resolved: make counter for redirects smaller

It can never go above 16, so let's use a narrower type.

Order will be adjusted later to remove holes.

src/resolve/resolved-dns-query.c

@@ -12,8 +12,10 @@
 
 #define QUERIES_MAX 2048
 #define AUXILIARY_QUERIES_MAX 64
+#define CNAME_REDIRECTS_MAX 16
 
 assert_cc(AUXILIARY_QUERIES_MAX < UINT8_MAX);
+assert_cc(CNAME_REDIRECTS_MAX < UINT8_MAX);
 
 static int dns_query_candidate_new(DnsQueryCandidate **ret, DnsQuery *q, DnsScope *s) {
         DnsQueryCandidate *c;
@@ -984,9 +986,9 @@ static int dns_query_cname_redirect(DnsQuery *q, const DnsResourceRecord *cname)
 
         assert(q);
 
-        q->n_cname_redirects++;
-        if (q->n_cname_redirects > CNAME_REDIRECT_MAX)
+        if (q->n_cname_redirects >= CNAME_REDIRECTS_MAX)
                 return -ELOOP;
+        q->n_cname_redirects++;
 
         r = dns_question_cname_redirect(q->question_idna, cname, &nq_idna);
         if (r < 0)

src/resolve/resolved-dns-query.h

@@ -64,7 +64,7 @@ struct DnsQuery {
         int ifindex;
 
         DnsTransactionState state;
-        unsigned n_cname_redirects;
+        uint8_t n_cname_redirects;
 
         LIST_HEAD(DnsQueryCandidate, candidates);
         sd_event_source *timeout_event_source;
@@ -154,5 +154,3 @@ static inline uint64_t dns_query_reply_flags_make(DnsQuery *q) {
                                       dns_query_fully_confidential(q)) |
                 (q->answer_query_flags & (SD_RESOLVED_FROM_MASK|SD_RESOLVED_SYNTHETIC));
 }
-
-#define CNAME_REDIRECT_MAX 16