kaniko/vendor/github.com/docker/go-connections/nat/parse.go

package nat

import (
	"fmt"
	"strconv"
	"strings"
)

// ParsePortRange parses and validates the specified string as a port-range (8000-9000)
func ParsePortRange(ports string) (uint64, uint64, error) {
	if ports == "" {
		return 0, 0, fmt.Errorf("empty string specified for ports")
	}
	if !strings.Contains(ports, "-") {
		start, err := strconv.ParseUint(ports, 10, 16)
		end := start
		return start, end, err
	}

	parts := strings.Split(ports, "-")
	start, err := strconv.ParseUint(parts[0], 10, 16)
	if err != nil {
		return 0, 0, err
	}
	end, err := strconv.ParseUint(parts[1], 10, 16)
	if err != nil {
		return 0, 0, err
	}
	if end < start {
		return 0, 0, fmt.Errorf("invalid range specified for port: %s", ports)
	}
	return start, end, nil
}