lib/lwres/lwres_gnba.c

/*
 * Copyright (C) 2000-2002, 2004, 2005, 2007, 2013, 2016  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 http://mozilla.org/MPL/2.0/.
 */

/* $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, (unsigned int)buflen);

    pkt->length = (lwres_uint32_t)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, (unsigned int)buflen);

    pkt->length = (lwres_uint32_t)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));
}