commit abb840bf6431cfeb4f5e32ae2774fcde29e7724d Author: David Goulet dgoulet@torproject.org Date: Fri Jul 21 15:19:32 2017 -0400
prop224: Client function to pick intro point
From an edge connection object, add a function that randomly pick an introduction point for the requested service.
This follows the code design of rend_client_get_random_intro() and returns an extend_info_t object ready to be used to extend to.
At this commit, it is not used yet.
Signed-off-by: David Goulet dgoulet@torproject.org --- src/or/hs_client.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++ src/or/hs_client.h | 4 +- 2 files changed, 120 insertions(+), 1 deletion(-)
diff --git a/src/or/hs_client.c b/src/or/hs_client.c index cf9bdba5a..a593999f2 100644 --- a/src/or/hs_client.c +++ b/src/or/hs_client.c @@ -20,6 +20,7 @@ #include "directory.h" #include "hs_client.h" #include "router.h" +#include "routerset.h" #include "circuitlist.h" #include "circuituse.h" #include "connection.h" @@ -387,6 +388,109 @@ client_rendezvous_circ_has_opened(origin_circuit_t *circ) hs_circ_send_establish_rendezvous(circ); }
+/* This is an helper function that convert a descriptor intro point object ip + * to a newly allocated extend_info_t object fully initialized. Return NULL if + * we can't convert it for which chances are that we are missing or malformed + * link specifiers. */ +static extend_info_t * +desc_intro_point_to_extend_info(const hs_desc_intro_point_t *ip) +{ + extend_info_t *ei; + smartlist_t *lspecs = smartlist_new(); + + tor_assert(ip); + + /* We first encode the descriptor link specifiers into the binary + * representation which is a trunnel object. */ + SMARTLIST_FOREACH_BEGIN(ip->link_specifiers, + const hs_desc_link_specifier_t *, desc_lspec) { + link_specifier_t *lspec = hs_desc_encode_lspec(desc_lspec); + smartlist_add(lspecs, lspec); + } SMARTLIST_FOREACH_END(desc_lspec); + + /* Explicitely put the direct connection option to 0 because this is client + * side and there is no such thing as a non anonymous client. */ + ei = hs_get_extend_info_from_lspecs(lspecs, &ip->onion_key, 0); + + SMARTLIST_FOREACH(lspecs, link_specifier_t *, ls, link_specifier_free(ls)); + smartlist_free(lspecs); + return ei; +} + +/* Using a descriptor desc, return a newly allocated extend_info_t object of a + * randomly picked introduction point from its list. Return NULL if none are + * usable. */ +static extend_info_t * +client_get_random_intro(const ed25519_public_key_t *service_pk) +{ + extend_info_t *ei = NULL, *ei_excluded = NULL; + smartlist_t *usable_ips = NULL; + const hs_descriptor_t *desc; + const hs_desc_encrypted_data_t *enc_data; + const or_options_t *options = get_options(); + + tor_assert(service_pk); + + desc = hs_cache_lookup_as_client(service_pk); + if (desc == NULL || !hs_client_any_intro_points_usable(desc)) { + log_info(LD_REND, "Unable to randomly select an introduction point " + "because descriptor %s.", + (desc) ? "doesn't have usable intro point" : "is missing"); + goto end; + } + + enc_data = &desc->encrypted_data; + usable_ips = smartlist_new(); + smartlist_add_all(usable_ips, enc_data->intro_points); + while (smartlist_len(usable_ips) != 0) { + int idx; + const hs_desc_intro_point_t *ip; + + /* Pick a random intro point and immediately remove it from the usable + * list so we don't pick it again if we have to iterate more. */ + idx = crypto_rand_int(smartlist_len(usable_ips)); + ip = smartlist_get(usable_ips, idx); + smartlist_del(usable_ips, idx); + + /* Generate an extend info object from the intro point object. */ + ei = desc_intro_point_to_extend_info(ip); + if (ei == NULL) { + /* We can get here for instance if the intro point is a private address + * and we aren't allowed to extend to those. */ + continue; + } + + /* Test the pick against ExcludeNodes. */ + if (routerset_contains_extendinfo(options->ExcludeNodes, ei)) { + /* If this pick is in the ExcludeNodes list, we keep its reference so if + * we ever end up not being able to pick anything else and StrictNodes is + * unset, we'll use it. */ + ei_excluded = ei; + continue; + } + /* XXX: Intro point can time out or just be unsuable, we need to keep + * track of this and check against such cache. */ + + /* Good pick! Let's go with this. */ + goto end; + } + + /* Reaching this point means a couple of things. Either we can't use any of + * the intro point listed because the IP address can't be extended to or it + * is listed in the ExcludeNodes list. In the later case, if StrictNodes is + * set, we are forced to not use anything. */ + ei = ei_excluded; + if (options->StrictNodes) { + log_warn(LD_REND, "Every introduction points are in the ExcludeNodes set " + "and StrictNodes is set. We can't connect."); + ei = NULL; + } + + end: + smartlist_free(usable_ips); + return ei; +} + /* ========== */ /* Public API */ /* ========== */ @@ -643,3 +747,16 @@ hs_client_desc_has_arrived(const hs_ident_dir_conn_t *ident) smartlist_free(conns); }
+/* Return a newly allocated extend_info_t for a randomly chosen introduction + * point for the given edge connection identifier ident. Return NULL if we + * can't pick any usable introduction points. */ +extend_info_t * +hs_client_get_random_intro_from_edge(const edge_connection_t *edge_conn) +{ + tor_assert(edge_conn); + + return (edge_conn->hs_ident) ? + client_get_random_intro(&edge_conn->hs_ident->identity_pk) : + rend_client_get_random_intro(edge_conn->rend_data); +} + diff --git a/src/or/hs_client.h b/src/or/hs_client.h index 50d0ad760..c41baa2ce 100644 --- a/src/or/hs_client.h +++ b/src/or/hs_client.h @@ -31,8 +31,10 @@ void hs_client_circuit_has_opened(origin_circuit_t *circ); int hs_client_receive_rendezvous_acked(origin_circuit_t *circ, const uint8_t *payload, size_t payload_len); - void hs_client_desc_has_arrived(const hs_ident_dir_conn_t *ident);
+extend_info_t *hs_client_get_random_intro_from_edge( + const edge_connection_t *edge_conn); + #endif /* TOR_HS_CLIENT_H */