Add log redacting, controlled by the new EnableLogRedacting config option (default true)

Imported redacting code from https://github.com/whuang8/redactrus (thanks William Huang)
Didn't use it as a dependency as it was too small and we want to keep dependencies at a minimum

log/log.go

@@ -16,6 +16,22 @@ type Level uint8
 
 type LevelFunc = func(ctx interface{}, msg interface{}, keyValuePairs ...interface{})
 
+var redacted = &Hook{
+	AcceptedLevels: logrus.AllLevels,
+	RedactionList: []string{
+		// Keys from the config
+		"(ApiKey:\")[\\w]*",
+		"(Secret:\")[\\w]*",
+		"(Spotify.*ID:\")[\\w]*",
+
+		// Subsonic query params
+		"([^\\w]t=)[\\w]+",
+		"([^\\w]s=)[\\w]+",
+		"([^\\w]p=)[\\w]+",
+		"([^\\w]jwt=)[\\w]+",
+	},
+}
+
 const (
 	LevelCritical = Level(logrus.FatalLevel)
 	LevelError    = Level(logrus.ErrorLevel)
@@ -65,6 +81,12 @@ func SetLogSourceLine(enabled bool) {
 	logSourceLine = enabled
 }
 
+func SetRedacting(enabled bool) {
+	if enabled {
+		defaultLogger.AddHook(redacted)
+	}
+}
+
 func NewContext(ctx context.Context, keyValuePairs ...interface{}) context.Context {
 	if ctx == nil {
 		ctx = context.Background()