Make the controller act more usefully when GETINFO fails

Right now it says "552 internal error" because there's no way for
getinfo_helper_*() countries to specify an error message.  This
patch changes the getinfo_helper_*() interface, and makes most of the
getinfo helpers give useful error messages in response to failures.

This should prevent recurrences of bug 1699, where a missing GeoIPFile
line in the torrc made GETINFO ip-to-county/* fail in a "not obvious
how to fix" way.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c
index 49bc8053ab..4834d13764 100644
--- a/src/or/networkstatus.c
+++ b/src/or/networkstatus.c
@@ -2124,7 +2124,8 @@ networkstatus_parse_flavor_name(const char *flavname)
  * ORs.  Return 0 on success, -1 on unrecognized question format. */
 int
 getinfo_helper_networkstatus(control_connection_t *conn,
-                             const char *question, char **answer)
+                             const char *question, char **answer,
+                             const char **errmsg)
 {
   routerstatus_t *status;
   (void) conn;
@@ -2148,8 +2149,10 @@ getinfo_helper_networkstatus(control_connection_t *conn,
   } else if (!strcmpstart(question, "ns/id/")) {
     char d[DIGEST_LEN];
 
-    if (base16_decode(d, DIGEST_LEN, question+6, strlen(question+6)))
+    if (base16_decode(d, DIGEST_LEN, question+6, strlen(question+6))) {
+      *errmsg = "Data not decodeable as hex";
       return -1;
+    }
     status = router_get_consensus_status_by_id(d);
   } else if (!strcmpstart(question, "ns/name/")) {
     status = router_get_consensus_status_by_nickname(question+8, 0);