/* $NetBSD: resolv.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $ */ /* resolv.c Parser for /etc/resolv.conf file. */ /* * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996-2003 by Internet Software Consortium * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Internet Systems Consortium, Inc. * PO Box 360 * Newmarket, NH 03857 USA * * https://www.isc.org/ * */ #include __RCSID("$NetBSD: resolv.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $"); #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; struct name_server *sp, *sl, *ns; struct domain_search_list *dp, *dl, *nd; isc_result_t status; if ((file = open (path_resolv_conf, O_RDONLY)) < 0) { log_error ("Can't open %s: %m", path_resolv_conf); return; } cfile = NULL; status = new_parse(&cfile, file, NULL, 0, path_resolv_conf, 1); if (status != ISC_R_SUCCESS || cfile == NULL) return; 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; } 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); } skip_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); skip_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 noticeable 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; } end_parse (&cfile); } /* Pick a name server from the /etc/resolv.conf file. */ struct name_server *first_name_server () { 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) { rcdate = cur_time + 1; read_resolv_conf (rcdate); } } return name_servers; }