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69 lines
2.2 KiB
69 lines
2.2 KiB
// Copyright 2012 The Go Authors. All rights reserved. |
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// Use of this source code is governed by a BSD-style |
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// license that can be found in the LICENSE file. |
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package ipv4 |
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import ( |
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"net" |
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"syscall" |
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"golang.org/x/net/internal/socket" |
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) |
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// BUG(mikio): On Windows, the ReadFrom and WriteTo methods of RawConn |
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// are not implemented. |
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// A packetHandler represents the IPv4 datagram handler. |
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type packetHandler struct { |
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*net.IPConn |
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*socket.Conn |
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rawOpt |
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} |
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func (c *packetHandler) ok() bool { return c != nil && c.IPConn != nil && c.Conn != nil } |
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// ReadFrom reads an IPv4 datagram from the endpoint c, copying the |
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// datagram into b. It returns the received datagram as the IPv4 |
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// header h, the payload p and the control message cm. |
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func (c *packetHandler) ReadFrom(b []byte) (h *Header, p []byte, cm *ControlMessage, err error) { |
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if !c.ok() { |
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return nil, nil, nil, syscall.EINVAL |
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} |
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return c.readFrom(b) |
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} |
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func slicePacket(b []byte) (h, p []byte, err error) { |
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if len(b) < HeaderLen { |
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return nil, nil, errHeaderTooShort |
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} |
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hdrlen := int(b[0]&0x0f) << 2 |
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return b[:hdrlen], b[hdrlen:], nil |
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} |
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// WriteTo writes an IPv4 datagram through the endpoint c, copying the |
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// datagram from the IPv4 header h and the payload p. The control |
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// message cm allows the datagram path and the outgoing interface to be |
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// specified. Currently only Darwin and Linux support this. The cm |
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// may be nil if control of the outgoing datagram is not required. |
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// |
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// The IPv4 header h must contain appropriate fields that include: |
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// |
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// Version = <must be specified> |
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// Len = <must be specified> |
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// TOS = <must be specified> |
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// TotalLen = <must be specified> |
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// ID = platform sets an appropriate value if ID is zero |
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// FragOff = <must be specified> |
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// TTL = <must be specified> |
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// Protocol = <must be specified> |
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// Checksum = platform sets an appropriate value if Checksum is zero |
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// Src = platform sets an appropriate value if Src is nil |
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// Dst = <must be specified> |
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// Options = optional |
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func (c *packetHandler) WriteTo(h *Header, p []byte, cm *ControlMessage) error { |
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if !c.ok() { |
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return syscall.EINVAL |
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} |
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return c.writeTo(h, p, cm) |
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}
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