diff options
Diffstat (limited to 'src/feature/relay/dns.c')
| -rw-r--r-- | src/feature/relay/dns.c | 95 |
1 files changed, 76 insertions, 19 deletions
diff --git a/src/feature/relay/dns.c b/src/feature/relay/dns.c index e20a39482f..7ab4ca0f45 100644 --- a/src/feature/relay/dns.c +++ b/src/feature/relay/dns.c @@ -1,6 +1,6 @@ /* Copyright (c) 2003-2004, Roger Dingledine. * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. - * Copyright (c) 2007-2019, The Tor Project, Inc. */ + * Copyright (c) 2007-2020, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** @@ -59,7 +59,7 @@ #include "core/or/connection_edge.h" #include "core/or/policies.h" #include "core/or/relay.h" -#include "feature/control/control.h" +#include "feature/control/control_events.h" #include "feature/relay/dns.h" #include "feature/relay/router.h" #include "feature/relay/routermode.h" @@ -1360,6 +1360,42 @@ evdns_err_is_transient(int err) } } +/** + * Return number of configured nameservers in <b>the_evdns_base</b>. + */ +size_t +number_of_configured_nameservers(void) +{ + return evdns_base_count_nameservers(the_evdns_base); +} + +#ifdef HAVE_EVDNS_BASE_GET_NAMESERVER_ADDR +/** + * Return address of configured nameserver in <b>the_evdns_base</b> + * at index <b>idx</b>. + */ +tor_addr_t * +configured_nameserver_address(const size_t idx) +{ + struct sockaddr_storage sa; + ev_socklen_t sa_len = sizeof(sa); + + if (evdns_base_get_nameserver_addr(the_evdns_base, (int)idx, + (struct sockaddr *)&sa, + sa_len) > 0) { + tor_addr_t *tor_addr = tor_malloc(sizeof(tor_addr_t)); + if (tor_addr_from_sockaddr(tor_addr, + (const struct sockaddr *)&sa, + NULL) == 0) { + return tor_addr; + } + tor_free(tor_addr); + } + + return NULL; +} +#endif /* defined(HAVE_EVDNS_BASE_GET_NAMESERVER_ADDR) */ + /** Configure eventdns nameservers if force is true, or if the configuration * has changed since the last time we called this function, or if we failed on * our last attempt. On Unix, this reads from /etc/resolv.conf or @@ -1391,16 +1427,23 @@ configure_nameservers(int force) evdns_set_log_fn(evdns_log_cb); if (conf_fname) { log_debug(LD_FS, "stat()ing %s", conf_fname); - if (stat(sandbox_intern_string(conf_fname), &st)) { + int missing_resolv_conf = 0; + int stat_res = stat(sandbox_intern_string(conf_fname), &st); + + if (stat_res) { log_warn(LD_EXIT, "Unable to stat resolver configuration in '%s': %s", conf_fname, strerror(errno)); - goto err; - } - if (!force && resolv_conf_fname && !strcmp(conf_fname,resolv_conf_fname) + missing_resolv_conf = 1; + } else if (!force && resolv_conf_fname && + !strcmp(conf_fname,resolv_conf_fname) && st.st_mtime == resolv_conf_mtime) { log_info(LD_EXIT, "No change to '%s'", conf_fname); return 0; } + + if (stat_res == 0 && st.st_size == 0) + missing_resolv_conf = 1; + if (nameservers_configured) { evdns_base_search_clear(the_evdns_base); evdns_base_clear_nameservers_and_suspend(the_evdns_base); @@ -1413,20 +1456,34 @@ configure_nameservers(int force) sandbox_intern_string("/etc/hosts")); } #endif /* defined(DNS_OPTION_HOSTSFILE) && defined(USE_LIBSECCOMP) */ - log_info(LD_EXIT, "Parsing resolver configuration in '%s'", conf_fname); - if ((r = evdns_base_resolv_conf_parse(the_evdns_base, flags, - sandbox_intern_string(conf_fname)))) { - log_warn(LD_EXIT, "Unable to parse '%s', or no nameservers in '%s' (%d)", - conf_fname, conf_fname, r); - goto err; - } - if (evdns_base_count_nameservers(the_evdns_base) == 0) { - log_warn(LD_EXIT, "Unable to find any nameservers in '%s'.", conf_fname); - goto err; + + if (!missing_resolv_conf) { + log_info(LD_EXIT, "Parsing resolver configuration in '%s'", conf_fname); + if ((r = evdns_base_resolv_conf_parse(the_evdns_base, flags, + sandbox_intern_string(conf_fname)))) { + log_warn(LD_EXIT, "Unable to parse '%s', or no nameservers " + "in '%s' (%d)", conf_fname, conf_fname, r); + + if (r != 6) // "r = 6" means "no DNS servers were in resolv.conf" - + goto err; // in which case we expect libevent to add 127.0.0.1 as + // fallback. + } + if (evdns_base_count_nameservers(the_evdns_base) == 0) { + log_warn(LD_EXIT, "Unable to find any nameservers in '%s'.", + conf_fname); + } + + tor_free(resolv_conf_fname); + resolv_conf_fname = tor_strdup(conf_fname); + resolv_conf_mtime = st.st_mtime; + } else { + log_warn(LD_EXIT, "Could not read your DNS config from '%s' - " + "please investigate your DNS configuration. " + "This is possibly a problem. Meanwhile, falling" + " back to local DNS at 127.0.0.1.", conf_fname); + evdns_base_nameserver_ip_add(the_evdns_base, "127.0.0.1"); } - tor_free(resolv_conf_fname); - resolv_conf_fname = tor_strdup(conf_fname); - resolv_conf_mtime = st.st_mtime; + if (nameservers_configured) evdns_base_resume(the_evdns_base); } |