/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * 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.
 */

#ifndef LWRES_LWRES_H
#define LWRES_LWRES_H 1

#include <inttypes.h>
#include <stdio.h>

#include <lwres/context.h>
#include <lwres/lang.h>
#include <lwres/list.h>
#include <lwres/lwpacket.h>
#include <lwres/platform.h>

/*! \file lwres/lwres.h */

/*!
 * Design notes:
 *
 * Each opcode has two structures and three functions which operate on each
 * structure.  For example, using the "no operation/ping" opcode as an
 * example:
 *
 *	<ul><li>lwres_nooprequest_t:
 *
 *		lwres_nooprequest_render() takes a lwres_nooprequest_t and
 *		and renders it into wire format, storing the allocated
 *		buffer information in a passed-in buffer.  When this buffer
 *		is no longer needed, it must be freed by
 *		lwres_context_freemem().  All other memory used by the
 *		caller must be freed manually, including the
 *		lwres_nooprequest_t passed in.<br /><br />
 *
 *		lwres_nooprequest_parse() takes a wire format message and
 *		breaks it out into a lwres_nooprequest_t.  The structure
 *		must be freed via lwres_nooprequest_free() when it is no longer
 *		needed.<br /><br />
 *
 *		lwres_nooprequest_free() releases into the lwres_context_t
 *		any space allocated during parsing.</li>
 *
 *	<li>lwres_noopresponse_t:
 *
 *		The functions used are similar to the three used for
 *		requests, just with different names.</li></ul>
 *
 * Typically, the client will use request_render, response_parse, and
 * response_free, while the daemon will use request_parse, response_render,
 * and request_free.
 *
 * The basic flow of a typical client is:
 *
 *	\li fill in a request_t, and call the render function.
 *
 *	\li Transmit the buffer returned to the daemon.
 *
 *	\li Wait for a response.
 *
 *	\li When a response is received, parse it into a response_t.
 *
 *	\li free the request buffer using lwres_context_freemem().
 *
 *	\li free the response structure and its associated buffer using
 *	response_free().
 */

#define LWRES_UDP_PORT		921	/*%< UDP Port Number */
#define LWRES_RECVLENGTH	16384 /*%< Maximum Packet Length */
#define LWRES_ADDR_MAXLEN	16	/*%< changing this breaks ABI */
#define LWRES_RESOLV_CONF	"/etc/resolv.conf" /*%< Location of resolv.conf */

/*% DNSSEC is not required (input).  Only relevant to rrset queries. */
#define LWRES_FLAG_TRUSTNOTREQUIRED	0x00000001U
/*% The data was crypto-verified with DNSSEC (output). */
#define LWRES_FLAG_SECUREDATA		0x00000002U

/*% no-op */
#define LWRES_OPCODE_NOOP		0x00000000U

/*% lwres_nooprequest_t */
typedef struct {
	/* public */
	uint16_t			datalength;
	unsigned char		       *data;
} lwres_nooprequest_t;

/*% lwres_noopresponse_t */
typedef struct {
	/* public */
	uint16_t			datalength;
	unsigned char		       *data;
} lwres_noopresponse_t;

/*% get addresses by name */
#define LWRES_OPCODE_GETADDRSBYNAME	0x00010001U

/*% lwres_addr_t */
typedef struct lwres_addr lwres_addr_t;

/*% LWRES_LIST */
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;

/*% lwres_addr */
struct lwres_addr {
	uint32_t			family;
	uint16_t			length;
	unsigned char			address[LWRES_ADDR_MAXLEN];
	uint32_t			zone;
	LWRES_LINK(lwres_addr_t)	link;
};

/*% lwres_gabnrequest_t */
typedef struct {
	/* public */
	uint32_t			flags;
	uint32_t			addrtypes;
	uint16_t			namelen;
	char			       *name;
} lwres_gabnrequest_t;

/*% lwres_gabnresponse_t */
typedef struct {
	/* public */
	uint32_t			flags;
	uint16_t			naliases;
	uint16_t			naddrs;
	char			       *realname;
	char			      **aliases;
	uint16_t			realnamelen;
	uint16_t		       *aliaslen;
	lwres_addrlist_t		addrs;
	/*! if base != NULL, it will be freed when this structure is freed. */
	void			       *base;
	size_t				baselen;
} lwres_gabnresponse_t;

/*% get name by address */
#define LWRES_OPCODE_GETNAMEBYADDR	0x00010002U

/*% lwres_gnbarequest_t */
typedef struct {
	/* public */
	uint32_t			flags;
	lwres_addr_t			addr;
} lwres_gnbarequest_t;

/*% lwres_gnbaresponse_t */
typedef struct {
	/* public */
	uint32_t			flags;
	uint16_t			naliases;
	char			       *realname;
	char			      **aliases;
	uint16_t			realnamelen;
	uint16_t		       *aliaslen;
	/*! if base != NULL, it will be freed when this structure is freed. */
	void			       *base;
	size_t				baselen;
} lwres_gnbaresponse_t;

/*% get rdata by name */
#define LWRES_OPCODE_GETRDATABYNAME	0x00010003U

/*% lwres_grbnrequest_t */
typedef struct {
	/* public */
	uint32_t			flags;
	uint16_t			rdclass;
	uint16_t			rdtype;
	uint16_t			namelen;
	char			       *name;
} lwres_grbnrequest_t;

/*% lwres_grbnresponse_t */
typedef struct {
	/* public */
	uint32_t			flags;
	uint16_t			rdclass;
	uint16_t			rdtype;
	uint32_t			ttl;
	uint16_t			nrdatas;
	uint16_t			nsigs;
	char			       *realname;
	uint16_t			realnamelen;
	unsigned char		      **rdatas;
	uint16_t		       *rdatalen;
	unsigned char		      **sigs;
	uint16_t		       *siglen;
	/*% if base != NULL, it will be freed when this structure is freed. */
	void			       *base;
	size_t				baselen;
} lwres_grbnresponse_t;

/*% Used by lwres_getrrsetbyname() */
#define LWRDATA_VALIDATED	0x00000001

/*!
 * resolv.conf data
 */

#define LWRES_CONFMAXNAMESERVERS 3	/*%< max 3 "nameserver" entries */
#define LWRES_CONFMAXLWSERVERS 1	/*%< max 1 "lwserver" entry */
#define LWRES_CONFMAXSEARCH 8		/*%< max 8 domains in "search" entry */
#define LWRES_CONFMAXLINELEN 256	/*%< max size of a line */
#define LWRES_CONFMAXSORTLIST 10	/*%< max 10 */

/*% lwres_conf_t */
typedef struct {
	lwres_context_t *lwctx;
	lwres_addr_t    nameservers[LWRES_CONFMAXNAMESERVERS];
	uint8_t	nsnext;		/*%< index for next free slot */

	lwres_addr_t	lwservers[LWRES_CONFMAXLWSERVERS];
	uint8_t	lwnext;		/*%< index for next free slot */

	char	       *domainname;

	char 	       *search[LWRES_CONFMAXSEARCH];
	uint8_t	searchnxt;	/*%< index for next free slot */

	struct {
		lwres_addr_t addr;
		/*% mask has a non-zero 'family' and 'length' if set */
		lwres_addr_t mask;
	} sortlist[LWRES_CONFMAXSORTLIST];
	uint8_t	sortlistnxt;

	uint8_t	resdebug;      /*%< non-zero if 'options debug' set */
	uint8_t	ndots;	       /*%< set to n in 'options ndots:n' */
	uint8_t	no_tld_query;  /*%< non-zero if 'options no_tld_query' */
	int32_t	attempts;      /*%< set to n in 'options attempts:n' */
	int32_t	timeout;       /*%< set to n in 'options timeout:n' */
} lwres_conf_t;

#define LWRES_ADDRTYPE_V4		0x00000001U	/*%< ipv4 */
#define LWRES_ADDRTYPE_V6		0x00000002U	/*%< ipv6 */

#define LWRES_MAX_ALIASES		16		/*%< max # of aliases */
#define LWRES_MAX_ADDRS			64		/*%< max # of addrs */

LWRES_LANG_BEGINDECLS

/*% This is in host byte order. */
LIBLWRES_EXTERNAL_DATA extern uint16_t lwres_udp_port;

LIBLWRES_EXTERNAL_DATA extern const char *lwres_resolv_conf;

lwres_result_t
lwres_gabnrequest_render(lwres_context_t *ctx, lwres_gabnrequest_t *req,
			 lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_gabnresponse_render(lwres_context_t *ctx, lwres_gabnresponse_t *req,
			  lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_gabnrequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_gabnrequest_t **structp);

lwres_result_t
lwres_gabnresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			 lwres_lwpacket_t *pkt,
			 lwres_gabnresponse_t **structp);

void
lwres_gabnrequest_free(lwres_context_t *ctx, lwres_gabnrequest_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

void
lwres_gabnresponse_free(lwres_context_t *ctx, lwres_gabnresponse_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */


lwres_result_t
lwres_gnbarequest_render(lwres_context_t *ctx, lwres_gnbarequest_t *req,
			 lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_gnbaresponse_render(lwres_context_t *ctx, lwres_gnbaresponse_t *req,
			  lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_gnbarequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_gnbarequest_t **structp);

lwres_result_t
lwres_gnbaresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			 lwres_lwpacket_t *pkt,
			 lwres_gnbaresponse_t **structp);

void
lwres_gnbarequest_free(lwres_context_t *ctx, lwres_gnbarequest_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

void
lwres_gnbaresponse_free(lwres_context_t *ctx, lwres_gnbaresponse_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

lwres_result_t
lwres_grbnrequest_render(lwres_context_t *ctx, lwres_grbnrequest_t *req,
			 lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_grbnresponse_render(lwres_context_t *ctx, lwres_grbnresponse_t *req,
			  lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_grbnrequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_grbnrequest_t **structp);

lwres_result_t
lwres_grbnresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			 lwres_lwpacket_t *pkt,
			 lwres_grbnresponse_t **structp);

void
lwres_grbnrequest_free(lwres_context_t *ctx, lwres_grbnrequest_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

void
lwres_grbnresponse_free(lwres_context_t *ctx, lwres_grbnresponse_t **structp);
/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

lwres_result_t
lwres_nooprequest_render(lwres_context_t *ctx, lwres_nooprequest_t *req,
			 lwres_lwpacket_t *pkt, lwres_buffer_t *b);
/**<
 * Allocate space and render into wire format a noop request packet.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	b != NULL, and points to a lwres_buffer_t.  The contents of the
 *	buffer structure will be initialized to contain the wire-format
 *	noop request packet.
 *
 *	Caller needs to fill in parts of "pkt" before calling:
 *		serial, maxrecv, result.
 *
 * Returns:
 *
 *	Returns 0 on success, non-zero on failure.
 *
 *	On successful return, *b will contain data about the wire-format
 *	packet.  It can be transmitted in any way, including lwres_sendblock().
 */

lwres_result_t
lwres_noopresponse_render(lwres_context_t *ctx, lwres_noopresponse_t *req,
			  lwres_lwpacket_t *pkt, lwres_buffer_t *b);

lwres_result_t
lwres_nooprequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_nooprequest_t **structp);
/**<
 * Parse a noop request.  Note that to get here, the lwpacket must have
 * already been parsed and removed by the caller, otherwise it would be
 * pretty hard for it to know this is the right function to call.
 *
 * The function verifies bits of the header, but does not modify it.
 */

lwres_result_t
lwres_noopresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			 lwres_lwpacket_t *pkt,
			 lwres_noopresponse_t **structp);

void
lwres_nooprequest_free(lwres_context_t *ctx, lwres_nooprequest_t **structp);

void
lwres_noopresponse_free(lwres_context_t *ctx, lwres_noopresponse_t **structp);

/**<
 * Frees any dynamically allocated memory for this structure.
 *
 * Requires:
 *
 *	ctx != NULL, and be a context returned via lwres_context_create().
 *
 *	structp != NULL && *structp != NULL.
 *
 * Ensures:
 *
 *	*structp == NULL.
 *
 *	All memory allocated by this structure will be returned to the
 *	system via the context's free function.
 */

lwres_result_t
lwres_conf_parse(lwres_context_t *ctx, const char *filename);
/**<
 * parses a resolv.conf-format file and stores the results in the structure
 * pointed to by *ctx.
 *
 * Requires:
 *	ctx != NULL
 *	filename != NULL && strlen(filename) > 0
 *
 * Returns:
 *	LWRES_R_SUCCESS on a successful parse.
 *	Anything else on error, although the structure may be partially filled
 *	in.
 */

lwres_result_t
lwres_conf_print(lwres_context_t *ctx, FILE *fp);
/**<
 * Prints a resolv.conf-format of confdata output to fp.
 *
 * Requires:
 *	ctx != NULL
 */

void
lwres_conf_init(lwres_context_t *ctx);
/**<
 * sets all internal fields to a default state. Used to initialize a new
 * lwres_conf_t structure (not reset a used on).
 *
 * Requires:
 *	ctx != NULL
 */

void
lwres_conf_clear(lwres_context_t *ctx);
/**<
 * frees all internally allocated memory in confdata. Uses the memory
 * routines supplied by ctx.
 *
 * Requires:
 *	ctx != NULL
 */

lwres_conf_t *
lwres_conf_get(lwres_context_t *ctx);
/**<
 * Be extremely cautions in modifying the contents of this structure; it
 * needs an API to return the various bits of data, walk lists, etc.
 *
 * Requires:
 *	ctx != NULL
 */

/*
 * Helper functions
 */

lwres_result_t
lwres_data_parse(lwres_buffer_t *b, unsigned char **p, uint16_t *len);

lwres_result_t
lwres_string_parse(lwres_buffer_t *b, char **c, uint16_t *len);

lwres_result_t
lwres_addr_parse(lwres_buffer_t *b, lwres_addr_t *addr);

lwres_result_t
lwres_getaddrsbyname(lwres_context_t *ctx, const char *name,
		     uint32_t addrtypes, lwres_gabnresponse_t **structp);

lwres_result_t
lwres_getnamebyaddr(lwres_context_t *ctx, uint32_t addrtype,
		    uint16_t addrlen, const unsigned char *addr,
		    lwres_gnbaresponse_t **structp);

lwres_result_t
lwres_getrdatabyname(lwres_context_t *ctx, const char *name,
		     uint16_t rdclass, uint16_t rdtype,
		     uint32_t flags, lwres_grbnresponse_t **structp);

LWRES_LANG_ENDDECLS

#endif /* LWRES_LWRES_H */