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.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/or/bridges.h b/src/or/bridges.h
index de23fe6eeb..27ea5e197c 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);