From a7de06ee5590b14def517e397624117e51c14609 Mon Sep 17 00:00:00 2001 From: Ted Lemon Date: Tue, 3 Jun 1997 00:25:43 +0000 Subject: [PATCH] Resolver subroutines --- common/resolv.c | 200 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 200 insertions(+) create mode 100644 common/resolv.c diff --git a/common/resolv.c b/common/resolv.c new file mode 100644 index 000000000..ed4fc7e9c --- /dev/null +++ b/common/resolv.c @@ -0,0 +1,200 @@ +/* resolv.c + + Parser for /etc/resolv.conf file. */ + +/* + * Copyright (c) 1995, 1996, 1997 The Internet Software Consortium. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of The Internet Software Consortium nor the names + * of its contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND + * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, + * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * This software has been written for the Internet Software Consortium + * by Ted Lemon in cooperation with Vixie + * Enterprises. To learn more about the Internet Software Consortium, + * see ``http://www.vix.com/isc''. To learn more about Vixie + * Enterprises, see ``http://www.vix.com''. + */ + +#ifndef lint +static char copyright[] = +"$Id: resolv.c,v 1.1 1997/06/03 00:25:43 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n"; +#endif /* not lint */ + +#include "dhcpd.h" +#include "dhctoken.h" + +struct name_server *name_servers; +struct domain_search_list *domains; +char path_resolv_conf [] = _PATH_RESOLV_CONF; + +void read_resolv_conf (parse_time) + TIME parse_time; +{ + FILE *cfile; + char *val; + int token; + int declaration = 0; + struct name_server *sp, *sl, *ns; + struct domain_search_list *dp, *dl, *nd; + struct iaddr *iaddr; + + new_parse (path_resolv_conf); + + eol_token = 1; + if ((cfile = fopen (path_resolv_conf, "r")) == NULL) + error ("Can't open %s: %m", path_resolv_conf); + do { + token = next_token (&val, cfile); + if (token == EOF) + break; + else if (token == EOL) + continue; + else if (token == DOMAIN || token == SEARCH) { + do { + struct domain_search_list *nd, **dp; + char *dn; + + dn = parse_host_name (cfile); + if (!dn) + break; + + dp = &domains; + for (nd = domains; nd; nd = nd -> next) { + dp = &nd -> next; + if (!strcmp (nd -> domain, dn)) + break; + } + if (!nd) { + nd = new_domain_search_list + ("read_resolv_conf"); + if (!nd) + error ("No memory for %s", dn); + nd -> next = + (struct domain_search_list *)0; + *dp = nd; + nd -> domain = dn; + dn = (char *)0; + } + nd -> rcdate = parse_time; + token = next_token (&val, cfile); + } while (token == COMMA); + if (token != EOL) { + parse_warn ("junk after domain declaration"); + skip_to_semi (cfile); + } + } else if (token == NAMESERVER) { + struct name_server *ns, **sp; + struct iaddr iaddr; + + parse_ip_addr (cfile, &iaddr); + + sp = &name_servers; + for (ns = name_servers; ns; ns = ns -> next) { + sp = &ns -> next; + if (!memcmp (&ns -> addr.sin_addr, + iaddr.iabuf, iaddr.len)) + break; + } + if (!ns) { + ns = new_name_server ("read_resolv_conf"); + if (!ns) + error ("No memory for nameserver %s", + piaddr (iaddr)); + ns -> next = (struct name_server *)0; + *sp = ns; + memcpy (&ns -> addr.sin_addr, + iaddr.iabuf, iaddr.len); +#ifdef HAVE_SA_LEN + ns -> addr.sin_len = sizeof ns -> addr; +#endif + ns -> addr.sin_family = AF_INET; + ns -> addr.sin_port = htons (53); + memset (ns -> addr.sin_zero, 0, + sizeof ns -> addr.sin_zero); + } + ns -> rcdate = parse_time; + skip_to_semi (cfile); + } + } while (1); + token = next_token (&val, cfile); /* Clear the peek buffer */ + + /* Lose servers that are no longer in /etc/resolv.conf. */ + sl = (struct name_server *)0; + for (sp = name_servers; sp; sp = ns) { + ns = sp -> next; + if (sp -> rcdate != parse_time) { + if (sl) + sl -> next = sp -> next; + else + name_servers = sp -> next; + free_name_server (sp, "pick_name_server"); + } else + sl = sp; + } + + /* Lose domains that are no longer in /etc/resolv.conf. */ + dl = (struct domain_search_list *)0; + for (dp = domains; dp; dp = nd) { + nd = dp -> next; + if (dp -> rcdate != parse_time) { + if (dl) + dl -> next = dp -> next; + else + domains = dp -> next; + free_domain_search_list (dp, "pick_name_server"); + } else + dl = dp; + } + eol_token = 0; +} + +/* Pick a name server from the /etc/resolv.conf file. */ + +struct sockaddr_in *pick_name_server () +{ + FILE *rc; + static TIME rcdate; + struct stat st; + + /* Check /etc/resolv.conf and reload it if it's changed. */ + if (cur_time > rcdate) { + if (stat (path_resolv_conf, &st) < 0) + error ("Can't stat %s", path_resolv_conf); + if (st.st_mtime > rcdate) { + char rcbuf [512]; + char *s, *t, *u; + rcdate = cur_time + 1; + + read_resolv_conf (rcdate); + } + } + + if (name_servers) + return &name_servers -> addr; + return (struct sockaddr_in *)0; +} -- 2.47.3