David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 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 | // +build !go1.9 |
| 6 | |
| 7 | package ipv4 |
| 8 | |
| 9 | import "net" |
| 10 | |
| 11 | func (c *packetHandler) readFrom(b []byte) (h *Header, p []byte, cm *ControlMessage, err error) { |
| 12 | c.rawOpt.RLock() |
| 13 | oob := NewControlMessage(c.rawOpt.cflags) |
| 14 | c.rawOpt.RUnlock() |
| 15 | n, nn, _, src, err := c.ReadMsgIP(b, oob) |
| 16 | if err != nil { |
| 17 | return nil, nil, nil, err |
| 18 | } |
| 19 | var hs []byte |
| 20 | if hs, p, err = slicePacket(b[:n]); err != nil { |
| 21 | return nil, nil, nil, err |
| 22 | } |
| 23 | if h, err = ParseHeader(hs); err != nil { |
| 24 | return nil, nil, nil, err |
| 25 | } |
| 26 | if nn > 0 { |
| 27 | cm = new(ControlMessage) |
| 28 | if err := cm.Parse(oob[:nn]); err != nil { |
| 29 | return nil, nil, nil, err |
| 30 | } |
| 31 | } |
| 32 | if src != nil && cm != nil { |
| 33 | cm.Src = src.IP |
| 34 | } |
| 35 | return |
| 36 | } |
| 37 | |
| 38 | func (c *packetHandler) writeTo(h *Header, p []byte, cm *ControlMessage) error { |
| 39 | oob := cm.Marshal() |
| 40 | wh, err := h.Marshal() |
| 41 | if err != nil { |
| 42 | return err |
| 43 | } |
| 44 | dst := new(net.IPAddr) |
| 45 | if cm != nil { |
| 46 | if ip := cm.Dst.To4(); ip != nil { |
| 47 | dst.IP = ip |
| 48 | } |
| 49 | } |
| 50 | if dst.IP == nil { |
| 51 | dst.IP = h.Dst |
| 52 | } |
| 53 | wh = append(wh, p...) |
| 54 | _, _, err = c.WriteMsgIP(wh, oob, dst) |
| 55 | return err |
| 56 | } |