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Make dns wildcarding checks work for ipv6

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This commit is contained in:
Nick Mathewson 2012-10-27 16:07:25 -04:00
parent 9016d9e829
commit 00633b9446
1 changed files with 59 additions and 30 deletions
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89
src/or/dns.c
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@ -1506,8 +1506,8 @@ static int dns_wildcarded_test_address_notice_given = 0;
/** True iff all addresses seem to be getting wildcarded. */
static int dns_is_completely_invalid = 0;
/** Called when we see <b>id</b> (a dotted quad) in response to a request for
* a hopefully bogus address. */
/** Called when we see <b>id</b> (a dotted quad or IPv6 address) in response
* to a request for a hopefully bogus address. */
static void
wildcard_increment_answer(const char *id)
{
@ -1579,17 +1579,27 @@ evdns_wildcard_check_callback(int result, char type, int count, int ttl,
{
(void)ttl;
++n_wildcard_requests;
if (result == DNS_ERR_NONE && type == DNS_IPv4_A && count) {
uint32_t *addrs = addresses;
int i;
if (result == DNS_ERR_NONE && count) {
char *string_address = arg;
for (i = 0; i < count; ++i) {
char answer_buf[INET_NTOA_BUF_LEN+1];
struct in_addr in;
in.s_addr = addrs[i];
tor_inet_ntoa(&in, answer_buf, sizeof(answer_buf));
wildcard_increment_answer(answer_buf);
int i;
if (type == DNS_IPv4_A) {
const uint32_t *addrs = addresses;
for (i = 0; i < count; ++i) {
char answer_buf[INET_NTOA_BUF_LEN+1];
struct in_addr in;
in.s_addr = addrs[i];
tor_inet_ntoa(&in, answer_buf, sizeof(answer_buf));
wildcard_increment_answer(answer_buf);
}
} else if (type == DNS_IPv6_AAAA) {
const struct in6_addr *addrs = addresses;
for (i = 0; i < count; ++i) {
char answer_buf[TOR_ADDR_BUF_LEN+1];
tor_inet_ntop(AF_INET6, &addrs[i], answer_buf, sizeof(answer_buf));
wildcard_increment_answer(answer_buf);
}
}
log(dns_wildcard_one_notice_given ? LOG_INFO : LOG_NOTICE, LD_EXIT,
"Your DNS provider gave an answer for \"%s\", which "
"is not supposed to exist. Apparently they are hijacking "
@ -1606,7 +1616,8 @@ evdns_wildcard_check_callback(int result, char type, int count, int ttl,
* <b>min_len</b> and <b>max_len</b> random (plausible) characters followed by
* <b>suffix</b> */
static void
launch_wildcard_check(int min_len, int max_len, const char *suffix)
launch_wildcard_check(int min_len, int max_len, int is_ipv6,
const char *suffix)
{
char *addr;
struct evdns_request *req;
@ -1616,7 +1627,15 @@ launch_wildcard_check(int min_len, int max_len, const char *suffix)
"domains with request for bogus hostname \"%s\"", addr);
tor_assert(the_evdns_base);
req = evdns_base_resolve_ipv4(
if (is_ipv6)
req = evdns_base_resolve_ipv6(
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);
else
req = evdns_base_resolve_ipv4(
the_evdns_base,
/* This "addr" tells us which address to resolve */
addr,
@ -1661,6 +1680,14 @@ launch_test_addresses(int fd, short event, void *args)
escaped_safe_str(address));
tor_free(a);
}
a = tor_strdup(address);
req = evdns_base_resolve_ipv6(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);
}
@ -1673,27 +1700,29 @@ launch_test_addresses(int fd, short event, void *args)
static void
dns_launch_wildcard_checks(void)
{
int i;
int i, ipv6;
log_info(LD_EXIT, "Launching checks to see whether our nameservers like "
"to hijack DNS failures.");
for (i = 0; i < N_WILDCARD_CHECKS; ++i) {
/* RFC2606 reserves these. Sadly, some DNS hijackers, in a silly attempt
* to 'comply' with rfc2606, refrain from giving A records for these.
* This is the standards-compliance equivalent of making sure that your
* crackhouse's elevator inspection certificate is up to date.
*/
launch_wildcard_check(2, 16, ".invalid");
launch_wildcard_check(2, 16, ".test");
for (ipv6 = 0; ipv6 <= 1; ++ipv6) {
for (i = 0; i < N_WILDCARD_CHECKS; ++i) {
/* RFC2606 reserves these. Sadly, some DNS hijackers, in a silly
* attempt to 'comply' with rfc2606, refrain from giving A records for
* these. This is the standards-compliance equivalent of making sure
* that your crackhouse's elevator inspection certificate is up to date.
*/
launch_wildcard_check(2, 16, ipv6, ".invalid");
launch_wildcard_check(2, 16, ipv6, ".test");
/* These will break specs if there are ever any number of
* 8+-character top-level domains. */
launch_wildcard_check(8, 16, "");
/* These will break specs if there are ever any number of
* 8+-character top-level domains. */
launch_wildcard_check(8, 16, ipv6, "");
/* Try some random .com/org/net domains. This will work fine so long as
* not too many resolve to the same place. */
launch_wildcard_check(8, 16, ".com");
launch_wildcard_check(8, 16, ".org");
launch_wildcard_check(8, 16, ".net");
/* Try some random .com/org/net domains. This will work fine so long as
* not too many resolve to the same place. */
launch_wildcard_check(8, 16, ipv6, ".com");
launch_wildcard_check(8, 16, ipv6, ".org");
launch_wildcard_check(8, 16, ipv6, ".net");
}
}
}