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 * $FreeBSD$
10 */
11
12 #ifndef lint
13 char sccsid[] = "@(#) workarounds.c 1.6 96/03/19 16:22:25";
14 #endif
15
16 #include <sys/types.h>
17 #include <sys/param.h>
18 #include <sys/socket.h>
19 #include <netinet/in.h>
20 #include <arpa/inet.h>
21 #include <netdb.h>
22 #include <errno.h>
23 #include <stdio.h>
24 #include <syslog.h>
25 #include <string.h>
26 #ifdef USE_GETDOMAIN
27 #include <unistd.h>
28 #endif
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
fix_inet_addr(char * string)62 long fix_inet_addr(char *string)
63 {
64 return (inet_addr(string).s_addr);
65 }
66
67 #endif /* INET_ADDR_BUG */
68
69 /*
70 * With some System-V versions, the fgets() library function does not
71 * account for partial reads from e.g. sockets. The result is that fgets()
72 * gives up too soon, causing username lookups to fail. Problem first
73 * reported for IRIX 4.0.5, by Steve Kotsopoulos <steve@ecf.toronto.edu>.
74 * The following code works around the problem. It does no harm on "normal"
75 * systems.
76 */
77
78 #ifdef BROKEN_FGETS
79
80 #undef fgets
81
fix_fgets(char * buf,int len,FILE * fp)82 char *fix_fgets(char *buf, int len, FILE *fp)
83 {
84 char *cp = buf;
85 int c;
86
87 /*
88 * Copy until the buffer fills up, until EOF, or until a newline is
89 * found.
90 */
91 while (len > 1 && (c = getc(fp)) != EOF) {
92 len--;
93 *cp++ = c;
94 if (c == '\n')
95 break;
96 }
97
98 /*
99 * Return 0 if nothing was read. This is correct even when a silly buffer
100 * length was specified.
101 */
102 if (cp > buf) {
103 *cp = 0;
104 return (buf);
105 } else {
106 return (0);
107 }
108 }
109
110 #endif /* BROKEN_FGETS */
111
112 /*
113 * With early SunOS 5 versions, recvfrom() does not completely fill in the
114 * source address structure when doing a non-destructive read. The following
115 * code works around the problem. It does no harm on "normal" systems.
116 */
117
118 #ifdef RECVFROM_BUG
119
120 #undef recvfrom
121
fix_recvfrom(int sock,char * buf,int buflen,int flags,struct sockaddr * from,int * fromlen)122 int fix_recvfrom(int sock, char *buf, int buflen, int flags,
123 struct sockaddr *from, int *fromlen)
124 {
125 int ret;
126
127 /* Assume that both ends of a socket belong to the same address family. */
128
129 if ((ret = recvfrom(sock, buf, buflen, flags, from, fromlen)) >= 0) {
130 if (from->sa_family == 0) {
131 struct sockaddr my_addr;
132 int my_addr_len = sizeof(my_addr);
133
134 if (getsockname(0, &my_addr, &my_addr_len)) {
135 tcpd_warn("getsockname: %m");
136 } else {
137 from->sa_family = my_addr.sa_family;
138 }
139 }
140 }
141 return (ret);
142 }
143
144 #endif /* RECVFROM_BUG */
145
146 /*
147 * The Apollo SR10.3 and some SYSV4 getpeername(2) versions do not return an
148 * error in case of a datagram-oriented socket. Instead, they claim that all
149 * UDP requests come from address 0.0.0.0. The following code works around
150 * the problem. It does no harm on "normal" systems.
151 */
152
153 #ifdef GETPEERNAME_BUG
154
155 #undef getpeername
156
fix_getpeername(int sock,struct sockaddr * sa,int * len)157 int fix_getpeername(int sock, struct sockaddr *sa, int *len)
158 {
159 int ret;
160 #ifdef INET6
161 struct sockaddr *sin = sa;
162 #else
163 struct sockaddr_in *sin = (struct sockaddr_in *) sa;
164 #endif
165
166 if ((ret = getpeername(sock, sa, len)) >= 0
167 #ifdef INET6
168 && ((sin->su_si.si_family == AF_INET6
169 && IN6_IS_ADDR_UNSPECIFIED(&sin->su_sin6.sin6_addr))
170 || (sin->su_si.si_family == AF_INET
171 && sin->su_sin.sin_addr.s_addr == 0))) {
172 #else
173 && sa->sa_family == AF_INET
174 && sin->sin_addr.s_addr == 0) {
175 #endif
176 errno = ENOTCONN;
177 return (-1);
178 } else {
179 return (ret);
180 }
181 }
182
183 #endif /* GETPEERNAME_BUG */
184
185 /*
186 * According to Karl Vogel (vogelke@c-17igp.wpafb.af.mil) some Pyramid
187 * versions have no yp_default_domain() function. We use getdomainname()
188 * instead.
189 */
190
191 #ifdef USE_GETDOMAIN
192
193 int yp_get_default_domain(char **ptr)
194 {
195 static char mydomain[MAXHOSTNAMELEN];
196
197 *ptr = mydomain;
198 return (getdomainname(mydomain, MAXHOSTNAMELEN));
199 }
200
201 #endif /* USE_GETDOMAIN */
202
203 #ifndef INADDR_NONE
204 #define INADDR_NONE 0xffffffff
205 #endif
206
207 /*
208 * Solaris 2.4 gethostbyname() has problems with multihomed hosts. When
209 * doing DNS through NIS, only one host address ends up in the address list.
210 * All other addresses end up in the hostname alias list, interspersed with
211 * copies of the official host name. This would wreak havoc with tcpd's
212 * hostname double checks. Below is a workaround that should do no harm when
213 * accidentally left in. A side effect of the workaround is that address
214 * list members are no longer properly aligned for structure access.
215 */
216
217 #ifdef SOLARIS_24_GETHOSTBYNAME_BUG
218
219 #undef gethostbyname
220
221 struct hostent *fix_gethostbyname(char *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
258 char *fix_strtok(char *buf, char *sep)
259 {
260 static char *state;
261 char *result;
262
263 if (buf)
264 state = buf;
265 while ((result = strsep(&state, sep)) && result[0] == 0)
266 /* void */ ;
267 return (result);
268 }
269
270 #endif /* USE_STRSEP */
271
272 /*
273 * IRIX 5.3 (and possibly earlier versions, too) library routines call the
274 * non-reentrant strtok() library routine, causing hosts to slip through
275 * allow/deny filters. Workaround: don't rely on the vendor and use our own
276 * strtok() function. FreeBSD 2.0 has a similar problem (fixed in 2.0.5).
277 */
278
279 #ifdef LIBC_CALLS_STRTOK
280
281 char *my_strtok(char *buf, char *sep)
282 {
283 static char *state;
284 char *result;
285
286 if (buf)
287 state = buf;
288
289 /*
290 * Skip over separator characters and detect end of string.
291 */
292 if (*(state += strspn(state, sep)) == 0)
293 return (0);
294
295 /*
296 * Skip over non-separator characters and terminate result.
297 */
298 result = state;
299 if (*(state += strcspn(state, sep)) != 0)
300 *state++ = 0;
301 return (result);
302 }
303
304 #endif /* LIBC_CALLS_STRTOK */
305