RPZ_DONE_CLIENT_IP 0x0002 /* client IP address checked */
#define DNS_RPZ_DONE_QNAME     0x0004 /* qname checked */
#define DNS_RPZ_DONE_QNAME_IP  0x0008 /* IP addresses of qname checked */
#define DNS_RPZ_DONE_NSDNAME   0x0010 /* NS name missed; checking addresses */
#define DNS_RPZ_DONE_IPv4      0x0020
#define DNS_RPZ_RECURSING      0x0040
#define DNS_RPZ_ACTIVE	       0x0080
	/*
	 * Best match so far.
	 */
	struct {
		dns_rpz_type_t	 type;
		dns_rpz_zone_t	*rpz;
		dns_rpz_prefix_t prefix;
		dns_rpz_policy_t policy;
		dns_ttl_t	 ttl;
		isc_result_t	 result;
		dns_zone_t	*zone;
		dns_db_t	*db;
		dns_dbversion_t *version;
		dns_dbnode_t	*node;
		dns_rdataset_t	*rdataset;
	} m;
	/*
	 * State for chasing IP addresses and NS names including recursion.
	 */
	struct {
		unsigned int	label;
		dns_db_t       *db;
		dns_rdataset_t *ns_rdataset;
		dns_rdatatype_t r_type;
		isc_result_t	r_result;
		dns_rdataset_t *r_rdataset;
	} r;

	/*
	 * State of real query while recursing for NSIP or NSDNAME.
	 */
	struct {
		isc_result_t	result;
		bool		is_zone;
		bool		authoritative;
		dns_zone_t     *zone;
		dns_db_t       *db;
		dns_dbnode_t   *node;
		dns_rdataset_t *rdataset;
		dns_rdataset_t *sigrdataset;
		dns_rdatatype_t qtype;
	} q;

	/*
	 * A copy of the 'have' and 'p' structures and the RPZ
	 * policy version as of the beginning of RPZ processing,
	 * used to avoid problems when policy is updated while
	 * RPZ recursion is ongoing.
	 */
	dns_rpz_have_t have;
	dns_rpz_popt_t popt;
	int	       rpz_ver;

	/*
	 * Shim db between BIND and DNRPS librpz.
	 */
	dns_db_t *rpsdb;

	/*
	 * p_name: current policy owner name
	 * r_name: recursing for this name to possible policy triggers
	 * f_name: saved found name from before recursion
	 */
	dns_name_t     *p_name;
	dns_name_t     *r_name;
	dns_name_t     *fname;
	dns_fixedname_t _p_namef;
	dns_fixedname_t _r_namef;
	dns_fixedname_t _fnamef;
} dns_rpz_st_t;

#define DNS_RPZ_TTL_DEFAULT		  5
#define DNS_RPZ_MAX_TTL_DEFAULT		  DNS_RPZ_TTL_DEFAULT
#define DNS_RPZ_MINUPDATEINTERVAL_DEFAULT 60

/*
 * So various response policy zone messages can be turned up or down.
 */
#define DNS_RPZ_ERROR_LEVEL  ISC_LOG_WARNING
#define DNS_RPZ_INFO_LEVEL   ISC_LOG_INFO
#define DNS_RPZ_DEBUG_LEVEL1 ISC_LOG_DEBUG(1)
#define DNS_RPZ_DEBUG_LEVEL2 ISC_LOG_DEBUG(2)
#define DNS_RPZ_DEBUG_LEVEL3 ISC_LOG_DEBUG(3)
#define DNS_RPZ_DEBUG_QUIET  (DNS_RPZ_DEBUG_LEVEL3 + 1)

const char *
dns_rpz_type2str(dns_rpz_type_t type);

dns_rpz_policy_t
dns_rpz_str2policy(const char *str);

const char *
dns_rpz_policy2str(dns_rpz_policy_t policy);

dns_rpz_policy_t
dns_rpz_decode_cname(dns_rpz_zone_t *rpz, dns_rdataset_t *rdataset,
		     dns_name_t *selfname);

isc_result_t
dns_rpz_new_zones(isc_mem_t *mctx, isc_taskmgr_t *taskmgr,
		  isc_timermgr_t *timermgr, char *rps_cstr,
		  size_t rps_cstr_size, dns_rpz_zones_t **rpzsp);

isc_result_t
dns_rpz_new_zone(dns_rpz_zones_t *rpzs, dns_rpz_zone_t **rpzp);

isc_result_t
dns_rpz_dbupdate_callback(dns_db_t *db, void *fn_arg);

void
dns_rpz_zones_shutdown(dns_rpz_zones_t *rpzs);

#ifdef DNS_RPZ_TRACE
/* Compatibility macros */
#define dns_rpz_detach_rpzs(rpzsp) \
	dns_rpz_zones__detach(rpzsp, __func__, __FILE__, __LINE__)
#define dns_rpz_attach_rpzs(rpzs, rpzsp) \
	dns_rpz_zones__attach(rpzs, rpzsp, __func__, __FILE__, __LINE__)
#define dns_rpz_ref_rpzs(ptr) \
	dns_rpz_zones__ref(ptr, __func__, __FILE__, __LINE__)
#define dns_rpz_unref_rpzs(ptr) \
	dns_rpz_zones__unref(ptr, __func__, __FILE__, __LINE__)
#define dns_rpz_shutdown_rpzs(rpzs) \
	dns_rpz_zones_shutdown(rpzs, __func__, __FILE__, __LINE__)

ISC_REFCOUNT_TRACE_DECL(dns_rpz_zones);
#else
/* Compatibility macros */
#define dns_rpz_detach_rpzs(rpzsp)	 dns_rpz_zones_detach(rpzsp)
#define dns_rpz_attach_rpzs(rpzs, rpzsp) dns_rpz_zones_attach(rpzs, rpzsp)
#define dns_rpz_shutdown_rpzs(rpzsp)	 dns_rpz_zones_shutdown(rpzsp)
#define dns_rpz_ref_rpzs(ptr)		 dns_rpz_zones_ref(ptr)
#define dns_rpz_unref_rpzs(ptr)		 dns_rpz_zones_unref(ptr)

ISC_REFCOUNT_DECL(dns_rpz_zones);
#endif

dns_rpz_num_t
dns_rpz_find_ip(dns_rpz_zones_t *rpzs, dns_rpz_type_t rpz_type,
		dns_rpz_zbits_t zbits, const isc_netaddr_t *netaddr,
		dns_name_t *ip_name, dns_rpz_prefix_t *prefixp);

dns_rpz_zbits_t
dns_rpz_find_name(dns_rpz_zones_t *rpzs, dns_rpz_type_t rpz_type,
		  dns_rpz_zbits_t zbits, dns_name_t *trig_name);

ISC_LANG_ENDDECLS