Merge pull request #1197 from pi-hole/fix/rate_limit_crash

Fix rare crashes when rate-limiting happens before queries are blocked

src/dnsmasq_interface.c

@@ -71,7 +71,7 @@ static void check_pihole_PTR(char *domain);
 static void _query_set_dnssec(queriesData *query, const enum dnssec_status dnssec, const char *file, const int line);
 
 // Static blocking metadata
-static const char *blockingreason = NULL;
+static const char *blockingreason = "";
 static union all_addr null_addrp = {{ 0 }};
 static enum reply_type force_next_DNS_reply = REPLY_UNKNOWN;
 static int last_regex_idx = -1;
@@ -295,11 +295,12 @@ size_t _FTL_make_answer(struct dns_header *header, char *limit, const size_t len
  // Setup reply header
  setup_reply(header, flags, *ede);
 
- // Add NEG flag when replying with NXDOMAIN. This is necessary to get proper logging in pihole.log
- // At the same time, we cannot add NEG before calling setup_reply() as it would, otherwise, result
- // in an incorrect "nowhere to forward to" log entry (because setup_reply() checks for equality of
- // flags instead of doing a bitmask comparison).
- if(flags == F_NXDOMAIN)
+ // Add NEG flag when replying with NXDOMAIN or NODATA. This is necessary
+ // to get proper logging in pihole.log At the same time, we cannot add
+ // NEG before calling setup_reply() as it would, otherwise, result in an
+ // incorrect "nowhere to forward to" log entry (because setup_reply()
+ // checks for equality of flags instead of doing a bitmask comparison).
+ if(flags == F_NXDOMAIN || flags == F_NOERR)
  flags |= F_NEG;
 
  // Add flags according to current blocking mode
@@ -388,6 +389,7 @@ size_t _FTL_make_answer(struct dns_header *header, char *limit, const size_t len
  else
  {
  // NODATA/NXDOMAIN
+ // gravity blocked abc.com is NODATA/NXDOMAIN
  log_query(flags, name, NULL, (char*)blockingreason, 0);
  }
  }