mirror of https://github.com/tailscale/tailscale/
net/netcheck,wgengine/magicsock: reduce coupling between netcheck and magicsock
Netcheck no longer performs I/O itself, instead it makes requests via SendPacket and expects users to route reply traffic to ReceiveSTUNPacket. Netcheck gains a Standalone function that stands up sockets and goroutines to implement I/O when used in a standalone fashion. Magicsock now unconditionally routes STUN traffic to the netcheck.Client that it hosts, and plumbs the send packet sink. The CLI is updated to make use of the Standalone mode. Fixes #8723 Signed-off-by: James Tucker <james@tailscale.com>pull/8848/head
James Tucker
10 months ago
committed by
James Tucker
parent
d5ac18d2c4
commit
de8e55fda6
@ -0,0 +1,99 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package netcheck
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import (
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"context"
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"errors"
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"net/netip"
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"tailscale.com/net/netaddr"
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"tailscale.com/net/netns"
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"tailscale.com/net/stun"
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"tailscale.com/types/logger"
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"tailscale.com/types/nettype"
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"tailscale.com/util/multierr"
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)
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// Standalone creates the necessary UDP sockets on the given bindAddr and starts
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// an IO loop so that the Client can perform active probes with no further need
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// for external driving of IO (no need to set/implement SendPacket, or call
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// ReceiveSTUNPacket). It must be called prior to starting any reports and is
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// shut down by cancellation of the provided context. If both IPv4 and IPv6 fail
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// to bind, errors will be returned, if one or both protocols can bind no error
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// is returned.
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func (c *Client) Standalone(ctx context.Context, bindAddr string) error {
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if bindAddr == "" {
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bindAddr = ":0"
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}
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var errs []error
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u4, err := nettype.MakePacketListenerWithNetIP(netns.Listener(c.logf, nil)).ListenPacket(ctx, "udp4", bindAddr)
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if err != nil {
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c.logf("udp4: %v", err)
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errs = append(errs, err)
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} else {
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go readPackets(ctx, c.logf, u4, c.ReceiveSTUNPacket)
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}
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u6, err := nettype.MakePacketListenerWithNetIP(netns.Listener(c.logf, nil)).ListenPacket(ctx, "udp6", bindAddr)
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if err != nil {
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c.logf("udp6: %v", err)
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errs = append(errs, err)
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} else {
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go readPackets(ctx, c.logf, u6, c.ReceiveSTUNPacket)
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}
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c.SendPacket = func(pkt []byte, dst netip.AddrPort) (int, error) {
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pc := u4
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if dst.Addr().Is6() {
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pc = u6
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}
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if pc == nil {
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return 0, errors.New("no UDP socket")
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}
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return pc.WriteToUDPAddrPort(pkt, dst)
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}
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// If both v4 and v6 failed, report an error, otherwise let one succeed.
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if len(errs) == 2 {
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return multierr.New(errs...)
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}
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return nil
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}
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// readPackets reads STUN packets from pc until there's an error or ctx is done.
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// In either case, it closes pc.
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func readPackets(ctx context.Context, logf logger.Logf, pc nettype.PacketConn, recv func([]byte, netip.AddrPort)) {
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done := make(chan struct{})
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defer close(done)
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go func() {
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select {
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case <-ctx.Done():
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case <-done:
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}
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pc.Close()
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}()
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var buf [64 << 10]byte
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for {
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n, addr, err := pc.ReadFromUDPAddrPort(buf[:])
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if err != nil {
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if ctx.Err() != nil {
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return
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}
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logf("ReadFrom: %v", err)
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return
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}
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pkt := buf[:n]
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if !stun.Is(pkt) {
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continue
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}
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if ap := netaddr.Unmap(addr); ap.IsValid() {
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recv(pkt, ap)
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}
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}
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}
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