Add a consensus_method argument to routerstatus_format_entry()

And pass ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD when it's not applicable.

Preparation for #23826.

src/or/dirserv.c

@@ -1897,21 +1897,28 @@ version_from_platform(const char *platform)
 /** Helper: write the router-status information in <b>rs</b> into a newly
  * allocated character buffer.  Use the same format as in network-status
  * documents.  If <b>version</b> is non-NULL, add a "v" line for the platform.
+ *
+ * consensus_method is the current consensus method when format is
+ * NS_V3_CONSENSUS or NS_V3_CONSENSUS_MICRODESC. It is ignored for other
+ * formats: pass ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD.
+ *
  * Return 0 on success, -1 on failure.
  *
  * The format argument has one of the following values:
  *   NS_V2 - Output an entry suitable for a V2 NS opinion document
  *   NS_V3_CONSENSUS - Output the first portion of a V3 NS consensus entry
+ *        for consensus_method.
  *   NS_V3_CONSENSUS_MICRODESC - Output the first portion of a V3 microdesc
- *        consensus entry.
+ *        consensus entry for consensus_method.
  *   NS_V3_VOTE - Output a complete V3 NS vote. If <b>vrs</b> is present,
  *        it contains additional information for the vote.
- *   NS_CONTROL_PORT - Output a NS document for the control port
+ *   NS_CONTROL_PORT - Output a NS document for the control port.
  */
 char *
 routerstatus_format_entry(const routerstatus_t *rs, const char *version,
                           const char *protocols,
                           routerstatus_format_type_t format,
+                          int consensus_method,
                           const vote_routerstatus_t *vrs)
 {
   char *summary;

src/or/dirserv.h

@@ -150,6 +150,7 @@ char *routerstatus_format_entry(
                               const char *version,
                               const char *protocols,
                               routerstatus_format_type_t format,
+                              int consensus_method,
                               const vote_routerstatus_t *vrs);
 void dirserv_free_all(void);
 void cached_dir_decref(cached_dir_t *d);

src/or/dirvote.c

@@ -278,7 +278,9 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
     vote_microdesc_hash_t *h;
     rsf = routerstatus_format_entry(&vrs->status,
                                     vrs->version, vrs->protocols,
-                                    NS_V3_VOTE, vrs);
+                                    NS_V3_VOTE,
+                                    ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD,
+                                    vrs);
     if (rsf)
       smartlist_add(chunks, rsf);
 
@@ -2100,7 +2102,8 @@ networkstatus_compute_consensus(smartlist_t *votes,
         char *buf;
         /* Okay!! Now we can write the descriptor... */
         /*     First line goes into "buf". */
-        buf = routerstatus_format_entry(&rs_out, NULL, NULL, rs_format, NULL);
+        buf = routerstatus_format_entry(&rs_out, NULL, NULL,
+                                        rs_format, consensus_method, NULL);
         if (buf)
           smartlist_add(chunks, buf);
       }

src/or/dirvote.h

@@ -51,6 +51,10 @@
 #define MIN_VOTE_INTERVAL_TESTING_INITIAL \
                 ((MIN_VOTE_SECONDS_TESTING)+(MIN_DIST_SECONDS_TESTING)+1)
 
+/* A placeholder for routerstatus_format_entry() when the consensus method
+ * argument is not applicable. */
+#define ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD 0
+
 /** The lowest consensus method that we currently support. */
 #define MIN_SUPPORTED_CONSENSUS_METHOD 13
 

src/or/networkstatus.c

@@ -2193,7 +2193,9 @@ signed_descs_update_status_from_consensus_networkstatus(smartlist_t *descs)
 char *
 networkstatus_getinfo_helper_single(const routerstatus_t *rs)
 {
-  return routerstatus_format_entry(rs, NULL, NULL, NS_CONTROL_PORT, NULL);
+  return routerstatus_format_entry(rs, NULL, NULL, NS_CONTROL_PORT,
+                                   ROUTERSTATUS_FORMAT_NO_CONSENSUS_METHOD,
+                                   NULL);
 }
 
 /** Alloc and return a string describing routerstatuses for the most