Phase 3: OpenSubsonic core (response envelope, error codes 42-44, getOpenSubsonicExtensions) and apiKeyAuthentication extension with tokenInfo, web API key management

internal/subsonic/errors.go

@@ -1,16 +1,20 @@
 package subsonic
 
-// Error codes from the Subsonic REST API specification.
+// Error codes from the Subsonic REST API specification, plus the
+// OpenSubsonic apiKeyAuthentication extension's additions (42, 43, 44).
 const (
-	ErrGeneric               = 0
-	ErrMissingParameter      = 10
-	ErrClientMustUpgrade     = 20 // client's protocol version is newer than this server supports
-	ErrServerMustUpgrade     = 30 // server requires a newer client
-	ErrWrongCredentials      = 40
-	ErrTokenAuthNotSupported = 41 // e.g. LDAP-backed accounts with no local password
-	ErrUnauthorized          = 50 // authenticated, but not permitted to perform this action
-	ErrTrialExpired          = 60 // VibeSonic never returns this: no license is required
-	ErrNotFound              = 70
+	ErrGeneric                  = 0
+	ErrMissingParameter         = 10
+	ErrClientMustUpgrade        = 20 // client's protocol version is newer than this server supports
+	ErrServerMustUpgrade        = 30 // server requires a newer client
+	ErrWrongCredentials         = 40
+	ErrTokenAuthNotSupported    = 41 // e.g. LDAP-backed accounts with no local password
+	ErrAuthMechanismUnsupported = 42 // provided authentication mechanism not supported
+	ErrConflictingAuth          = 43 // multiple conflicting authentication mechanisms provided
+	ErrInvalidAPIKey            = 44
+	ErrUnauthorized             = 50 // authenticated, but not permitted to perform this action
+	ErrTrialExpired             = 60 // VibeSonic never returns this: no license is required
+	ErrNotFound                 = 70
 )
 
 // apiError is a Subsonic protocol error carrying an HTTP-agnostic code
@@ -21,6 +25,7 @@ const (
 type apiError struct {
 	Code    int
 	Message string
+	HelpURL string
 }
 
 func (e *apiError) Error() string { return e.Message }
@@ -29,6 +34,10 @@ func newError(code int, message string) *apiError {
 	return &apiError{Code: code, Message: message}
 }
 
+func newErrorWithHelp(code int, message, helpURL string) *apiError {
+	return &apiError{Code: code, Message: message, HelpURL: helpURL}
+}
+
 func errMissingParameter(name string) *apiError {
 	return newError(ErrMissingParameter, "Required parameter '"+name+"' is missing")
 }
@@ -41,8 +50,12 @@ func errUnauthorized(action string) *apiError {
 	return newError(ErrUnauthorized, "User is not authorized for the requested "+action)
 }
 
+const apiKeyHelpURL = "/settings#api-keys"
+
 var (
 	errWrongCredentials      = newError(ErrWrongCredentials, "Wrong username or password")
 	errClientMustUpgrade     = newError(ErrClientMustUpgrade, "Incompatible Subsonic REST protocol version. Client must upgrade.")
 	errTokenAuthNotSupported = newError(ErrTokenAuthNotSupported, "Token authentication is not supported for this account; use password authentication")
+	errConflictingAuth       = newErrorWithHelp(ErrConflictingAuth, "Provide either 'u' (with 'p' or 't'/'s') or 'apiKey', not both", apiKeyHelpURL)
+	errInvalidAPIKey         = newErrorWithHelp(ErrInvalidAPIKey, "Invalid API key", apiKeyHelpURL)
 )