text: /*
   * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
   * Copyright (C) 2000-2002  Internet Software Consortium.
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
   * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
   * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
   * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
   * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
   * PERFORMANCE OF THIS SOFTWARE.
   */
  
  /* $Id: lwres_gnba.c,v 1.28 2007/09/24 17:18:25 each Exp $ */
  
  /*! \file lwres_gnba.c
     These are low-level routines for creating and parsing lightweight
     resolver address-to-name lookup request and response messages.
  
     There are four main functions for the getnamebyaddr opcode. One
   render function converts a getnamebyaddr request structure --
     lwres_gnbarequest_t -- to the lightweight resolver's canonical
     format. It is complemented by a parse function that converts a
     packet in this canonical format to a getnamebyaddr request
     structure. Another render function converts the getnamebyaddr
     response structure -- lwres_gnbaresponse_t to the canonical format.
     This is complemented by a parse function which converts a packet in
     canonical format to a getnamebyaddr response structure.       
  
     These structures are defined in \link lwres.h <lwres/lwres.h.>\endlink They are shown
     below.
  
  \code
  #define LWRES_OPCODE_GETNAMEBYADDR      0x00010002U
  
  typedef struct {
          lwres_uint32_t  flags;
          lwres_addr_t    addr;
  } lwres_gnbarequest_t;
  
  typedef struct {
          lwres_uint32_t  flags;
          lwres_uint16_t  naliases;
          char           *realname;
          char          **aliases;
          lwres_uint16_t  realnamelen;
          lwres_uint16_t *aliaslen;
          void           *base;
          size_t          baselen;
  } lwres_gnbaresponse_t;
  \endcode
  
     lwres_gnbarequest_render() uses resolver context ctx to convert
     getnamebyaddr 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_gnbaresponse_render() performs the same task, except
     it converts a getnamebyaddr response structure lwres_gnbaresponse_t
     to the lightweight resolver's canonical format.
  
     lwres_gnbarequest_parse() uses context ctx to convert the contents
     of packet pkt to a lwres_gnbarequest_t structure. Buffer b provides
     space to be used for storing this structure. When the function
     succeeds, the resulting lwres_gnbarequest_t is made available
     through *structp. lwres_gnbaresponse_parse() offers the same   
  semantics as lwres_gnbarequest_parse() except it yields a    
     lwres_gnbaresponse_t structure.
  
     lwres_gnbaresponse_free() and lwres_gnbarequest_free() release the
     memory in resolver context ctx that was allocated to the     
     lwres_gnbaresponse_t or lwres_gnbarequest_t structures referenced  
     via structp. Any memory associated with ancillary buffers and      
     strings for those structures is also discarded.
  
  \section lwres_gbna_return Return Values
  
     The getnamebyaddr opcode functions lwres_gnbarequest_render(),
     lwres_gnbaresponse_render() lwres_gnbarequest_parse() and
     lwres_gnbaresponse_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_gnbarequest_t and lwres_gnbaresponse_t structures.
     lwres_gnbarequest_parse() and lwres_gnbaresponse_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_gbna_see See Also
  
     \link lwpacket.c lwres_packet\endlink
  
   */
  
  #include <config.h>
  
  #include <assert.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 getnamebyaddr request structure req to canonical format. */
  lwres_result_t
  lwres_gnbarequest_render(lwres_context_t *ctx, lwres_gnbarequest_t *req,
  			 lwres_lwpacket_t *pkt, lwres_buffer_t *b)
  {
  	unsigned char *buf;
  	size_t buflen;
  	int ret;
  	size_t payload_length;
  
  	REQUIRE(ctx != NULL);
  	REQUIRE(req != NULL);
  	REQUIRE(req->addr.family != 0);
  	REQUIRE(req->addr.length != 0);
  	REQUIRE(pkt != NULL);
  	REQUIRE(b != NULL);
  
  	payload_length = 4 + 4 + 2 + + req->addr.length;
  
  	buflen = LWRES_LWPACKET_LENGTH + payload_length;
  	buf = CTXMALLOC(buflen);
  	if (buf == NULL)
  		return (LWRES_R_NOMEMORY);
  	lwres_buffer_init(b, buf, buflen);
  
  	pkt->length = buflen;
  	pkt->version = LWRES_LWPACKETVERSION_0;
  	pkt->pktflags &= ~LWRES_LWPACKETFLAG_RESPONSE;
  	pkt->opcode = LWRES_OPCODE_GETNAMEBYADDR;
  	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));
  
  	/*
  	 * Put the length and the data.  We know this will fit because we
  	 * just checked for it.
  	 */
  	lwres_buffer_putuint32(b, req->flags);
  	lwres_buffer_putuint32(b, req->addr.family);
  	lwres_buffer_putuint16(b, req->addr.length);
  	lwres_buffer_putmem(b, (unsigned char *)req->addr.address,
  			    req->addr.length);
  
  	INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
  
  	return (LWRES_R_SUCCESS);
  }
  
  /*% Converts a getnamebyaddr response structure lwres_gnbaresponse_t to the lightweight resolver's canonical format. */
  lwres_result_t
  lwres_gnbaresponse_render(lwres_context_t *ctx, lwres_gnbaresponse_t *req,
  			  lwres_lwpacket_t *pkt, lwres_buffer_t *b)
  {
  	unsigned char *buf;
  	size_t buflen;
  	int ret;
  	size_t payload_length;
  	lwres_uint16_t datalen;
  	int x;
  
  	REQUIRE(ctx != NULL);
  	REQUIRE(req != NULL);
  	REQUIRE(pkt != NULL);
  	REQUIRE(b != NULL);
  
  	/*
  	 * Calculate packet size.
  	 */
  	payload_length = 4;			       /* flags */
  	payload_length += 2;			       /* naliases */
  	payload_length += 2 + req->realnamelen + 1;    /* real name encoding */
  	for (x = 0; x < req->naliases; x++)	       /* each alias */
  		payload_length += 2 + req->aliaslen[x] + 1;
  
  	buflen = LWRES_LWPACKET_LENGTH + payload_length;
  	buf = CTXMALLOC(buflen);
  	if (buf == NULL)
  		return (LWRES_R_NOMEMORY);
  	lwres_buffer_init(b, buf, buflen);
  
  	pkt->length = buflen;
  	pkt->version = LWRES_LWPACKETVERSION_0;
  	pkt->pktflags |= LWRES_LWPACKETFLAG_RESPONSE;
  	pkt->opcode = LWRES_OPCODE_GETNAMEBYADDR;
  	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));
  	lwres_buffer_putuint32(b, req->flags);
  
  	/* encode naliases */
  	lwres_buffer_putuint16(b, req->naliases);
  
  	/* 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);
  	}
  
  	INSIST(LWRES_BUFFER_AVAILABLECOUNT(b) == 0);
  
  	return (LWRES_R_SUCCESS);
  }
  
  /*% Uses context ctx to convert the contents of packet pkt to a lwres_gnbarequest_t structure. */
  lwres_result_t
  lwres_gnbarequest_parse(lwres_context_t *ctx, lwres_buffer_t *b,
  			lwres_lwpacket_t *pkt, lwres_gnbarequest_t **structp)
  {
  	int ret;
  	lwres_gnbarequest_t *gnba;
  
  	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))
  		return (LWRES_R_UNEXPECTEDEND);
  
  	gnba = CTXMALLOC(sizeof(lwres_gnbarequest_t));
  	if (gnba == NULL)
  		return (LWRES_R_NOMEMORY);
  
  	gnba->flags = lwres_buffer_getuint32(b);
  
  	ret = lwres_addr_parse(b, &gnba->addr);
  	if (ret != LWRES_R_SUCCESS)
  		goto out;
  
  	if (LWRES_BUFFER_REMAINING(b) != 0) {
  		ret = LWRES_R_TRAILINGDATA;
  		goto out;
  	}
  
  	*structp = gnba;
  	return (LWRES_R_SUCCESS);
  
   out:
  	if (gnba != NULL)
  		lwres_gnbarequest_free(ctx, &gnba);
  
  	return (ret);
  }
  
  /*% Offers the same semantics as lwres_gnbarequest_parse() except it yields a lwres_gnbaresponse_t structure. */
  
  lwres_result_t
  lwres_gnbaresponse_parse(lwres_context_t *ctx, lwres_buffer_t *b,
  			 lwres_lwpacket_t *pkt, lwres_gnbaresponse_t **structp)
  {
  	int ret;
  	unsigned int x;
  	lwres_uint32_t flags;
  	lwres_uint16_t naliases;
  	lwres_gnbaresponse_t *gnba;
  
  	REQUIRE(ctx != NULL);
  	REQUIRE(pkt != NULL);
  	REQUIRE(b != NULL);
  	REQUIRE(structp != NULL && *structp == NULL);
  
  	gnba = NULL;
  
  	if ((pkt->pktflags & LWRES_LWPACKETFLAG_RESPONSE) == 0)
  		return (LWRES_R_FAILURE);
  
  	/*
  	 * Pull off flags & naliases
  	 */
  	if (!SPACE_REMAINING(b, 4 + 2))
  		return (LWRES_R_UNEXPECTEDEND);
  	flags = lwres_buffer_getuint32(b);
  	naliases = lwres_buffer_getuint16(b);
  
  	gnba = CTXMALLOC(sizeof(lwres_gnbaresponse_t));
  	if (gnba == NULL)
  		return (LWRES_R_NOMEMORY);
  	gnba->base = NULL;
  	gnba->aliases = NULL;
  	gnba->aliaslen = NULL;
  
  	gnba->flags = flags;
  	gnba->naliases = naliases;
  
  	if (naliases > 0) {
  		gnba->aliases = CTXMALLOC(sizeof(char *) * naliases);
  		if (gnba->aliases == NULL) {
  			ret = LWRES_R_NOMEMORY;
  			goto out;
  		}
  
  		gnba->aliaslen = CTXMALLOC(sizeof(lwres_uint16_t) * naliases);
  		if (gnba->aliaslen == NULL) {
  			ret = LWRES_R_NOMEMORY;
  			goto out;
  		}
  	}
  
  	/*
  	 * Now, pull off the real name.
  	 */
  	ret = lwres_string_parse(b, &gnba->realname, &gnba->realnamelen);
  	if (ret != LWRES_R_SUCCESS)
  		goto out;
  
  	/*
  	 * Parse off the aliases.
  	 */
  	for (x = 0; x < gnba->naliases; x++) {
  		ret = lwres_string_parse(b, &gnba->aliases[x],
  					 &gnba->aliaslen[x]);
  		if (ret != LWRES_R_SUCCESS)
  			goto out;
  	}
  
  	if (LWRES_BUFFER_REMAINING(b) != 0) {
  		ret = LWRES_R_TRAILINGDATA;
  		goto out;
  	}
  
  	*structp = gnba;
  	return (LWRES_R_SUCCESS);
  
   out:
  	if (gnba != NULL) {
  		if (gnba->aliases != NULL)
  			CTXFREE(gnba->aliases, sizeof(char *) * naliases);
  		if (gnba->aliaslen != NULL)
  			CTXFREE(gnba->aliaslen,
  				sizeof(lwres_uint16_t) * naliases);
  		CTXFREE(gnba, sizeof(lwres_gnbaresponse_t));
  	}
  
  	return (ret);
  }
  
  /*% Release the memory in resolver context ctx that was allocated to the lwres_gnbarequest_t. */
  void
  lwres_gnbarequest_free(lwres_context_t *ctx, lwres_gnbarequest_t **structp)
  {
  	lwres_gnbarequest_t *gnba;
  
  	REQUIRE(ctx != NULL);
  	REQUIRE(structp != NULL && *structp != NULL);
  
  	gnba = *structp;
  	*structp = NULL;
  
  	CTXFREE(gnba, sizeof(lwres_gnbarequest_t));
  }
  
  /*% Release the memory in resolver context ctx that was allocated to the lwres_gnbaresponse_t. */
  void
  lwres_gnbaresponse_free(lwres_context_t *ctx, lwres_gnbaresponse_t **structp)
  {
  	lwres_gnbaresponse_t *gnba;
  
  	REQUIRE(ctx != NULL);
  	REQUIRE(structp != NULL && *structp != NULL);
  
  	gnba = *structp;
  	*structp = NULL;
  
  	if (gnba->naliases > 0) {
  		CTXFREE(gnba->aliases, sizeof(char *) * gnba->naliases);
  		CTXFREE(gnba->aliaslen,
  			sizeof(lwres_uint16_t) * gnba->naliases);
  	}
  	if (gnba->base != NULL)
  		CTXFREE(gnba->base, gnba->baselen);
  	CTXFREE(gnba, sizeof(lwres_gnbaresponse_t));
  }
  