support range ports mapping by go template (#4073)

pkg/config/load.go

@@ -80,7 +80,10 @@ func DetectLegacyINIFormatFromFile(path string) bool {
 }
 
 func RenderWithTemplate(in []byte, values *Values) ([]byte, error) {
-	tmpl, err := template.New("frp").Parse(string(in))
+	tmpl, err := template.New("frp").Funcs(template.FuncMap{
+		"parseNumberRange":     parseNumberRange,
+		"parseNumberRangePair": parseNumberRangePair,
+	}).Parse(string(in))
 	if err != nil {
 		return nil, err
 	}

pkg/config/template.go

@@ -0,0 +1,52 @@
+// Copyright 2024 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"fmt"
+
+	"github.com/fatedier/frp/pkg/util/util"
+)
+
+type NumberPair struct {
+	First  int64
+	Second int64
+}
+
+func parseNumberRangePair(firstRangeStr, secondRangeStr string) ([]NumberPair, error) {
+	firstRangeNumbers, err := util.ParseRangeNumbers(firstRangeStr)
+	if err != nil {
+		return nil, err
+	}
+	secondRangeNumbers, err := util.ParseRangeNumbers(secondRangeStr)
+	if err != nil {
+		return nil, err
+	}
+	if len(firstRangeNumbers) != len(secondRangeNumbers) {
+		return nil, fmt.Errorf("first and second range numbers are not in pairs")
+	}
+	pairs := make([]NumberPair, 0, len(firstRangeNumbers))
+	for i := 0; i < len(firstRangeNumbers); i++ {
+		pairs = append(pairs, NumberPair{
+			First:  firstRangeNumbers[i],
+			Second: secondRangeNumbers[i],
+		})
+	}
+	return pairs, nil
+}
+
+func parseNumberRange(firstRangeStr string) ([]int64, error) {
+	return util.ParseRangeNumbers(firstRangeStr)
+}