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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build !plan9,!windows
package ipv4
import (
"net"
"syscall"
)
// ReadFrom reads a payload of the received IPv4 datagram, from the
// endpoint c, copying the payload into b. It returns the number of
// bytes copied into b, the control message cm and the source address
// src of the received datagram.
func (c *payloadHandler) ReadFrom(b []byte) (n int, cm *ControlMessage, src net.Addr, err error) {
if !c.ok() {
return 0, nil, nil, syscall.EINVAL
}
oob := newControlMessage(&c.rawOpt)
var oobn int
switch c := c.PacketConn.(type) {
case *net.UDPConn:
if n, oobn, _, src, err = c.ReadMsgUDP(b, oob); err != nil {
return 0, nil, nil, err
}
case *net.IPConn:
if sockOpts[ssoStripHeader].name > 0 {
if n, oobn, _, src, err = c.ReadMsgIP(b, oob); err != nil {
return 0, nil, nil, err
}
} else {
nb := make([]byte, maxHeaderLen+len(b))
if n, oobn, _, src, err = c.ReadMsgIP(nb, oob); err != nil {
return 0, nil, nil, err
}
hdrlen := int(nb[0]&0x0f) << 2
copy(b, nb[hdrlen:])
n -= hdrlen
}
default:
return 0, nil, nil, errInvalidConnType
}
if cm, err = parseControlMessage(oob[:oobn]); err != nil {
return 0, nil, nil, err
}
if cm != nil {
cm.Src = netAddrToIP4(src)
}
return
}
// WriteTo writes a payload of the IPv4 datagram, to the destination
// address dst through the endpoint c, copying the payload from b. It
// returns the number of bytes written. The control message cm allows
// the datagram path and the outgoing interface to be specified.
// Currently only Darwin and Linux support this. The cm may be nil if
// control of the outgoing datagram is not required.
func (c *payloadHandler) WriteTo(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error) {
if !c.ok() {
return 0, syscall.EINVAL
}
oob := marshalControlMessage(cm)
if dst == nil {
return 0, errMissingAddress
}
switch c := c.PacketConn.(type) {
case *net.UDPConn:
n, _, err = c.WriteMsgUDP(b, oob, dst.(*net.UDPAddr))
case *net.IPConn:
n, _, err = c.WriteMsgIP(b, oob, dst.(*net.IPAddr))
default:
return 0, errInvalidConnType
}
if err != nil {
return 0, err
}
return
}
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