lib/irs/getnameinfo.c

	getnameinfo.c revision 0401db53f9f3481ea859f37845772dd3209e0f8a
/*
 * Copyright (C) 2009, 2011-2014, 2016, 2017  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/.
 */

/*! \file */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/**
 *    getnameinfo() returns the hostname for the struct sockaddr sa which is
 *    salen bytes long. The hostname is of length hostlen and is returned via
 *    *host. The maximum length of the hostname is 1025 bytes: #NI_MAXHOST.
 *
 *    The name of the service associated with the port number in sa is
 *    returned in *serv. It is servlen bytes long. The maximum length of the
 *    service name is #NI_MAXSERV - 32 bytes.
 *
 *    The flags argument sets the following bits:
 *
 * \li   #NI_NOFQDN:
 *           A fully qualified domain name is not required for local hosts.
 *           The local part of the fully qualified domain name is returned
 *           instead.
 *
 * \li   #NI_NUMERICHOST
 *           Return the address in numeric form, as if calling inet_ntop(),
 *           instead of a host name.
 *
 * \li   #NI_NAMEREQD
 *           A name is required. If the hostname cannot be found in the DNS
 *           and this flag is set, a non-zero error code is returned. If the
 *           hostname is not found and the flag is not set, the address is
 *           returned in numeric form.
 *
 * \li   #NI_NUMERICSERV
 *           The service name is returned as a digit string representing the
 *           port number.
 *
 * \li   #NI_DGRAM
 *           Specifies that the service being looked up is a datagram
 *           service, and causes getservbyport() to be called with a second
 *           argument of "udp" instead of its default of "tcp". This is
 *           required for the few ports (512-514) that have different
 *           services for UDP and TCP.
 *
 * \section getnameinfo_return Return Values
 *
 *    getnameinfo() returns 0 on success or a non-zero error code if
 *    an error occurs.
 *
 * \section getname_see See Also
 *
 *    RFC3493, getservbyport(),
 *    getnamebyaddr(). inet_ntop().
 */

#include <config.h>

#include <stdio.h>
#include <string.h>

#include <isc/netaddr.h>
#include <isc/print.h>
#include <isc/sockaddr.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/byaddr.h>
#include <dns/client.h>
#include <dns/fixedname.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rdatastruct.h>
#include <dns/result.h>

#include <irs/context.h>
#include <irs/netdb.h>

#define SUCCESS 0

/*% afd structure definition */
static struct afd {
    int a_af;
    size_t a_addrlen;
    size_t a_socklen;
} afdl [] = {
    /*!
     * First entry is linked last...
     */
    { AF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in) },
    { AF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6) },
    {0, 0, 0},
};

/*!
 * The test against 0 is there to keep the Solaris compiler
 * from complaining about "end-of-loop code not reached".
 */
#define ERR(code) \
    do { result = (code);           \
        if (result != 0) goto cleanup;  \
    } while (0)

int
getnameinfo(const struct sockaddr *sa, IRS_GETNAMEINFO_SOCKLEN_T salen,
        char *host, IRS_GETNAMEINFO_BUFLEN_T hostlen,
        char *serv, IRS_GETNAMEINFO_BUFLEN_T servlen,
        IRS_GETNAMEINFO_FLAGS_T flags)
{
    struct afd *afd = NULL;
    struct servent *sp;
    unsigned short port = 0;
#ifdef IRS_PLATFORM_HAVESALEN
    size_t len;
#endif
    int family, i;
    const void *addr = NULL;
    char *p;
#if 0
    unsigned long v4a;
    unsigned char pfx;
#endif
    char numserv[sizeof("65000")];
    char numaddr[sizeof("abcd:abcd:abcd:abcd:abcd:abcd:255.255.255.255")
            + 1 + sizeof("4294967295")];
    const char *proto;
    int result = SUCCESS;

    if (sa == NULL)
        ERR(EAI_FAIL);

#ifdef IRS_PLATFORM_HAVESALEN
    len = sa->sa_len;
    if (len != salen)
        ERR(EAI_FAIL);
#endif

    family = sa->sa_family;
    for (i = 0; afdl[i].a_af; i++)
        if (afdl[i].a_af == family) {
            afd = &afdl[i];
            goto found;
        }
    ERR(EAI_FAMILY);

 found:
    if (salen != afd->a_socklen)
        ERR(EAI_FAIL);

    switch (family) {
    case AF_INET:
        port = ((const struct sockaddr_in *)sa)->sin_port;
        addr = &((const struct sockaddr_in *)sa)->sin_addr.s_addr;
        break;

    case AF_INET6:
        port = ((const struct sockaddr_in6 *)sa)->sin6_port;
        addr = ((const struct sockaddr_in6 *)sa)->sin6_addr.s6_addr;
        break;

    default:
        INSIST(0);
    }
    proto = (flags & NI_DGRAM) ? "udp" : "tcp";

    if (serv == NULL || servlen == 0U) {
        /*
         * Caller does not want service.
         */
    } else if ((flags & NI_NUMERICSERV) != 0 ||
           (sp = getservbyport(port, proto)) == NULL) {
        snprintf(numserv, sizeof(numserv), "%d", ntohs(port));
        if ((strlen(numserv) + 1) > servlen)
            ERR(EAI_OVERFLOW);
        strlcpy(serv, numserv, servlen);
    } else {
        if ((strlen(sp->s_name) + 1) > servlen)
            ERR(EAI_OVERFLOW);
        strlcpy(serv, sp->s_name, servlen);
    }

#if 0
    switch (sa->sa_family) {
    case AF_INET:
        v4a = ((struct sockaddr_in *)sa)->sin_addr.s_addr;
        if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
            flags |= NI_NUMERICHOST;
        v4a >>= IN_CLASSA_NSHIFT;
        if (v4a == 0 || v4a == IN_LOOPBACKNET)
            flags |= NI_NUMERICHOST;
        break;

    case AF_INET6:
        pfx = ((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr[0];
        if (pfx == 0 || pfx == 0xfe || pfx == 0xff)
            flags |= NI_NUMERICHOST;
        break;
    }
#endif

    if (host == NULL || hostlen == 0U) {
        /*
         * do nothing in this case.
         * in case you are wondering if "&&" is more correct than
         * "||" here: RFC3493 says that host == NULL or hostlen == 0
         * means that the caller does not want the result.
         */
    } else if ((flags & NI_NUMERICHOST) != 0) {
        if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
            == NULL)
            ERR(EAI_SYSTEM);
#if defined(IRS_HAVE_SIN6_SCOPE_ID)
        if (afd->a_af == AF_INET6 &&
            ((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
            char *p = numaddr + strlen(numaddr);
            const char *stringscope = NULL;
#ifdef VENDOR_SPECIFIC
            /*
             * Vendors may want to add support for
             * non-numeric scope identifier.
             */
            stringscope = foo;
#endif
            if (stringscope == NULL) {
                snprintf(p, sizeof(numaddr) - (p - numaddr),
                    "%%%u",
                    ((const struct sockaddr_in6 *)sa)->sin6_scope_id);
            } else {
                snprintf(p, sizeof(numaddr) - (p - numaddr),
                    "%%%s", stringscope);
            }
        }
#endif
        if (strlen(numaddr) + 1 > hostlen)
            ERR(EAI_OVERFLOW);
        strlcpy(host, numaddr, hostlen);
    } else {
        isc_netaddr_t netaddr;
        dns_fixedname_t ptrfname;
        dns_name_t *ptrname;
        irs_context_t *irsctx = NULL;
        dns_client_t *client;
        isc_boolean_t found = ISC_FALSE;
        dns_namelist_t answerlist;
        dns_rdataset_t *rdataset;
        isc_region_t hostregion;
        char hoststr[1024]; /* is this enough? */
        isc_result_t iresult;

        /* Get IRS context and the associated DNS client object */
        iresult = irs_context_get(&irsctx);
        if (iresult != ISC_R_SUCCESS)
            ERR(EAI_FAIL);
        client = irs_context_getdnsclient(irsctx);

        /* Make query name */
        isc_netaddr_fromsockaddr(&netaddr, (const isc_sockaddr_t *)sa);
        dns_fixedname_init(&ptrfname);
        ptrname = dns_fixedname_name(&ptrfname);
        iresult = dns_byaddr_createptrname2(&netaddr, 0, ptrname);
        if (iresult != ISC_R_SUCCESS)
            ERR(EAI_FAIL);

        /* Get the PTR RRset */
        ISC_LIST_INIT(answerlist);
        iresult = dns_client_resolve(client, ptrname,
                         dns_rdataclass_in,
                         dns_rdatatype_ptr,
                         DNS_CLIENTRESOPT_ALLOWRUN,
                         &answerlist);
        switch (iresult) {
        case ISC_R_SUCCESS:
        /*
         * a 'non-existent' error is not necessarily fatal for
         * getnameinfo().
         */
        case DNS_R_NCACHENXDOMAIN:
        case DNS_R_NCACHENXRRSET:
            break;
        case DNS_R_SIGINVALID:
        case DNS_R_SIGEXPIRED:
        case DNS_R_SIGFUTURE:
        case DNS_R_KEYUNAUTHORIZED:
        case DNS_R_MUSTBESECURE:
        case DNS_R_COVERINGNSEC:
        case DNS_R_NOTAUTHORITATIVE:
        case DNS_R_NOVALIDKEY:
        case DNS_R_NOVALIDDS:
        case DNS_R_NOVALIDSIG:
            /*
             * Don't use ERR as GCC 7 wants to raise a
             * warning with ERR about possible falling
             * through which is impossible.
             */
            result = EAI_INSECUREDATA;
            goto cleanup;
        default:
            ERR(EAI_FAIL);
        }

        /* Parse the answer for the hostname */
        for (ptrname = ISC_LIST_HEAD(answerlist); ptrname != NULL;
             ptrname = ISC_LIST_NEXT(ptrname, link)) {
            for (rdataset = ISC_LIST_HEAD(ptrname->list);
                 rdataset != NULL;
                 rdataset = ISC_LIST_NEXT(rdataset, link)) {
                if (!dns_rdataset_isassociated(rdataset))
                    continue;
                if (rdataset->type != dns_rdatatype_ptr)
                    continue;

                for (iresult = dns_rdataset_first(rdataset);
                     iresult == ISC_R_SUCCESS;
                     iresult = dns_rdataset_next(rdataset)) {
                    dns_rdata_t rdata;
                    dns_rdata_ptr_t rdata_ptr;
                    isc_buffer_t b;

                    dns_rdata_init(&rdata);
                    dns_rdataset_current(rdataset, &rdata);
                    dns_rdata_tostruct(&rdata, &rdata_ptr,
                               NULL);

                    isc_buffer_init(&b, hoststr,
                            sizeof(hoststr));
                    iresult =
                        dns_name_totext(&rdata_ptr.ptr,
                                ISC_TRUE, &b);
                    dns_rdata_freestruct(&rdata_ptr);
                    if (iresult == ISC_R_SUCCESS) {
                        /*
                         * We ignore the rest of the
                         * answer.  After all,
                         * getnameinfo() can return
                         * at most one hostname.
                         */
                        found = ISC_TRUE;
                        isc_buffer_usedregion(
                            &b, &hostregion);
                        goto ptrfound;
                    }

                }
            }
        }
    ptrfound:
        dns_client_freeresanswer(client, &answerlist);
        if (found) {
            if ((flags & NI_NOFQDN) != 0) {
                p = strchr(hoststr, '.');
                if (p)
                    *p = '\0';
            }
            if (hostregion.length + 1 > hostlen)
                ERR(EAI_OVERFLOW);
            snprintf(host, hostlen, "%.*s",
                 (int)hostregion.length,
                 (char *)hostregion.base);
        } else {
            if ((flags & NI_NAMEREQD) != 0)
                ERR(EAI_NONAME);
            if (inet_ntop(afd->a_af, addr, numaddr,
                      sizeof(numaddr)) == NULL)
                ERR(EAI_SYSTEM);
            if ((strlen(numaddr) + 1) > hostlen)
                ERR(EAI_OVERFLOW);
            strlcpy(host, numaddr, hostlen);
        }
    }
    result = SUCCESS;

 cleanup:
    return (result);
}