[tor-commits] [tor/master] Implement voting on the protocol-version options

[nickm at torproject.org]

commit a3e82563df3b549a36a49a4efdb2f1aeef0e0b07
Author: Nick Mathewson <nickm at torproject.org>
Date:   Thu Aug 25 14:24:34 2016 -0400

    Implement voting on the protocol-version options
---
 src/or/dirvote.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/or/dirvote.h | 12 ++++++++-
 2 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/src/or/dirvote.c b/src/or/dirvote.c
index e1d0d84..2d840a5 100644
--- a/src/or/dirvote.c
+++ b/src/or/dirvote.c
@@ -13,6 +13,7 @@
 #include "microdesc.h"
 #include "networkstatus.h"
 #include "policies.h"
+#include "protover.h"
 #include "rephist.h"
 #include "router.h"
 #include "routerkeys.h"
@@ -1198,6 +1199,72 @@ update_total_bandwidth_weights(const routerstatus_t *rs,
   }
 }
 
+/** Considering the different recommended/required protocols sets as a
+ * 4-element array, return the element from <b>vote</b> for that protocol
+ * set.
+ */
+static const char *
+get_nth_protocol_set_vote(int n, const networkstatus_t *vote)
+{
+  switch (n) {
+    case 0: return vote->recommended_client_protocols;
+    case 1: return vote->recommended_relay_protocols;
+    case 2: return vote->required_client_protocols;
+    case 3: return vote->required_relay_protocols;
+    default:
+      tor_assert_unreached();
+      return NULL;
+  }
+}
+
+/** Considering the different recommended/required protocols sets as a
+ * 4-element array, return a newly allocated string for the consensus value
+ * for the n'th set.
+ */
+static char *
+compute_nth_protocol_set(int n, int n_voters, const smartlist_t *votes)
+{
+  const char *keyword;
+  smartlist_t *proto_votes = smartlist_new();
+  int threshold;
+  switch (n) {
+    case 0:
+      keyword = "recommended-client-protocols";
+      threshold = CEIL_DIV(n_voters, 2);
+      break;
+    case 1:
+      keyword = "recommended-relay-protocols";
+      threshold = CEIL_DIV(n_voters, 2);
+      break;
+    case 2:
+      keyword = "required-client-protocols";
+      threshold = CEIL_DIV(n_voters * 2, 3);
+      break;
+    case 3:
+      keyword = "required-relay-protocols";
+      threshold = CEIL_DIV(n_voters * 2, 3);
+      break;
+    default:
+      tor_assert_unreached();
+      return NULL;
+  }
+
+  SMARTLIST_FOREACH_BEGIN(votes, const networkstatus_t *, ns) {
+    const char *v = get_nth_protocol_set_vote(n, ns);
+    if (v)
+      smartlist_add(proto_votes, (void*)v);
+  } SMARTLIST_FOREACH_END(ns);
+
+  char *protocols = compute_protover_vote(proto_votes, threshold);
+  smartlist_free(proto_votes);
+
+  char *result = NULL;
+  tor_asprintf(&result, "%s %s\n", keyword, protocols);
+  tor_free(protocols);
+
+  return result;
+}
+
 /** Given a list of vote networkstatus_t in <b>votes</b>, our public
  * authority <b>identity_key</b>, our private authority <b>signing_key</b>,
  * and the number of <b>total_authorities</b> that we believe exist in our
@@ -1377,6 +1444,17 @@ networkstatus_compute_consensus(smartlist_t *votes,
     tor_free(flaglist);
   }
 
+  if (consensus_method >= MIN_METHOD_FOR_RECOMMENDED_PROTOCOLS) {
+    int num_dirauth = get_n_authorities(V3_DIRINFO);
+    int idx;
+    for (idx = 0; idx < 4; ++idx) {
+      char *proto_line = compute_nth_protocol_set(idx, num_dirauth, votes);
+      if (BUG(!proto_line))
+        continue;
+      smartlist_add(chunks, proto_line);
+    }
+  }
+
   param_list = dirvote_compute_params(votes, consensus_method,
                                       total_authorities);
   if (smartlist_len(param_list)) {
diff --git a/src/or/dirvote.h b/src/or/dirvote.h
index a1f71ce..f29fe97 100644
--- a/src/or/dirvote.h
+++ b/src/or/dirvote.h
@@ -55,7 +55,7 @@
 #define MIN_SUPPORTED_CONSENSUS_METHOD 13
 
 /** The highest consensus method that we currently support. */
-#define MAX_SUPPORTED_CONSENSUS_METHOD 23
+#define MAX_SUPPORTED_CONSENSUS_METHOD 24
 
 /** Lowest consensus method where microdesc consensuses omit any entry
  * with no microdesc. */
@@ -99,6 +99,16 @@
  * value(s). */
 #define MIN_METHOD_FOR_SHARED_RANDOM 23
 
+/** Lowest consensus method where authorities vote on required/recommended
+ * protocols. */
+#define MIN_METHOD_FOR_RECOMMENDED_PROTOCOLS 24
+
+#if 0
+/** Lowest consensus method where authorities add protocols to routerstatus
+ * entries. */
+#define MIN_METHOD_FOR_RS_PROTOCOLS 24
+#endif
+
 /** Default bandwidth to clip unmeasured bandwidths to using method >=
  * MIN_METHOD_TO_CLIP_UNMEASURED_BW.  (This is not a consensus method; do not
  * get confused with the above macros.) */