Add custom urls for gists (#183)

internal/web/util.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/crypto/argon2"
 	"html/template"
 	"net/http"
+	"regexp"
 	"strconv"
 	"strings"
 )
@@ -135,6 +136,8 @@ type OpengistValidator struct {
 func NewValidator() *OpengistValidator {
 	v := validator.New()
 	_ = v.RegisterValidation("notreserved", validateReservedKeywords)
+	_ = v.RegisterValidation("alphanumdash", validateAlphaNumDash)
+	_ = v.RegisterValidation("alphanumdashorempty", validateAlphaNumDashOrEmpty)
 	return &OpengistValidator{v}
 }
 
@@ -158,6 +161,9 @@ func validationMessages(err *error) string {
 			messages[i] = e.Field() + " should not include a sub directory"
 		case "alphanum":
 			messages[i] = e.Field() + " should only contain alphanumeric characters"
+		case "alphanumdash":
+		case "alphanumdashorempty":
+			messages[i] = e.Field() + " should only contain alphanumeric characters and dashes"
 		case "min":
 			messages[i] = "Not enough " + e.Field()
 		case "notreserved":
@@ -181,6 +187,14 @@ func validateReservedKeywords(fl validator.FieldLevel) bool {
 	return !ok
 }
 
+func validateAlphaNumDash(fl validator.FieldLevel) bool {
+	return regexp.MustCompile(`^[a-zA-Z0-9-]+$`).MatchString(fl.Field().String())
+}
+
+func validateAlphaNumDashOrEmpty(fl validator.FieldLevel) bool {
+	return regexp.MustCompile(`^$|^[a-zA-Z0-9-]+$`).MatchString(fl.Field().String())
+}
+
 func getPage(ctx echo.Context) int {
 	page := ctx.QueryParam("page")
 	if page == "" {