/* * Workarounds for known system software bugs. This module provides wrappers * around library functions and system calls that are known to have problems * on some systems. Most of these workarounds won't do any harm on regular * systems. * * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. * * $FreeBSD$ */ #ifndef lint char sccsid[] = "@(#) workarounds.c 1.6 96/03/19 16:22:25"; #endif #include #include #include #include #include #include #include #include #include #include extern int errno; #include "tcpd.h" /* * Some AIX versions advertise a too small MAXHOSTNAMELEN value (32). * Result: long hostnames would be truncated, and connections would be * dropped because of host name verification failures. Adrian van Bloois * (A.vanBloois@info.nic.surfnet.nl) figured out what was the problem. */ #if (MAXHOSTNAMELEN < 64) #undef MAXHOSTNAMELEN #endif /* In case not defined in . */ #ifndef MAXHOSTNAMELEN #define MAXHOSTNAMELEN 256 /* storage for host name */ #endif /* * Some DG/UX inet_addr() versions return a struct/union instead of a long. * You have this problem when the compiler complains about illegal lvalues * or something like that. The following code fixes this mutant behaviour. * It should not be enabled on "normal" systems. * * Bug reported by ben@piglet.cr.usgs.gov (Rev. Ben A. Mesander). */ #ifdef INET_ADDR_BUG #undef inet_addr long fix_inet_addr(string) char *string; { return (inet_addr(string).s_addr); } #endif /* INET_ADDR_BUG */ /* * With some System-V versions, the fgets() library function does not * account for partial reads from e.g. sockets. The result is that fgets() * gives up too soon, causing username lookups to fail. Problem first * reported for IRIX 4.0.5, by Steve Kotsopoulos . * The following code works around the problem. It does no harm on "normal" * systems. */ #ifdef BROKEN_FGETS #undef fgets char *fix_fgets(buf, len, fp) char *buf; int len; FILE *fp; { char *cp = buf; int c; /* * Copy until the buffer fills up, until EOF, or until a newline is * found. */ while (len > 1 && (c = getc(fp)) != EOF) { len--; *cp++ = c; if (c == '\n') break; } /* * Return 0 if nothing was read. This is correct even when a silly buffer * length was specified. */ if (cp > buf) { *cp = 0; return (buf); } else { return (0); } } #endif /* BROKEN_FGETS */ /* * With early SunOS 5 versions, recvfrom() does not completely fill in the * source address structure when doing a non-destructive read. The following * code works around the problem. It does no harm on "normal" systems. */ #ifdef RECVFROM_BUG #undef recvfrom int fix_recvfrom(sock, buf, buflen, flags, from, fromlen) int sock; char *buf; int buflen; int flags; struct sockaddr *from; int *fromlen; { int ret; /* Assume that both ends of a socket belong to the same address family. */ if ((ret = recvfrom(sock, buf, buflen, flags, from, fromlen)) >= 0) { if (from->sa_family == 0) { struct sockaddr my_addr; int my_addr_len = sizeof(my_addr); if (getsockname(0, &my_addr, &my_addr_len)) { tcpd_warn("getsockname: %m"); } else { from->sa_family = my_addr.sa_family; } } } return (ret); } #endif /* RECVFROM_BUG */ /* * The Apollo SR10.3 and some SYSV4 getpeername(2) versions do not return an * error in case of a datagram-oriented socket. Instead, they claim that all * UDP requests come from address 0.0.0.0. The following code works around * the problem. It does no harm on "normal" systems. */ #ifdef GETPEERNAME_BUG #undef getpeername int fix_getpeername(sock, sa, len) int sock; struct sockaddr *sa; int *len; { int ret; #ifdef INET6 struct sockaddr *sin = sa; #else struct sockaddr_in *sin = (struct sockaddr_in *) sa; #endif if ((ret = getpeername(sock, sa, len)) >= 0 #ifdef INET6 && ((sin->su_si.si_family == AF_INET6 && IN6_IS_ADDR_UNSPECIFIED(&sin->su_sin6.sin6_addr)) || (sin->su_si.si_family == AF_INET && sin->su_sin.sin_addr.s_addr == 0))) { #else && sa->sa_family == AF_INET && sin->sin_addr.s_addr == 0) { #endif errno = ENOTCONN; return (-1); } else { return (ret); } } #endif /* GETPEERNAME_BUG */ /* * According to Karl Vogel (vogelke@c-17igp.wpafb.af.mil) some Pyramid * versions have no yp_default_domain() function. We use getdomainname() * instead. */ #ifdef USE_GETDOMAIN int yp_get_default_domain(ptr) char **ptr; { static char mydomain[MAXHOSTNAMELEN]; *ptr = mydomain; return (getdomainname(mydomain, MAXHOSTNAMELEN)); } #endif /* USE_GETDOMAIN */ #ifndef INADDR_NONE #define INADDR_NONE 0xffffffff #endif /* * Solaris 2.4 gethostbyname() has problems with multihomed hosts. When * doing DNS through NIS, only one host address ends up in the address list. * All other addresses end up in the hostname alias list, interspersed with * copies of the official host name. This would wreak havoc with tcpd's * hostname double checks. Below is a workaround that should do no harm when * accidentally left in. A side effect of the workaround is that address * list members are no longer properly aligned for structure access. */ #ifdef SOLARIS_24_GETHOSTBYNAME_BUG #undef gethostbyname struct hostent *fix_gethostbyname(name) char *name; { struct hostent *hp; struct in_addr addr; char **o_addr_list; char **o_aliases; char **n_addr_list; int broken_gethostbyname = 0; if ((hp = gethostbyname(name)) && !hp->h_addr_list[1] && hp->h_aliases[1]) { for (o_aliases = n_addr_list = hp->h_aliases; *o_aliases; o_aliases++) { if ((addr.s_addr = inet_addr(*o_aliases)) != INADDR_NONE) { memcpy(*n_addr_list++, (char *) &addr, hp->h_length); broken_gethostbyname = 1; } } if (broken_gethostbyname) { o_addr_list = hp->h_addr_list; memcpy(*n_addr_list++, *o_addr_list, hp->h_length); *n_addr_list = 0; hp->h_addr_list = hp->h_aliases; hp->h_aliases = o_addr_list + 1; } } return (hp); } #endif /* SOLARIS_24_GETHOSTBYNAME_BUG */ /* * Horror! Some FreeBSD 2.0 libc routines call strtok(). Since tcpd depends * heavily on strtok(), strange things may happen. Workaround: use our * private strtok(). This has been fixed in the meantime. */ #ifdef USE_STRSEP char *fix_strtok(buf, sep) char *buf; char *sep; { static char *state; char *result; if (buf) state = buf; while ((result = strsep(&state, sep)) && result[0] == 0) /* void */ ; return (result); } #endif /* USE_STRSEP */ /* * IRIX 5.3 (and possibly earlier versions, too) library routines call the * non-reentrant strtok() library routine, causing hosts to slip through * allow/deny filters. Workaround: don't rely on the vendor and use our own * strtok() function. FreeBSD 2.0 has a similar problem (fixed in 2.0.5). */ #ifdef LIBC_CALLS_STRTOK char *my_strtok(buf, sep) char *buf; char *sep; { static char *state; char *result; if (buf) state = buf; /* * Skip over separator characters and detect end of string. */ if (*(state += strspn(state, sep)) == 0) return (0); /* * Skip over non-separator characters and terminate result. */ result = state; if (*(state += strcspn(state, sep)) != 0) *state++ = 0; return (result); } #endif /* LIBC_CALLS_STRTOK */