70 lines
2.2 KiB
Go
70 lines
2.2 KiB
Go
// 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.
|
|
|
|
package ipv4
|
|
|
|
import (
|
|
"net"
|
|
"syscall"
|
|
|
|
"golang.org/x/net/internal/socket"
|
|
)
|
|
|
|
// BUG(mikio): On Windows, the ReadFrom and WriteTo methods of RawConn
|
|
// are not implemented.
|
|
|
|
// A packetHandler represents the IPv4 datagram handler.
|
|
type packetHandler struct {
|
|
*net.IPConn
|
|
*socket.Conn
|
|
rawOpt
|
|
}
|
|
|
|
func (c *packetHandler) ok() bool { return c != nil && c.IPConn != nil && c.Conn != nil }
|
|
|
|
// ReadFrom reads an IPv4 datagram from the endpoint c, copying the
|
|
// datagram into b. It returns the received datagram as the IPv4
|
|
// header h, the payload p and the control message cm.
|
|
func (c *packetHandler) ReadFrom(b []byte) (h *Header, p []byte, cm *ControlMessage, err error) {
|
|
if !c.ok() {
|
|
return nil, nil, nil, syscall.EINVAL
|
|
}
|
|
return c.readFrom(b)
|
|
}
|
|
|
|
func slicePacket(b []byte) (h, p []byte, err error) {
|
|
if len(b) < HeaderLen {
|
|
return nil, nil, errHeaderTooShort
|
|
}
|
|
hdrlen := int(b[0]&0x0f) << 2
|
|
return b[:hdrlen], b[hdrlen:], nil
|
|
}
|
|
|
|
// WriteTo writes an IPv4 datagram through the endpoint c, copying the
|
|
// datagram from the IPv4 header h and the payload p. 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.
|
|
//
|
|
// The IPv4 header h must contain appropriate fields that include:
|
|
//
|
|
// Version = <must be specified>
|
|
// Len = <must be specified>
|
|
// TOS = <must be specified>
|
|
// TotalLen = <must be specified>
|
|
// ID = platform sets an appropriate value if ID is zero
|
|
// FragOff = <must be specified>
|
|
// TTL = <must be specified>
|
|
// Protocol = <must be specified>
|
|
// Checksum = platform sets an appropriate value if Checksum is zero
|
|
// Src = platform sets an appropriate value if Src is nil
|
|
// Dst = <must be specified>
|
|
// Options = optional
|
|
func (c *packetHandler) WriteTo(h *Header, p []byte, cm *ControlMessage) error {
|
|
if !c.ok() {
|
|
return syscall.EINVAL
|
|
}
|
|
return c.writeTo(h, p, cm)
|
|
}
|