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   * $FreeBSD: src/contrib/tcp_wrappers/workarounds.c,v 1.2 2000/02/03 10:27:01 shin Exp $
10   * $DragonFly: src/contrib/tcp_wrappers/workarounds.c,v 1.2 2003/06/17 04:24:06 dillon Exp $
11   */
12 
13 #ifndef lint
14 char    sccsid[] = "@(#) workarounds.c 1.6 96/03/19 16:22:25";
15 #endif
16 
17 #include <sys/types.h>
18 #include <sys/param.h>
19 #include <sys/socket.h>
20 #include <netinet/in.h>
21 #include <arpa/inet.h>
22 #include <netdb.h>
23 #include <errno.h>
24 #include <stdio.h>
25 #include <syslog.h>
26 #include <string.h>
27 
28 extern int errno;
29 
30 #include "tcpd.h"
31 
32  /*
33   * Some AIX versions advertise a too small MAXHOSTNAMELEN value (32).
34   * Result: long hostnames would be truncated, and connections would be
35   * dropped because of host name verification failures. Adrian van Bloois
36   * (A.vanBloois@info.nic.surfnet.nl) figured out what was the problem.
37   */
38 
39 #if (MAXHOSTNAMELEN < 64)
40 #undef MAXHOSTNAMELEN
41 #endif
42 
43 /* In case not defined in <sys/param.h>. */
44 
45 #ifndef MAXHOSTNAMELEN
46 #define MAXHOSTNAMELEN  256             /* storage for host name */
47 #endif
48 
49  /*
50   * Some DG/UX inet_addr() versions return a struct/union instead of a long.
51   * You have this problem when the compiler complains about illegal lvalues
52   * or something like that. The following code fixes this mutant behaviour.
53   * It should not be enabled on "normal" systems.
54   *
55   * Bug reported by ben@piglet.cr.usgs.gov (Rev. Ben A. Mesander).
56   */
57 
58 #ifdef INET_ADDR_BUG
59 
60 #undef inet_addr
61 
62 long    fix_inet_addr(string)
63 char   *string;
64 {
65     return (inet_addr(string).s_addr);
66 }
67 
68 #endif /* INET_ADDR_BUG */
69 
70  /*
71   * With some System-V versions, the fgets() library function does not
72   * account for partial reads from e.g. sockets. The result is that fgets()
73   * gives up too soon, causing username lookups to fail. Problem first
74   * reported for IRIX 4.0.5, by Steve Kotsopoulos <steve@ecf.toronto.edu>.
75   * The following code works around the problem. It does no harm on "normal"
76   * systems.
77   */
78 
79 #ifdef BROKEN_FGETS
80 
81 #undef fgets
82 
83 char   *fix_fgets(buf, len, fp)
84 char   *buf;
85 int     len;
86 FILE   *fp;
87 {
88     char   *cp = buf;
89     int     c;
90 
91     /*
92      * Copy until the buffer fills up, until EOF, or until a newline is
93      * found.
94      */
95     while (len > 1 && (c = getc(fp)) != EOF) {
96 	len--;
97 	*cp++ = c;
98 	if (c == '\n')
99 	    break;
100     }
101 
102     /*
103      * Return 0 if nothing was read. This is correct even when a silly buffer
104      * length was specified.
105      */
106     if (cp > buf) {
107 	*cp = 0;
108 	return (buf);
109     } else {
110 	return (0);
111     }
112 }
113 
114 #endif /* BROKEN_FGETS */
115 
116  /*
117   * With early SunOS 5 versions, recvfrom() does not completely fill in the
118   * source address structure when doing a non-destructive read. The following
119   * code works around the problem. It does no harm on "normal" systems.
120   */
121 
122 #ifdef RECVFROM_BUG
123 
124 #undef recvfrom
125 
126 int     fix_recvfrom(sock, buf, buflen, flags, from, fromlen)
127 int     sock;
128 char   *buf;
129 int     buflen;
130 int     flags;
131 struct sockaddr *from;
132 int    *fromlen;
133 {
134     int     ret;
135 
136     /* Assume that both ends of a socket belong to the same address family. */
137 
138     if ((ret = recvfrom(sock, buf, buflen, flags, from, fromlen)) >= 0) {
139 	if (from->sa_family == 0) {
140 	    struct sockaddr my_addr;
141 	    int     my_addr_len = sizeof(my_addr);
142 
143 	    if (getsockname(0, &my_addr, &my_addr_len)) {
144 		tcpd_warn("getsockname: %m");
145 	    } else {
146 		from->sa_family = my_addr.sa_family;
147 	    }
148 	}
149     }
150     return (ret);
151 }
152 
153 #endif /* RECVFROM_BUG */
154 
155  /*
156   * The Apollo SR10.3 and some SYSV4 getpeername(2) versions do not return an
157   * error in case of a datagram-oriented socket. Instead, they claim that all
158   * UDP requests come from address 0.0.0.0. The following code works around
159   * the problem. It does no harm on "normal" systems.
160   */
161 
162 #ifdef GETPEERNAME_BUG
163 
164 #undef getpeername
165 
166 int     fix_getpeername(sock, sa, len)
167 int     sock;
168 struct sockaddr *sa;
169 int    *len;
170 {
171     int     ret;
172 #ifdef INET6
173     struct sockaddr *sin = sa;
174 #else
175     struct sockaddr_in *sin = (struct sockaddr_in *) sa;
176 #endif
177 
178     if ((ret = getpeername(sock, sa, len)) >= 0
179 #ifdef INET6
180 	&& ((sin->su_si.si_family == AF_INET6
181 	     && IN6_IS_ADDR_UNSPECIFIED(&sin->su_sin6.sin6_addr))
182 	    || (sin->su_si.si_family == AF_INET
183 		&& sin->su_sin.sin_addr.s_addr == 0))) {
184 #else
185 	&& sa->sa_family == AF_INET
186 	&& sin->sin_addr.s_addr == 0) {
187 #endif
188 	errno = ENOTCONN;
189 	return (-1);
190     } else {
191 	return (ret);
192     }
193 }
194 
195 #endif /* GETPEERNAME_BUG */
196 
197  /*
198   * According to Karl Vogel (vogelke@c-17igp.wpafb.af.mil) some Pyramid
199   * versions have no yp_default_domain() function. We use getdomainname()
200   * instead.
201   */
202 
203 #ifdef USE_GETDOMAIN
204 
205 int     yp_get_default_domain(ptr)
206 char  **ptr;
207 {
208     static char mydomain[MAXHOSTNAMELEN];
209 
210     *ptr = mydomain;
211     return (getdomainname(mydomain, MAXHOSTNAMELEN));
212 }
213 
214 #endif /* USE_GETDOMAIN */
215 
216 #ifndef INADDR_NONE
217 #define INADDR_NONE 0xffffffff
218 #endif
219 
220  /*
221   * Solaris 2.4 gethostbyname() has problems with multihomed hosts. When
222   * doing DNS through NIS, only one host address ends up in the address list.
223   * All other addresses end up in the hostname alias list, interspersed with
224   * copies of the official host name. This would wreak havoc with tcpd's
225   * hostname double checks. Below is a workaround that should do no harm when
226   * accidentally left in. A side effect of the workaround is that address
227   * list members are no longer properly aligned for structure access.
228   */
229 
230 #ifdef SOLARIS_24_GETHOSTBYNAME_BUG
231 
232 #undef gethostbyname
233 
234 struct hostent *fix_gethostbyname(name)
235 char   *name;
236 {
237     struct hostent *hp;
238     struct in_addr addr;
239     char  **o_addr_list;
240     char  **o_aliases;
241     char  **n_addr_list;
242     int     broken_gethostbyname = 0;
243 
244     if ((hp = gethostbyname(name)) && !hp->h_addr_list[1] && hp->h_aliases[1]) {
245 	for (o_aliases = n_addr_list = hp->h_aliases; *o_aliases; o_aliases++) {
246 	    if ((addr.s_addr = inet_addr(*o_aliases)) != INADDR_NONE) {
247 		memcpy(*n_addr_list++, (char *) &addr, hp->h_length);
248 		broken_gethostbyname = 1;
249 	    }
250 	}
251 	if (broken_gethostbyname) {
252 	    o_addr_list = hp->h_addr_list;
253 	    memcpy(*n_addr_list++, *o_addr_list, hp->h_length);
254 	    *n_addr_list = 0;
255 	    hp->h_addr_list = hp->h_aliases;
256 	    hp->h_aliases = o_addr_list + 1;
257 	}
258     }
259     return (hp);
260 }
261 
262 #endif /* SOLARIS_24_GETHOSTBYNAME_BUG */
263 
264  /*
265   * Horror! Some FreeBSD 2.0 libc routines call strtok(). Since tcpd depends
266   * heavily on strtok(), strange things may happen. Workaround: use our
267   * private strtok(). This has been fixed in the meantime.
268   */
269 
270 #ifdef USE_STRSEP
271 
272 char   *fix_strtok(buf, sep)
273 char   *buf;
274 char   *sep;
275 {
276     static char *state;
277     char   *result;
278 
279     if (buf)
280 	state = buf;
281     while ((result = strsep(&state, sep)) && result[0] == 0)
282 	 /* void */ ;
283     return (result);
284 }
285 
286 #endif /* USE_STRSEP */
287 
288  /*
289   * IRIX 5.3 (and possibly earlier versions, too) library routines call the
290   * non-reentrant strtok() library routine, causing hosts to slip through
291   * allow/deny filters. Workaround: don't rely on the vendor and use our own
292   * strtok() function. FreeBSD 2.0 has a similar problem (fixed in 2.0.5).
293   */
294 
295 #ifdef LIBC_CALLS_STRTOK
296 
297 char   *my_strtok(buf, sep)
298 char   *buf;
299 char   *sep;
300 {
301     static char *state;
302     char   *result;
303 
304     if (buf)
305 	state = buf;
306 
307     /*
308      * Skip over separator characters and detect end of string.
309      */
310     if (*(state += strspn(state, sep)) == 0)
311 	return (0);
312 
313     /*
314      * Skip over non-separator characters and terminate result.
315      */
316     result = state;
317     if (*(state += strcspn(state, sep)) != 0)
318 	*state++ = 0;
319     return (result);
320 }
321 
322 #endif /* LIBC_CALLS_STRTOK */
323