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[tor-commits] [tor/release-0.2.9] In circuit_pick_extend_handshake, assume all hops support EXTEND2 and ntor
commit 26d7a07ad773713403a0db1c49ccb58e071763b2
Author: teor <teor2345@xxxxxxxxx>
Date: Thu Oct 27 15:52:46 2016 +1100
In circuit_pick_extend_handshake, assume all hops support EXTEND2 and ntor
This simplifies the function: if we have an ntor key, use ntor/EXTEND2,
otherwise, use TAP/EXTEND.
Bugfix on commit 10aa913 from 19163 in 0.2.9.3-alpha.
---
changes/bug20472 | 4 ++++
src/or/circuitbuild.c | 57 +++++++++++++++++----------------------------------
2 files changed, 23 insertions(+), 38 deletions(-)
diff --git a/changes/bug20472 b/changes/bug20472
new file mode 100644
index 0000000..b035037
--- /dev/null
+++ b/changes/bug20472
@@ -0,0 +1,4 @@
+ o Minor bugfixes (circuits):
+ - Remove a BUG warning in circuit_pick_extend_handshake. Instead, assume
+ all nodes support EXTEND2. Use ntor whenever a key is available.
+ Bugfix on commit 10aa913 from 19163 in 0.2.9.3-alpha. Fixes bug 20472.
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index cc9b184..9893215 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -814,7 +814,8 @@ circuit_timeout_want_to_count_circ(origin_circuit_t *circ)
/** Decide whether to use a TAP or ntor handshake for connecting to <b>ei</b>
* directly, and set *<b>cell_type_out</b> and *<b>handshake_type_out</b>
* accordingly.
- * Note that TAP handshakes are only used for direct connections:
+ * Note that TAP handshakes in CREATE cells are only used for direct
+ * connections:
* - from Tor2web to intro points not in the client's consensus, and
* - from Single Onions to rend points not in the service's consensus.
* This is checked in onion_populate_cpath. */
@@ -823,7 +824,8 @@ circuit_pick_create_handshake(uint8_t *cell_type_out,
uint16_t *handshake_type_out,
const extend_info_t *ei)
{
- /* XXXX030 Remove support for deciding to use TAP. */
+ /* torspec says: In general, clients SHOULD use CREATE whenever they are
+ * using the TAP handshake, and CREATE2 otherwise. */
if (extend_info_supports_ntor(ei)) {
*cell_type_out = CELL_CREATE2;
*handshake_type_out = ONION_HANDSHAKE_TYPE_NTOR;
@@ -834,47 +836,31 @@ circuit_pick_create_handshake(uint8_t *cell_type_out,
*handshake_type_out = ONION_HANDSHAKE_TYPE_TAP;
}
-/** Decide whether to use a TAP or ntor handshake for connecting to <b>ei</b>
- * directly, and set *<b>handshake_type_out</b> accordingly. Decide whether,
- * in extending through <b>node</b> to do so, we should use an EXTEND2 or an
- * EXTEND cell to do so, and set *<b>cell_type_out</b> and
- * *<b>create_cell_type_out</b> accordingly.
- * Note that TAP handshakes are only used for extend handshakes:
+/** Decide whether to use a TAP or ntor handshake for extending to <b>ei</b>
+ * and set *<b>handshake_type_out</b> accordingly. Decide whether we should
+ * use an EXTEND2 or an EXTEND cell to do so, and set *<b>cell_type_out</b>
+ * and *<b>create_cell_type_out</b> accordingly.
+ * Note that TAP handshakes in EXTEND cells are only used:
* - from clients to intro points, and
* - from hidden services to rend points.
- * This is checked in onion_populate_cpath. */
+ * This is checked in onion_populate_cpath.
+ */
static void
circuit_pick_extend_handshake(uint8_t *cell_type_out,
uint8_t *create_cell_type_out,
uint16_t *handshake_type_out,
- const node_t *node_prev,
const extend_info_t *ei)
{
uint8_t t;
circuit_pick_create_handshake(&t, handshake_type_out, ei);
- /* XXXX030 Remove support for deciding to use TAP. */
-
- /* It is an error to extend if there is no previous node. */
- if (BUG(node_prev == NULL)) {
- *cell_type_out = RELAY_COMMAND_EXTEND;
- *create_cell_type_out = CELL_CREATE;
- return;
- }
-
- /* It is an error for a node with a known version to be so old it does not
- * support ntor. */
- tor_assert_nonfatal(routerstatus_version_supports_ntor(node_prev->rs, 1));
-
- /* Assume relays without tor versions or routerstatuses support ntor.
- * The authorities enforce ntor support, and assuming and failing is better
- * than allowing a malicious node to perform a protocol downgrade to TAP. */
- if (*handshake_type_out != ONION_HANDSHAKE_TYPE_TAP &&
- (node_has_curve25519_onion_key(node_prev) ||
- (routerstatus_version_supports_ntor(node_prev->rs, 1)))) {
+ /* torspec says: Clients SHOULD use the EXTEND format whenever sending a TAP
+ * handshake... In other cases, clients SHOULD use EXTEND2. */
+ if (*handshake_type_out != ONION_HANDSHAKE_TYPE_TAP) {
*cell_type_out = RELAY_COMMAND_EXTEND2;
*create_cell_type_out = CELL_CREATE2;
} else {
+ /* XXXX030 Remove support for deciding to use TAP and EXTEND. */
*cell_type_out = RELAY_COMMAND_EXTEND;
*create_cell_type_out = CELL_CREATE;
}
@@ -1030,15 +1016,10 @@ circuit_send_next_onion_skin(origin_circuit_t *circ)
return - END_CIRC_REASON_INTERNAL;
}
- {
- const node_t *prev_node;
- prev_node = node_get_by_id(hop->prev->extend_info->identity_digest);
- circuit_pick_extend_handshake(&ec.cell_type,
- &ec.create_cell.cell_type,
- &ec.create_cell.handshake_type,
- prev_node,
- hop->extend_info);
- }
+ circuit_pick_extend_handshake(&ec.cell_type,
+ &ec.create_cell.cell_type,
+ &ec.create_cell.handshake_type,
+ hop->extend_info);
tor_addr_copy(&ec.orport_ipv4.addr, &hop->extend_info->addr);
ec.orport_ipv4.port = hop->extend_info->port;
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