commit 948dd2c79ea9ca1fd06c13f275515a1745c46986 Author: Nick Mathewson nickm@torproject.org Date: Mon Apr 16 10:38:55 2018 -0400

Check for "the right descriptor", not just "any descriptor".

This patch adds a new node_has_preferred_descriptor() function, and replaces most users of node_has_descriptor() with it. That's an important change, since as of d1874b433953f64 (our fix for #25213), we are willing to say that a node has _some_ descriptor, but not the _right_ descriptor for a particular use case.

Part of a fix for 25691 and 25692. --- src/or/circuitbuild.c | 28 ++++++++++++---------------- src/or/circuituse.c | 4 ++-- src/or/entrynodes.c | 7 ++++--- src/or/hs_common.c | 15 +++++++++++---- src/or/nodelist.c | 30 +++++++++++++++++++++++++++++- src/or/nodelist.h | 2 ++ src/or/rendservice.c | 2 +- 7 files changed, 61 insertions(+), 27 deletions(-)

diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 5f1f8122f..019b9c51f 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -417,7 +417,7 @@ onion_populate_cpath(origin_circuit_t *circ) circ->cpath->extend_info->identity_digest); /* If we don't know the node and its descriptor, we must be bootstrapping. */ - if (!node || !node_has_descriptor(node)) { + if (!node || !node_has_preferred_descriptor(node, 1)) { return 0; } } @@ -1869,7 +1869,7 @@ choose_good_exit_server_general(int need_uptime, int need_capacity) */ continue; } - if (!node_has_descriptor(node)) { + if (!node_has_preferred_descriptor(node, 0)) { n_supported[i] = -1; continue; } @@ -2443,6 +2443,10 @@ circuit_extend_to_new_exit(origin_circuit_t *circ, extend_info_t *exit_ei)

/** Return the number of routers in <b>routers</b> that are currently up * and available for building circuits through. + * + * (Note that this function may overcount or undercount, if we have + * descriptors that are not the type we would prefer to use for some + * particular router. See bug #25885.) */ MOCK_IMPL(STATIC int, count_acceptable_nodes, (smartlist_t *nodes)) @@ -2847,9 +2851,10 @@ extend_info_new(const char *nickname, * of the node (i.e. its IPv4 address) unless * <b>for_direct_connect</b> is true, in which case the preferred * address is used instead. May return NULL if there is not enough - * info about <b>node</b> to extend to it--for example, if there is no - * routerinfo_t or microdesc_t, or if for_direct_connect is true and none of - * the node's addresses are allowed by tor's firewall and IP version config. + * info about <b>node</b> to extend to it--for example, if the preferred + * routerinfo_t or microdesc_t is missing, or if for_direct_connect is + * true and none of the node's addresses is allowed by tor's firewall + * and IP version config. **/ extend_info_t * extend_info_from_node(const node_t *node, int for_direct_connect) @@ -2857,17 +2862,8 @@ extend_info_from_node(const node_t *node, int for_direct_connect) tor_addr_port_t ap; int valid_addr = 0;

- const int is_bridge = node_is_a_configured_bridge(node); - const int we_use_mds = we_use_microdescriptors_for_circuits(get_options()); - - if ((is_bridge && for_direct_connect) || !we_use_mds) { - /* We need an ri in this case. */ - if (!node->ri) - return NULL; - } else { - /* Otherwise we need an md. */ - if (node->rs == NULL || node->md == NULL) - return NULL; + if (!node_has_preferred_descriptor(node, for_direct_connect)) { + return NULL; }

/* Choose a preferred address first, but fall back to an allowed address. diff --git a/src/or/circuituse.c b/src/or/circuituse.c index 3125fff65..5d8af4c6c 100644 --- a/src/or/circuituse.c +++ b/src/or/circuituse.c @@ -2384,7 +2384,7 @@ circuit_get_open_circ_or_launch(entry_connection_t *conn, const node_t *r; int opt = conn->chosen_exit_optional; r = node_get_by_nickname(conn->chosen_exit_name, 0); - if (r && node_has_descriptor(r)) { + if (r && node_has_preferred_descriptor(r, conn->want_onehop ? 1 : 0)) { /* We might want to connect to an IPv6 bridge for loading descriptors so we use the preferred address rather than the primary. */ @@ -2394,7 +2394,7 @@ circuit_get_open_circ_or_launch(entry_connection_t *conn, "Discarding this circuit.", conn->chosen_exit_name); return -1; } - } else { /* ! (r && node_has_descriptor(r)) */ + } else { /* ! (r && node_has_preferred_descriptor(...)) */ log_debug(LD_DIR, "considering %d, %s", want_onehop, conn->chosen_exit_name); if (want_onehop && conn->chosen_exit_name[0] == '$') { diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 2b6ff38c9..54638810f 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -185,14 +185,14 @@ should_apply_guardfraction(const networkstatus_t *ns) return options->UseGuardFraction; }

-/** Return true iff we know a descriptor for <b>guard</b> */ +/** Return true iff we know a preferred descriptor for <b>guard</b> */ static int guard_has_descriptor(const entry_guard_t *guard) { const node_t *node = node_get_by_id(guard->identity); if (!node) return 0; - return node_has_descriptor(node); + return node_has_preferred_descriptor(node, 1); }

/** @@ -2269,7 +2269,8 @@ entry_guard_pick_for_circuit(guard_selection_t *gs, // XXXX #20827 check Ed ID. if (! node) goto fail; - if (BUG(usage != GUARD_USAGE_DIRGUARD && !node_has_descriptor(node))) + if (BUG(usage != GUARD_USAGE_DIRGUARD && + !node_has_preferred_descriptor(node, 1))) goto fail;

*chosen_node_out = node; diff --git a/src/or/hs_common.c b/src/or/hs_common.c index 6d97c8775..10b56c0ba 100644 --- a/src/or/hs_common.c +++ b/src/or/hs_common.c @@ -1280,8 +1280,10 @@ node_has_hsdir_index(const node_t *node) tor_assert(node_supports_v3_hsdir(node));

/* A node can't have an HSDir index without a descriptor since we need desc - * to get its ed25519 key */ - if (!node_has_descriptor(node)) { + * to get its ed25519 key. for_direct_connect should be zero, since we + * always use the consensus-indexed node's keys to build the hash ring, even + * if some of the consensus-indexed nodes are also bridges. */ + if (!node_has_preferred_descriptor(node, 0)) { return 0; }

@@ -1612,12 +1614,17 @@ hs_pick_hsdir(smartlist_t *responsible_dirs, const char *req_key_str) hs_clean_last_hid_serv_requests(now);

/* Only select those hidden service directories to which we did not send a - * request recently and for which we have a router descriptor here. */ + * request recently and for which we have a router descriptor here. + * + * Use for_direct_connect==0 even if we will be connecting to the node + * directly, since we always use the key information in the + * consensus-indexed node descriptors for building the index. + **/ SMARTLIST_FOREACH_BEGIN(responsible_dirs, routerstatus_t *, dir) { time_t last = hs_lookup_last_hid_serv_request(dir, req_key_str, 0, 0); const node_t *node = node_get_by_id(dir->identity_digest); if (last + hs_hsdir_requery_period(options) >= now || - !node || !node_has_descriptor(node)) { + !node || !node_has_preferred_descriptor(node, 0)) { SMARTLIST_DEL_CURRENT(responsible_dirs, dir); continue; } diff --git a/src/or/nodelist.c b/src/or/nodelist.c index 3a26aee61..2962d3cb4 100644 --- a/src/or/nodelist.c +++ b/src/or/nodelist.c @@ -43,6 +43,7 @@ #include "or.h" #include "address.h" #include "address_set.h" +#include "bridges.h" #include "config.h" #include "control.h" #include "dirserv.h" @@ -1139,6 +1140,32 @@ node_has_descriptor(const node_t *node) (node->rs && node->md)); }

+/** Return true iff <b>node</b> has the kind of descriptor we would prefer to + * use for it, given our configuration and how we intend to use the node. + * + * If <b>for_direct_connect</b> is true, we intend to connect to the node + * directly, as the first hop of a circuit; otherwise, we intend to connect to + * it indirectly, or use it as if we were connecting to it indirectly. */ +int +node_has_preferred_descriptor(const node_t *node, + int for_direct_connect) +{ + const int is_bridge = node_is_a_configured_bridge(node); + const int we_use_mds = we_use_microdescriptors_for_circuits(get_options()); + + if ((is_bridge && for_direct_connect) || !we_use_mds) { + /* We need an ri in this case. */ + if (!node->ri) + return 0; + } else { + /* Otherwise we need an rs and an md. */ + if (node->rs == NULL || node->md == NULL) + return 0; + } + + return 1; +} + /** Return the router_purpose of <b>node</b>. */ int node_get_purpose(const node_t *node) @@ -2221,7 +2248,8 @@ compute_frac_paths_available(const networkstatus_t *consensus, nu);

SMARTLIST_FOREACH_BEGIN(myexits_unflagged, const node_t *, node) { - if (node_has_descriptor(node) && node_exit_policy_rejects_all(node)) { + if (node_has_preferred_descriptor(node, 0) && + node_exit_policy_rejects_all(node)) { SMARTLIST_DEL_CURRENT(myexits_unflagged, node); /* this node is not actually an exit */ np--; diff --git a/src/or/nodelist.h b/src/or/nodelist.h index 043d7b341..5e7254f60 100644 --- a/src/or/nodelist.h +++ b/src/or/nodelist.h @@ -47,6 +47,8 @@ void node_get_verbose_nickname_by_id(const char *id_digest, char *verbose_name_out); int node_is_dir(const node_t *node); int node_has_descriptor(const node_t *node); +int node_has_preferred_descriptor(const node_t *node, + int for_direct_connect); int node_get_purpose(const node_t *node); #define node_is_bridge(node) \ (node_get_purpose((node)) == ROUTER_PURPOSE_BRIDGE) diff --git a/src/or/rendservice.c b/src/or/rendservice.c index cc2242977..1a93c3643 100644 --- a/src/or/rendservice.c +++ b/src/or/rendservice.c @@ -3596,7 +3596,7 @@ directory_post_to_hs_dir(rend_service_descriptor_t *renddesc, /* Don't upload descriptor if we succeeded in doing so last time. */ continue; node = node_get_by_id(hs_dir->identity_digest); - if (!node || !node_has_descriptor(node)) { + if (!node || !node_has_preferred_descriptor(node,0)) { log_info(LD_REND, "Not launching upload for for v2 descriptor to " "hidden service directory %s; we don't have its " "router descriptor. Queuing for later upload.",