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This code is useful to other packages writing tests. Signed-off-by: David Crawshaw <[email protected]>
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,150 @@ | ||
| /* SPDX-License-Identifier: MIT | ||
| * | ||
| * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved. | ||
| */ | ||
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| package tuntest | ||
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| import ( | ||
| "encoding/binary" | ||
| "io" | ||
| "net" | ||
| "os" | ||
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| "golang.zx2c4.com/wireguard/tun" | ||
| ) | ||
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| func Ping(dst, src net.IP) []byte { | ||
| localPort := uint16(1337) | ||
| seq := uint16(0) | ||
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| payload := make([]byte, 4) | ||
| binary.BigEndian.PutUint16(payload[0:], localPort) | ||
| binary.BigEndian.PutUint16(payload[2:], seq) | ||
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| return genICMPv4(payload, dst, src) | ||
| } | ||
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| // Checksum is the "internet checksum" from https://tools.ietf.org/html/rfc1071. | ||
| func checksum(buf []byte, initial uint16) uint16 { | ||
| v := uint32(initial) | ||
| for i := 0; i < len(buf)-1; i += 2 { | ||
| v += uint32(binary.BigEndian.Uint16(buf[i:])) | ||
| } | ||
| if len(buf)%2 == 1 { | ||
| v += uint32(buf[len(buf)-1]) << 8 | ||
| } | ||
| for v > 0xffff { | ||
| v = (v >> 16) + (v & 0xffff) | ||
| } | ||
| return ^uint16(v) | ||
| } | ||
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| func genICMPv4(payload []byte, dst, src net.IP) []byte { | ||
| const ( | ||
| icmpv4ProtocolNumber = 1 | ||
| icmpv4Echo = 8 | ||
| icmpv4ChecksumOffset = 2 | ||
| icmpv4Size = 8 | ||
| ipv4Size = 20 | ||
| ipv4TotalLenOffset = 2 | ||
| ipv4ChecksumOffset = 10 | ||
| ttl = 65 | ||
| ) | ||
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| hdr := make([]byte, ipv4Size+icmpv4Size) | ||
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| ip := hdr[0:ipv4Size] | ||
| icmpv4 := hdr[ipv4Size : ipv4Size+icmpv4Size] | ||
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| // https://tools.ietf.org/html/rfc792 | ||
| icmpv4[0] = icmpv4Echo // type | ||
| icmpv4[1] = 0 // code | ||
| chksum := ^checksum(icmpv4, checksum(payload, 0)) | ||
| binary.BigEndian.PutUint16(icmpv4[icmpv4ChecksumOffset:], chksum) | ||
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| // https://tools.ietf.org/html/rfc760 section 3.1 | ||
| length := uint16(len(hdr) + len(payload)) | ||
| ip[0] = (4 << 4) | (ipv4Size / 4) | ||
| binary.BigEndian.PutUint16(ip[ipv4TotalLenOffset:], length) | ||
| ip[8] = ttl | ||
| ip[9] = icmpv4ProtocolNumber | ||
| copy(ip[12:], src.To4()) | ||
| copy(ip[16:], dst.To4()) | ||
| chksum = ^checksum(ip[:], 0) | ||
| binary.BigEndian.PutUint16(ip[ipv4ChecksumOffset:], chksum) | ||
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| var v []byte | ||
| v = append(v, hdr...) | ||
| v = append(v, payload...) | ||
| return []byte(v) | ||
| } | ||
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| // TODO(crawshaw): find a reusable home for this. package devicetest? | ||
| type ChannelTUN struct { | ||
| Inbound chan []byte // incoming packets, closed on TUN close | ||
| Outbound chan []byte // outbound packets, blocks forever on TUN close | ||
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| closed chan struct{} | ||
| events chan tun.Event | ||
| tun chTun | ||
| } | ||
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| func NewChannelTUN() *ChannelTUN { | ||
| c := &ChannelTUN{ | ||
| Inbound: make(chan []byte), | ||
| Outbound: make(chan []byte), | ||
| closed: make(chan struct{}), | ||
| events: make(chan tun.Event, 1), | ||
| } | ||
| c.tun.c = c | ||
| c.events <- tun.EventUp | ||
| return c | ||
| } | ||
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| func (c *ChannelTUN) TUN() tun.Device { | ||
| return &c.tun | ||
| } | ||
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| type chTun struct { | ||
| c *ChannelTUN | ||
| } | ||
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| func (t *chTun) File() *os.File { return nil } | ||
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| func (t *chTun) Read(data []byte, offset int) (int, error) { | ||
| select { | ||
| case <-t.c.closed: | ||
| return 0, io.EOF // TODO(crawshaw): what is the correct error value? | ||
| case msg := <-t.c.Outbound: | ||
| return copy(data[offset:], msg), nil | ||
| } | ||
| } | ||
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| // Write is called by the wireguard device to deliver a packet for routing. | ||
| func (t *chTun) Write(data []byte, offset int) (int, error) { | ||
| if offset == -1 { | ||
| close(t.c.closed) | ||
| close(t.c.events) | ||
| return 0, io.EOF | ||
| } | ||
| msg := make([]byte, len(data)-offset) | ||
| copy(msg, data[offset:]) | ||
| select { | ||
| case <-t.c.closed: | ||
| return 0, io.EOF // TODO(crawshaw): what is the correct error value? | ||
| case t.c.Inbound <- msg: | ||
| return len(data) - offset, nil | ||
| } | ||
| } | ||
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| const DefaultMTU = 1420 | ||
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| func (t *chTun) Flush() error { return nil } | ||
| func (t *chTun) MTU() (int, error) { return DefaultMTU, nil } | ||
| func (t *chTun) Name() (string, error) { return "loopbackTun1", nil } | ||
| func (t *chTun) Events() chan tun.Event { return t.c.events } | ||
| func (t *chTun) Close() error { | ||
| t.Write(nil, -1) | ||
| return nil | ||
| } |