.

gemini/errors.go

@@ -0,0 +1,100 @@
+package gemini
+
+import (
+	"errors"
+	"fmt"
+)
+
+type ErrGeminiStatusCode struct {
+	Msg    string
+	Code   int
+	Header string
+}
+
+func (e *ErrGeminiStatusCode) Error() string {
+	return fmt.Sprintf("%s: %s", e.Msg, e.Header)
+}
+
+func NewErrGeminiStatusCode(code int, header string) error {
+	var msg string
+	switch {
+	case code >= 10 && code < 20:
+		msg = "needs input"
+	case code >= 30 && code < 40:
+		msg = "redirect"
+	case code >= 40 && code < 50:
+		msg = "bad request"
+	case code >= 50 && code < 60:
+		msg = "server error"
+	case code >= 60 && code < 70:
+		msg = "TLS error"
+	default:
+		msg = "unexpected status code"
+	}
+	return &ErrGeminiStatusCode{
+		Msg:    msg,
+		Code:   code,
+		Header: header,
+	}
+}
+
+var (
+	ErrGemini                 = errors.New("gemini general error")
+	ErrGeminiRobotsParse      = errors.New("gemini robots.txt parse error")
+	ErrGeminiRobotsDisallowed = errors.New("gemini robots.txt disallowed")
+	ErrGeminiResponseHeader   = errors.New("gemini response header error")
+	ErrGeminiLinkLineParse    = errors.New("gemini link line parse error")
+
+	ErrURLParse  = errors.New("URL parse error")
+	ErrURLDecode = errors.New("URL decode error")
+	ErrUTF8Parse = errors.New("UTF-8 parse error")
+	ErrTextParse = errors.New("text parse error")
+
+	ErrNetwork                        = errors.New("network error")
+	ErrNetworkDNS                     = errors.New("network DNS error")
+	ErrNetworkTLS                     = errors.New("network TLS error")
+	ErrNetworkSetConnectionDeadline   = errors.New("network error - cannot set connection deadline")
+	ErrNetworkCannotWrite             = errors.New("network error - cannot write")
+	ErrNetworkResponseSizeExceededMax = errors.New("network error - response size exceeded maximum size")
+
+	ErrDatabase = errors.New("database error")
+)
+
+// We could have used a map for speed, but
+// we would lose ability to check wrapped
+// errors via errors.Is().
+
+var KnownErrors = []error{
+	ErrGemini,
+	ErrGeminiLinkLineParse,
+	ErrGeminiRobotsParse,
+	ErrGeminiRobotsDisallowed,
+	ErrGeminiResponseHeader,
+
+	ErrURLParse,
+	ErrURLDecode,
+	ErrUTF8Parse,
+	ErrTextParse,
+
+	ErrNetwork,
+	ErrNetworkDNS,
+	ErrNetworkTLS,
+	ErrNetworkSetConnectionDeadline,
+	ErrNetworkCannotWrite,
+	ErrNetworkResponseSizeExceededMax,
+
+	ErrDatabase,
+}
+
+func IsKnownError(err error) bool {
+	var errGeminiStatusCode *ErrGeminiStatusCode
+	if errors.As(err, &errGeminiStatusCode) {
+		return true
+	}
+	for _, known := range KnownErrors {
+		if errors.Is(err, known) {
+			return true
+		}
+	}
+	return false
+}