#21900: Fallback to local DNS when no other nameservers are known #273
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| Original file line number | Diff line number | Diff line change |
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@@ -1385,42 +1385,63 @@ configure_nameservers(int force) | |
| evdns_set_log_fn(evdns_log_cb); | ||
| if (conf_fname) { | ||
| log_debug(LD_FS, "stat()ing %s", conf_fname); | ||
| int missing_resolv_conf = 0; | ||
| int stat_res = stat(sandbox_intern_string(conf_fname), &st); | ||
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| if (stat_res) { | ||
| log_warn(LD_EXIT, "unable to stat resolver configuration in '%s': %s", | ||
| conf_fname, strerror(errno)); | ||
| 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; | ||
| } | ||
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| if (st.st_size == 0) | ||
| missing_resolv_conf = 1; | ||
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| if (nameservers_configured) { | ||
| evdns_base_search_clear(the_evdns_base); | ||
| evdns_base_clear_nameservers_and_suspend(the_evdns_base); | ||
| } | ||
| #if defined(DNS_OPTION_HOSTSFILE) && defined(USE_LIBSECCOMP) | ||
| if (flags & DNS_OPTION_HOSTSFILE) { | ||
| flags ^= DNS_OPTION_HOSTSFILE; | ||
| log_debug(LD_FS, "loading /etc/hosts"); | ||
| evdns_base_load_hosts(the_evdns_base, | ||
| sandbox_intern_string("/etc/hosts")); | ||
| } | ||
| #endif /* defined(dns_option_hostsfile) && defined(use_libseccomp) */ | ||
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| if (!missing_resolv_conf) { | ||
| log_info(LD_EXIT, "parsing resolver configuration in '%s'", conf_fname); | ||
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There was a problem hiding this comment. It looks like this log message, and the messages after it, are still lower-cased in the latest version of the branch? There was a problem hiding this comment. Reverted the last changes to lowercase in 917eeed. |
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| 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); | ||
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| 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); | ||
| } | ||
| resolv_conf_fname = tor_strdup(conf_fname); | ||
|
There was a problem hiding this comment. If resolv_conf_fname was already set, this will leak memory |
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| resolv_conf_mtime = st.st_mtime; | ||
| } else { | ||
| log_warn(LD_EXIT, "Could not read your resolv.conf - " | ||
|
There was a problem hiding this comment. This message should say what actual filename it tried to read. There was a problem hiding this comment. Logging filename in a1656c9. |
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| "please investigate your DNS configuration. " | ||
| "This is possibly a problem. Meanwhile, falling" | ||
| " back to local DNS at 127.0.0.1."); | ||
| evdns_base_nameserver_ip_add(the_evdns_base, "127.0.0.1"); | ||
| } | ||
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| tor_free(resolv_conf_fname); | ||
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There was a problem hiding this comment. This tor_free() here will clear the value of rsolv_conf_fname that you set above... |
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| if (nameservers_configured) | ||
| evdns_base_resume(the_evdns_base); | ||
| } | ||
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@@ -1431,12 +1452,12 @@ configure_nameservers(int force) | |
| evdns_base_clear_nameservers_and_suspend(the_evdns_base); | ||
| } | ||
| if (evdns_base_config_windows_nameservers(the_evdns_base)) { | ||
| log_warn(LD_EXIT,"could not config nameservers."); | ||
| goto err; | ||
| } | ||
| if (evdns_base_count_nameservers(the_evdns_base) == 0) { | ||
| log_warn(LD_EXIT, "unable to find any platform nameservers in " | ||
| "your windows configuration."); | ||
| goto err; | ||
| } | ||
| if (nameservers_configured) | ||
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If the stat() call failed above, then at this point, st.st_size will be uninitialized, and we're not allowed to look at it.
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Checking if
stat()succeeded in 770aee4.