add custom logger

fixes #45

utils/log.go

@@ -0,0 +1,45 @@
+package utils
+
+import "fmt"
+
+// LogLevel of quic-go
+type LogLevel uint8
+
+const (
+	// LogLevelDebug enables debug logs (e.g. packet contents)
+	LogLevelDebug LogLevel = iota
+	// LogLevelInfo enables info logs (e.g. packets)
+	LogLevelInfo
+	// LogLevelError enables err logs
+	LogLevelError
+	// LogLevelNothing disables
+	LogLevelNothing
+)
+
+var logLevel = LogLevelNothing
+
+// SetLogLevel sets the log level
+func SetLogLevel(level LogLevel) {
+	logLevel = level
+}
+
+// Debugf logs something
+func Debugf(format string, args ...interface{}) {
+	if logLevel == LogLevelDebug {
+		fmt.Printf(format+"\n", args...)
+	}
+}
+
+// Infof logs something
+func Infof(format string, args ...interface{}) {
+	if logLevel <= LogLevelInfo {
+		fmt.Printf(format+"\n", args...)
+	}
+}
+
+// Errorf logs something
+func Errorf(format string, args ...interface{}) {
+	if logLevel <= LogLevelError {
+		fmt.Printf(format+"\n", args...)
+	}
+}