commit 766fc86df46ff88364610b18e28904c3b45f98f1 Author: teor teor@riseup.net Date: Wed May 13 13:17:41 2020 +1000

circuitbuild: Do node checks when choosing exits

And check that the correct flags are passed when choosing exits.

Adds the following checks for exits: * must support EXTEND2 cells, * must have an ntor circuit crypto key, * can't require the guard flag, * can't be a direct connection.

All these checks are already implied by other code.

Part of 34200. --- src/core/or/circuitbuild.c | 48 ++++++++++++++++++---------------------------- 1 file changed, 19 insertions(+), 29 deletions(-)

diff --git a/src/core/or/circuitbuild.c b/src/core/or/circuitbuild.c index b840ca7a7..bac82eb9f 100644 --- a/src/core/or/circuitbuild.c +++ b/src/core/or/circuitbuild.c @@ -1563,7 +1563,23 @@ choose_good_exit_server_general(router_crn_flags_t flags) const node_t *selected_node=NULL; const int need_uptime = (flags & CRN_NEED_UPTIME) != 0; const int need_capacity = (flags & CRN_NEED_CAPACITY) != 0; - const int direct_conn = (flags & CRN_DIRECT_CONN) != 0; + + /* We should not require guard flags on exits. */ + IF_BUG_ONCE(flags & CRN_NEED_GUARD) + return NULL; + + /* We reject single-hop exits for all node positions. */ + IF_BUG_ONCE(flags & CRN_DIRECT_CONN) + return NULL; + + /* This isn't the function for picking rendezvous nodes. */ + IF_BUG_ONCE(flags & CRN_RENDEZVOUS_V3) + return NULL; + + /* We only want exits to extend if we cannibalize the circuit. + * But we don't require IPv6 extends yet. */ + IF_BUG_ONCE(flags & CRN_INITIATE_IPV6_EXTEND) + return NULL;

connections = get_connection_array();

@@ -1596,19 +1612,14 @@ choose_good_exit_server_general(router_crn_flags_t flags) */ continue; } - if (!node_has_preferred_descriptor(node, direct_conn)) { + if (!router_can_choose_node(node, flags)) { n_supported[i] = -1; continue; } - if (!node->is_running || node->is_bad_exit) { + if (node->is_bad_exit) { n_supported[i] = -1; continue; /* skip routers that are known to be down or bad exits */ } - if (node_get_purpose(node) != ROUTER_PURPOSE_GENERAL) { - /* never pick a non-general node as a random exit. */ - n_supported[i] = -1; - continue; - } if (routerset_contains_node(options->ExcludeExitNodesUnion_, node)) { n_supported[i] = -1; continue; /* user asked us not to use it, no matter what */ @@ -1618,27 +1629,6 @@ choose_good_exit_server_general(router_crn_flags_t flags) n_supported[i] = -1; continue; /* not one of our chosen exit nodes */ } - - if (node_is_unreliable(node, need_uptime, need_capacity, 0)) { - n_supported[i] = -1; - continue; /* skip routers that are not suitable. Don't worry if - * this makes us reject all the possible routers: if so, - * we'll retry later in this function with need_update and - * need_capacity set to 0. */ - } - if (!(node->is_valid)) { - /* if it's invalid and we don't want it */ - n_supported[i] = -1; -// log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- invalid router.", -// router->nickname, i); - continue; /* skip invalid routers */ - } - /* We do not allow relays that allow single hop exits by default. Option - * was deprecated in 0.2.9.2-alpha and removed in 0.3.1.0-alpha. */ - if (node_allows_single_hop_exits(node)) { - n_supported[i] = -1; - continue; - } if (node_exit_policy_rejects_all(node)) { n_supported[i] = -1; // log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it rejects all.",