64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
// Copyright 2011 Miek Gieben. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package dns
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import (
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"net"
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"syscall"
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)
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type sessionUDP struct {
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raddr *net.UDPAddr
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context []byte
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}
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func (s *sessionUDP) RemoteAddr() net.Addr { return s.raddr }
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// setUDPSocketOptions sets the UDP socket options.
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// This function is implemented on a per platform basis. See udp_*.go for more details
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func setUDPSocketOptions(conn *net.UDPConn) error {
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file, err := conn.File()
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if err != nil {
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return err
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}
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sa, err := syscall.Getsockname(int(file.Fd()))
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switch sa.(type) {
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case *syscall.SockaddrInet6:
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// dual stack. See http://stackoverflow.com/questions/1618240/how-to-support-both-ipv4-and-ipv6-connections
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v6only, err := syscall.GetsockoptInt(int(file.Fd()), syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY)
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if err != nil {
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return err
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}
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setUDPSocketOptions6(conn)
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if v6only == 0 {
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setUDPSocketOptions4(conn)
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}
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case *syscall.SockaddrInet4:
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setUDPSocketOptions4(conn)
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}
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return nil
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}
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// readFromSessionUDP ... Just like net.UDPConn.ReadFrom(), but returns a session object instead of net.UDPAddr
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// (RemoteAddr() is available from the UDPSession object)
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func readFromSessionUDP(conn *net.UDPConn, b []byte) (int, *sessionUDP, error) {
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oob := make([]byte, 40)
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n, oobn, _, raddr, err := conn.ReadMsgUDP(b, oob)
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if err != nil {
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return n, nil, err
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}
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session := &sessionUDP{raddr, oob[:oobn]}
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return n, session, err
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}
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// writeToSessionUDP Just like net.UDPConn.WritetTo(), but uses a session object instead of net.Addr
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func writeToSessionUDP(conn *net.UDPConn, b []byte, session *sessionUDP) (int, error) {
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n, _, err := conn.WriteMsgUDP(b, session.context, session.raddr)
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return n, err
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}
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