lib/lwres/lwres_gabn.c

/*
 * 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.
 */

/*! \file lwres_gabn.c
   These are low-level routines for creating and parsing lightweight
   resolver name-to-address lookup request and response messages.

   There are four main functions for the getaddrbyname opcode. One render
   function converts a getaddrbyname request structure --
   lwres_gabnrequest_t -- to the lighweight resolver's canonical format.
   It is complemented by a parse function that converts a packet in this
   canonical format to a getaddrbyname request structure. Another render
   function converts the getaddrbyname response structure --
   lwres_gabnresponse_t -- to the canonical format. This is complemented
   by a parse function which converts a packet in canonical format to a
   getaddrbyname response structure.

   These structures are defined in \link lwres.h <lwres/lwres.h>.\endlink They are shown below.

\code
#define LWRES_OPCODE_GETADDRSBYNAME     0x00010001U

typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;

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

typedef struct {
	uint32_t          flags;
	uint16_t          naliases;
	uint16_t          naddrs;
	char                   *realname;
	char                  **aliases;
	uint16_t          realnamelen;
	uint16_t         *aliaslen;
	lwres_addrlist_t        addrs;
	void                   *base;
	size_t                  baselen;
} lwres_gabnresponse_t;
\endcode

   lwres_gabnrequest_render() uses resolver context ctx to convert
   getaddrbyname request structure req to canonical format. The packet
   header structure pkt is initialised and transferred to buffer b. The
   contents of *req are then appended to the buffer in canonical format.
   lwres_gabnresponse_render() performs the same task, except it converts
   a getaddrbyname response structure lwres_gabnresponse_t to the
   lightweight resolver's canonical format.

   lwres_gabnrequest_parse() uses context ctx to convert the contents of
   packet pkt to a lwres_gabnrequest_t structure. Buffer b provides space
   to be used for storing this structure. When the function succeeds, the
   resulting lwres_gabnrequest_t is made available through *structp.
   lwres_gabnresponse_parse() offers the same semantics as
   lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t
   structure.

   lwres_gabnresponse_free() and lwres_gabnrequest_free() release the
   memory in resolver context ctx that was allocated to the
   lwres_gabnresponse_t or lwres_gabnrequest_t structures referenced via
   structp. Any memory associated with ancillary buffers and strings for
   those structures is also discarded.

\section lwres_gabn_return Return Values

   The getaddrbyname opcode functions lwres_gabnrequest_render(),
   lwres_gabnresponse_render() lwres_gabnrequest_parse() and
   lwres_gabnresponse_parse() all return #LWRES_R_SUCCESS on success. They
   return #LWRES_R_NOMEMORY if memory allocation fails.
   #LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer
   b is too small to accommodate the packet header or the
   lwres_gabnrequest_t and lwres_gabnresponse_t structures.
   lwres_gabnrequest_parse() and lwres_gabnresponse_parse() will return
   #LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the
   received packet. These functions will return #LWRES_R_FAILURE if
   pktflags in the packet header structure #lwres_lwpacket_t indicate that
   the packet is not a response to an earlier query.

\section lwres_gabn_see See Also

   \link lwpacket.c lwres_lwpacket \endlink
 */

#include <config.h>

#include <assert.h>
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>

#include <lwres/lwbuffer.h>
#include <lwres/lwpacket.h>
#include <lwres/lwres.h>
#include <lwres/result.h>

#include "context_p.h"
#include "assert_p.h"

/*% uses resolver context ctx to convert getaddrbyname request structure req to canonical format. */
lwres_result_t
lwres_gabnrequest_render(lwres_context_t *ctx, lwres_gabnrequest_t *req,
			 lwres_lwpacket_t *pkt, lwres_buffer_t *b)
{
	unsigned char *buf;
	size_t buflen;
	int ret;
	size_t payload_length;
	uint16_t datalen;

	REQUIRE(ctx != NULL);
	REQUIRE(req != NULL);
	REQUIRE(req->name != NULL);
	REQUIRE(pkt != NULL);
	REQUIRE(b != NULL);

	datalen = (uint16_t) strlen(req->name);

	payload_length = 4 + 4 + 2 + req->namelen + 1;

	buflen = LWRES_LWPACKET_LENGTH + payload_length;
	buf = CTXMALLOC(buflen);
	if (buf == NULL)
		return (LWRES_R_NOMEMORY);

	lwres_buffer_init(b, buf, (unsigned int)buflen);

	pkt->length = (uint32_t)buflen;
	pkt->version = LWRES_LWPACKETVERSION_0;
	pkt->pktflags &= ~LWRES_LWPACKETFLAG_RESPONSE;
	pkt->opcode = LWRES_OPCODE_GETADDRSBYNAME;
	pkt->result = 0;
	pkt->authtype = 0;
	pkt->authlength = 0;

	ret = lwres_lwpacket_renderheader(b, pkt);
	if (ret != LWRES_R_SUCCESS) {
		lwres_buffer_invalidate(b);
		CTXFREE(buf, buflen);
		return (ret);
	}

	INSIST(SPACE_OK(b, payload_length));

	/*
	 * Flags.
	 */
	lwres_buffer_putuint32(b, req->flags);

	/*
	 * Address types we'll accept.
	 */
	lwres_buffer_putuint32(b, req->addrtypes);

	/*
	 * Put the length and the data.  We know this will fit because we
	 * just checked for it.
	 */
	lwres_buffer_putuint16(b, datalen);
	lwres_buffer_putmem(b, (unsigned char *)req->name, datalen);
	lwres_buffer_putuint8(b, 0); /* trailing NUL */

	INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);

	return (LWRES_R_SUCCESS);
}
/*% converts a getaddrbyname response structure lwres_gabnresponse_t to the lightweight resolver's canonical format. */
lwres_result_t
lwres_gabnresponse_render(lwres_context_t *ctx, lwres_gabnresponse_t *req,
			  lwres_lwpacket_t *pkt, lwres_buffer_t *b)
{
	unsigned char *buf;
	size_t buflen;
	int ret;
	size_t payload_length;
	uint16_t datalen;
	lwres_addr_t *addr;
	int x;

	REQUIRE(ctx != NULL);
	REQUIRE(req != NULL);
	REQUIRE(pkt != NULL);
	REQUIRE(b != NULL);

	/* naliases, naddrs */
	payload_length = 4 + 2 + 2;
	/* real name encoding */
	payload_length += 2 + req->realnamelen + 1;
	/* each alias */
	for (x = 0; x < req->naliases; x++)
		payload_length += 2 + req->aliaslen[x] + 1;
	/* each address */
	x = 0;
	addr = LWRES_LIST_HEAD(req->addrs);
	while (addr != NULL) {
		payload_length += 4 + 2;
		payload_length += addr->length;
		addr = LWRES_LIST_NEXT(addr, link);
		x++;
	}
	INSIST(x == req->naddrs);

	buflen = LWRES_LWPACKET_LENGTH + payload_length;
	buf = CTXMALLOC(buflen);
	if (buf == NULL)
		return (LWRES_R_NOMEMORY);
	lwres_buffer_init(b, buf, (unsigned int)buflen);

	pkt->length = (uint32_t)buflen;
	pkt->version = LWRES_LWPACKETVERSION_0;
	pkt->pktflags |= LWRES_LWPACKETFLAG_RESPONSE;
	pkt->opcode = LWRES_OPCODE_GETADDRSBYNAME;
	pkt->authtype = 0;
	pkt->authlength = 0;

	ret = lwres_lwpacket_renderheader(b, pkt);
	if (ret != LWRES_R_SUCCESS) {
		lwres_buffer_invalidate(b);
		CTXFREE(buf, buflen);
		return (ret);
	}

	/*
	 * Check space needed here.
	 */
	INSIST(SPACE_OK(b, payload_length));

	/* Flags. */
	lwres_buffer_putuint32(b, req->flags);

	/* encode naliases and naddrs */
	lwres_buffer_putuint16(b, req->naliases);
	lwres_buffer_putuint16(b, req->naddrs);

	/* encode the real name */
	datalen = req->realnamelen;
	lwres_buffer_putuint16(b, datalen);
	lwres_buffer_putmem(b, (unsigned char *)req->realname, datalen);
	lwres_buffer_putuint8(b, 0);

	/* encode the aliases */
	for (x = 0; x < req->naliases; x++) {
		datalen = req->aliaslen[x];
		lwres_buffer_putuint16(b, datalen);
		lwres_buffer_putmem(b, (unsigned char *)req->aliases[x],
				    datalen);
		lwres_buffer_putuint8(b, 0);
	}

	/* encode the addresses */
	addr = LWRES_LIST_HEAD(req->addrs);
	while (addr != NULL) {
		lwres_buffer_putuint32(b, addr->family);
		lwres_buffer_putuint16(b, addr->length);
		lwres_buffer_putmem(b, addr->address, addr->length);
		addr = LWRES_LIST_NEXT(addr, link);
	}

	INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
	INSIST(LWRES_BUFFER_USEDCOUNT(b) == pkt->length);

	return (LWRES_R_SUCCESS);
}
/*% Uses context ctx to convert the contents of packet pkt to a lwres_gabnrequest_t structure. */
lwres_result_t
lwres_gabnrequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_gabnrequest_t **structp)
{
	int ret;
	char *name;
	lwres_gabnrequest_t *gabn;
	uint32_t addrtypes;
	uint32_t flags;
	uint16_t namelen;

	REQUIRE(ctx != NULL);
	REQUIRE(pkt != NULL);
	REQUIRE(b != NULL);
	REQUIRE(structp != NULL && *structp == NULL);

	if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) != 0)
		return (LWRES_R_FAILURE);

	if (!SPACE_REMAINING(b, 4 + 4))
		return (LWRES_R_UNEXPECTEDEND);

	flags = lwres_buffer_getuint32(b);
	addrtypes = lwres_buffer_getuint32(b);

	/*
	 * Pull off the name itself
	 */
	ret = lwres_string_parse(b, &name, &namelen);
	if (ret != LWRES_R_SUCCESS)
		return (ret);

	if (LWRES_BUFFER_REMAINING(b) != 0)
		return (LWRES_R_TRAILINGDATA);

	gabn = CTXMALLOC(sizeof(lwres_gabnrequest_t));
	if (gabn == NULL)
		return (LWRES_R_NOMEMORY);

	gabn->flags = flags;
	gabn->addrtypes = addrtypes;
	gabn->name = name;
	gabn->namelen = namelen;

	*structp = gabn;
	return (LWRES_R_SUCCESS);
}

/*% Offers the same semantics as lwres_gabnrequest_parse() except it yields a lwres_gabnresponse_t structure. */

lwres_result_t
lwres_gabnresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
			lwres_lwpacket_t *pkt, lwres_gabnresponse_t **structp)
{
	lwres_result_t ret;
	unsigned int x;
	uint32_t flags;
	uint16_t naliases;
	uint16_t naddrs;
	lwres_gabnresponse_t *gabn;
	lwres_addrlist_t addrlist;
	lwres_addr_t *addr;

	REQUIRE(ctx != NULL);
	REQUIRE(pkt != NULL);
	REQUIRE(b != NULL);
	REQUIRE(structp != NULL && *structp == NULL);

	gabn = NULL;

	if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) == 0)
		return (LWRES_R_FAILURE);

	/*
	 * Pull off the name itself
	 */
	if (!SPACE_REMAINING(b, 4 + 2 + 2))
		return (LWRES_R_UNEXPECTEDEND);
	flags = lwres_buffer_getuint32(b);
	naliases = lwres_buffer_getuint16(b);
	naddrs = lwres_buffer_getuint16(b);

	gabn = CTXMALLOC(sizeof(lwres_gabnresponse_t));
	if (gabn == NULL)
		return (LWRES_R_NOMEMORY);
	gabn->aliases = NULL;
	gabn->aliaslen = NULL;
	LWRES_LIST_INIT(gabn->addrs);
	gabn->base = NULL;

	gabn->flags = flags;
	gabn->naliases = naliases;
	gabn->naddrs = naddrs;

	LWRES_LIST_INIT(addrlist);

	if (naliases > 0) {
		gabn->aliases = CTXMALLOC(sizeof(char *) * naliases);
		if (gabn->aliases == NULL) {
			ret = LWRES_R_NOMEMORY;
			goto out;
		}

		gabn->aliaslen = CTXMALLOC(sizeof(uint16_t) * naliases);
		if (gabn->aliaslen == NULL) {
			ret = LWRES_R_NOMEMORY;
			goto out;
		}
	}

	for (x = 0; x < naddrs; x++) {
		addr = CTXMALLOC(sizeof(lwres_addr_t));
		if (addr == NULL) {
			ret = LWRES_R_NOMEMORY;
			goto out;
		}
		LWRES_LINK_INIT(addr, link);
		LWRES_LIST_APPEND(addrlist, addr, link);
	}

	/*
	 * Now, pull off the real name.
	 */
	ret = lwres_string_parse(b, &gabn->realname, &gabn->realnamelen);
	if (ret != LWRES_R_SUCCESS)
		goto out;

	/*
	 * Parse off the aliases.
	 */
	for (x = 0; x < gabn->naliases; x++) {
		ret = lwres_string_parse(b, &gabn->aliases[x],
					 &gabn->aliaslen[x]);
		if (ret != LWRES_R_SUCCESS)
			goto out;
	}

	/*
	 * Pull off the addresses.  We already strung the linked list
	 * up above.
	 */
	addr = LWRES_LIST_HEAD(addrlist);
	for (x = 0; x < gabn->naddrs; x++) {
		INSIST(addr != NULL);
		ret = lwres_addr_parse(b, addr);
		if (ret != LWRES_R_SUCCESS)
			goto out;
		addr = LWRES_LIST_NEXT(addr, link);
	}

	if (LWRES_BUFFER_REMAINING(b) != 0) {
		ret = LWRES_R_TRAILINGDATA;
		goto out;
	}

	gabn->addrs = addrlist;

	*structp = gabn;
	return (LWRES_R_SUCCESS);

 out:
	if (gabn != NULL) {
		if (gabn->aliases != NULL)
			CTXFREE(gabn->aliases, sizeof(char *) * naliases);
		if (gabn->aliaslen != NULL)
			CTXFREE(gabn->aliaslen,
				sizeof(uint16_t) * naliases);
		addr = LWRES_LIST_HEAD(addrlist);
		while (addr != NULL) {
			LWRES_LIST_UNLINK(addrlist, addr, link);
			CTXFREE(addr, sizeof(lwres_addr_t));
			addr = LWRES_LIST_HEAD(addrlist);
		}
		CTXFREE(gabn, sizeof(lwres_gabnresponse_t));
	}

	return (ret);
}

/*% Release the memory in resolver context ctx that was allocated to the lwres_gabnrequest_t. */
void
lwres_gabnrequest_free(lwres_context_t *ctx, lwres_gabnrequest_t **structp)
{
	lwres_gabnrequest_t *gabn;

	REQUIRE(ctx != NULL);
	REQUIRE(structp != NULL && *structp != NULL);

	gabn = *structp;
	*structp = NULL;

	CTXFREE(gabn, sizeof(lwres_gabnrequest_t));
}

/*% Release the memory in resolver context ctx that was allocated to the lwres_gabnresponse_t. */
void
lwres_gabnresponse_free(lwres_context_t *ctx, lwres_gabnresponse_t **structp)
{
	lwres_gabnresponse_t *gabn;
	lwres_addr_t *addr;

	REQUIRE(ctx != NULL);
	REQUIRE(structp != NULL && *structp != NULL);

	gabn = *structp;
	*structp = NULL;

	if (gabn->naliases > 0) {
		CTXFREE(gabn->aliases, sizeof(char *) * gabn->naliases);
		CTXFREE(gabn->aliaslen,
			sizeof(uint16_t) * gabn->naliases);
	}
	addr = LWRES_LIST_HEAD(gabn->addrs);
	while (addr != NULL) {
		LWRES_LIST_UNLINK(gabn->addrs, addr, link);
		CTXFREE(addr, sizeof(lwres_addr_t));
		addr = LWRES_LIST_HEAD(gabn->addrs);
	}
	if (gabn->base != NULL)
		CTXFREE(gabn->base, gabn->baselen);
	CTXFREE(gabn, sizeof(lwres_gabnresponse_t));
}