xref: /illumos-gate/usr/src/lib/libwrap/workarounds.c (revision 7c478bd9)
1 /*
2  * Copyright 2001 Sun Microsystems, Inc.  All rights reserved.
3  * Use is subject to license terms.
4  */
5 #pragma ident	"%Z%%M%	%I%	%E% SMI"
6 
7  /*
8   * Workarounds for known system software bugs. This module provides wrappers
9   * around library functions and system calls that are known to have problems
10   * on some systems. Most of these workarounds won't do any harm on regular
11   * systems.
12   *
13   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
14   */
15 
16 #ifndef lint
17 char    sccsid[] = "@(#) workarounds.c 1.6 96/03/19 16:22:25";
18 #endif
19 
20 #include <sys/types.h>
21 #include <sys/param.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <arpa/inet.h>
25 #include <netdb.h>
26 #include <errno.h>
27 #include <stdio.h>
28 #include <syslog.h>
29 #include <string.h>
30 
31 extern int errno;
32 
33 #include "tcpd.h"
34 
35  /*
36   * Some AIX versions advertise a too small MAXHOSTNAMELEN value (32).
37   * Result: long hostnames would be truncated, and connections would be
38   * dropped because of host name verification failures. Adrian van Bloois
39   * (A.vanBloois@info.nic.surfnet.nl) figured out what was the problem.
40   */
41 
42 #if (MAXHOSTNAMELEN < 64)
43 #undef MAXHOSTNAMELEN
44 #endif
45 
46 /* In case not defined in <sys/param.h>. */
47 
48 #ifndef MAXHOSTNAMELEN
49 #define MAXHOSTNAMELEN  256             /* storage for host name */
50 #endif
51 
52  /*
53   * Some DG/UX inet_addr() versions return a struct/union instead of a long.
54   * You have this problem when the compiler complains about illegal lvalues
55   * or something like that. The following code fixes this mutant behaviour.
56   * It should not be enabled on "normal" systems.
57   *
58   * Bug reported by ben@piglet.cr.usgs.gov (Rev. Ben A. Mesander).
59   */
60 
61 #ifdef INET_ADDR_BUG
62 
63 #undef inet_addr
64 
fix_inet_addr(string)65 long    fix_inet_addr(string)
66 char   *string;
67 {
68     return (inet_addr(string).s_addr);
69 }
70 
71 #endif /* INET_ADDR_BUG */
72 
73  /*
74   * With some System-V versions, the fgets() library function does not
75   * account for partial reads from e.g. sockets. The result is that fgets()
76   * gives up too soon, causing username lookups to fail. Problem first
77   * reported for IRIX 4.0.5, by Steve Kotsopoulos <steve@ecf.toronto.edu>.
78   * The following code works around the problem. It does no harm on "normal"
79   * systems.
80   */
81 
82 #ifdef BROKEN_FGETS
83 
84 #undef fgets
85 
fix_fgets(buf,len,fp)86 char   *fix_fgets(buf, len, fp)
87 char   *buf;
88 int     len;
89 FILE   *fp;
90 {
91     char   *cp = buf;
92     int     c;
93 
94     /*
95      * Copy until the buffer fills up, until EOF, or until a newline is
96      * found.
97      */
98     while (len > 1 && (c = getc(fp)) != EOF) {
99 	len--;
100 	*cp++ = c;
101 	if (c == '\n')
102 	    break;
103     }
104 
105     /*
106      * Return 0 if nothing was read. This is correct even when a silly buffer
107      * length was specified.
108      */
109     if (cp > buf) {
110 	*cp = 0;
111 	return (buf);
112     } else {
113 	return (0);
114     }
115 }
116 
117 #endif /* BROKEN_FGETS */
118 
119  /*
120   * With early SunOS 5 versions, recvfrom() does not completely fill in the
121   * source address structure when doing a non-destructive read. The following
122   * code works around the problem. It does no harm on "normal" systems.
123   */
124 
125 #ifdef RECVFROM_BUG
126 
127 #undef recvfrom
128 
fix_recvfrom(sock,buf,buflen,flags,from,fromlen)129 int     fix_recvfrom(sock, buf, buflen, flags, from, fromlen)
130 int     sock;
131 char   *buf;
132 int     buflen;
133 int     flags;
134 struct sockaddr *from;
135 int    *fromlen;
136 {
137     int     ret;
138 
139     /* Assume that both ends of a socket belong to the same address family. */
140 
141     if ((ret = recvfrom(sock, buf, buflen, flags, from, fromlen)) >= 0) {
142 	if (from->sa_family == 0) {
143 	    struct sockaddr my_addr;
144 	    int     my_addr_len = sizeof(my_addr);
145 
146 	    if (getsockname(0, &my_addr, &my_addr_len)) {
147 		tcpd_warn("getsockname: %m");
148 	    } else {
149 		from->sa_family = my_addr.sa_family;
150 	    }
151 	}
152     }
153     return (ret);
154 }
155 
156 #endif /* RECVFROM_BUG */
157 
158  /*
159   * The Apollo SR10.3 and some SYSV4 getpeername(2) versions do not return an
160   * error in case of a datagram-oriented socket. Instead, they claim that all
161   * UDP requests come from address 0.0.0.0. The following code works around
162   * the problem. It does no harm on "normal" systems.
163   */
164 
165 #ifdef GETPEERNAME_BUG
166 
167 #undef getpeername
168 
fix_getpeername(sock,sa,len)169 int     fix_getpeername(sock, sa, len)
170 int     sock;
171 struct sockaddr *sa;
172 int    *len;
173 {
174     int     ret;
175     struct sockaddr_in *sin = (struct sockaddr_in *) sa;
176 
177     if ((ret = getpeername(sock, sa, len)) >= 0
178 	&& sa->sa_family == AF_INET
179 	&& sin->sin_addr.s_addr == 0) {
180 	errno = ENOTCONN;
181 	return (-1);
182     } else {
183 	return (ret);
184     }
185 }
186 
187 #endif /* GETPEERNAME_BUG */
188 
189  /*
190   * According to Karl Vogel (vogelke@c-17igp.wpafb.af.mil) some Pyramid
191   * versions have no yp_default_domain() function. We use getdomainname()
192   * instead.
193   */
194 
195 #ifdef USE_GETDOMAIN
196 
yp_get_default_domain(ptr)197 int     yp_get_default_domain(ptr)
198 char  **ptr;
199 {
200     static char mydomain[MAXHOSTNAMELEN];
201 
202     *ptr = mydomain;
203     return (getdomainname(mydomain, MAXHOSTNAMELEN));
204 }
205 
206 #endif /* USE_GETDOMAIN */
207 
208 #ifndef INADDR_NONE
209 #define INADDR_NONE 0xffffffff
210 #endif
211 
212  /*
213   * Solaris 2.4 gethostbyname() has problems with multihomed hosts. When
214   * doing DNS through NIS, only one host address ends up in the address list.
215   * All other addresses end up in the hostname alias list, interspersed with
216   * copies of the official host name. This would wreak havoc with tcpd's
217   * hostname double checks. Below is a workaround that should do no harm when
218   * accidentally left in. A side effect of the workaround is that address
219   * list members are no longer properly aligned for structure access.
220   */
221 
222 #ifdef SOLARIS_24_GETHOSTBYNAME_BUG
223 
224 #undef gethostbyname
225 
fix_gethostbyname(name)226 struct hostent *fix_gethostbyname(name)
227 char   *name;
228 {
229     struct hostent *hp;
230     struct in_addr addr;
231     char  **o_addr_list;
232     char  **o_aliases;
233     char  **n_addr_list;
234     int     broken_gethostbyname = 0;
235 
236     if ((hp = gethostbyname(name)) && !hp->h_addr_list[1] && hp->h_aliases[1]) {
237 	for (o_aliases = n_addr_list = hp->h_aliases; *o_aliases; o_aliases++) {
238 	    if ((addr.s_addr = inet_addr(*o_aliases)) != INADDR_NONE) {
239 		memcpy(*n_addr_list++, (char *) &addr, hp->h_length);
240 		broken_gethostbyname = 1;
241 	    }
242 	}
243 	if (broken_gethostbyname) {
244 	    o_addr_list = hp->h_addr_list;
245 	    memcpy(*n_addr_list++, *o_addr_list, hp->h_length);
246 	    *n_addr_list = 0;
247 	    hp->h_addr_list = hp->h_aliases;
248 	    hp->h_aliases = o_addr_list + 1;
249 	}
250     }
251     return (hp);
252 }
253 
254 #endif /* SOLARIS_24_GETHOSTBYNAME_BUG */
255 
256  /*
257   * Horror! Some FreeBSD 2.0 libc routines call strtok(). Since tcpd depends
258   * heavily on strtok(), strange things may happen. Workaround: use our
259   * private strtok(). This has been fixed in the meantime.
260   */
261 
262 #ifdef USE_STRSEP
263 
fix_strtok(buf,sep)264 char   *fix_strtok(buf, sep)
265 char   *buf;
266 char   *sep;
267 {
268     static char *state;
269     char   *result;
270 
271     if (buf)
272 	state = buf;
273     while ((result = strsep(&state, sep)) && result[0] == 0)
274 	 /* void */ ;
275     return (result);
276 }
277 
278 #endif /* USE_STRSEP */
279 
280  /*
281   * IRIX 5.3 (and possibly earlier versions, too) library routines call the
282   * non-reentrant strtok() library routine, causing hosts to slip through
283   * allow/deny filters. Workaround: don't rely on the vendor and use our own
284   * strtok() function. FreeBSD 2.0 has a similar problem (fixed in 2.0.5).
285   */
286 
287 #ifdef LIBC_CALLS_STRTOK
288 
my_strtok(buf,sep)289 char   *my_strtok(buf, sep)
290 char   *buf;
291 char   *sep;
292 {
293     static char *state;
294     char   *result;
295 
296     if (buf)
297 	state = buf;
298 
299     /*
300      * Skip over separator characters and detect end of string.
301      */
302     if (*(state += strspn(state, sep)) == 0)
303 	return (0);
304 
305     /*
306      * Skip over non-separator characters and terminate result.
307      */
308     result = state;
309     if (*(state += strcspn(state, sep)) != 0)
310 	*state++ = 0;
311     return (result);
312 }
313 
314 #endif /* LIBC_CALLS_STRTOK */
315