[or-cvs] [tor/master] Fix a crash when using evdns from Libevent 2.
Nick Mathewson
nickm at seul.org
Tue Oct 13 21:57:51 UTC 2009
Author: Nick Mathewson <nickm at torproject.org>
Date: Tue, 13 Oct 2009 17:54:04 -0400
Subject: Fix a crash when using evdns from Libevent 2.
Commit: 81eee0ecfff3dac1e9438719d2f7dc0ba7e84a71
When we tried to use the deprecated non-threadsafe evdns
interfaces in Libevent 2 without using the also-deprecated
event_init() interface, Libevent 2 would sensibly crash, since it
has no guess where to find the Libevent library.
Here we use the evdns_base_*() functions instead if they're
present, and fake them if they aren't.
---
ChangeLog | 4 ++
src/or/dns.c | 142 ++++++++++++++++++++++++++++++++++++++++------------------
2 files changed, 102 insertions(+), 44 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 72f4aa8..9ed1cbd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,10 @@ Changes in version 0.2.2.6-alpha - 2009-10-??
- Numerous changes, bugfixes, and workarounds from Nathan Freitas
to help Tor build correctly for Android phones.
+ o Minor bugfixes:
+ - Fix a crash bug when trying to initialize the evdns module in
+ Libevent 2.
+
Changes in version 0.2.2.5-alpha - 2009-10-11
o Major bugfixes:
diff --git a/src/or/dns.c b/src/or/dns.c
index c6f9e8b..6021ca5 100644
--- a/src/or/dns.c
+++ b/src/or/dns.c
@@ -16,7 +16,6 @@
#ifdef HAVE_EVENT2_DNS_H
#include <event2/event.h>
#include <event2/dns.h>
-#include <event2/dns_compat.h>
#else
#include <event.h>
#include "eventdns.h"
@@ -25,6 +24,33 @@
#endif
#endif
+#ifndef HAVE_EVENT2_DNS_H
+struct evdns_base;
+struct evdns_request;
+#define evdns_base_new(x,y) tor_malloc(1)
+#define evdns_base_clear_nameservers_and_suspend(base) \
+ evdns_clear_nameservers_and_suspend()
+#define evdns_base_search_clear(base) evdns_search_clear()
+#define evdns_base_set_default_outgoing_bind_address(base, a, len) \
+ evdns_set_default_outgoing_bind_address((a),(len))
+#define evdns_base_resolv_conf_parse(base, options, fname) \
+ evdns_resolv_conf_parse((options), (fname))
+#define evdns_base_count_nameservers(base) \
+ evdns_count_nameservers()
+#define evdns_base_resume(base) \
+ evdns_resume()
+#define evdns_base_config_windows_nameservers(base) \
+ evdns_config_windows_nameservers()
+#define evdns_base_set_option(base, opt, val, flags) \
+ evdns_set_option((opt),(val),(flags))
+#define evdns_base_resolve_ipv4(base, addr, options, cb, ptr) \
+ ((evdns_resolve_ipv4(addr, options, cb, ptr)<0) ? NULL : ((void*)1))
+#define evdns_base_resolve_reverse(base, addr, options, cb, ptr) \
+ ((evdns_resolve_reverse(addr, options, cb, ptr)<0) ? NULL : ((void*)1))
+#define evdns_base_resolve_reverse_ipv6(base, addr, options, cb, ptr) \
+ ((evdns_resolve_reverse_ipv6(addr, options, cb, ptr)<0) ? NULL : ((void*)1))
+#endif
+
/** Longest hostname we're willing to resolve. */
#define MAX_ADDRESSLEN 256
@@ -38,6 +64,9 @@
#define DNS_RESOLVE_FAILED_PERMANENT 2
#define DNS_RESOLVE_SUCCEEDED 3
+/** Our evdns_base; this structure handles all our name lookups. */
+static struct evdns_base *the_evdns_base = NULL;
+
/** Have we currently configured nameservers with eventdns? */
static int nameservers_configured = 0;
/** Did our most recent attempt to configure nameservers with eventdns fail? */
@@ -221,8 +250,8 @@ dns_reset(void)
{
or_options_t *options = get_options();
if (! server_mode(options)) {
- evdns_clear_nameservers_and_suspend();
- evdns_search_clear();
+ evdns_base_clear_nameservers_and_suspend(the_evdns_base);
+ evdns_base_search_clear(the_evdns_base);
nameservers_configured = 0;
tor_free(resolv_conf_fname);
resolv_conf_mtime = 0;
@@ -1118,6 +1147,13 @@ configure_nameservers(int force)
conf_fname = "/etc/resolv.conf";
#endif
+ if (!the_evdns_base) {
+ if (!(the_evdns_base = evdns_base_new(tor_libevent_get_base(), 0))) {
+ log_err(LD_BUG, "Couldn't create an evdns_base");
+ return -1;
+ }
+ }
+
#ifdef HAVE_EVDNS_SET_DEFAULT_OUTGOING_BIND_ADDRESS
if (options->OutboundBindAddress) {
tor_addr_t addr;
@@ -1133,18 +1169,14 @@ configure_nameservers(int force)
log_warn(LD_BUG, "Couldn't convert outbound bind address to sockaddr."
" Ignoring.");
} else {
- evdns_set_default_outgoing_bind_address((struct sockaddr *)&ss,
- socklen);
+ evdns_base_set_default_outgoing_bind_address(the_evdns_base,
+ (struct sockaddr *)&ss,
+ socklen);
}
}
}
#endif
- if (options->ServerDNSRandomizeCase)
- evdns_set_option("randomize-case:", "1", DNS_OPTIONS_ALL);
- else
- evdns_set_option("randomize-case:", "0", DNS_OPTIONS_ALL);
-
evdns_set_log_fn(evdns_log_cb);
if (conf_fname) {
if (stat(conf_fname, &st)) {
@@ -1158,16 +1190,17 @@ configure_nameservers(int force)
return 0;
}
if (nameservers_configured) {
- evdns_search_clear();
- evdns_clear_nameservers_and_suspend();
+ evdns_base_search_clear(the_evdns_base);
+ evdns_base_clear_nameservers_and_suspend(the_evdns_base);
}
log_info(LD_EXIT, "Parsing resolver configuration in '%s'", conf_fname);
- if ((r = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, conf_fname))) {
+ if ((r = evdns_base_resolv_conf_parse(the_evdns_base,
+ DNS_OPTIONS_ALL, 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_count_nameservers() == 0) {
+ if (evdns_base_count_nameservers(the_evdns_base) == 0) {
log_warn(LD_EXIT, "Unable to find any nameservers in '%s'.", conf_fname);
goto err;
}
@@ -1175,38 +1208,48 @@ configure_nameservers(int force)
resolv_conf_fname = tor_strdup(conf_fname);
resolv_conf_mtime = st.st_mtime;
if (nameservers_configured)
- evdns_resume();
+ evdns_base_resume(the_evdns_base);
}
#ifdef MS_WINDOWS
else {
if (nameservers_configured) {
- evdns_search_clear();
- evdns_clear_nameservers_and_suspend();
+ evdns_base_search_clear(the_evdns_base);
+ evdns_base_clear_nameservers_and_suspend(the_evdns_base);
}
- if (evdns_config_windows_nameservers()) {
+ if (evdns_base_config_windows_nameservers(the_evdns_base)) {
log_warn(LD_EXIT,"Could not config nameservers.");
goto err;
}
- if (evdns_count_nameservers() == 0) {
+ 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)
- evdns_resume();
+ evdns_base_resume(the_evdns_base);
tor_free(resolv_conf_fname);
resolv_conf_mtime = 0;
}
#endif
- if (evdns_count_nameservers() == 1) {
- evdns_set_option("max-timeouts:", "16", DNS_OPTIONS_ALL);
- evdns_set_option("timeout:", "10", DNS_OPTIONS_ALL);
+#define SET(k,v) \
+ evdns_base_set_option(the_evdns_base, (k), (v), DNS_OPTIONS_ALL)
+
+ if (evdns_base_count_nameservers(the_evdns_base) == 1) {
+ SET("max-timeouts:", "16");
+ SET("timeout:", "10");
} else {
- evdns_set_option("max-timeouts:", "3", DNS_OPTIONS_ALL);
- evdns_set_option("timeout:", "5", DNS_OPTIONS_ALL);
+ SET("max-timeouts:", "3");
+ SET("timeout:", "5");
}
+ if (options->ServerDNSRandomizeCase)
+ SET("randomize-case:", "1");
+ else
+ SET("randomize-case:", "0");
+
+#undef SET
+
dns_servers_relaunch_checks();
nameservers_configured = 1;
@@ -1304,6 +1347,7 @@ static int
launch_resolve(edge_connection_t *exitconn)
{
char *addr = tor_strdup(exitconn->_base.address);
+ struct evdns_request *req = NULL;
tor_addr_t a;
int r;
int options = get_options()->ServerDNSSearchDomains ? 0
@@ -1322,25 +1366,28 @@ launch_resolve(edge_connection_t *exitconn)
if (r == 0) {
log_info(LD_EXIT, "Launching eventdns request for %s",
escaped_safe_str(exitconn->_base.address));
- r = evdns_resolve_ipv4(exitconn->_base.address, options,
- evdns_callback, addr);
+ req = evdns_base_resolve_ipv4(the_evdns_base,
+ exitconn->_base.address, options,
+ evdns_callback, addr);
} else if (r == 1) {
log_info(LD_EXIT, "Launching eventdns reverse request for %s",
escaped_safe_str(exitconn->_base.address));
if (tor_addr_family(&a) == AF_INET)
- r = evdns_resolve_reverse(tor_addr_to_in(&a), DNS_QUERY_NO_SEARCH,
+ req = evdns_base_resolve_reverse(the_evdns_base,
+ tor_addr_to_in(&a), DNS_QUERY_NO_SEARCH,
evdns_callback, addr);
else
- r = evdns_resolve_reverse_ipv6(tor_addr_to_in6(&a), DNS_QUERY_NO_SEARCH,
+ req = evdns_base_resolve_reverse_ipv6(the_evdns_base,
+ tor_addr_to_in6(&a), DNS_QUERY_NO_SEARCH,
evdns_callback, addr);
} else if (r == -1) {
log_warn(LD_BUG, "Somehow a malformed in-addr.arpa address reached here.");
}
- if (r) {
- log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
- escaped_safe_str(addr), r);
- r = evdns_err_is_transient(r) ? -2 : -1;
+ r = 0;
+ if (!req) {
+ log_warn(LD_EXIT, "eventdns rejected address %s.", escaped_safe_str(addr));
+ r = -1;
tor_free(addr); /* There is no evdns request in progress; stop
* addr from getting leaked. */
}
@@ -1478,17 +1525,19 @@ static void
launch_wildcard_check(int min_len, int max_len, const char *suffix)
{
char *addr;
- int r;
+ struct evdns_request *req;
addr = crypto_random_hostname(min_len, max_len, "", suffix);
log_info(LD_EXIT, "Testing whether our DNS server is hijacking nonexistent "
"domains with request for bogus hostname \"%s\"", addr);
- r = evdns_resolve_ipv4(/* This "addr" tells us which address to resolve */
+ req = evdns_base_resolve_ipv4(
+ the_evdns_base,
+ /* This "addr" tells us which address to resolve */
addr,
DNS_QUERY_NO_SEARCH, evdns_wildcard_check_callback,
/* This "addr" is an argument to the callback*/ addr);
- if (r) {
+ if (!req) {
/* There is no evdns request in progress; stop addr from getting leaked */
tor_free(addr);
}
@@ -1500,6 +1549,7 @@ static void
launch_test_addresses(int fd, short event, void *args)
{
or_options_t *options = get_options();
+ struct evdns_request *req;
(void)fd;
(void)event;
(void)args;
@@ -1511,14 +1561,18 @@ launch_test_addresses(int fd, short event, void *args)
* be an exit server.*/
if (!options->ServerDNSTestAddresses)
return;
- SMARTLIST_FOREACH(options->ServerDNSTestAddresses, const char *, address,
- {
- int r = evdns_resolve_ipv4(address, DNS_QUERY_NO_SEARCH, evdns_callback,
- tor_strdup(address));
- if (r)
- log_info(LD_EXIT, "eventdns rejected test address %s: error %d",
- escaped_safe_str(address), r);
- });
+ SMARTLIST_FOREACH_BEGIN(options->ServerDNSTestAddresses,
+ const char *, address) {
+ char *a = tor_strdup(address);
+ req = evdns_base_resolve_ipv4(the_evdns_base,
+ address, DNS_QUERY_NO_SEARCH, evdns_callback, a);
+
+ if (!req) {
+ log_info(LD_EXIT, "eventdns rejected test address %s",
+ escaped_safe_str(address));
+ tor_free(a);
+ }
+ } SMARTLIST_FOREACH_END(address);
}
#define N_WILDCARD_CHECKS 2
--
1.5.6.5
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