~vtuson/scopecreator/twitter-template

1 by Victor Palau
public release
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// Copyright 2013 The Go Authors.  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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// +build !nacl,!plan9,!windows
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package ipv6
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import (
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	"net"
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	"syscall"
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)
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// ReadFrom reads a payload of the received IPv6 datagram, from the
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// endpoint c, copying the payload into b.  It returns the number of
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// bytes copied into b, the control message cm and the source address
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// src of the received datagram.
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func (c *payloadHandler) ReadFrom(b []byte) (n int, cm *ControlMessage, src net.Addr, err error) {
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	if !c.ok() {
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		return 0, nil, nil, syscall.EINVAL
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	}
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	oob := newControlMessage(&c.rawOpt)
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	var oobn int
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	switch c := c.PacketConn.(type) {
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	case *net.UDPConn:
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		if n, oobn, _, src, err = c.ReadMsgUDP(b, oob); err != nil {
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			return 0, nil, nil, err
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		}
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	case *net.IPConn:
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		if n, oobn, _, src, err = c.ReadMsgIP(b, oob); err != nil {
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			return 0, nil, nil, err
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		}
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	default:
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		return 0, nil, nil, errInvalidConnType
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	}
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	if cm, err = parseControlMessage(oob[:oobn]); err != nil {
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		return 0, nil, nil, err
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	}
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	if cm != nil {
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		cm.Src = netAddrToIP16(src)
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	}
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	return
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}
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// WriteTo writes a payload of the IPv6 datagram, to the destination
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// address dst through the endpoint c, copying the payload from b.  It
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// returns the number of bytes written.  The control message cm allows
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// the IPv6 header fields and the datagram path to be specified.  The
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// cm may be nil if control of the outgoing datagram is not required.
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func (c *payloadHandler) WriteTo(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error) {
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	if !c.ok() {
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		return 0, syscall.EINVAL
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	}
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	oob := marshalControlMessage(cm)
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	if dst == nil {
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		return 0, errMissingAddress
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	}
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	switch c := c.PacketConn.(type) {
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	case *net.UDPConn:
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		n, _, err = c.WriteMsgUDP(b, oob, dst.(*net.UDPAddr))
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	case *net.IPConn:
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		n, _, err = c.WriteMsgIP(b, oob, dst.(*net.IPAddr))
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	default:
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		return 0, errInvalidConnType
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	}
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	if err != nil {
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		return 0, err
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	}
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	return
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}