/* * $Id: dnsserver.c,v 1.57.2.1 2001/01/12 00:51:47 wessels Exp $ * * DEBUG: section 0 DNS Resolver * AUTHOR: Harvest Derived * * SQUID Web Proxy Cache http://www.squid-cache.org/ * ---------------------------------------------------------- * * Squid is the result of efforts by numerous individuals from * the Internet community; see the CONTRIBUTORS file for full * details. Many organizations have provided support for Squid's * development; see the SPONSORS file for full details. Squid is * Copyrighted (C) 2001 by the Regents of the University of * California; see the COPYRIGHT file for full details. Squid * incorporates software developed and/or copyrighted by other * sources; see the CREDITS file for full details. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. * */ #include "config.h" #if HAVE_UNISTD_H #include #endif #if HAVE_STDLIB_H #include #endif #if HAVE_STDIO_H #include #endif #if HAVE_SYS_TYPES_H #include #endif #if HAVE_CTYPE_H #include #endif #if HAVE_ERRNO_H #include #endif #if HAVE_FCNTL_H #include #endif #if HAVE_GRP_H #include #endif #if HAVE_GNUMALLOC_H #include #elif HAVE_MALLOC_H && !defined(_SQUID_FREEBSD_) && !defined(_SQUID_NEXT_) #include #endif #if HAVE_MEMORY_H #include #endif #if HAVE_NETDB_H && !defined(_SQUID_NETDB_H_) /* protect NEXTSTEP */ #define _SQUID_NETDB_H_ #include #endif #if HAVE_PWD_H #include #endif #if HAVE_SIGNAL_H #include #endif #if HAVE_TIME_H #include #endif #if HAVE_SYS_PARAM_H #include #endif #if HAVE_SYS_TIME_H #include #endif #if HAVE_SYS_RESOURCE_H #include /* needs sys/time.h above it */ #endif #if HAVE_SYS_SOCKET_H #include #endif #if HAVE_NETINET_IN_H #include #endif #if HAVE_ARPA_INET_H #include #endif #if HAVE_SYS_STAT_H #include #endif #if HAVE_SYS_UN_H #include #endif #if HAVE_SYS_WAIT_H #include #endif #if HAVE_LIBC_H #include #endif #ifdef HAVE_SYS_SYSCALL_H #include #endif #ifdef HAVE_STRING_H #include #endif #ifdef HAVE_STRINGS_H #include #endif #if HAVE_BSTRING_H #include #endif #ifdef HAVE_CRYPT_H #include #endif #if HAVE_SYS_SELECT_H #include #endif #if HAVE_ARPA_NAMESER_H #include #endif #if HAVE_RESOLV_H #include #endif #include "util.h" #include "snprintf.h" #if !defined(_SQUID_AIX_) extern int h_errno; #endif #if LIBRESOLV_DNS_TTL_HACK extern int _dns_ttl_; /* this is a really *dirty* hack - bne */ #endif #ifdef _SQUID_NEXT_ /* This is a really bloody hack. frank@langen.bull.de * Workaround bug in gethostbyname which sets h_errno wrong * WARNING: This hack queries only the resolver and not NetInfo or YP */ struct hostent *_res_gethostbyname(char *name); #define gethostbyname _res_gethostbyname #endif /* _SQUID_NEXT_ */ static struct in_addr no_addr; #ifdef _SQUID_OS2_ struct state _res = {0}; /* it's not in any of the libraries */ #endif /* error messages from gethostbyname() */ static char * my_h_msgs(int x) { if (x == HOST_NOT_FOUND) return "Host not found (authoritative)"; else if (x == TRY_AGAIN) return "Host not found (non-authoritative)"; else if (x == NO_RECOVERY) return "Non recoverable errors"; else if (x == NO_DATA || x == NO_ADDRESS) return "Valid name, no data record of requested type"; else return "Unknown DNS problem"; } #define REQ_SZ 512 static void lookup(const char *buf) { const struct hostent *result = NULL; int reverse = 0; int ttl = 0; int retry = 0; int i; struct in_addr addr; if (0 == strcmp(buf, "$shutdown")) exit(0); if (0 == strcmp(buf, "$hello")) { printf("$alive\n"); return; } /* check if it's already an IP address in text form. */ for (;;) { if (safe_inet_addr(buf, &addr)) { reverse = 1; result = gethostbyaddr((char *) &addr.s_addr, 4, AF_INET); } else { result = gethostbyname(buf); } if (NULL != result) break; if (h_errno != TRY_AGAIN) break; if (++retry == 3) break; sleep(1); } if (NULL == result) { if (h_errno == TRY_AGAIN) { printf("$fail Name Server for domain '%s' is unavailable.\n", buf); } else { printf("$fail DNS Domain '%s' is invalid: %s.\n", buf, my_h_msgs(h_errno)); } return; } #if LIBRESOLV_DNS_TTL_HACK /* DNS TTL handling - bne@CareNet.hu * for first try it's a dirty hack, by hacking getanswer * to place the ttl in a global variable */ if (_dns_ttl_ > -1) ttl = _dns_ttl_; #endif if (reverse) { printf("$name %d %s\n", ttl, result->h_name); return; } printf("$addr %d", ttl); for (i = 0; NULL != result->h_addr_list[i]; i++) { if (32 == i) break; xmemcpy(&addr, result->h_addr_list[i], sizeof(addr)); printf(" %s", inet_ntoa(addr)); } printf("\n"); } static void usage(void) { fprintf(stderr, "usage: dnsserver -Dhv -s nameserver\n" "\t-D Enable resolver RES_DEFNAMES and RES_DNSRCH options\n" "\t-h Help\n" "\t-v Version\n" "\t-s nameserver Specify alternate name server(s). 'nameserver'\n" "\t must be an IP address, -s option may be repeated\n"); } int main(int argc, char *argv[]) { char request[512]; char *t = NULL; int c; int opt_s = 0; extern char *optarg; safe_inet_addr("255.255.255.255", &no_addr); #if HAVE_RES_INIT res_init(); #ifdef RES_DEFAULT _res.options = RES_DEFAULT; #endif #ifdef RES_DEFNAMES _res.options &= ~RES_DEFNAMES; #endif #ifdef RES_DNSRCH _res.options &= ~RES_DNSRCH; #endif #endif while ((c = getopt(argc, argv, "Dhs:v")) != -1) { switch (c) { case 'D': #ifdef RES_DEFNAMES _res.options |= RES_DEFNAMES; #endif #ifdef RES_DNSRCH _res.options |= RES_DNSRCH; #endif break; case 's': #if HAVE_RES_INIT if (opt_s == 0) { _res.nscount = 0; /* * Setting RES_INIT here causes coredumps when -s is * used with -D option. It looks to me like setting * RES_INIT is wrong. The resolver code sets RES_INIT * after calling res_init(). When we change the _res * structure and set RES_INIT, some internal resolver * structures get confused. -DW 2.1.p1 */ #if SEEMS_WRONG _res.options |= RES_INIT; #endif opt_s = 1; } else if (_res.nscount == MAXNS) { fprintf(stderr, "Too many -s options, only %d are allowed\n", MAXNS); break; } #if HAVE_RES_NSADDR_LIST _res.nsaddr_list[_res.nscount] = _res.nsaddr_list[0]; safe_inet_addr(optarg, &_res.nsaddr_list[_res.nscount++].sin_addr); #elif HAVE_RES_NS_LIST _res.ns_list[_res.nscount] = _res.ns_list[0]; safe_inet_addr(optarg, &_res.ns_list[_res.nscount++].addr.sin_addr); #else /* Unknown NS list format */ fprintf(stderr, "-s is not supported on this resolver\n"); #endif #else /* !HAVE_RES_INIT */ fprintf(stderr, "-s is not supported on this resolver\n"); #endif /* HAVE_RES_INIT */ break; case 'v': printf("dnsserver version %s\n", SQUID_VERSION); exit(0); break; case 'h': default: usage(); exit(1); break; } } for (;;) { memset(request, '\0', REQ_SZ); if (fgets(request, REQ_SZ, stdin) == NULL) exit(1); t = strrchr(request, '\n'); if (t == NULL) /* Ignore if no newline */ continue; *t = '\0'; /* strip NL */ if ((t = strrchr(request, '\r')) != NULL) *t = '\0'; /* strip CR */ lookup(request); fflush(stdout); } /* NOTREACHED */ return 0; }