[or-cvs] r8478: Backport candidate: Fix a long-standing server-side DNS bug. (in tor/trunk: . doc src/or)
nickm at seul.org
nickm at seul.org
Sun Sep 24 17:05:04 UTC 2006
Author: nickm
Date: 2006-09-24 13:05:00 -0400 (Sun, 24 Sep 2006)
New Revision: 8478
Modified:
tor/trunk/ChangeLog
tor/trunk/doc/TODO
tor/trunk/src/or/connection_edge.c
tor/trunk/src/or/dns.c
tor/trunk/src/or/or.h
Log:
Backport candidate: Fix a long-standing server-side DNS bug. When a
client asks us to resolve (not connect to) an address, and we have a
cached answer, give them the cached answer. Previously, we would give
them no answer at all.
Modified: tor/trunk/ChangeLog
===================================================================
--- tor/trunk/ChangeLog 2006-09-24 16:06:31 UTC (rev 8477)
+++ tor/trunk/ChangeLog 2006-09-24 17:05:00 UTC (rev 8478)
@@ -24,6 +24,11 @@
descriptor for a named server with that name, we might return an old
one.
+ o Major bugfixes
+ - When a client asks us to resolve (not connect to) an address,
+ and we have a cached answer, give them the cached answer.
+ Previously, we would give them no answer at all.
+
o Minor Bugfixes
- Small performance improvements on parsing descriptors (x2).
- Major performance descriptor on inserting descriptors; change
Modified: tor/trunk/doc/TODO
===================================================================
--- tor/trunk/doc/TODO 2006-09-24 16:06:31 UTC (rev 8477)
+++ tor/trunk/doc/TODO 2006-09-24 17:05:00 UTC (rev 8478)
@@ -111,7 +111,7 @@
o Connect to resolve cells, server-side.
o Add element to routerinfo to note routers that aren't using eventdns,
so we can avoid sending them reverse DNS etc.
- - Fix the bug with server-side caching, whatever is causing it.
+ o Fix the bug with server-side caching, whatever is causing it.
. Add client-side interface
o SOCKS interface: specify
o SOCKS interface: implement
Modified: tor/trunk/src/or/connection_edge.c
===================================================================
--- tor/trunk/src/or/connection_edge.c 2006-09-24 16:06:31 UTC (rev 8477)
+++ tor/trunk/src/or/connection_edge.c 2006-09-24 17:05:00 UTC (rev 8478)
@@ -1899,7 +1899,7 @@
log_debug(LD_EXIT,"about to start the dns_resolve().");
/* send it off to the gethostbyname farm */
- switch (dns_resolve(n_stream)) {
+ switch (dns_resolve(n_stream, NULL)) {
case 1: /* resolve worked */
/* add it into the linked list of n_streams on this circuit */
@@ -1912,6 +1912,7 @@
connection_exit_connect(n_stream);
return 0;
case -1: /* resolve failed */
+ /* XXXX send back indication of failure for connect case? -NM*/
/* n_stream got freed. don't touch it. */
break;
case 0: /* resolve added to pending list */
@@ -1954,7 +1955,7 @@
dummy_conn->_base.purpose = EXIT_PURPOSE_RESOLVE;
/* send it off to the gethostbyname farm */
- switch (dns_resolve(dummy_conn)) {
+ switch (dns_resolve(dummy_conn, circ)) {
case -1: /* Impossible to resolve; a resolved cell was sent. */
/* Connection freed; don't touch it. */
return 0;
Modified: tor/trunk/src/or/dns.c
===================================================================
--- tor/trunk/src/or/dns.c 2006-09-24 16:06:31 UTC (rev 8477)
+++ tor/trunk/src/or/dns.c 2006-09-24 17:05:00 UTC (rev 8478)
@@ -113,8 +113,9 @@
static void dns_found_answer(const char *address, int is_reverse,
uint32_t addr, const char *hostname, char outcome,
uint32_t ttl);
-static void send_resolved_cell(edge_connection_t *conn, uint8_t answer_type);
-static int launch_resolve(edge_connection_t *exitconn);
+static void send_resolved_cell(edge_connection_t *conn, or_circuit_t *circ,
+ uint8_t answer_type);
+static int launch_resolve(edge_connection_t *exitconn, or_circuit_t *circ);
#ifndef USE_EVENTDNS
static void dnsworkers_rotate(void);
static void dnsworker_main(void *data);
@@ -385,9 +386,15 @@
}
/** Send a response to the RESOLVE request of a connection. answer_type must
- * be one of RESOLVED_TYPE_(IPV4|ERROR|ERROR_TRANSIENT) */
+ * be one of RESOLVED_TYPE_(IPV4|ERROR|ERROR_TRANSIENT)
+ *
+ * If <b>circ</b> is provided, and we have a cached answer, send the
+ * answer back along circ; otherwise, send the answer back along *
+ * <b>exitconn</b>'s attached circuit.
+ */
static void
-send_resolved_cell(edge_connection_t *conn, uint8_t answer_type)
+send_resolved_cell(edge_connection_t *conn, or_circuit_t *circ,
+ uint8_t answer_type)
{
char buf[RELAY_PAYLOAD_SIZE];
size_t buflen;
@@ -421,7 +428,14 @@
return;
}
// log_notice(LD_EXIT, "Sending a regular RESOLVED reply: ");
- connection_edge_send_command(conn, circuit_get_by_edge_conn(conn),
+
+ if (!circ) {
+ circuit_t *tmp = circuit_get_by_edge_conn(conn);
+ if (! CIRCUIT_IS_ORIGIN(tmp))
+ circ = TO_OR_CIRCUIT(tmp);
+ }
+
+ connection_edge_send_command(conn, TO_CIRCUIT(circ),
RELAY_COMMAND_RESOLVED, buf, buflen,
conn->cpath_layer);
}
@@ -429,9 +443,14 @@
/** Send a response to the RESOLVE request of a connection for an in-addr.arpa
* address on connection <b>conn</b> which yielded the result <b>hostname</b>.
* The answer type will be RESOLVED_HOSTNAME.
+ *
+ * If <b>circ</b> is provided, and we have a cached answer, send the
+ * answer back along circ; otherwise, send the answer back along
+ * <b>exitconn</b>'s attached circuit.
*/
static void
-send_resolved_hostname_cell(edge_connection_t *conn, const char *hostname)
+send_resolved_hostname_cell(edge_connection_t *conn, or_circuit_t *circ,
+ const char *hostname)
{
char buf[RELAY_PAYLOAD_SIZE];
size_t buflen;
@@ -447,8 +466,14 @@
set_uint32(buf+2+namelen, htonl(ttl));
buflen = 2+namelen+4;
+ if (!circ) {
+ circuit_t *tmp = circuit_get_by_edge_conn(conn);
+ if (! CIRCUIT_IS_ORIGIN(tmp))
+ circ = TO_OR_CIRCUIT(tmp);
+ }
+
// log_notice(LD_EXIT, "Sending a reply RESOLVED reply: %s", hostname);
- connection_edge_send_command(conn, circuit_get_by_edge_conn(conn),
+ connection_edge_send_command(conn, TO_CIRCUIT(circ),
RELAY_COMMAND_RESOLVED, buf, buflen,
conn->cpath_layer);
// log_notice(LD_EXIT, "Sent");
@@ -500,6 +525,10 @@
* if resolve valid, put it into <b>exitconn</b>-\>addr and return 1.
* If resolve failed, unlink exitconn if needed, free it, and return -1.
*
+ * If <b>circ</b> is provided, and this is a resolve request, we have
+ * a cached answer, send the answer back along circ; otherwise, send
+ * the answer back along <b>exitconn</b>'s attached circuit.
+ *
* Else, if seen before and pending, add conn to the pending list,
* and return 0.
*
@@ -507,7 +536,7 @@
* dns farm, and return 0.
*/
int
-dns_resolve(edge_connection_t *exitconn)
+dns_resolve(edge_connection_t *exitconn, or_circuit_t *oncirc)
{
cached_resolve_t *resolve;
cached_resolve_t search;
@@ -529,7 +558,7 @@
exitconn->_base.addr = ntohl(in.s_addr);
exitconn->address_ttl = DEFAULT_DNS_TTL;
if (is_resolve)
- send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
+ send_resolved_cell(exitconn, oncirc, RESOLVED_TYPE_IPV4);
return 1;
}
@@ -566,7 +595,7 @@
#endif
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
- send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
+ send_resolved_cell(exitconn, oncirc, RESOLVED_TYPE_ERROR);
circ = circuit_get_by_edge_conn(exitconn);
if (circ)
circuit_detach_stream(circ, exitconn);
@@ -602,19 +631,21 @@
exitconn->address_ttl = resolve->ttl;
if (resolve->is_reverse) {
tor_assert(is_resolve);
- send_resolved_hostname_cell(exitconn, resolve->result.hostname);
+ send_resolved_hostname_cell(exitconn, oncirc,
+ resolve->result.hostname);
} else {
exitconn->_base.addr = resolve->result.addr;
if (is_resolve)
- send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
+ send_resolved_cell(exitconn, oncirc, RESOLVED_TYPE_IPV4);
}
return 1;
case CACHE_STATE_CACHED_FAILED:
log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s",
exitconn->_base.s,
escaped_safe_str(exitconn->_base.address));
+ /* XXXX send back indication of failure for connect case? -NM*/
if (is_resolve)
- send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
+ send_resolved_cell(exitconn, oncirc, RESOLVED_TYPE_ERROR);
circ = circuit_get_by_edge_conn(exitconn);
if (circ)
circuit_detach_stream(circ, exitconn);
@@ -647,7 +678,7 @@
log_debug(LD_EXIT,"Launching %s.",
escaped_safe_str(exitconn->_base.address));
assert_cache_ok();
- return launch_resolve(exitconn);
+ return launch_resolve(exitconn, oncirc);
}
/** Log an error and abort if conn is waiting for a DNS resolve.
@@ -903,7 +934,7 @@
/* This detach must happen after we send the end cell. */
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
} else {
- send_resolved_cell(pendconn, RESOLVED_TYPE_ERROR);
+ send_resolved_cell(pendconn, NULL, RESOLVED_TYPE_ERROR);
/* This detach must happen after we send the resolved cell. */
circuit_detach_stream(circuit_get_by_edge_conn(pendconn), pendconn);
}
@@ -930,9 +961,9 @@
* but it does the right thing. */
pendconn->_base.state = EXIT_CONN_STATE_RESOLVEFAILED;
if (is_reverse)
- send_resolved_hostname_cell(pendconn, hostname);
+ send_resolved_hostname_cell(pendconn, NULL, hostname);
else
- send_resolved_cell(pendconn, RESOLVED_TYPE_IPV4);
+ send_resolved_cell(pendconn, NULL, RESOLVED_TYPE_IPV4);
circ = circuit_get_by_edge_conn(pendconn);
tor_assert(circ);
circuit_detach_stream(circ, pendconn);
@@ -963,7 +994,7 @@
* <b>exitconn</b>-\>address; tell that dns worker to begin resolving.
*/
static int
-launch_resolve(edge_connection_t *exitconn)
+launch_resolve(edge_connection_t *exitconn, or_circuit_t *circ)
{
connection_t *dnsconn;
unsigned char len;
@@ -983,7 +1014,7 @@
if (!dnsconn) {
log_warn(LD_EXIT,"no idle dns workers. Failing.");
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
- send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
+ send_resolved_cell(exitconn, circ, RESOLVED_TYPE_ERROR_TRANSIENT);
goto err;
}
@@ -1533,7 +1564,7 @@
/** For eventdns: start resolving as necessary to find the target for
* <b>exitconn</b> */
static int
-launch_resolve(edge_connection_t *exitconn)
+launch_resolve(edge_connection_t *exitconn, or_circuit_t *circ)
{
char *addr = tor_strdup(exitconn->_base.address);
struct in_addr in;
@@ -1568,10 +1599,10 @@
escaped_safe_str(addr), r);
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE) {
if (eventdns_err_is_transient(r))
- send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
+ send_resolved_cell(exitconn, circ, RESOLVED_TYPE_ERROR_TRANSIENT);
else {
exitconn->address_ttl = DEFAULT_DNS_TTL;
- send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
+ send_resolved_cell(exitconn, circ, RESOLVED_TYPE_ERROR);
}
}
dns_cancel_pending_resolve(addr); /* also sends end and frees */
Modified: tor/trunk/src/or/or.h
===================================================================
--- tor/trunk/src/or/or.h 2006-09-24 16:06:31 UTC (rev 8477)
+++ tor/trunk/src/or/or.h 2006-09-24 17:05:00 UTC (rev 8478)
@@ -2160,7 +2160,7 @@
void assert_connection_edge_not_dns_pending(edge_connection_t *conn);
void assert_all_pending_dns_resolves_ok(void);
void dns_cancel_pending_resolve(const char *question);
-int dns_resolve(edge_connection_t *exitconn);
+int dns_resolve(edge_connection_t *exitconn, or_circuit_t *circ);
void dns_launch_wildcard_checks(void);
/********************************* hibernate.c **********************/
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