David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 1 | // Copyright 2017 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 ( |
| 10 | "net" |
| 11 | |
| 12 | "golang.org/x/net/internal/socket" |
| 13 | ) |
| 14 | |
| 15 | func (c *packetHandler) readFrom(b []byte) (h *Header, p []byte, cm *ControlMessage, err error) { |
| 16 | c.rawOpt.RLock() |
| 17 | m := socket.Message{ |
| 18 | Buffers: [][]byte{b}, |
| 19 | OOB: NewControlMessage(c.rawOpt.cflags), |
| 20 | } |
| 21 | c.rawOpt.RUnlock() |
| 22 | if err := c.RecvMsg(&m, 0); err != nil { |
| 23 | return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err} |
| 24 | } |
| 25 | var hs []byte |
| 26 | if hs, p, err = slicePacket(b[:m.N]); err != nil { |
| 27 | return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err} |
| 28 | } |
| 29 | if h, err = ParseHeader(hs); err != nil { |
| 30 | return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err} |
| 31 | } |
| 32 | if m.NN > 0 { |
| 33 | cm = new(ControlMessage) |
| 34 | if err := cm.Parse(m.OOB[:m.NN]); err != nil { |
| 35 | return nil, nil, nil, &net.OpError{Op: "read", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Err: err} |
| 36 | } |
| 37 | } |
| 38 | if src, ok := m.Addr.(*net.IPAddr); ok && cm != nil { |
| 39 | cm.Src = src.IP |
| 40 | } |
| 41 | return |
| 42 | } |
| 43 | |
| 44 | func (c *packetHandler) writeTo(h *Header, p []byte, cm *ControlMessage) error { |
| 45 | m := socket.Message{ |
| 46 | OOB: cm.Marshal(), |
| 47 | } |
| 48 | wh, err := h.Marshal() |
| 49 | if err != nil { |
| 50 | return err |
| 51 | } |
| 52 | m.Buffers = [][]byte{wh, p} |
| 53 | dst := new(net.IPAddr) |
| 54 | if cm != nil { |
| 55 | if ip := cm.Dst.To4(); ip != nil { |
| 56 | dst.IP = ip |
| 57 | } |
| 58 | } |
| 59 | if dst.IP == nil { |
| 60 | dst.IP = h.Dst |
| 61 | } |
| 62 | m.Addr = dst |
| 63 | if err := c.SendMsg(&m, 0); err != nil { |
| 64 | return &net.OpError{Op: "write", Net: c.IPConn.LocalAddr().Network(), Source: c.IPConn.LocalAddr(), Addr: opAddr(dst), Err: err} |
| 65 | } |
| 66 | return nil |
| 67 | } |