1 // Copyright 2012 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
6 7 package ipv4
8 9 import (
10 "net"
11 12 "golang.org/x/net/internal/socket"
13 )
14 15 // ReadFrom reads a payload of the received IPv4 datagram, from the
16 // endpoint c, copying the payload into b. It returns the number of
17 // bytes copied into b, the control message cm and the source address
18 // src of the received datagram.
19 func (c *payloadHandler) ReadFrom(b []byte) (n int, cm *ControlMessage, src net.Addr, err error) {
20 if !c.ok() {
21 return 0, nil, nil, errInvalidConn
22 }
23 c.rawOpt.RLock()
24 m := socket.Message{
25 OOB: NewControlMessage(c.rawOpt.cflags),
26 }
27 c.rawOpt.RUnlock()
28 switch c.PacketConn.(type) {
29 case *net.UDPConn:
30 m.Buffers = [][]byte{b}
31 if err := c.RecvMsg(&m, 0); err != nil {
32 return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
33 }
34 case *net.IPConn:
35 h := make([]byte, HeaderLen)
36 m.Buffers = [][]byte{h, b}
37 if err := c.RecvMsg(&m, 0); err != nil {
38 return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
39 }
40 hdrlen := int(h[0]&0x0f) << 2
41 if hdrlen > len(h) {
42 d := hdrlen - len(h)
43 copy(b, b[d:])
44 m.N -= d
45 } else {
46 m.N -= hdrlen
47 }
48 default:
49 return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: errInvalidConnType}
50 }
51 if m.NN > 0 {
52 if compatFreeBSD32 {
53 adjustFreeBSD32(&m)
54 }
55 cm = new(ControlMessage)
56 if err := cm.Parse(m.OOB[:m.NN]); err != nil {
57 return 0, nil, nil, &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err}
58 }
59 cm.Src = netAddrToIP4(m.Addr)
60 }
61 return m.N, cm, m.Addr, nil
62 }
63 64 // WriteTo writes a payload of the IPv4 datagram, to the destination
65 // address dst through the endpoint c, copying the payload from b. It
66 // returns the number of bytes written. The control message cm allows
67 // the datagram path and the outgoing interface to be specified.
68 // Currently only Darwin and Linux support this. The cm may be nil if
69 // control of the outgoing datagram is not required.
70 func (c *payloadHandler) WriteTo(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error) {
71 if !c.ok() {
72 return 0, errInvalidConn
73 }
74 m := socket.Message{
75 Buffers: [][]byte{b},
76 OOB: cm.Marshal(),
77 Addr: dst,
78 }
79 err = c.SendMsg(&m, 0)
80 if err != nil {
81 err = &net.OpError{Op: "write", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Addr: opAddr(dst), Err: err}
82 }
83 return m.N, err
84 }
85