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@@ -309,6 +309,223 @@ encode_protocol_list(const smartlist_t *sl)
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return result;
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}
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+/** Voting helper: Given a list of proto_entry_t, return a newly allocated
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+ * smartlist of newly allocated strings, one for each included protocol
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+ * version. (So 'Foo=3,5-7' expands to a list of 'Foo=3', 'Foo=5', 'Foo=6',
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+ * 'Foo=7'.)
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+ *
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+ * Do not list any protocol version more than once. */
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+static smartlist_t *
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+expand_protocol_list(const smartlist_t *protos)
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+{
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+ // XXXX This can make really huge lists from small inputs; that's a DoS
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+ // problem.
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+
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+ smartlist_t *expanded = smartlist_new();
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+ if (!protos)
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+ return expanded;
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+
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+ SMARTLIST_FOREACH_BEGIN(protos, const proto_entry_t *, ent) {
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+ const char *name = ent->name;
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+ SMARTLIST_FOREACH_BEGIN(ent->ranges, const proto_range_t *, range) {
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+ uint32_t u;
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+ for (u = range->low; u <= range->high; ++u) {
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+ smartlist_add_asprintf(expanded, "%s=%lu", name, (unsigned long)u);
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+ }
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+ } SMARTLIST_FOREACH_END(range);
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+ } SMARTLIST_FOREACH_END(ent);
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+
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+ smartlist_sort_strings(expanded);
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+ smartlist_uniq_strings(expanded); // This makes voting work. do not remove
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+ return expanded;
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+}
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+
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+/** Voting helper: compare two singleton proto_entry_t items by version
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+ * alone. (A singleton item is one with a single range entry where
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+ * low==high.) */
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+static int
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+cmp_single_ent_by_version(const void **a_, const void **b_)
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+{
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+ const proto_entry_t *ent_a = *a_;
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+ const proto_entry_t *ent_b = *b_;
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+
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+ tor_assert(smartlist_len(ent_a->ranges) == 1);
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+ tor_assert(smartlist_len(ent_b->ranges) == 1);
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+
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+ const proto_range_t *a = smartlist_get(ent_a->ranges, 0);
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+ const proto_range_t *b = smartlist_get(ent_b->ranges, 0);
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+
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+ tor_assert(a->low == a->high);
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+ tor_assert(b->low == b->high);
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+
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+ if (a->low < b->low) {
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+ return -1;
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+ } else if (a->low == b->low) {
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+ return 0;
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+ } else {
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+ return 1;
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+ }
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+}
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+
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+/** Voting helper: Given a list of singleton protocol strings (of the form
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+ * Foo=7), return a canonical listing of all the protocol versions listed,
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+ * with as few ranges as possible, with protocol versions sorted lexically and
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+ * versions sorted in numerically increasing order, using as few range entries
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+ * as possible.
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+ **/
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+static char *
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+contract_protocol_list(const smartlist_t *proto_strings)
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+{
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+ // map from name to list of single-version entries
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+ strmap_t *entry_lists_by_name = strmap_new();
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+ // list of protocol names
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+ smartlist_t *all_names = smartlist_new();
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+ // list of strings for the output we're building
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+ smartlist_t *chunks = smartlist_new();
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+
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+ // Parse each item and stick it entry_lists_by_name. Build
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+ // 'all_names' at the same time.
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+ SMARTLIST_FOREACH_BEGIN(proto_strings, const char *, s) {
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+ proto_entry_t *ent = parse_single_entry(s, s+strlen(s));
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+ if (BUG(!ent))
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+ continue;
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+ smartlist_t *lst = strmap_get(entry_lists_by_name, ent->name);
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+ if (!lst) {
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+ smartlist_add(all_names, ent->name);
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+ lst = smartlist_new();
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+ strmap_set(entry_lists_by_name, ent->name, lst);
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+ }
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+ smartlist_add(lst, ent);
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+ } SMARTLIST_FOREACH_END(s);
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+
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+ // We want to output the protocols sorted by their name.
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+ smartlist_sort_strings(all_names);
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+
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+ SMARTLIST_FOREACH_BEGIN(all_names, const char *, name) {
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+ const int first_entry = (name_sl_idx == 0);
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+ smartlist_t *lst = strmap_get(entry_lists_by_name, name);
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+ tor_assert(lst);
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+ // Sort every entry with this name by version. They are
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+ // singletons, so there can't be overlap.
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+ smartlist_sort(lst, cmp_single_ent_by_version);
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+
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+ if (! first_entry)
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+ smartlist_add(chunks, tor_strdup(" "));
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+
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+ /* We're going to construct this entry from the ranges. */
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+ proto_entry_t *entry = tor_malloc_zero(sizeof(proto_entry_t));
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+ entry->ranges = smartlist_new();
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+ entry->name = tor_strdup(name);
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+
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+ // Now, find all the ranges of versions start..end where
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+ // all of start, start+1, start+2, ..end are included.
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+ int start_of_cur_series = 0;
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+ while (start_of_cur_series < smartlist_len(lst)) {
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+ const proto_entry_t *ent = smartlist_get(lst, start_of_cur_series);
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+ const proto_range_t *range = smartlist_get(ent->ranges, 0);
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+ const uint32_t ver_low = range->low;
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+ uint32_t ver_high = ver_low;
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+
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+ int idx;
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+ for (idx = start_of_cur_series+1; idx < smartlist_len(lst); ++idx) {
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+ ent = smartlist_get(lst, idx);
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+ range = smartlist_get(ent->ranges, 0);
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+ if (range->low != ver_high + 1)
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+ break;
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+ ver_high += 1;
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+ }
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+
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+ // Now idx is either off the end of the list, or the first sequence
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+ // break in the list.
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+ start_of_cur_series = idx;
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+
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+ proto_range_t *new_range = tor_malloc_zero(sizeof(proto_range_t));
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+ new_range->low = ver_low;
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+ new_range->high = ver_high;
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+ smartlist_add(entry->ranges, new_range);
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+ }
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+ proto_entry_encode_into(chunks, entry);
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+ proto_entry_free(entry);
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+
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+ } SMARTLIST_FOREACH_END(name);
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+
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+ // Build the result...
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+ char *result = smartlist_join_strings(chunks, "", 0, NULL);
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+
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+ // And free all the stuff we allocated.
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+ SMARTLIST_FOREACH_BEGIN(all_names, const char *, name) {
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+ smartlist_t *lst = strmap_get(entry_lists_by_name, name);
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+ tor_assert(lst);
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+ SMARTLIST_FOREACH(lst, proto_entry_t *, e, proto_entry_free(e));
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+ smartlist_free(lst);
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+ } SMARTLIST_FOREACH_END(name);
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+
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+ strmap_free(entry_lists_by_name, NULL);
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+ smartlist_free(all_names);
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+ SMARTLIST_FOREACH(chunks, char *, cp, tor_free(cp));
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+ smartlist_free(chunks);
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+
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+ return result;
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+}
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+
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+/**
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+ * Protocol voting implementation.
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+ *
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+ * Given a list of strings describing protocol versions, return a newly
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+ * allocated string encoding all of the protocols that are listed by at
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+ * least <b>threshold</b> of the inputs.
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+ *
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+ * The string is minimal and sorted according to the rules of
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+ * contract_protocol_list above.
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+ */
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+char *
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+compute_protover_vote(const smartlist_t *list_of_proto_strings,
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+ int threshold)
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+{
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+ // XXXX This algorithm can be made to use too much RAM. Fix that.
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+
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+ smartlist_t *all_entries = smartlist_new();
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+
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+ // First, parse the inputs and break them into singleton entries.
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+ SMARTLIST_FOREACH_BEGIN(list_of_proto_strings, const char *, vote) {
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+ smartlist_t *unexpanded = parse_protocol_list(vote);
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+ smartlist_t *this_vote = expand_protocol_list(unexpanded);
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+ smartlist_add_all(all_entries, this_vote);
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+ smartlist_free(this_vote);
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+ SMARTLIST_FOREACH(unexpanded, proto_entry_t *, e, proto_entry_free(e));
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+ smartlist_free(unexpanded);
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+ } SMARTLIST_FOREACH_END(vote);
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+
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+ // Now sort the singleton entries
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+ smartlist_sort_strings(all_entries);
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+
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+ // Now find all the strings that appear at least 'threshold' times.
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+ smartlist_t *include_entries = smartlist_new();
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+ const char *cur_entry = smartlist_get(all_entries, 0);
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+ int n_times = 0;
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+ SMARTLIST_FOREACH_BEGIN(all_entries, const char *, ent) {
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+ if (!strcmp(ent, cur_entry)) {
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+ n_times++;
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+ } else {
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+ if (n_times >= threshold)
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+ smartlist_add(include_entries, (void*)cur_entry);
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+ cur_entry = ent;
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+ n_times = 1 ;
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+ }
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+ } SMARTLIST_FOREACH_END(ent);
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+
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+ if (n_times >= threshold)
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+ smartlist_add(include_entries, (void*)cur_entry);
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+
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+ // Finally, compress that list.
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+ char *result = contract_protocol_list(include_entries);
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+ smartlist_free(include_entries);
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+ SMARTLIST_FOREACH(all_entries, char *, cp, tor_free(cp));
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+ smartlist_free(all_entries);
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+
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+ return result;
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+}
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+
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/** Return true if every protocol version described in the string <b>s</b> is
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* one that we support, and false otherwise. If <b>missing_out</b> is
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* provided, set it to the list of protocols we do not support.
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