prop250: Use the new dirvote_get_intermediate_param_value for AuthDirNumSRVAgreements (4a1904c1) · Commits · Nick Mathewson / Tor

src/or/dirvote.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -1341,8 +1341,16 @@ networkstatus_compute_consensus(smartlist_t *votes,
		}

		if (consensus_method >= MIN_METHOD_FOR_SHARED_RANDOM) {
		int num_dirauth = get_n_authorities(V3_DIRINFO);
		/* Default value of this is 2/3 of the total number of authorities. For
		* instance, if we have 9 dirauth, the default value is 6. The following
		* calculation will round it down. */
		int32_t num_srv_agreements =
		dirvote_get_intermediate_param_value(param_list,
		"AuthDirNumSRVAgreements",
		(num_dirauth * 2) / 3);
		/* Add the shared random value. */
		char *srv_lines = sr_get_string_for_consensus(votes);
		char *srv_lines = sr_get_string_for_consensus(votes, num_srv_agreements);
		if (srv_lines != NULL) {
		smartlist_add(chunks, srv_lines);
		}

src/or/shared_random.c

+30 −18

Original line number	Diff line number	Diff line
		@@ -105,6 +105,12 @@ static const char current_srv_str[] = "shared-rand-current-value";
		static const char commit_ns_str[] = "shared-rand-commit";
		static const char sr_flag_ns_str[] = "shared-rand-participate";

		/* The value of the consensus param AuthDirNumSRVAgreements found in the
		* vote. This is set once the consensus creation subsystem requests the
		* SRV(s) that should be put in the consensus. We use this value to decide
		* if we keep or not an SRV. */
		static int32_t num_srv_agreements_from_vote;

		/* Return a heap allocated copy of the SRV <b>orig</b>. */
		STATIC sr_srv_t *
		srv_dup(const sr_srv_t *orig)
		@@ -737,18 +743,6 @@ save_commit_to_state(sr_commit_t *commit)
		}
		}

		/* Return the number of required participants of the SR protocol. This is based
		* on a consensus params. */
		static int
		get_n_voters_for_srv_agreement(void)
		{
		int num_dirauths = get_n_authorities(V3_DIRINFO);
		/* If the params is not found, default value should always be the maximum
		* number of trusted authorities. Let's not take any chances. */
		return networkstatus_get_param(NULL, "AuthDirNumSRVAgreements",
		num_dirauths, 1, num_dirauths);
		}

		/* Return 1 if we should we keep an SRV voted by <b>n_agreements</b> auths.
		* Return 0 if we should ignore it. */
		static int
		@@ -769,11 +763,9 @@ should_keep_srv(int n_agreements)
		* to keep it. */
		if (sr_state_srv_is_fresh()) {
		/* Check if we have super majority for this new SRV value. */
		int num_required_agreements = get_n_voters_for_srv_agreement();

		if (n_agreements < num_required_agreements) {
		if (n_agreements < num_srv_agreements_from_vote) {
		log_notice(LD_DIR, "SR: New SRV didn't reach agreement [%d/%d]!",
		n_agreements, num_required_agreements);
		n_agreements, num_srv_agreements_from_vote);
		return 0;
		}
		}
		@@ -1253,9 +1245,14 @@ sr_get_string_for_vote(void)
		*
		* This is called when a consensus (any flavor) is bring created thus it
		* should NEVER change the state nor the state should be changed in between
		* consensus creation. */
		* consensus creation.
		*
		* <b>num_srv_agreements</b> is taken from the votes thus the voted value
		* that should be used.
		* */
		char *
		sr_get_string_for_consensus(const smartlist_t *votes)
		sr_get_string_for_consensus(const smartlist_t *votes,
		int32_t num_srv_agreements)
		{
		char *srv_str;
		const or_options_t *options = get_options();
		@@ -1269,6 +1266,9 @@ sr_get_string_for_consensus(const smartlist_t *votes)
		goto end;
		}

		/* Set the global value of AuthDirNumSRVAgreements found in the votes. */
		num_srv_agreements_from_vote = num_srv_agreements;

		/* Check the votes and figure out if SRVs should be included in the final
		* consensus. */
		sr_srv_t *prev_srv = get_majority_srv_from_votes(votes, 0);
		@@ -1340,3 +1340,15 @@ sr_save_and_cleanup(void)
		sr_state_save();
		sr_cleanup();
		}

		#ifdef TOR_UNIT_TESTS

		/* Set the global value of number of SRV agreements so the test can play
		* along by calling specific functions that don't parse the votes prior for
		* the AuthDirNumSRVAgreements value. */
		void set_num_srv_agreements(int32_t value)
		{
		num_srv_agreements_from_vote = value;
		}

		#endif /* TOR_UNIT_TESTS */

src/or/shared_random.h

+8 −1

Original line number	Diff line number	Diff line
		@@ -112,7 +112,8 @@ void sr_handle_received_commits(smartlist_t *commits,
		sr_commit_t sr_parse_commit(const smartlist_t args);
		sr_srv_t sr_parse_srv(const smartlist_t args);
		char *sr_get_string_for_vote(void);
		char sr_get_string_for_consensus(const smartlist_t votes);
		char sr_get_string_for_consensus(const smartlist_t votes,
		int32_t num_srv_agreements);
		void sr_commit_free(sr_commit_t *commit);
		void sr_srv_encode(char dst, size_t dst_len, const sr_srv_t srv);

		@@ -156,4 +157,10 @@ STATIC void save_commit_during_reveal_phase(const sr_commit_t *commit);

		#endif /* SHARED_RANDOM_PRIVATE */

		#ifdef TOR_UNIT_TESTS

		void set_num_srv_agreements(int32_t value);

		#endif /* TOR_UNIT_TESTS */

		#endif /* TOR_SHARED_RANDOM_H */

src/test/test_shared_random.c

+3 −31

Original line number	Diff line number	Diff line
		@@ -830,14 +830,6 @@ get_test_vote_with_curr_srv(const char *srv)
		return vote;
		}

		/* Mock function to return the value located in the options instead of the
		* consensus so we can modify it at will. */
		static networkstatus_t *
		mock_networkstatus_get_latest_consensus(void)
		{
		return mock_consensus;
		}

		/* Test the function that picks the right SRV given a bunch of votes. Make sure
		* that the function returns an SRV iff the majority/agreement requirements are
		* met. */
		@@ -894,31 +886,13 @@ test_sr_get_majority_srv_from_votes(void *arg)

		/* Now we achieve majority for SRV_1, but not the AuthDirNumSRVAgreements
		requirement. So still not picking an SRV. */
		set_num_srv_agreements(8);
		chosen_srv = get_majority_srv_from_votes(votes, 1);
		tt_assert(!chosen_srv);

		/* We will now lower the AuthDirNumSRVAgreements requirement by tweaking the
		* consensus parameter and we will try again. This time it should work. */
		{
		char *my_net_params;
		/* Set a dummy consensus parameter in every vote */
		SMARTLIST_FOREACH_BEGIN(votes, networkstatus_t *, vote) {
		vote->net_params = smartlist_new();
		smartlist_split_string(vote->net_params,
		"AuthDirNumSRVAgreements=7", NULL, 0, 0);
		} SMARTLIST_FOREACH_END(vote);

		/* Pretend you are making a consensus out of the votes */
		mock_consensus = tor_malloc_zero(sizeof(networkstatus_t));
		mock_consensus->net_params = smartlist_new();
		my_net_params = dirvote_compute_params(votes, 66, smartlist_len(votes));
		smartlist_split_string(mock_consensus->net_params, my_net_params, " ",
		SPLIT_SKIP_SPACE\|SPLIT_IGNORE_BLANK, 0);
		}

		/* Use our fake consensus for finding consensus parameters. */
		MOCK(networkstatus_get_latest_consensus,
		mock_networkstatus_get_latest_consensus);
		set_num_srv_agreements(7);
		chosen_srv = get_majority_srv_from_votes(votes, 1);
		tt_assert(chosen_srv);
		tt_int_op(chosen_srv->num_reveals, ==, 42);
		@@ -928,8 +902,6 @@ test_sr_get_majority_srv_from_votes(void *arg)
		SMARTLIST_FOREACH(votes, networkstatus_t *, vote,
		networkstatus_vote_free(vote));
		smartlist_free(votes);
		networkstatus_vote_free(mock_consensus);
		UNMOCK(networkstatus_get_latest_consensus);
		}

		static void