Annotation of embedaddon/dhcp/common/resolv.c, revision 1.1
1.1 ! misho 1: /* resolv.c
! 2:
! 3: Parser for /etc/resolv.conf file. */
! 4:
! 5: /*
! 6: * Copyright (c) 2004-2007,2009 by Internet Systems Consortium, Inc. ("ISC")
! 7: * Copyright (c) 1996-2003 by Internet Software Consortium
! 8: *
! 9: * Permission to use, copy, modify, and distribute this software for any
! 10: * purpose with or without fee is hereby granted, provided that the above
! 11: * copyright notice and this permission notice appear in all copies.
! 12: *
! 13: * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
! 14: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
! 15: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
! 16: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
! 17: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
! 18: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
! 19: * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
! 20: *
! 21: * Internet Systems Consortium, Inc.
! 22: * 950 Charter Street
! 23: * Redwood City, CA 94063
! 24: * <info@isc.org>
! 25: * https://www.isc.org/
! 26: *
! 27: * This software has been written for Internet Systems Consortium
! 28: * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc.
! 29: * To learn more about Internet Systems Consortium, see
! 30: * ``https://www.isc.org/''. To learn more about Vixie Enterprises,
! 31: * see ``http://www.vix.com''. To learn more about Nominum, Inc., see
! 32: * ``http://www.nominum.com''.
! 33: */
! 34:
! 35: #include "dhcpd.h"
! 36:
! 37: struct name_server *name_servers;
! 38: struct domain_search_list *domains;
! 39: char path_resolv_conf [] = _PATH_RESOLV_CONF;
! 40:
! 41: void read_resolv_conf (parse_time)
! 42: TIME parse_time;
! 43: {
! 44: int file;
! 45: struct parse *cfile;
! 46: const char *val;
! 47: int token;
! 48: struct name_server *sp, *sl, *ns;
! 49: struct domain_search_list *dp, *dl, *nd;
! 50: isc_result_t status;
! 51:
! 52: if ((file = open (path_resolv_conf, O_RDONLY)) < 0) {
! 53: log_error ("Can't open %s: %m", path_resolv_conf);
! 54: return;
! 55: }
! 56:
! 57: cfile = NULL;
! 58: status = new_parse(&cfile, file, NULL, 0, path_resolv_conf, 1);
! 59: if (status != ISC_R_SUCCESS || cfile == NULL)
! 60: return;
! 61:
! 62: do {
! 63: token = next_token (&val, (unsigned *)0, cfile);
! 64: if (token == END_OF_FILE)
! 65: break;
! 66: else if (token == EOL)
! 67: continue;
! 68: else if (token == DOMAIN || token == SEARCH) {
! 69: do {
! 70: struct domain_search_list *nd, **dp;
! 71: char *dn;
! 72:
! 73: dn = parse_host_name (cfile);
! 74: if (!dn)
! 75: break;
! 76:
! 77: dp = &domains;
! 78: for (nd = domains; nd; nd = nd -> next) {
! 79: dp = &nd -> next;
! 80: if (!strcmp (nd -> domain, dn))
! 81: break;
! 82: }
! 83: if (!nd) {
! 84: nd = new_domain_search_list (MDL);
! 85: if (!nd)
! 86: log_fatal ("No memory for %s",
! 87: dn);
! 88: nd -> next =
! 89: (struct domain_search_list *)0;
! 90: *dp = nd;
! 91: nd -> domain = dn;
! 92: dn = (char *)0;
! 93: }
! 94: nd -> rcdate = parse_time;
! 95: token = peek_token (&val,
! 96: (unsigned *)0, cfile);
! 97: } while (token != EOL);
! 98: if (token != EOL) {
! 99: parse_warn (cfile,
! 100: "junk after domain declaration");
! 101: skip_to_semi (cfile);
! 102: }
! 103: token = next_token (&val, (unsigned *)0, cfile);
! 104: } else if (token == NAMESERVER) {
! 105: struct name_server *ns, **sp;
! 106: struct iaddr iaddr;
! 107:
! 108: parse_ip_addr (cfile, &iaddr);
! 109:
! 110: sp = &name_servers;
! 111: for (ns = name_servers; ns; ns = ns -> next) {
! 112: sp = &ns -> next;
! 113: if (!memcmp (&ns -> addr.sin_addr,
! 114: iaddr.iabuf, iaddr.len))
! 115: break;
! 116: }
! 117: if (!ns) {
! 118: ns = new_name_server (MDL);
! 119: if (!ns)
! 120: log_fatal ("No memory for nameserver %s",
! 121: piaddr (iaddr));
! 122: ns -> next = (struct name_server *)0;
! 123: *sp = ns;
! 124: memcpy (&ns -> addr.sin_addr,
! 125: iaddr.iabuf, iaddr.len);
! 126: #ifdef HAVE_SA_LEN
! 127: ns -> addr.sin_len = sizeof ns -> addr;
! 128: #endif
! 129: ns -> addr.sin_family = AF_INET;
! 130: ns -> addr.sin_port = htons (53);
! 131: memset (ns -> addr.sin_zero, 0,
! 132: sizeof ns -> addr.sin_zero);
! 133: }
! 134: ns -> rcdate = parse_time;
! 135: skip_to_semi (cfile);
! 136: } else
! 137: skip_to_semi (cfile); /* Ignore what we don't grok. */
! 138: } while (1);
! 139: token = next_token (&val, (unsigned *)0, cfile);
! 140:
! 141: /* Lose servers that are no longer in /etc/resolv.conf. */
! 142: sl = (struct name_server *)0;
! 143: for (sp = name_servers; sp; sp = ns) {
! 144: ns = sp -> next;
! 145: if (sp -> rcdate != parse_time) {
! 146: if (sl)
! 147: sl -> next = sp -> next;
! 148: else
! 149: name_servers = sp -> next;
! 150: /* We can't actually free the name server structure,
! 151: because somebody might be hanging on to it. If
! 152: your /etc/resolv.conf file changes a lot, this
! 153: could be a noticeable memory leak. */
! 154: } else
! 155: sl = sp;
! 156: }
! 157:
! 158: /* Lose domains that are no longer in /etc/resolv.conf. */
! 159: dl = (struct domain_search_list *)0;
! 160: for (dp = domains; dp; dp = nd) {
! 161: nd = dp -> next;
! 162: if (dp -> rcdate != parse_time) {
! 163: if (dl)
! 164: dl -> next = dp -> next;
! 165: else
! 166: domains = dp -> next;
! 167: free_domain_search_list (dp, MDL);
! 168: } else
! 169: dl = dp;
! 170: }
! 171: end_parse (&cfile);
! 172: }
! 173:
! 174: /* Pick a name server from the /etc/resolv.conf file. */
! 175:
! 176: struct name_server *first_name_server ()
! 177: {
! 178: static TIME rcdate;
! 179: struct stat st;
! 180:
! 181: /* Check /etc/resolv.conf and reload it if it's changed. */
! 182: if (cur_time > rcdate) {
! 183: if (stat (path_resolv_conf, &st) < 0) {
! 184: log_error ("Can't stat %s", path_resolv_conf);
! 185: return (struct name_server *)0;
! 186: }
! 187: if (st.st_mtime > rcdate) {
! 188: rcdate = cur_time + 1;
! 189:
! 190: read_resolv_conf (rcdate);
! 191: }
! 192: }
! 193:
! 194: return name_servers;
! 195: }
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