commit 0bcc9ad58d18bdd9fb73db33b9a7fe4cfd2ac93b
Author: David Goulet <dgou...@torproject.org>
Date: Wed Apr 19 12:23:43 2017 -0400
prop224: Add a responsible HSDir function
Signed-off-by: David Goulet <dgou...@torproject.org>
---
src/or/hs_common.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++
src/or/hs_common.h | 4 ++
2 files changed, 156 insertions(+)
diff --git a/src/or/hs_common.c b/src/or/hs_common.c
index 4ea92aaea..4d5417afa 100644
--- a/src/or/hs_common.c
+++ b/src/or/hs_common.c
@@ -15,11 +15,13 @@
#include "config.h"
#include "networkstatus.h"
+#include "nodelist.h"
#include "hs_cache.h"
#include "hs_common.h"
#include "hs_service.h"
#include "rendcommon.h"
#include "rendservice.h"
+#include "router.h"
#include "shared_random.h"
/* Ed25519 Basepoint value. Taken from section 5 of
@@ -30,6 +32,48 @@ static const char *str_ed25519_basepoint =
"463168356949264781694283940034751631413"
"07993866256225615783033603165251855960)";
+/* Helper function: The key is a digest that we compare to a node_t object
+ * current hsdir_index. */
+static int
+compare_digest_to_current_hsdir_index(const void *_key, const void **_member)
+{
+ const char *key = _key;
+ const node_t *node = *_member;
+ return tor_memcmp(key, node->hsdir_index->current, DIGEST256_LEN);
+}
+
+/* Helper function: The key is a digest that we compare to a node_t object
+ * next hsdir_index. */
+static int
+compare_digest_to_next_hsdir_index(const void *_key, const void **_member)
+{
+ const char *key = _key;
+ const node_t *node = *_member;
+ return tor_memcmp(key, node->hsdir_index->next, DIGEST256_LEN);
+}
+
+/* Helper function: Compare two node_t objects current hsdir_index. */
+static int
+compare_node_current_hsdir_index(const void **a, const void **b)
+{
+ const node_t *node1= *a;
+ const node_t *node2 = *b;
+ return tor_memcmp(node1->hsdir_index->current,
+ node2->hsdir_index->current,
+ DIGEST256_LEN);
+}
+
+/* Helper function: Compare two node_t objects next hsdir_index. */
+static int
+compare_node_next_hsdir_index(const void **a, const void **b)
+{
+ const node_t *node1= *a;
+ const node_t *node2 = *b;
+ return tor_memcmp(node1->hsdir_index->next,
+ node2->hsdir_index->next,
+ DIGEST256_LEN);
+}
+
/* Allocate and return a string containing the path to filename in directory.
* This function will never return NULL. The caller must free this path. */
char *
@@ -887,6 +931,114 @@ hs_get_hsdir_spread_store(void)
HS_DEFAULT_HSDIR_SPREAD_STORE, 1, 128);
}
+/* For a given blinded key and time period number, get the responsible HSDir
+ * and put their routerstatus_t object in the responsible_dirs list. If
+ * is_next_period is true, the next hsdir_index of the node_t is used. If
+ * is_client is true, the spread fetch consensus parameter is used else the
+ * spread store is used which is only for upload. This function can't fail but
+ * it is possible that the responsible_dirs list contains fewer nodes than
+ * expected.
+ *
+ * This function goes over the latest consensus routerstatus list and sorts it
+ * by their node_t hsdir_index then does a binary search to find the closest
+ * node. All of this makes it a bit CPU intensive so use it wisely. */
+void
+hs_get_responsible_hsdirs(const ed25519_public_key_t *blinded_pk,
+ uint64_t time_period_num, int is_next_period,
+ int is_client, smartlist_t *responsible_dirs)
+{
+ smartlist_t *sorted_nodes;
+ /* The compare function used for the smartlist bsearch. We have two
+ * different depending on is_next_period. */
+ int (*cmp_fct)(const void *, const void **);
+
+ tor_assert(blinded_pk);
+ tor_assert(responsible_dirs);
+
+ sorted_nodes = smartlist_new();
+
+ /* Add every node_t that support HSDir v3 for which we do have a valid
+ * hsdir_index already computed for them for this consensus. */
+ {
+ networkstatus_t *c = networkstatus_get_latest_consensus();
+ if (!c || smartlist_len(c->routerstatus_list) == 0) {
+ log_warn(LD_REND, "No valid consensus so we can't get the responsible "
+ "hidden service directories.");
+ goto done;
+ }
+ SMARTLIST_FOREACH_BEGIN(c->routerstatus_list, const routerstatus_t *, rs) {
+ /* Even though this node_t object won't be modified and should be const,
+ * we can't add const object in a smartlist_t. */
+ node_t *n = node_get_mutable_by_id(rs->identity_digest);
+ tor_assert(n);
+ if (node_supports_v3_hsdir(n) && rs->is_hs_dir) {
+ if (BUG(n->hsdir_index == NULL)) {
+ continue;
+ }
+ smartlist_add(sorted_nodes, n);
+ }
+ } SMARTLIST_FOREACH_END(rs);
+ }
+ if (smartlist_len(sorted_nodes) == 0) {
+ log_warn(LD_REND, "No nodes found to be HSDir or supporting v3.");
+ goto done;
+ }
+
+ /* First thing we have to do is sort all node_t by hsdir_index. The
+ * is_next_period tells us if we want the current or the next one. Set the
+ * bsearch compare function also while we are at it. */
+ if (is_next_period) {
+ smartlist_sort(sorted_nodes, compare_node_next_hsdir_index);
+ cmp_fct = compare_digest_to_next_hsdir_index;
+ } else {
+ smartlist_sort(sorted_nodes, compare_node_current_hsdir_index);
+ cmp_fct = compare_digest_to_current_hsdir_index;
+ }
+
+ /* For all replicas, we'll select a set of HSDirs using the consensus
+ * parameters and the sorted list. The replica starting at value 1 is
+ * defined by the specification. */
+ for (int replica = 1; replica <= hs_get_hsdir_n_replicas(); replica++) {
+ int idx, start, found, n_added = 0;
+ uint8_t hs_index[DIGEST256_LEN] = {0};
+ /* Number of node to add to the responsible dirs list depends on if we are
+ * trying to fetch or store. A client always fetches. */
+ int n_to_add = (is_client) ? hs_get_hsdir_spread_fetch() :
+ hs_get_hsdir_spread_store();
+
+ /* Get the index that we should use to select the node. */
+ hs_build_hs_index(replica, blinded_pk, time_period_num, hs_index);
+ /* The compare function pointer has been set correctly earlier. */
+ start = idx = smartlist_bsearch_idx(sorted_nodes, hs_index, cmp_fct,
+ &found);
+ /* Getting the length of the list if no member is greater than the key we
+ * are looking for so start at the first element. */
+ if (idx == smartlist_len(sorted_nodes)) {
+ start = idx = 0;
+ }
+ while (n_added < n_to_add) {
+ const node_t *node = smartlist_get(sorted_nodes, idx);
+ /* If the node has already been selected which is possible between
+ * replicas, the specification says to skip over. */
+ if (!smartlist_contains(responsible_dirs, node->rs)) {
+ smartlist_add(responsible_dirs, node->rs);
+ ++n_added;
+ }
+ if (++idx == smartlist_len(sorted_nodes)) {
+ /* Wrap if we've reached the end of the list. */
+ idx = 0;
+ }
+ if (idx == start) {
+ /* We've gone over the whole list, stop and avoid infinite loop. */
+ break;
+ }
+ }
+ }
+
+ done:
+ smartlist_free(sorted_nodes);
+}
+
/* Initialize the entire HS subsytem. This is called in tor_init() before any
* torrc options are loaded. Only for >= v3. */
void
diff --git a/src/or/hs_common.h b/src/or/hs_common.h
index d367e815e..695f0b895 100644
--- a/src/or/hs_common.h
+++ b/src/or/hs_common.h
@@ -214,6 +214,10 @@ int32_t hs_get_hsdir_n_replicas(void);
int32_t hs_get_hsdir_spread_fetch(void);
int32_t hs_get_hsdir_spread_store(void);
+void hs_get_responsible_hsdirs(const ed25519_public_key_t *blinded_pk,
+ uint64_t time_period_num, int is_next_period,
+ int is_client, smartlist_t *responsible_dirs);
+
#ifdef HS_COMMON_PRIVATE
#ifdef TOR_UNIT_TESTS
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