251 lines
6.6 KiB
C
251 lines
6.6 KiB
C
/*
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* Copyright (c) 1995, 1996, 1998 Theo de Raadt. All rights reserved.
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* Copyright (c) 1983, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <ctype.h>
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#include <limits.h>
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#include <netdb.h>
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#include <netgroup.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <syslog.h>
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#include <unistd.h>
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static int checkhost(struct sockaddr *, socklen_t, const char *);
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static char *gethostloop(struct sockaddr *, socklen_t);
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/*
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* Check whether the specified addr is listed in hostf.
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* Returns 0 if allowed, else -1.
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*/
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int
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allowedhost(FILE *hostf, struct sockaddr *raddr, socklen_t salen)
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{
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char *cp, *ep, *line = NULL;
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char *ahost, *rhost = (char *)-1;
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char domain[HOST_NAME_MAX+1];
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size_t linesize = 0;
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ssize_t linelen;
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int hostok = 0;
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getdomainname(domain, sizeof(domain));
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while ((linelen = getline(&line, &linesize, hostf)) != -1) {
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cp = line;
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ep = line + linelen;
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if (*cp == '#')
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continue;
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while (cp < ep && !isspace((unsigned char)*cp)) {
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if (!isprint((unsigned char)*cp))
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goto bail;
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*cp = isupper((unsigned char)*cp) ?
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tolower((unsigned char)*cp) : *cp;
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cp++;
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}
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if (cp == line)
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continue;
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*cp = '\0';
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ahost = line;
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if (strlen(ahost) > HOST_NAME_MAX)
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continue;
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/*
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* innetgr() must lookup a hostname (we do not attempt
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* to change the semantics so that netgroups may have
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* #.#.#.# addresses in the list.)
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*/
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switch (ahost[0]) {
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case '+':
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case '-':
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switch (ahost[1]) {
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case '\0':
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hostok = 1;
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break;
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case '@':
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if (rhost == (char *)-1)
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rhost = gethostloop(raddr, salen);
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hostok = 0;
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if (rhost)
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hostok = innetgr(&ahost[2], rhost,
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NULL, domain);
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break;
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default:
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hostok = checkhost(raddr, salen, &ahost[1]);
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break;
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}
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if (ahost[0] == '-')
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hostok = -hostok;
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break;
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default:
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hostok = checkhost(raddr, salen, ahost);
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break;
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}
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/* Check if we got a match (positive or negative). */
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if (hostok != 0)
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break;
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}
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bail:
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free(line);
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return (hostok > 0 ? 0 : -1);
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}
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/*
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* Returns 1 if match, 0 if no match. If we do not find any
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* semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work.
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*/
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static int
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checkhost(struct sockaddr *raddr, socklen_t salen, const char *lhost)
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{
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struct addrinfo hints, *res, *r;
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char h1[NI_MAXHOST], h2[NI_MAXHOST];
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int error;
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const int niflags = NI_NUMERICHOST;
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h1[0] = '\0';
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if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, niflags) != 0)
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return (0);
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/* Resolve laddr into sockaddr */
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = raddr->sa_family;
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hints.ai_socktype = SOCK_DGRAM; /*dummy*/
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res = NULL;
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error = getaddrinfo(lhost, "0", &hints, &res);
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if (error)
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return (0);
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/*
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* Try string comparisons between raddr and laddr.
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*/
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for (r = res; r; r = r->ai_next) {
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h2[0] = '\0';
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if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
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NULL, 0, niflags) != 0)
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continue;
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if (strcasecmp(h1, h2) == 0) {
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freeaddrinfo(res);
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return (1);
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}
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}
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/* No match. */
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freeaddrinfo(res);
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return (0);
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}
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/*
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* Return the hostname associated with the supplied address.
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* Do a reverse lookup as well for security. If a loop cannot
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* be found, pack the result of inet_ntoa() into the string.
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*/
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static char *
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gethostloop(struct sockaddr *raddr, socklen_t salen)
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{
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static char remotehost[NI_MAXHOST];
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char h1[NI_MAXHOST], h2[NI_MAXHOST];
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struct addrinfo hints, *res, *r;
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int error;
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const int niflags = NI_NUMERICHOST;
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h1[0] = remotehost[0] = '\0';
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if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost),
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NULL, 0, NI_NAMEREQD) != 0)
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return (NULL);
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if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, niflags) != 0)
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return (NULL);
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/*
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* Look up the name and check that the supplied
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* address is in the list
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = raddr->sa_family;
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hints.ai_socktype = SOCK_DGRAM; /*dummy*/
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hints.ai_flags = AI_CANONNAME;
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res = NULL;
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error = getaddrinfo(remotehost, "0", &hints, &res);
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if (error)
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return (NULL);
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for (r = res; r; r = r->ai_next) {
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h2[0] = '\0';
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if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
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NULL, 0, niflags) != 0)
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continue;
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if (strcasecmp(h1, h2) == 0) {
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freeaddrinfo(res);
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return (remotehost);
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}
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}
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/*
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* Either the DNS administrator has made a configuration
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* mistake, or someone has attempted to spoof us.
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*/
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syslog(LOG_NOTICE, "lpd: address %s not listed for host %s",
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h1, res->ai_canonname ? res->ai_canonname : remotehost);
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freeaddrinfo(res);
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return (NULL);
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}
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#ifdef DEBUG
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int
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main(int argc, char *argv[])
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{
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struct addrinfo hints;
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int i;
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = PF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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for (i = 1; i < argc; i++) {
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struct addrinfo *res0;
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int error = getaddrinfo(argv[i], NULL, &hints, &res0);
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if (error) {
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printf("%s: %s\n", argv[i], gai_strerror(error));
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continue;
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}
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error = allowedhost(stdin, res0->ai_addr, res0->ai_addrlen);
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printf("%s: %s\n", argv[i], error ? "denied" : "allowed");
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}
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exit(0);
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}
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#endif /* DEBUG */
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