1 files changed, 104 insertions, 0 deletions
diff --git a/helper/args.go b/helper/args.go
new file mode 100644
index 0000000..5651cb4
--- /dev/null
+++ b/helper/args.go
@@ -0,0 +1,104 @@
+package main
+
+import (
+	"log"
+	"net"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+const (
+	openvpnUser  = "nobody"
+	openvpnGroup = "nobody"
+	nameserver   = "10.42.0.1"
+)
+
+var (
+	fixedArgs = []string{
+		"--nobind",
+		"--client",
+		"--dev", "tun",
+		"--tls-client",
+		"--remote-cert-tls", "server",
+		"--dhcp-option", "DNS", nameserver,
+		"--user", openvpnUser,
+		"--group", openvpnGroup,
+		"--log", logFolder + "openvpn.log",
+	}
+
+	allowendArgs = map[string][]string{
+		"--remote":            []string{"IP", "NUMBER", "PROTO"},
+		"--tls-cipher":        []string{"CIPHER"},
+		"--cipher":            []string{"CIPHER"},
+		"--auth":              []string{"CIPHER"},
+		"--management-client": []string{},
+		"--management":        []string{"IP", "NUMBER"},
+		"--cert":              []string{"FILE"},
+		"--key":               []string{"FILE"},
+		"--ca":                []string{"FILE"},
+		"--fragment":          []string{"NUMBER"},
+		"--keepalive":         []string{"NUMBER", "NUMBER"},
+		"--verb":              []string{"NUMBER"},
+		"--tun-ipv6":          []string{},
+	}
+
+	cipher  = regexp.MustCompile("^[A-Z0-9-]+$")
+	formats = map[string]func(s string) bool{
+		"NUMBER": isNumber,
+		"PROTO":  isProto,
+		"IP":     isIP,
+		"CIPHER": cipher.MatchString,
+		"FILE":   isFile,
+	}
+)
+
+func parseOpenvpnArgs(args []string) []string {
+	newArgs := fixedArgs
+	for i := 0; i < len(args); i++ {
+		params, ok := allowendArgs[args[i]]
+		if !ok {
+			log.Printf("Invalid openvpn arg: %s", args[i])
+			continue
+		}
+		for j, arg := range args[i+1 : i+len(params)+1] {
+			if !formats[params[j]](arg) {
+				ok = false
+				break
+			}
+		}
+		if ok {
+			newArgs = append(newArgs, args[i:i+len(params)+1]...)
+			i = i + len(params)
+		} else {
+			log.Printf("Invalid openvpn arg params: %v", args[i:i+len(params)+1])
+		}
+	}
+	return newArgs
+}
+
+func isNumber(s string) bool {
+	_, err := strconv.Atoi(s)
+	return err == nil
+}
+
+func isProto(s string) bool {
+	for _, proto := range []string{"tcp", "udp", "tcp4", "udp4", "tcp6", "udp6"} {
+		if s == proto {
+			return true
+		}
+	}
+	return false
+}
+
+func isIP(s string) bool {
+	return net.ParseIP(s) != nil
+}
+
+func isFile(s string) bool {
+	info, err := os.Stat(s)
+	if err != nil {
+		return false
+	}
+	return !info.IsDir()
+}