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// Copyright 2016 Cong Ding
//
// 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 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
}
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