Add a consensus method for IPv6 address lines in the microdesc consensus

Implements #23826.

src/or/dirserv.c

@@ -1949,8 +1949,10 @@ routerstatus_format_entry(const routerstatus_t *rs, const char *version,
    * networkstatus_type_t values, with an additional control port value
    * added -MP */
 
-  /* V3 microdesc consensuses don't have "a" lines. */
-  if (format == NS_V3_CONSENSUS_MICRODESC)
+  /* V3 microdesc consensuses only have "a" lines in later consensus methods
+   */
+  if (format == NS_V3_CONSENSUS_MICRODESC &&
+      consensus_method < MIN_METHOD_FOR_A_LINES_IN_MICRODESC_CONSENSUS)
     goto done;
 
   /* Possible "a" line. At most one for now. */
@@ -1959,7 +1961,7 @@ routerstatus_format_entry(const routerstatus_t *rs, const char *version,
                            fmt_addrport(&rs->ipv6_addr, rs->ipv6_orport));
   }
 
-  if (format == NS_V3_CONSENSUS)
+  if (format == NS_V3_CONSENSUS || format == NS_V3_CONSENSUS_MICRODESC)
     goto done;
 
   smartlist_add_asprintf(chunks,

src/or/dirvote.h

@@ -59,7 +59,7 @@
 #define MIN_SUPPORTED_CONSENSUS_METHOD 13
 
 /** The highest consensus method that we currently support. */
-#define MAX_SUPPORTED_CONSENSUS_METHOD 26
+#define MAX_SUPPORTED_CONSENSUS_METHOD 27
 
 /** Lowest consensus method where microdesc consensuses omit any entry
  * with no microdesc. */
@@ -119,6 +119,10 @@
  * instead of 0. See #14881 */
 #define MIN_METHOD_FOR_INIT_BW_WEIGHTS_ONE 26
 
+/** Lowest consensus method where the microdesc consensus contains relay IPv6
+ * addresses. See #23826 and #20916. */
+#define MIN_METHOD_FOR_A_LINES_IN_MICRODESC_CONSENSUS 27
+
 /** 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.) */