mirror of https://github.com/tailscale/tailscale/
wgengine: on TCP connect fail/timeout, log some clues about why it failed
So users can see why things aren't working. A start. More diagnostics coming. Updates #1094pull/1112/head
Brad Fitzpatrick
4 years ago
parent
5eeaea9ef9
commit
85e54af0d7
@ -0,0 +1,157 @@
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// Copyright (c) 2021 Tailscale Inc & 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 wgengine
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import (
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"os"
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"strconv"
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"time"
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"tailscale.com/net/flowtrack"
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"tailscale.com/net/packet"
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"tailscale.com/wgengine/filter"
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"tailscale.com/wgengine/tstun"
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)
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const tcpTimeoutBeforeDebug = 5 * time.Second
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// debugConnectFailures reports whether the local node should track
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// outgoing TCP connections and log which ones fail and why.
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func debugConnectFailures() bool {
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s := os.Getenv("TS_DEBUG_CONNECT_FAILURES")
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if s == "" {
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return true
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}
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v, _ := strconv.ParseBool(s)
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return v
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}
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type pendingOpenFlow struct {
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timer *time.Timer // until giving up on the flow
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}
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func (e *userspaceEngine) trackOpenPreFilterIn(pp *packet.Parsed, t *tstun.TUN) (res filter.Response) {
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res = filter.Accept // always
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if pp.IPVersion == 0 ||
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pp.IPProto != packet.TCP ||
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pp.TCPFlags&(packet.TCPSyn|packet.TCPRst) == 0 {
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return
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}
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flow := flowtrack.Tuple{Dst: pp.Src, Src: pp.Dst} // src/dst reversed
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e.mu.Lock()
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defer e.mu.Unlock()
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of, ok := e.pendOpen[flow]
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if !ok {
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// Not a tracked flow.
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return
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}
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of.timer.Stop()
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delete(e.pendOpen, flow)
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if pp.TCPFlags&packet.TCPRst != 0 {
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// TODO(bradfitz): have peer send a IP proto 99 "why"
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// packet first with details and log that instead
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// (e.g. ACL prohibited, shields up, etc).
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e.logf("open-conn-track: flow %v got RST by peer", flow)
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return
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}
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return
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}
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func (e *userspaceEngine) trackOpenPostFilterOut(pp *packet.Parsed, t *tstun.TUN) (res filter.Response) {
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res = filter.Accept // always
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if pp.IPVersion == 0 ||
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pp.IPProto != packet.TCP ||
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pp.TCPFlags&packet.TCPSyn == 0 {
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return
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}
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flow := flowtrack.Tuple{Src: pp.Src, Dst: pp.Dst}
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timer := time.AfterFunc(tcpTimeoutBeforeDebug, func() {
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e.onOpenTimeout(flow)
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})
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e.mu.Lock()
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defer e.mu.Unlock()
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if e.pendOpen == nil {
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e.pendOpen = make(map[flowtrack.Tuple]*pendingOpenFlow)
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}
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if _, dup := e.pendOpen[flow]; dup {
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// Duplicates are expected when the OS retransmits. Ignore.
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return
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}
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e.pendOpen[flow] = &pendingOpenFlow{timer: timer}
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return filter.Accept
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}
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func (e *userspaceEngine) onOpenTimeout(flow flowtrack.Tuple) {
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e.mu.Lock()
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if _, ok := e.pendOpen[flow]; !ok {
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// Not a tracked flow, or already handled & deleted.
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e.mu.Unlock()
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return
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}
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delete(e.pendOpen, flow)
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e.mu.Unlock()
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// Diagnose why it might've timed out.
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n, ok := e.magicConn.PeerForIP(flow.Dst.IP)
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if !ok {
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e.logf("open-conn-track: timeout opening %v; no associated peer node", flow)
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return
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}
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if n.DiscoKey.IsZero() {
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e.logf("open-conn-track: timeout opening %v; peer node %v running pre-0.100", flow, n.Key.ShortString())
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return
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}
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if n.DERP == "" {
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e.logf("open-conn-track: timeout opening %v; peer node %v not connected to any DERP relay", flow, n.Key.ShortString())
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return
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}
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var lastSeen time.Time
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if n.LastSeen != nil {
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lastSeen = *n.LastSeen
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}
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var ps *PeerStatus
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if st, err := e.getStatus(); err == nil {
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for _, v := range st.Peers {
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if v.NodeKey == n.Key {
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v := v // copy
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ps = &v
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}
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}
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} else {
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e.logf("open-conn-track: timeout opening %v to node %v; failed to get engine status: %v", flow, n.Key.ShortString(), err)
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return
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}
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if ps == nil {
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e.logf("open-conn-track: timeout opening %v; target node %v in netmap but unknown to wireguard", flow, n.Key.ShortString())
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return
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}
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// TODO(bradfitz): figure out what PeerStatus.LastHandshake
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// is. It appears to be the last time we sent a handshake,
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// which isn't what I expected. I thought it was when a
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// handshake completed, which is what I want.
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_ = ps.LastHandshake
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e.logf("open-conn-track: timeout opening %v to node %v; lastSeen=%v, lastRecv=%v",
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flow, n.Key.ShortString(),
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agoOrNever(lastSeen), agoOrNever(e.magicConn.LastRecvActivityOfDisco(n.DiscoKey)))
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}
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func agoOrNever(t time.Time) string {
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if t.IsZero() {
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return "never"
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}
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return time.Since(t).Round(time.Second).String()
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}
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