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
7 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
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 1.3 2005/04/29 01:00:27 joerg Exp $
14 char sccsid[] = "@(#) workarounds.c 1.6 96/03/19 16:22:25";
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>
31 * Some AIX versions advertise a too small MAXHOSTNAMELEN value (32).
32 * Result: long hostnames would be truncated, and connections would be
33 * dropped because of host name verification failures. Adrian van Bloois
34 * (A.vanBloois@info.nic.surfnet.nl) figured out what was the problem.
37 #if (MAXHOSTNAMELEN < 64)
41 /* In case not defined in <sys/param.h>. */
43 #ifndef MAXHOSTNAMELEN
44 #define MAXHOSTNAMELEN 256 /* storage for host name */
48 * Some DG/UX inet_addr() versions return a struct/union instead of a long.
49 * You have this problem when the compiler complains about illegal lvalues
50 * or something like that. The following code fixes this mutant behaviour.
51 * It should not be enabled on "normal" systems.
53 * Bug reported by ben@piglet.cr.usgs.gov (Rev. Ben A. Mesander).
60 long fix_inet_addr(string)
63 return (inet_addr(string).s_addr);
66 #endif /* INET_ADDR_BUG */
69 * With some System-V versions, the fgets() library function does not
70 * account for partial reads from e.g. sockets. The result is that fgets()
71 * gives up too soon, causing username lookups to fail. Problem first
72 * reported for IRIX 4.0.5, by Steve Kotsopoulos <steve@ecf.toronto.edu>.
73 * The following code works around the problem. It does no harm on "normal"
81 char *fix_fgets(buf, len, fp)
90 * Copy until the buffer fills up, until EOF, or until a newline is
93 while (len > 1 && (c = getc(fp)) != EOF) {
101 * Return 0 if nothing was read. This is correct even when a silly buffer
102 * length was specified.
112 #endif /* BROKEN_FGETS */
115 * With early SunOS 5 versions, recvfrom() does not completely fill in the
116 * source address structure when doing a non-destructive read. The following
117 * code works around the problem. It does no harm on "normal" systems.
124 int fix_recvfrom(sock, buf, buflen, flags, from, fromlen)
129 struct sockaddr *from;
134 /* Assume that both ends of a socket belong to the same address family. */
136 if ((ret = recvfrom(sock, buf, buflen, flags, from, fromlen)) >= 0) {
137 if (from->sa_family == 0) {
138 struct sockaddr my_addr;
139 int my_addr_len = sizeof(my_addr);
141 if (getsockname(0, &my_addr, &my_addr_len)) {
142 tcpd_warn("getsockname: %m");
144 from->sa_family = my_addr.sa_family;
151 #endif /* RECVFROM_BUG */
154 * The Apollo SR10.3 and some SYSV4 getpeername(2) versions do not return an
155 * error in case of a datagram-oriented socket. Instead, they claim that all
156 * UDP requests come from address 0.0.0.0. The following code works around
157 * the problem. It does no harm on "normal" systems.
160 #ifdef GETPEERNAME_BUG
164 int fix_getpeername(sock, sa, len)
171 struct sockaddr *sin = sa;
173 struct sockaddr_in *sin = (struct sockaddr_in *) sa;
176 if ((ret = getpeername(sock, sa, len)) >= 0
178 && ((sin->su_si.si_family == AF_INET6
179 && IN6_IS_ADDR_UNSPECIFIED(&sin->su_sin6.sin6_addr))
180 || (sin->su_si.si_family == AF_INET
181 && sin->su_sin.sin_addr.s_addr == 0))) {
183 && sa->sa_family == AF_INET
184 && sin->sin_addr.s_addr == 0) {
193 #endif /* GETPEERNAME_BUG */
196 * According to Karl Vogel (vogelke@c-17igp.wpafb.af.mil) some Pyramid
197 * versions have no yp_default_domain() function. We use getdomainname()
203 int yp_get_default_domain(ptr)
206 static char mydomain[MAXHOSTNAMELEN];
209 return (getdomainname(mydomain, MAXHOSTNAMELEN));
212 #endif /* USE_GETDOMAIN */
215 #define INADDR_NONE 0xffffffff
219 * Solaris 2.4 gethostbyname() has problems with multihomed hosts. When
220 * doing DNS through NIS, only one host address ends up in the address list.
221 * All other addresses end up in the hostname alias list, interspersed with
222 * copies of the official host name. This would wreak havoc with tcpd's
223 * hostname double checks. Below is a workaround that should do no harm when
224 * accidentally left in. A side effect of the workaround is that address
225 * list members are no longer properly aligned for structure access.
228 #ifdef SOLARIS_24_GETHOSTBYNAME_BUG
232 struct hostent *fix_gethostbyname(name)
240 int broken_gethostbyname = 0;
242 if ((hp = gethostbyname(name)) && !hp->h_addr_list[1] && hp->h_aliases[1]) {
243 for (o_aliases = n_addr_list = hp->h_aliases; *o_aliases; o_aliases++) {
244 if ((addr.s_addr = inet_addr(*o_aliases)) != INADDR_NONE) {
245 memcpy(*n_addr_list++, (char *) &addr, hp->h_length);
246 broken_gethostbyname = 1;
249 if (broken_gethostbyname) {
250 o_addr_list = hp->h_addr_list;
251 memcpy(*n_addr_list++, *o_addr_list, hp->h_length);
253 hp->h_addr_list = hp->h_aliases;
254 hp->h_aliases = o_addr_list + 1;
260 #endif /* SOLARIS_24_GETHOSTBYNAME_BUG */
263 * Horror! Some FreeBSD 2.0 libc routines call strtok(). Since tcpd depends
264 * heavily on strtok(), strange things may happen. Workaround: use our
265 * private strtok(). This has been fixed in the meantime.
270 char *fix_strtok(buf, sep)
279 while ((result = strsep(&state, sep)) && result[0] == 0)
284 #endif /* USE_STRSEP */
287 * IRIX 5.3 (and possibly earlier versions, too) library routines call the
288 * non-reentrant strtok() library routine, causing hosts to slip through
289 * allow/deny filters. Workaround: don't rely on the vendor and use our own
290 * strtok() function. FreeBSD 2.0 has a similar problem (fixed in 2.0.5).
293 #ifdef LIBC_CALLS_STRTOK
295 char *my_strtok(buf, sep)
306 * Skip over separator characters and detect end of string.
308 if (*(state += strspn(state, sep)) == 0)
312 * Skip over non-separator characters and terminate result.
315 if (*(state += strcspn(state, sep)) != 0)
320 #endif /* LIBC_CALLS_STRTOK */