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Diffstat (limited to 'common/resolv.c')
| -rw-r--r-- | common/resolv.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/common/resolv.c b/common/resolv.c new file mode 100644 index 0000000..b29d4cf --- /dev/null +++ b/common/resolv.c @@ -0,0 +1,195 @@ +/* resolv.c + + Parser for /etc/resolv.conf file. */ + +/* + * Copyright (c) 2004-2007,2009 by Internet Systems Consortium, Inc. ("ISC") + * Copyright (c) 1996-2003 by Internet Software Consortium + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * 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. + * 950 Charter Street + * Redwood City, CA 94063 + * <info@isc.org> + * https://www.isc.org/ + * + * This software has been written for Internet Systems Consortium + * by Ted Lemon in cooperation with Vixie Enterprises and Nominum, Inc. + * To learn more about Internet Systems Consortium, see + * ``https://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''. + */ + +#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; + 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 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; +} |