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vender/github.com/ccding/go-stun/stun/utils.go

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+// Copyright 2016, Cong Ding. All rights reserved.
+//
+// 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.
+//
+// Author: Cong Ding <dinggnu@gmail.com>
+
+package stun
+
+import (
+	"net"
+)
+
+// Padding the length of the byte slice to multiple of 4.
+func padding(bytes []byte) []byte {
+	length := uint16(len(bytes))
+	return append(bytes, make([]byte, align(length)-length)...)
+}
+
+// Align the uint16 number to the smallest multiple of 4, which is larger than
+// or equal to the uint16 number.
+func align(n uint16) uint16 {
+	return (n + 3) & 0xfffc
+}
+
+// isLocalAddress check if localRemote is a local address.
+func isLocalAddress(local, localRemote string) bool {
+	// Resolve the IP returned by the STUN server first.
+	localRemoteAddr, err := net.ResolveUDPAddr("udp", localRemote)
+	if err != nil {
+		return false
+	}
+	// Try comparing with the local address on the socket first, but only if
+	// it's actually specified.
+	addr, err := net.ResolveUDPAddr("udp", local)
+	if err == nil && addr.IP != nil && !addr.IP.IsUnspecified() {
+		return addr.IP.Equal(localRemoteAddr.IP)
+	}
+	// Fallback to checking IPs of all interfaces
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return false
+	}
+	for _, addr := range addrs {
+		ip, _, err := net.ParseCIDR(addr.String())
+		if err != nil {
+			continue
+		}
+		if ip.Equal(localRemoteAddr.IP) {
+			return true
+		}
+	}
+	return false
+}