82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
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// Copyright 2012 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 !plan9,!windows
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package ipv4
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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 IPv4 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 sockOpts[ssoStripHeader].name > 0 {
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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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} else {
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nb := make([]byte, maxHeaderLen+len(b))
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if n, oobn, _, src, err = c.ReadMsgIP(nb, oob); err != nil {
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return 0, nil, nil, err
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}
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hdrlen := int(nb[0]&0x0f) << 2
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copy(b, nb[hdrlen:])
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n -= hdrlen
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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 = netAddrToIP4(src)
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}
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return
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}
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// WriteTo writes a payload of the IPv4 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 datagram path and the outgoing interface to be specified.
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// Currently only Darwin and Linux support this. The cm may be nil if
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// 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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}
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