Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/net/ruserok.c	Lines:	0	164	0.0 %
Date:	2017-11-07	Branches:	0	140	0.0 %


/*
 * Copyright (c) 1995, 1996, 1998 Theo de Raadt.  All rights reserved.
 * Copyright (c) 1983, 1993, 1994
 *	The Regents of the University of California.  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 University 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 REGENTS 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 REGENTS 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.
 */

#include <sys/socket.h>
#include <sys/stat.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <netdb.h>
#include <netgroup.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

static int __ivaliduser_sa(FILE *, struct sockaddr *, socklen_t,
	    const char *, const char *);
static int __icheckhost(struct sockaddr *, socklen_t, const char *);
static char *__gethostloop(struct sockaddr *, socklen_t);
static int iruserok_sa(const void *, int, int, const char *, const char *);

int
ruserok(const char *rhost, int superuser, const char *ruser, const char *luser)
{
	struct addrinfo hints, *res, *r;
	int error;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
	error = getaddrinfo(rhost, "0", &hints, &res);
	if (error)
		return (-1);

	for (r = res; r; r = r->ai_next) {
		if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser,
		    luser) == 0) {
			freeaddrinfo(res);
			return (0);
		}
	}
	freeaddrinfo(res);
	return (-1);
}

int
iruserok_sa(const void *raddr, int rlen, int superuser, const char *ruser,
    const char *luser)
{
	struct sockaddr *sa;
	char *cp;
	struct stat sbuf;
	struct passwd pwstore, *pwd;
	FILE *hostf;
	uid_t uid;
	int first;
	char pbuf[PATH_MAX], pwbuf[_PW_BUF_LEN];

	sa = (struct sockaddr *)raddr;
	first = 1;
	hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "re");
again:
	if (hostf) {
		if (__ivaliduser_sa(hostf, sa, rlen, luser, ruser) == 0) {
			(void)fclose(hostf);
			return (0);
		}
		(void)fclose(hostf);
	}
	if (first == 1) {
		int len;

		first = 0;
		pwd = NULL;
		getpwnam_r(luser, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
		if (pwd == NULL)
			return (-1);
		len = snprintf(pbuf, sizeof pbuf, "%s/.rhosts", pwd->pw_dir);
		if (len < 0 || len >= sizeof pbuf)
			return (-1);

		/*
		 * Change effective uid while opening .rhosts.  If root and
		 * reading an NFS mounted file system, can't read files that
		 * are protected read/write owner only.
		 */
		uid = geteuid();
		(void)seteuid(pwd->pw_uid);
		hostf = fopen(pbuf, "re");
		(void)seteuid(uid);

		if (hostf == NULL)
			return (-1);
		/*
		 * If not a regular file, or is owned by someone other than
		 * user or root or if writeable by anyone but the owner, quit.
		 */
		cp = NULL;
		if (lstat(pbuf, &sbuf) < 0)
			cp = ".rhosts lstat failed";
		else if (!S_ISREG(sbuf.st_mode))
			cp = ".rhosts not regular file";
		else if (fstat(fileno(hostf), &sbuf) < 0)
			cp = ".rhosts fstat failed";
		else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
			cp = "bad .rhosts owner";
		else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
			cp = ".rhosts writable by other than owner";
		/* If there were any problems, quit. */
		if (cp) {
			(void)fclose(hostf);
			return (-1);
		}
		goto again;
	}
	return (-1);
}

int
__ivaliduser_sa(FILE *hostf, struct sockaddr *raddr, socklen_t salen,
    const char *luser, const char *ruser)
{
	char *user, *p;
	char *buf;
	const char *auser, *ahost;
	int hostok, userok;
	char *rhost = (char *)-1;
	char domain[HOST_NAME_MAX+1];
	size_t buflen;

	getdomainname(domain, sizeof(domain));

	while ((buf = fgetln(hostf, &buflen))) {
		p = buf;
		if (*p == '#')
			continue;
		while (p < buf + buflen && *p != '\n' && *p != ' ' && *p != '\t') {
			if (!isprint((unsigned char)*p))
				goto bail;
			*p = isupper((unsigned char)*p) ?
			    tolower((unsigned char)*p) : *p;
			p++;
		}
		if (p >= buf + buflen)
			continue;
		if (*p == ' ' || *p == '\t') {
			*p++ = '\0';
			while (p < buf + buflen && (*p == ' ' || *p == '\t'))
				p++;
			if (p >= buf + buflen)
				continue;
			user = p;
			while (p < buf + buflen && *p != '\n' && *p != ' ' &&
			    *p != '\t') {
				if (!isprint((unsigned char)*p))
					goto bail;
				p++;
			}
		} else
			user = p;
		*p = '\0';

		if (p == buf)
			continue;

		auser = *user ? user : luser;
		ahost = buf;

		if (strlen(ahost) > HOST_NAME_MAX)
			continue;

		/*
		 * innetgr() must lookup a hostname (we do not attempt
		 * to change the semantics so that netgroups may have
		 * #.#.#.# addresses in the list.)
		 */
		if (ahost[0] == '+')
			switch (ahost[1]) {
			case '\0':
				hostok = 1;
				break;
			case '@':
				if (rhost == (char *)-1)
					rhost = __gethostloop(raddr, salen);
				hostok = 0;
				if (rhost)
					hostok = innetgr(&ahost[2], rhost,
					    NULL, domain);
				break;
			default:
				hostok = __icheckhost(raddr, salen, &ahost[1]);
				break;
			}
		else if (ahost[0] == '-')
			switch (ahost[1]) {
			case '\0':
				hostok = -1;
				break;
			case '@':
				if (rhost == (char *)-1)
					rhost = __gethostloop(raddr, salen);
				hostok = 0;
				if (rhost)
					hostok = -innetgr(&ahost[2], rhost,
					    NULL, domain);
				break;
			default:
				hostok = -__icheckhost(raddr, salen, &ahost[1]);
				break;
			}
		else
			hostok = __icheckhost(raddr, salen, ahost);


		if (auser[0] == '+')
			switch (auser[1]) {
			case '\0':
				userok = 1;
				break;
			case '@':
				userok = innetgr(&auser[2], NULL, ruser,
				    domain);
				break;
			default:
				userok = strcmp(ruser, &auser[1]) ? 0 : 1;
				break;
			}
		else if (auser[0] == '-')
			switch (auser[1]) {
			case '\0':
				userok = -1;
				break;
			case '@':
				userok = -innetgr(&auser[2], NULL, ruser,
				    domain);
				break;
			default:
				userok = strcmp(ruser, &auser[1]) ? 0 : -1;
				break;
			}
		else
			userok = strcmp(ruser, auser) ? 0 : 1;

		/* Check if one component did not match */
		if (hostok == 0 || userok == 0)
			continue;

		/* Check if we got a forbidden pair */
		if (userok <= -1 || hostok <= -1)
			return (-1);

		/* Check if we got a valid pair */
		if (hostok >= 1 && userok >= 1)
			return (0);
	}
bail:
	return (-1);
}

/*
 * Returns "true" if match, 0 if no match.  If we do not find any
 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work.
 */
static int
__icheckhost(struct sockaddr *raddr, socklen_t salen, const char *lhost)
{
	struct addrinfo hints, *res, *r;
	char h1[NI_MAXHOST], h2[NI_MAXHOST];
	int error;
	const int niflags = NI_NUMERICHOST;

	h1[0] = '\0';
	if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
	    niflags) != 0)
		return (0);

	/* Resolve laddr into sockaddr */
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = raddr->sa_family;
	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
	res = NULL;
	error = getaddrinfo(lhost, "0", &hints, &res);
	if (error)
		return (0);

	/*
	 * Try string comparisons between raddr and laddr.
	 */
	for (r = res; r; r = r->ai_next) {
		h2[0] = '\0';
		if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
		    NULL, 0, niflags) != 0)
			continue;
		if (strcmp(h1, h2) == 0) {
			freeaddrinfo(res);
			return (1);
		}
	}

	/* No match. */
	freeaddrinfo(res);
	return (0);
}

/*
 * Return the hostname associated with the supplied address.
 * Do a reverse lookup as well for security. If a loop cannot
 * be found, pack the result of inet_ntoa() into the string.
 */
static char *
__gethostloop(struct sockaddr *raddr, socklen_t salen)
{
	static char remotehost[NI_MAXHOST];
	char h1[NI_MAXHOST], h2[NI_MAXHOST];
	struct addrinfo hints, *res, *r;
	int error;
	const int niflags = NI_NUMERICHOST;

	h1[0] = remotehost[0] = '\0';
	if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost),
	    NULL, 0, NI_NAMEREQD) != 0)
		return (NULL);
	if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
	    niflags) != 0)
		return (NULL);

	/*
	 * Look up the name and check that the supplied
	 * address is in the list
	 */
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = raddr->sa_family;
	hints.ai_socktype = SOCK_DGRAM;	/*dummy*/
	hints.ai_flags = AI_CANONNAME;
	res = NULL;
	error = getaddrinfo(remotehost, "0", &hints, &res);
	if (error)
		return (NULL);

	for (r = res; r; r = r->ai_next) {
		h2[0] = '\0';
		if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
		    NULL, 0, niflags) != 0)
			continue;
		if (strcmp(h1, h2) == 0) {
			freeaddrinfo(res);
			return (remotehost);
		}
	}

	/*
	 * either the DNS adminstrator has made a configuration
	 * mistake, or someone has attempted to spoof us
	 */
	freeaddrinfo(res);
	return (NULL);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/*
2			* Copyright (c) 1995, 1996, 1998 Theo de Raadt. All rights reserved.
3			* Copyright (c) 1983, 1993, 1994
4			* The Regents of the University of California. All rights reserved.
5			*
6			* Redistribution and use in source and binary forms, with or without
7			* modification, are permitted provided that the following conditions
8			* are met:
9			* 1. Redistributions of source code must retain the above copyright
10			* notice, this list of conditions and the following disclaimer.
11			* 2. Redistributions in binary form must reproduce the above copyright
12			* notice, this list of conditions and the following disclaimer in the
13			* documentation and/or other materials provided with the distribution.
14			* 3. Neither the name of the University nor the names of its contributors
15			* may be used to endorse or promote products derived from this software
16			* without specific prior written permission.
17			*
18			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28			* SUCH DAMAGE.
29			*/
30
31			#include <sys/socket.h>
32			#include <sys/stat.h>
33
34			#include <netinet/in.h>
35			#include <arpa/inet.h>
36
37			#include <ctype.h>
38			#include <errno.h>
39			#include <fcntl.h>
40			#include <limits.h>
41			#include <netdb.h>
42			#include <netgroup.h>
43			#include <pwd.h>
44			#include <signal.h>
45			#include <stdio.h>
46			#include <stdlib.h>
47			#include <string.h>
48			#include <syslog.h>
49			#include <unistd.h>
50
51			static int __ivaliduser_sa(FILE , struct sockaddr , socklen_t,
52			const char , const char );
53			static int __icheckhost(struct sockaddr , socklen_t, const char );
54			static char __gethostloop(struct sockaddr , socklen_t);
55			static int iruserok_sa(const void , int, int, const char , const char *);
56
57			int
58			ruserok(const char rhost, int superuser, const char ruser, const char *luser)
59			{
60			struct addrinfo hints, res, r;
61			int error;
62
63			memset(&hints, 0, sizeof(hints));
64			hints.ai_family = PF_UNSPEC;
65			hints.ai_socktype = SOCK_DGRAM; /dummy/
66			error = getaddrinfo(rhost, "0", &hints, &res);
67			if (error)
68			return (-1);
69
70			for (r = res; r; r = r->ai_next) {
71			if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser,
72			luser) == 0) {
73			freeaddrinfo(res);
74			return (0);
75			}
76			}
77			freeaddrinfo(res);
78			return (-1);
79			}
80
81			int
82			iruserok_sa(const void raddr, int rlen, int superuser, const char ruser,
83			const char *luser)
84			{
85			struct sockaddr *sa;
86			char *cp;
87			struct stat sbuf;
88			struct passwd pwstore, *pwd;
89			FILE *hostf;
90			uid_t uid;
91			int first;
92			char pbuf[PATH_MAX], pwbuf[_PW_BUF_LEN];
93
94			sa = (struct sockaddr *)raddr;
95			first = 1;
96			hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "re");
97			again:
98			if (hostf) {
99			if (__ivaliduser_sa(hostf, sa, rlen, luser, ruser) == 0) {
100			(void)fclose(hostf);
101			return (0);
102			}
103			(void)fclose(hostf);
104			}
105			if (first == 1) {
106			int len;
107
108			first = 0;
109			pwd = NULL;
110			getpwnam_r(luser, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
111			if (pwd == NULL)
112			return (-1);
113			len = snprintf(pbuf, sizeof pbuf, "%s/.rhosts", pwd->pw_dir);
114			if (len < 0 \|\| len >= sizeof pbuf)
115			return (-1);
116
117			/*
118			* Change effective uid while opening .rhosts. If root and
119			* reading an NFS mounted file system, can't read files that
120			* are protected read/write owner only.
121			*/
122			uid = geteuid();
123			(void)seteuid(pwd->pw_uid);
124			hostf = fopen(pbuf, "re");
125			(void)seteuid(uid);
126
127			if (hostf == NULL)
128			return (-1);
129			/*
130			* If not a regular file, or is owned by someone other than
131			* user or root or if writeable by anyone but the owner, quit.
132			*/
133			cp = NULL;
134			if (lstat(pbuf, &sbuf) < 0)
135			cp = ".rhosts lstat failed";
136			else if (!S_ISREG(sbuf.st_mode))
137			cp = ".rhosts not regular file";
138			else if (fstat(fileno(hostf), &sbuf) < 0)
139			cp = ".rhosts fstat failed";
140			else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
141			cp = "bad .rhosts owner";
142			else if (sbuf.st_mode & (S_IWGRP\|S_IWOTH))
143			cp = ".rhosts writable by other than owner";
144			/* If there were any problems, quit. */
145			if (cp) {
146			(void)fclose(hostf);
147			return (-1);
148			}
149			goto again;
150			}
151			return (-1);
152			}
153
154			int
155			__ivaliduser_sa(FILE hostf, struct sockaddr raddr, socklen_t salen,
156			const char luser, const char ruser)
157			{
158			char user, p;
159			char *buf;
160			const char auser, ahost;
161			int hostok, userok;
162			char rhost = (char )-1;
163			char domain[HOST_NAME_MAX+1];
164			size_t buflen;
165
166			getdomainname(domain, sizeof(domain));
167
168			while ((buf = fgetln(hostf, &buflen))) {
169			p = buf;
170			if (*p == '#')
171			continue;
172			while (p < buf + buflen && p != '\n' && p != ' ' && *p != '\t') {
173			if (!isprint((unsigned char)*p))
174			goto bail;
175			p = isupper((unsigned char)p) ?
176			tolower((unsigned char)p) : p;
177			p++;
178			}
179			if (p >= buf + buflen)
180			continue;
181			if (p == ' ' \|\| p == '\t') {
182			*p++ = '\0';
183			while (p < buf + buflen && (p == ' ' \|\| p == '\t'))
184			p++;
185			if (p >= buf + buflen)
186			continue;
187			user = p;
188			while (p < buf + buflen && p != '\n' && p != ' ' &&
189			*p != '\t') {
190			if (!isprint((unsigned char)*p))
191			goto bail;
192			p++;
193			}
194			} else
195			user = p;
196			*p = '\0';
197
198			if (p == buf)
199			continue;
200
201			auser = *user ? user : luser;
202			ahost = buf;
203
204			if (strlen(ahost) > HOST_NAME_MAX)
205			continue;
206
207			/*
208			* innetgr() must lookup a hostname (we do not attempt
209			* to change the semantics so that netgroups may have
210			* #.#.#.# addresses in the list.)
211			*/
212			if (ahost[0] == '+')
213			switch (ahost[1]) {
214			case '\0':
215			hostok = 1;
216			break;
217			case '@':
218			if (rhost == (char *)-1)
219			rhost = __gethostloop(raddr, salen);
220			hostok = 0;
221			if (rhost)
222			hostok = innetgr(&ahost[2], rhost,
223			NULL, domain);
224			break;
225			default:
226			hostok = __icheckhost(raddr, salen, &ahost[1]);
227			break;
228			}
229			else if (ahost[0] == '-')
230			switch (ahost[1]) {
231			case '\0':
232			hostok = -1;
233			break;
234			case '@':
235			if (rhost == (char *)-1)
236			rhost = __gethostloop(raddr, salen);
237			hostok = 0;
238			if (rhost)
239			hostok = -innetgr(&ahost[2], rhost,
240			NULL, domain);
241			break;
242			default:
243			hostok = -__icheckhost(raddr, salen, &ahost[1]);
244			break;
245			}
246			else
247			hostok = __icheckhost(raddr, salen, ahost);
248
249
250			if (auser[0] == '+')
251			switch (auser[1]) {
252			case '\0':
253			userok = 1;
254			break;
255			case '@':
256			userok = innetgr(&auser[2], NULL, ruser,
257			domain);
258			break;
259			default:
260			userok = strcmp(ruser, &auser[1]) ? 0 : 1;
261			break;
262			}
263			else if (auser[0] == '-')
264			switch (auser[1]) {
265			case '\0':
266			userok = -1;
267			break;
268			case '@':
269			userok = -innetgr(&auser[2], NULL, ruser,
270			domain);
271			break;
272			default:
273			userok = strcmp(ruser, &auser[1]) ? 0 : -1;
274			break;
275			}
276			else
277			userok = strcmp(ruser, auser) ? 0 : 1;
278
279			/* Check if one component did not match */
280			if (hostok == 0 \|\| userok == 0)
281			continue;
282
283			/* Check if we got a forbidden pair */
284			if (userok <= -1 \|\| hostok <= -1)
285			return (-1);
286
287			/* Check if we got a valid pair */
288			if (hostok >= 1 && userok >= 1)
289			return (0);
290			}
291			bail:
292			return (-1);
293			}
294
295			/*
296			* Returns "true" if match, 0 if no match. If we do not find any
297			* semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work.
298			*/
299			static int
300			__icheckhost(struct sockaddr raddr, socklen_t salen, const char lhost)
301			{
302			struct addrinfo hints, res, r;
303			char h1[NI_MAXHOST], h2[NI_MAXHOST];
304			int error;
305			const int niflags = NI_NUMERICHOST;
306
307			h1[0] = '\0';
308			if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
309			niflags) != 0)
310			return (0);
311
312			/* Resolve laddr into sockaddr */
313			memset(&hints, 0, sizeof(hints));
314			hints.ai_family = raddr->sa_family;
315			hints.ai_socktype = SOCK_DGRAM; /dummy/
316			res = NULL;
317			error = getaddrinfo(lhost, "0", &hints, &res);
318			if (error)
319			return (0);
320
321			/*
322			* Try string comparisons between raddr and laddr.
323			*/
324			for (r = res; r; r = r->ai_next) {
325			h2[0] = '\0';
326			if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
327			NULL, 0, niflags) != 0)
328			continue;
329			if (strcmp(h1, h2) == 0) {
330			freeaddrinfo(res);
331			return (1);
332			}
333			}
334
335			/* No match. */
336			freeaddrinfo(res);
337			return (0);
338			}
339
340			/*
341			* Return the hostname associated with the supplied address.
342			* Do a reverse lookup as well for security. If a loop cannot
343			* be found, pack the result of inet_ntoa() into the string.
344			*/
345			static char *
346			__gethostloop(struct sockaddr *raddr, socklen_t salen)
347			{
348			static char remotehost[NI_MAXHOST];
349			char h1[NI_MAXHOST], h2[NI_MAXHOST];
350			struct addrinfo hints, res, r;
351			int error;
352			const int niflags = NI_NUMERICHOST;
353
354			h1[0] = remotehost[0] = '\0';
355			if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost),
356			NULL, 0, NI_NAMEREQD) != 0)
357			return (NULL);
358			if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0,
359			niflags) != 0)
360			return (NULL);
361
362			/*
363			* Look up the name and check that the supplied
364			* address is in the list
365			*/
366			memset(&hints, 0, sizeof(hints));
367			hints.ai_family = raddr->sa_family;
368			hints.ai_socktype = SOCK_DGRAM; /dummy/
369			hints.ai_flags = AI_CANONNAME;
370			res = NULL;
371			error = getaddrinfo(remotehost, "0", &hints, &res);
372			if (error)
373			return (NULL);
374
375			for (r = res; r; r = r->ai_next) {
376			h2[0] = '\0';
377			if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2),
378			NULL, 0, niflags) != 0)
379			continue;
380			if (strcmp(h1, h2) == 0) {
381			freeaddrinfo(res);
382			return (remotehost);
383			}
384			}
385
386			/*
387			* either the DNS adminstrator has made a configuration
388			* mistake, or someone has attempted to spoof us
389			*/
390			freeaddrinfo(res);
391			return (NULL);
392			}