/* resolv.c Parser for /etc/resolv.conf file. */ /* * Copyright (c) 1996-2002 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 and Nominum, Inc. * To learn more about the Internet Software Consortium, see * ``http://www.isc.org/''. To learn more about Vixie Enterprises, * see ``http://www.vix.com''. To learn more about Nominum, Inc., see * ``http://www.nominum.com''. */ #ifndef lint static char copyright[] = "$Id: resolv.c,v 1.16.2.1 2002/11/17 02:26:59 dhankins Exp $ Copyright (c) 1996-2002 The Internet Software Consortium. All rights reserved.\n"; #endif /* not lint */ #include "dhcpd.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; { int file; struct parse *cfile; const char *val; int token; int declaration = 0; struct name_server *sp, *sl, *ns; struct domain_search_list *dp, *dl, *nd; struct iaddr *iaddr; if ((file = open (path_resolv_conf, O_RDONLY)) < 0) { log_error ("Can't open %s: %m", path_resolv_conf); return; } cfile = (struct parse *)0; new_parse (&cfile, file, (char *)0, 0, path_resolv_conf, 1); do { token = next_token (&val, (unsigned *)0, cfile); if (token == END_OF_FILE) 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 (MDL); if (!nd) log_fatal ("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 = peek_token (&val, (unsigned *)0, cfile); } while (token != EOL); if (token != EOL) { parse_warn (cfile, "junk after domain declaration"); skip_to_semi (cfile); } token = next_token (&val, (unsigned *)0, 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 (MDL); if (!ns) log_fatal ("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); } else skip_to_semi (cfile); /* Ignore what we don't grok. */ } while (1); token = next_token (&val, (unsigned *)0, cfile); /* 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; /* We can't actually free the name server structure, because somebody might be hanging on to it. If your /etc/resolv.conf file changes a lot, this could be a noticable memory leak. */ } 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, MDL); } else dl = dp; } close (file); end_parse (&cfile); } /* Pick a name server from the /etc/resolv.conf file. */ struct name_server *first_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) { log_error ("Can't stat %s", path_resolv_conf); return (struct name_server *)0; } if (st.st_mtime > rcdate) { char rcbuf [512]; char *s, *t, *u; rcdate = cur_time + 1; read_resolv_conf (rcdate); } } return name_servers; }