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338 lines
7.9 KiB
Go
338 lines
7.9 KiB
Go
// 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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// The derpprobe binary probes derpers.
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package main // import "tailscale.com/cmd/derper/derpprobe"
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import (
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"bytes"
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"context"
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crand "crypto/rand"
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"encoding/json"
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"flag"
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"fmt"
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"html"
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"io"
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"log"
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"net/http"
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"sort"
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"sync"
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"time"
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"tailscale.com/derp"
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"tailscale.com/derp/derphttp"
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"tailscale.com/tailcfg"
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"tailscale.com/types/key"
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)
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var (
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derpMapURL = flag.String("derp-map", "https://login.tailscale.com/derpmap/default", "URL to DERP map (https:// or file://)")
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listen = flag.String("listen", ":8030", "HTTP listen address")
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)
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var (
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mu sync.Mutex
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state = map[nodePair]pairStatus{}
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lastDERPMap *tailcfg.DERPMap
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lastDERPMapAt time.Time
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)
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func main() {
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flag.Parse()
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go probeLoop()
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log.Fatal(http.ListenAndServe(*listen, http.HandlerFunc(serve)))
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}
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type overallStatus struct {
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good, bad []string
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}
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func (st *overallStatus) addBadf(format string, a ...interface{}) {
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st.bad = append(st.bad, fmt.Sprintf(format, a...))
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}
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func (st *overallStatus) addGoodf(format string, a ...interface{}) {
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st.good = append(st.good, fmt.Sprintf(format, a...))
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}
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func getOverallStatus() (o overallStatus) {
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mu.Lock()
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defer mu.Unlock()
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if lastDERPMap == nil {
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o.addBadf("no DERP map")
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return
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}
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now := time.Now()
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if age := now.Sub(lastDERPMapAt); age > time.Minute {
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o.addBadf("DERPMap hasn't been successfully refreshed in %v", age.Round(time.Second))
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}
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for _, reg := range sortedRegions(lastDERPMap) {
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for _, from := range reg.Nodes {
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for _, to := range reg.Nodes {
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pair := nodePair{from.Name, to.Name}
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st, ok := state[pair]
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age := now.Sub(st.at).Round(time.Second)
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switch {
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case !ok:
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o.addBadf("no state for %v", pair)
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case st.err != nil:
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o.addBadf("%v: %v", pair, st.err)
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case age > 90*time.Second:
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o.addBadf("%v: update is %v old", pair, age)
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default:
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o.addGoodf("%v: %v, %v ago", pair, st.latency.Round(time.Millisecond), age)
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}
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}
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}
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}
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return
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}
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func serve(w http.ResponseWriter, r *http.Request) {
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st := getOverallStatus()
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summary := "All good"
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if len(st.bad) > 0 {
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w.WriteHeader(500)
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summary = fmt.Sprintf("%d problems", len(st.bad))
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}
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io.WriteString(w, "<html><head><style>.bad { font-weight: bold; color: #700; }</style></head>\n")
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fmt.Fprintf(w, "<body><h1>derp probe</h1>\n%s:<ul>", summary)
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for _, s := range st.bad {
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fmt.Fprintf(w, "<li class=bad>%s</li>\n", html.EscapeString(s))
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}
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for _, s := range st.good {
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fmt.Fprintf(w, "<li>%s</li>\n", html.EscapeString(s))
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}
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io.WriteString(w, "</ul></body></html>\n")
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}
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func sortedRegions(dm *tailcfg.DERPMap) []*tailcfg.DERPRegion {
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ret := make([]*tailcfg.DERPRegion, 0, len(dm.Regions))
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for _, r := range dm.Regions {
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ret = append(ret, r)
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}
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sort.Slice(ret, func(i, j int) bool { return ret[i].RegionID < ret[j].RegionID })
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return ret
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}
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type nodePair struct {
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from, to string // DERPNode.Name
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}
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func (p nodePair) String() string { return fmt.Sprintf("(%s→%s)", p.from, p.to) }
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type pairStatus struct {
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err error
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latency time.Duration
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at time.Time
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}
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func setDERPMap(dm *tailcfg.DERPMap) {
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mu.Lock()
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defer mu.Unlock()
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lastDERPMap = dm
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lastDERPMapAt = time.Now()
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}
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func setState(p nodePair, latency time.Duration, err error) {
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mu.Lock()
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defer mu.Unlock()
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st := pairStatus{
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err: err,
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latency: latency,
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at: time.Now(),
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}
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state[p] = st
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if err != nil {
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log.Printf("%+v error: %v", p, err)
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} else {
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log.Printf("%+v: %v", p, latency.Round(time.Millisecond))
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}
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}
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func probeLoop() {
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ticker := time.NewTicker(15 * time.Second)
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for {
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err := probe()
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if err != nil {
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log.Printf("probe: %v", err)
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}
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<-ticker.C
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}
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}
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func probe() error {
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ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
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defer cancel()
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dm, err := getDERPMap(ctx)
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if err != nil {
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return err
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}
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var wg sync.WaitGroup
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wg.Add(len(dm.Regions))
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for _, reg := range dm.Regions {
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reg := reg
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go func() {
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defer wg.Done()
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for _, from := range reg.Nodes {
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for _, to := range reg.Nodes {
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latency, err := probeNodePair(ctx, dm, from, to)
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setState(nodePair{from.Name, to.Name}, latency, err)
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}
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}
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}()
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}
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wg.Wait()
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return ctx.Err()
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}
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func probeNodePair(ctx context.Context, dm *tailcfg.DERPMap, from, to *tailcfg.DERPNode) (latency time.Duration, err error) {
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fromc, err := newConn(ctx, dm, from)
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if err != nil {
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return 0, err
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}
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defer fromc.Close()
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toc, err := newConn(ctx, dm, to)
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if err != nil {
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return 0, err
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}
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defer toc.Close()
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// Make a random packet
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pkt := make([]byte, 8)
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crand.Read(pkt)
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t0 := time.Now()
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// Send the random packet.
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sendc := make(chan error, 1)
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go func() {
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sendc <- fromc.Send(toc.SelfPublicKey(), pkt)
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}()
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select {
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case <-ctx.Done():
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return 0, fmt.Errorf("timeout sending via %q: %w", from.Name, ctx.Err())
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case err := <-sendc:
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if err != nil {
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return 0, fmt.Errorf("error sending via %q: %w", from.Name, err)
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}
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}
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// Receive the random packet.
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recvc := make(chan interface{}, 1) // either derp.ReceivedPacket or error
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go func() {
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for {
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m, err := toc.Recv()
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if err != nil {
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recvc <- err
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return
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}
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switch v := m.(type) {
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case derp.ReceivedPacket:
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recvc <- v
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default:
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log.Printf("%v: ignoring Recv frame type %T", to.Name, v)
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// Loop.
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}
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}
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}()
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select {
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case <-ctx.Done():
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return 0, fmt.Errorf("timeout receiving from %q: %w", to.Name, ctx.Err())
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case v := <-recvc:
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if err, ok := v.(error); ok {
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return 0, fmt.Errorf("error receiving from %q: %w", to.Name, err)
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}
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p := v.(derp.ReceivedPacket)
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if p.Source != fromc.SelfPublicKey() {
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return 0, fmt.Errorf("got data packet from unexpected source, %v", p.Source)
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}
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if !bytes.Equal(p.Data, pkt) {
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return 0, fmt.Errorf("unexpected data packet %q", p.Data)
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}
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}
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return time.Since(t0), nil
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}
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func newConn(ctx context.Context, dm *tailcfg.DERPMap, n *tailcfg.DERPNode) (*derphttp.Client, error) {
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priv := key.NewPrivate()
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dc := derphttp.NewRegionClient(priv, log.Printf, func() *tailcfg.DERPRegion {
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rid := n.RegionID
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return &tailcfg.DERPRegion{
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RegionID: rid,
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RegionCode: fmt.Sprintf("%s-%s", dm.Regions[rid].RegionCode, n.Name),
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RegionName: dm.Regions[rid].RegionName,
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Nodes: []*tailcfg.DERPNode{n},
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}
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})
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dc.IsProber = true
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err := dc.Connect(ctx)
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if err != nil {
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return nil, err
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}
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errc := make(chan error, 1)
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go func() {
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m, err := dc.Recv()
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if err != nil {
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errc <- err
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return
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}
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switch m.(type) {
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case derp.ServerInfoMessage:
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errc <- nil
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default:
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errc <- fmt.Errorf("unexpected first message type %T", errc)
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}
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}()
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select {
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case err := <-errc:
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if err != nil {
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go dc.Close()
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return nil, err
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}
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case <-ctx.Done():
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go dc.Close()
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return nil, fmt.Errorf("timeout waiting for ServerInfoMessage: %w", ctx.Err())
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}
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return dc, nil
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}
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var httpOrFileClient = &http.Client{Transport: httpOrFileTransport()}
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func httpOrFileTransport() http.RoundTripper {
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tr := http.DefaultTransport.(*http.Transport).Clone()
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tr.RegisterProtocol("file", http.NewFileTransport(http.Dir("/")))
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return tr
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}
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func getDERPMap(ctx context.Context) (*tailcfg.DERPMap, error) {
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req, err := http.NewRequestWithContext(ctx, "GET", *derpMapURL, nil)
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if err != nil {
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return nil, err
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}
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res, err := httpOrFileClient.Do(req)
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if err != nil {
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mu.Lock()
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defer mu.Unlock()
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if lastDERPMap != nil && time.Since(lastDERPMapAt) < 10*time.Minute {
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// Assume that control is restarting and use
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// the same one for a bit.
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return lastDERPMap, nil
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}
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return nil, err
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}
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defer res.Body.Close()
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if res.StatusCode != 200 {
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return nil, fmt.Errorf("fetching %s: %s", *derpMapURL, res.Status)
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}
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dm := new(tailcfg.DERPMap)
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if err := json.NewDecoder(res.Body).Decode(dm); err != nil {
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return nil, fmt.Errorf("decoding %s JSON: %v", *derpMapURL, err)
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}
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setDERPMap(dm)
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return dm, nil
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}
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