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