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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 aix darwin dragonfly freebsd linux netbsd openbsd solaris
package ipv4
import (
"net"
"golang.org/x/net/internal/socket"
)
// 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, errInvalidConn
}
c.rawOpt.RLock()
m := socket.Message{
OOB: NewControlMessage(c.rawOpt.cflags),
}
c.rawOpt.RUnlock()
switch c.PacketConn.(type) {
case *net.UDPConn:
m.Buffers = [][]byte{b}
if err := c.RecvMsg(&m, 0); err != nil {
return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
}
case *net.IPConn:
h := make([]byte, HeaderLen)
m.Buffers = [][]byte{h, b}
if err := c.RecvMsg(&m, 0); err != nil {
return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
}
hdrlen := int(h[0]&0x0f) << 2
if hdrlen > len(h) {
d := hdrlen - len(h)
copy(b, b[d:])
m.N -= d
} else {
m.N -= hdrlen
}
default:
return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: errInvalidConnType}
}
if m.NN > 0 {
if compatFreeBSD32 {
adjustFreeBSD32(&m)
}
cm = new(ControlMessage)
if err := cm.Parse(m.OOB[:m.NN]); err != nil {
return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
}
cm.Src = netAddrToIP4(m.Addr)
}
return m.N, cm, m.Addr, nil
}
// 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, errInvalidConn
}
m := socket.Message{
Buffers: [][]byte{b},
OOB: cm.Marshal(),
Addr: dst,
}
err = c.SendMsg(&m, 0)
if err != nil {
err = &net.OpError{Op: "write", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Addr: opAddr(dst), Err: err}
}
return m.N, err
}
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