Fix relay_command_to_string(); solve 12700.

Two bugs here:
  1) We didn't add EXTEND2/EXTENDED2 to relay_command_to_string().

  2) relay_command_to_string() didn't log the value of unrecognized
     commands.

Both fixed here.

changes/bug12700

@@ -0,0 +1,10 @@
+  o Minor bugfixes:
+    - When logging information about an EXTEND2 or EXTENDED2 cell, log
+      their names correctly. Fixes part of bug 12700; bugfix on
+      0.2.4.8-alpha.
+
+  o Minor bugfixes:
+    - When logging information about a relay cell whose command we
+      don't recognize, log its command as an integer. Fixes part of
+      bug 12700; bugfix on 0.2.1.10-alpha.
+

src/or/relay.c

@@ -517,6 +517,7 @@ relay_header_unpack(relay_header_t *dest, const uint8_t *src)
 static const char *
 relay_command_to_string(uint8_t command)
 {
+  static char buf[64];
   switch (command) {
     case RELAY_COMMAND_BEGIN: return "BEGIN";
     case RELAY_COMMAND_DATA: return "DATA";
@@ -541,7 +542,12 @@ relay_command_to_string(uint8_t command)
     case RELAY_COMMAND_RENDEZVOUS_ESTABLISHED:
       return "RENDEZVOUS_ESTABLISHED";
     case RELAY_COMMAND_INTRODUCE_ACK: return "INTRODUCE_ACK";
-    default: return "(unrecognized)";
+    case RELAY_COMMAND_EXTEND2: return "EXTEND2";
+    case RELAY_COMMAND_EXTENDED2: return "EXTENDED2";
+    default:
+      tor_snprintf(buf, sizeof(buf), "Unrecognized relay command %u",
+                   (unsigned)command);
+      return buf;
   }
 }