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