[tor-commits] [tor/master] Check if there are exits in the consensus
nickm at torproject.org
nickm at torproject.org
Tue Dec 30 14:08:00 UTC 2014
commit 9b2d106e49ba4ea12f31af9cea02910869f19a4b
Author: teor <teor2345 at gmail.com>
Date: Fri Dec 26 00:10:40 2014 +1100
Check if there are exits in the consensus
Add router_have_consensus_path() which reports whether
the consensus has exit paths, internal paths, or whether it
just doesn't know.
Used by #13718 and #13814.
---
changes/bug13718-check-consensus-exits | 6 ++++
src/or/nodelist.c | 59 ++++++++++++++++++++++++++++++--
src/or/nodelist.h | 22 ++++++++++++
3 files changed, 84 insertions(+), 3 deletions(-)
diff --git a/changes/bug13718-check-consensus-exits b/changes/bug13718-check-consensus-exits
new file mode 100644
index 0000000..5ca4b11
--- /dev/null
+++ b/changes/bug13718-check-consensus-exits
@@ -0,0 +1,6 @@
+ o Minor enhancement:
+ - Check if there are exits in the consensus.
+ Add router_have_consensus_path() which reports whether
+ the consensus has exit paths, internal paths, or whether it
+ just doesn't know.
+ Used by #13718 and #13814.
diff --git a/src/or/nodelist.c b/src/or/nodelist.c
index 796d0ec..77196a4 100644
--- a/src/or/nodelist.c
+++ b/src/or/nodelist.c
@@ -1275,6 +1275,10 @@ router_set_status(const char *digest, int up)
/** True iff, the last time we checked whether we had enough directory info
* to build circuits, the answer was "yes". */
static int have_min_dir_info = 0;
+
+/** Does the consensus contain nodes that can exit? */
+static consensus_path_type_t have_consensus_path = CONSENSUS_PATH_UNKNOWN;
+
/** True iff enough has changed since the last time we checked whether we had
* enough directory info to build circuits that our old answer can no longer
* be trusted. */
@@ -1308,6 +1312,24 @@ router_have_minimum_dir_info(void)
return have_min_dir_info;
}
+/** Set to CONSENSUS_PATH_EXIT if there is at least one exit node
+ * in the consensus. We update this flag in compute_frac_paths_available if
+ * there is at least one relay that has an Exit flag in the consensus.
+ * Used to avoid building exit circuits when they will almost certainly fail.
+ * Set to CONSENSUS_PATH_INTERNAL if there are no exits in the consensus.
+ * (This situation typically occurs during bootstrap of a test network.)
+ * Set to CONSENSUS_PATH_UNKNOWN if we have never checked, or have
+ * reason to believe our last known value was invalid or has expired.
+ * If we're in a network with TestingDirAuthVoteExit set,
+ * this can cause router_have_consensus_path() to be set to
+ * CONSENSUS_PATH_EXIT, even if there are no nodes with accept exit policies.
+ */
+consensus_path_type_t
+router_have_consensus_path(void)
+{
+ return have_consensus_path;
+}
+
/** Called when our internal view of the directory has changed. This can be
* when the authorities change, networkstatuses change, the list of routerdescs
* changes, or number of running routers changes.
@@ -1396,7 +1418,11 @@ compute_frac_paths_available(const networkstatus_t *consensus,
smartlist_t *myexits= smartlist_new();
smartlist_t *myexits_unflagged = smartlist_new();
double f_guard, f_mid, f_exit, f_myexit, f_myexit_unflagged;
- int np, nu; /* Ignored */
+ double f_path = 0.0;
+ /* Used to determine whether there are any exits in the consensus */
+ int np = 0;
+ /* Used to determine whether there are any exits with descriptors */
+ int nu = 0;
const int authdir = authdir_mode_v3(options);
count_usable_descriptors(num_present_out, num_usable_out,
@@ -1417,7 +1443,13 @@ compute_frac_paths_available(const networkstatus_t *consensus,
});
}
- /* All nodes with exit flag */
+ /* All nodes with exit flag
+ * If we're in a network with TestingDirAuthVoteExit set,
+ * this can cause false positives on have_consensus_path,
+ * incorrectly setting it to CONSENSUS_PATH_EXIT. This is
+ * an unavoidable feature of forcing authorities to declare
+ * certain nodes as exits.
+ */
count_usable_descriptors(&np, &nu, exits, consensus, options, now,
NULL, USABLE_DESCRIPTOR_EXIT_ONLY);
log_debug(LD_NET,
@@ -1426,6 +1458,27 @@ compute_frac_paths_available(const networkstatus_t *consensus,
np,
nu);
+ /* We need at least 1 exit present in the consensus to consider
+ * building exit paths */
+ /* Update our understanding of whether the consensus has exits */
+ consensus_path_type_t old_have_consensus_path = have_consensus_path;
+ have_consensus_path = ((np > 0) ?
+ CONSENSUS_PATH_EXIT :
+ CONSENSUS_PATH_INTERNAL);
+
+ if (have_consensus_path == CONSENSUS_PATH_INTERNAL
+ && old_have_consensus_path != have_consensus_path) {
+ log_notice(LD_NET,
+ "The current consensus has no exit nodes. "
+ "Tor can only build internal paths, "
+ "such as paths to hidden services.");
+
+ /* However, exit nodes can reachability self-test using this consensus,
+ * join the network, and appear in a later consensus. This will allow
+ * the network to build exit paths, such as paths for world wide web
+ * browsing (as distinct from hidden service web browsing). */
+ }
+
/* All nodes with exit flag in ExitNodes option */
count_usable_descriptors(&np, &nu, myexits, consensus, options, now,
options->ExitNodes, USABLE_DESCRIPTOR_EXIT_ONLY);
@@ -1620,7 +1673,7 @@ update_router_have_minimum_dir_info(void)
* should only do while circuits are working, like reachability tests
* and fetching bridge descriptors only over circuits. */
note_that_we_maybe_cant_complete_circuits();
-
+ have_consensus_path = CONSENSUS_PATH_UNKNOWN;
control_event_client_status(LOG_NOTICE, "NOT_ENOUGH_DIR_INFO");
}
have_min_dir_info = res;
diff --git a/src/or/nodelist.h b/src/or/nodelist.h
index 48b0e94..56cfffa 100644
--- a/src/or/nodelist.h
+++ b/src/or/nodelist.h
@@ -80,6 +80,28 @@ int router_exit_policy_all_nodes_reject(const tor_addr_t *addr, uint16_t port,
int need_uptime);
void router_set_status(const char *digest, int up);
int router_have_minimum_dir_info(void);
+
+/** Set to CONSENSUS_PATH_EXIT if there is at least one exit node
+ * in the consensus. We update this flag in compute_frac_paths_available if
+ * there is at least one relay that has an Exit flag in the consensus.
+ * Used to avoid building exit circuits when they will almost certainly fail.
+ * Set to CONSENSUS_PATH_INTERNAL if there are no exits in the consensus.
+ * (This situation typically occurs during bootstrap of a test network.)
+ * Set to CONSENSUS_PATH_UNKNOWN if we have never checked, or have
+ * reason to believe our last known value was invalid or has expired.
+ */
+typedef enum {
+ /* we haven't checked yet, or we have invalidated our previous check */
+ CONSENSUS_PATH_UNKNOWN = -1,
+ /* The consensus only has internal relays, and we should only
+ * create internal paths, circuits, streams, ... */
+ CONSENSUS_PATH_INTERNAL = 0,
+ /* The consensus has at least one exit, and can therefore (potentially)
+ * create exit and internal paths, circuits, streams, ... */
+ CONSENSUS_PATH_EXIT = 1
+} consensus_path_type_t;
+consensus_path_type_t router_have_consensus_path(void);
+
void router_dir_info_changed(void);
const char *get_dir_info_status_string(void);
int count_loading_descriptors_progress(void);
More information about the tor-commits
mailing list