commit 9b2d106e49ba4ea12f31af9cea02910869f19a4b Author: teor teor2345@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);