lib/lwres/lwres_gabn.c

/*
 * Copyright (C) 2000, 2001, 2004, 2005, 2007, 2013, 2015, 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_gabn.c,v 1.33 2007/06/19 23:47:22 tbox Exp $ */

/*! \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 {
    lwres_uint32_t  flags;
    lwres_uint32_t  addrtypes;
    lwres_uint16_t  namelen;
    char           *name;
} lwres_gabnrequest_t;

typedef struct {
    lwres_uint32_t          flags;
    lwres_uint16_t          naliases;
    lwres_uint16_t          naddrs;
    char                   *realname;
    char                  **aliases;
    lwres_uint16_t          realnamelen;
    lwres_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 <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;
    lwres_uint16_t datalen;

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

    datalen = (lwres_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 = (lwres_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;
    lwres_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 = (lwres_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;
    lwres_uint32_t addrtypes;
    lwres_uint32_t flags;
    lwres_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;
    lwres_uint32_t flags;
    lwres_uint16_t naliases;
    lwres_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(lwres_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(lwres_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(lwres_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));
}