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[tor-commits] [tor/maint-0.3.0] Change approach to preventing duplicate guards.
commit 1582adabbb13871bcf6f91be4fa8523aeb36f79a
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date: Tue Feb 14 12:21:31 2017 -0500
Change approach to preventing duplicate guards.
Previously I'd made a bad assumption in the implementation of
prop271 in 0.3.0.1-alpha: I'd assumed that there couldn't be two
guards with the same identity. That's true for non-bridges, but in
the bridge case, we allow two bridges to have the same ID if they
have different addr:port combinations -- in order to have the same
bridge ID running multiple PTs.
Fortunately, this assumption wasn't deeply ingrained: we stop
enforcing the "one guard per ID" rule in the bridge case, and
instead enforce "one guard per <id,addr,port>".
We also needed to tweak our implementation of
get_bridge_info_for_guard, since it made the same incorrect
assumption.
Fixes bug 21027; bugfix on 0.3.0.1-alpha.
---
changes/bug21027 | 8 ++++++++
src/or/bridges.c | 27 +++++++++++++++++++++++++++
src/or/bridges.h | 4 ++++
src/or/entrynodes.c | 29 +++++++++++++++--------------
4 files changed, 54 insertions(+), 14 deletions(-)
diff --git a/changes/bug21027 b/changes/bug21027
new file mode 100644
index 0000000..d20df87
--- /dev/null
+++ b/changes/bug21027
@@ -0,0 +1,8 @@
+ o Major bugfixes (bridges):
+
+ - When the same bridge is configured multiple times at different
+ address:port combinations (but with the same identity), treat
+ those bridge instances as separate guards. This allows clients to
+ configure the same bridge with multiple pluggable transports, once
+ again. Fixes bug 21027; bugfix on 0.3.0.1-alpha.
+
diff --git a/src/or/bridges.c b/src/or/bridges.c
index 8b37f41..f766931 100644
--- a/src/or/bridges.c
+++ b/src/or/bridges.c
@@ -199,6 +199,33 @@ get_configured_bridge_by_addr_port_digest(const tor_addr_t *addr,
return NULL;
}
+/**
+ * As get_configured_bridge_by_addr_port, but require that the
+ * address match <b>addr</b>:<b>port</b>, and that the ID digest match
+ * <b>digest</b>. (The other function will ignore the address if the
+ * digest matches.)
+ */
+bridge_info_t *
+get_configured_bridge_by_exact_addr_port_digest(const tor_addr_t *addr,
+ uint16_t port,
+ const char *digest)
+{
+ if (!bridge_list)
+ return NULL;
+ SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge) {
+ if (!tor_addr_compare(&bridge->addr, addr, CMP_EXACT) &&
+ bridge->port == port) {
+
+ if (digest && tor_memeq(bridge->identity, digest, DIGEST_LEN))
+ return bridge;
+ else if (!digest)
+ return bridge;
+ }
+
+ } SMARTLIST_FOREACH_END(bridge);
+ return NULL;
+}
+
/** If we have a bridge configured whose digest matches <b>digest</b>, or a
* bridge with no known digest whose address matches <b>addr</b>:<b>port</b>,
* return 1. Else return 0. If <b>digest</b> is NULL, check for
diff --git a/src/or/bridges.h b/src/or/bridges.h
index de23fe6..27ea5e1 100644
--- a/src/or/bridges.h
+++ b/src/or/bridges.h
@@ -27,6 +27,10 @@ bridge_info_t *get_configured_bridge_by_addr_port_digest(
const tor_addr_t *addr,
uint16_t port,
const char *digest);
+bridge_info_t *get_configured_bridge_by_exact_addr_port_digest(
+ const tor_addr_t *addr,
+ uint16_t port,
+ const char *digest);
int addr_is_a_configured_bridge(const tor_addr_t *addr, uint16_t port,
const char *digest);
diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c
index 93dd2bd..3e87147 100644
--- a/src/or/entrynodes.c
+++ b/src/or/entrynodes.c
@@ -768,11 +768,6 @@ get_sampled_guard_for_bridge(guard_selection_t *gs,
const uint8_t *id = bridge_get_rsa_id_digest(bridge);
const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
entry_guard_t *guard;
- if (id) {
- guard = get_sampled_guard_with_id(gs, id);
- if (guard)
- return guard;
- }
if (BUG(!addrport))
return NULL; // LCOV_EXCL_LINE
guard = get_sampled_guard_by_bridge_addr(gs, addrport);
@@ -787,16 +782,17 @@ get_sampled_guard_for_bridge(guard_selection_t *gs,
static bridge_info_t *
get_bridge_info_for_guard(const entry_guard_t *guard)
{
+ const uint8_t *identity = NULL;
if (! tor_digest_is_zero(guard->identity)) {
- bridge_info_t *bridge = find_bridge_by_digest(guard->identity);
- if (bridge)
- return bridge;
+ identity = (const uint8_t *)guard->identity;
}
if (BUG(guard->bridge_addr == NULL))
return NULL;
- return get_configured_bridge_by_addr_port_digest(&guard->bridge_addr->addr,
- guard->bridge_addr->port,
- NULL);
+
+ return get_configured_bridge_by_exact_addr_port_digest(
+ &guard->bridge_addr->addr,
+ guard->bridge_addr->port,
+ (const char*)identity);
}
/**
@@ -820,6 +816,10 @@ entry_guard_add_to_sample(guard_selection_t *gs,
log_info(LD_GUARD, "Adding %s as to the entry guard sample set.",
node_describe(node));
+ /* make sure that the guard is not already sampled. */
+ if (BUG(have_sampled_guard_with_id(gs, (const uint8_t*)node->identity)))
+ return NULL; // LCOV_EXCL_LINE
+
return entry_guard_add_to_sample_impl(gs,
(const uint8_t*)node->identity,
node_get_nickname(node),
@@ -843,9 +843,6 @@ entry_guard_add_to_sample_impl(guard_selection_t *gs,
// XXXX #20827 take ed25519 identity here too.
- /* make sure that the guard is not already sampled. */
- if (rsa_id_digest && BUG(have_sampled_guard_with_id(gs, rsa_id_digest)))
- return NULL; // LCOV_EXCL_LINE
/* Make sure we can actually identify the guard. */
if (BUG(!rsa_id_digest && !bridge_addrport))
return NULL; // LCOV_EXCL_LINE
@@ -890,6 +887,10 @@ entry_guard_add_bridge_to_sample(guard_selection_t *gs,
tor_assert(addrport);
+ /* make sure that the guard is not already sampled. */
+ if (BUG(get_sampled_guard_for_bridge(gs, bridge)))
+ return NULL; // LCOV_EXCL_LINE
+
return entry_guard_add_to_sample_impl(gs, id_digest, NULL, addrport);
}
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