Log the literal value, not a format string (#5425)

Signed-off-by: Andy Lindeman <andy@lindeman.io>

plugin/log/log.go

@@ -46,7 +46,7 @@ func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 		}
 		if ok || ok1 {
 			logstr := l.repl.Replace(ctx, state, rrw, rule.Format)
-			clog.Infof(logstr)
+			clog.Info(logstr)
 		}
 
 		return rc, err

plugin/log/log_test.go

@@ -202,6 +202,19 @@ func TestLogged(t *testing.T) {
 			ShouldLog:    true,
 			ShouldString: "\"0\"",
 		},
+		{
+			Rules: []Rule{
+				{
+					NameScope: ".",
+					Format:    CombinedLogFormat,
+					Class:     map[response.Class]struct{}{response.All: {}},
+				},
+			},
+			Domain:          "foo.%s.example.org.",
+			ShouldLog:       true,
+			ShouldString:    "foo.%s.example.org.",
+			ShouldNOTString: "%!s(MISSING)",
+		},
 	}
 
 	for _, tc := range tests {