vendor/golang.org/x/net/ipv4/packet.go

这里只显示每个文件的开头 60 行。登录后可以解锁完整代码。

微信扫码关注公众号，代码整理好后第一时间通知你。

// 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"

	"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, errInvalidConn
	}
	c.rawOpt.RLock()
	m := socket.Message{
		Buffers: [][]byte{b},
		OOB:     NewControlMessage(c.rawOpt.cflags),
	}
	c.rawOpt.RUnlock()
	if err := c.RecvMsg(&m, 0); err != nil {
		return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err}
	}
	var hs []byte
	if hs, p, err = slicePacket(b[:m.N]); err != nil {
		return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err}
	}
	if h, err = ParseHeader(hs); err != nil {
		return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err}
	}
	if m.NN > 0 {
		if compatFreeBSD32 {
			adjustFreeBSD32(&m)
		}
		cm = new(ControlMessage)
		if err := cm.Parse(m.OOB[:m.NN]); err != nil {
			return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err}
		}
	}
	if src, ok := m.Addr.(*net.IPAddr); ok && cm != nil {
		cm.Src = src.IP
	}
	return