diff options
author | David Crawshaw <crawshaw@tailscale.com> | 2020-01-07 07:43:17 -0800 |
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committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2020-05-02 01:46:42 -0600 |
commit | 1a1c3d096888816c94cf1eb7c2747e83f008549f (patch) | |
tree | e5e7229c8198cf3fea04d173d6e41a99f2ce82c8 /tun/tuntest | |
parent | 85a45a9651d2b38e3616a7899800601656cf143e (diff) |
tuntest: split out testing package
This code is useful to other packages writing tests.
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
Diffstat (limited to 'tun/tuntest')
-rw-r--r-- | tun/tuntest/tuntest.go | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/tun/tuntest/tuntest.go b/tun/tuntest/tuntest.go new file mode 100644 index 0000000..bdd96ac --- /dev/null +++ b/tun/tuntest/tuntest.go @@ -0,0 +1,150 @@ +/* SPDX-License-Identifier: MIT + * + * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved. + */ + +package tuntest + +import ( + "encoding/binary" + "io" + "net" + "os" + + "golang.zx2c4.com/wireguard/tun" +) + +func Ping(dst, src net.IP) []byte { + localPort := uint16(1337) + seq := uint16(0) + + payload := make([]byte, 4) + binary.BigEndian.PutUint16(payload[0:], localPort) + binary.BigEndian.PutUint16(payload[2:], seq) + + return genICMPv4(payload, dst, src) +} + +// 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) +} + +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 + ) + + hdr := make([]byte, ipv4Size+icmpv4Size) + + ip := hdr[0:ipv4Size] + icmpv4 := hdr[ipv4Size : ipv4Size+icmpv4Size] + + // 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) + + // 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) + + var v []byte + v = append(v, hdr...) + v = append(v, payload...) + return []byte(v) +} + +// 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 + + closed chan struct{} + events chan tun.Event + tun chTun +} + +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 +} + +func (c *ChannelTUN) TUN() tun.Device { + return &c.tun +} + +type chTun struct { + c *ChannelTUN +} + +func (t *chTun) File() *os.File { return nil } + +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 + } +} + +// 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 + } +} + +const DefaultMTU = 1420 + +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 +} |