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