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| author | Andrew Dunham <andrew@du.nham.ca> | 2024-02-26 14:34:56 -0500 |
|---|---|---|
| committer | Andrew Dunham <andrew@du.nham.ca> | 2024-02-26 16:33:10 -0500 |
| commit | 35dc1fea725f3b947870ca9994bfbead26433eaf (patch) | |
| tree | b987f413e7a1145be06c7926c243da5896ee17e0 /wgengine/netstack/debug.go | |
| parent | 50fb8b912324f8cfb17ba456ca9f0fff7fb58785 (diff) | |
| download | tailscale-andrew/netstack-forwarder-debug.tar.xz tailscale-andrew/netstack-forwarder-debug.zip | |
wgengine/netstack: add debug page for TCP forwarderandrew/netstack-forwarder-debug
To help in debugging issues with subnet routers in userspace mode–for
example, hitting the max inflight limit.
Updates tailscale/corp#12184
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Idd922f4ae37695f6598a914c2d050574755ef309
Diffstat (limited to 'wgengine/netstack/debug.go')
| -rw-r--r-- | wgengine/netstack/debug.go | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/wgengine/netstack/debug.go b/wgengine/netstack/debug.go new file mode 100644 index 000000000..1259f63a9 --- /dev/null +++ b/wgengine/netstack/debug.go @@ -0,0 +1,129 @@ +// Copyright (c) Tailscale Inc & AUTHORS +// SPDX-License-Identifier: BSD-3-Clause + +package netstack + +import ( + "html/template" + "net/http" + "net/netip" + "slices" + "time" + + xmaps "golang.org/x/exp/maps" + "gvisor.dev/gvisor/pkg/tcpip" +) + +var tcpForwarderTemplate = template.Must(template.New("").Parse(` +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1"> + <style> + body { font-family: monospace; font-size: 12; } + td { padding: 0.3em; } + </style> + </head> + <body> + <h1>TCP Forwarder</h1> + + <h2>TCP Statistics</h2> + <table border=1> + <tr> + <th>Metric</th> + <th>Value</th> + </tr> + {{ range .Stats }} + <tr><td>{{ .Key }}</td><td>{{ .Value }}</td></tr> + {{ end }} + </table> + + <h2>In-Flight Outbound Connections</h2> + <table border=1> + <tr> + <th>Start Time</th> + <th>Client IP</th> + <th>Remote IP</th> + </tr> + {{ range .InFlightDials }} + <tr> + <td>{{ .Start.Format "2006-01-02T15:04:05Z07:00" }} ({{ printf "%.2f" .DurationSecs }} seconds ago)</td> + <td>{{ .ClientIP }}</td> + <td>{{ .RemoteAddr }}</td> + </tr> + {{ end }} + </table> +</body> +</html> +`)) + +// DebugTCPForwarder writes debug information about this netstack +// implementation's current TCP forwarder in HTML format. +func (ns *Impl) DebugTCPForwarder(w http.ResponseWriter, r *http.Request) { + // Grab data while holding the mutex + ns.tcpDebugMu.Lock() + tcpDials := xmaps.Values(ns.inFlightDials) + ns.tcpDebugMu.Unlock() + + slices.SortFunc(tcpDials, func(a, b tcpDialInfo) int { + return a.start.Compare(b.start) + }) + + type templateDataStats struct { + Key string + Value uint64 + } + type templateDataDial struct { + Start time.Time + DurationSecs float64 + ClientIP netip.Addr + RemoteAddr netip.AddrPort + } + type templateData struct { + Stats []templateDataStats + InFlightDials []templateDataDial + } + + var data templateData + + // Statistics from gVisor + tcpStats := ns.ipstack.Stats().TCP + tcpMetrics := []struct { + name string + field *tcpip.StatCounter + }{ + {"Active Connection Openings", tcpStats.ActiveConnectionOpenings}, + {"Passive Connection Openings", tcpStats.PassiveConnectionOpenings}, + {"Established Connections", tcpStats.CurrentEstablished}, + {"Connected Connections", tcpStats.CurrentConnected}, + {"Dropped In-Flight Forwarder Connections", tcpStats.ForwardMaxInFlightDrop}, + {"Established Resets", tcpStats.EstablishedResets}, + {"Established Timeout", tcpStats.EstablishedTimedout}, + {"Failed Connection Attempts", tcpStats.FailedConnectionAttempts}, + {"Retransmits", tcpStats.Retransmits}, + {"Timeouts", tcpStats.Timeouts}, + {"Checksum Errors", tcpStats.ChecksumErrors}, + {"Failed Port Reservations", tcpStats.FailedPortReservations}, + } + for _, metric := range tcpMetrics { + data.Stats = append(data.Stats, templateDataStats{ + Key: metric.name, + Value: metric.field.Value(), + }) + } + + // Any in-flight DialContext calls in the TCP forwarding path. + now := time.Now() + for _, dial := range tcpDials { + elapsed := now.Sub(dial.start) + data.InFlightDials = append(data.InFlightDials, templateDataDial{ + Start: dial.start, + DurationSecs: elapsed.Seconds(), + ClientIP: dial.clientRemoteIP, + RemoteAddr: dial.dialAddr, + }) + } + + w.Header().Set("Content-Type", "text/html; charset=utf-8") + w.Header().Set("Cache-Control", "no-cache") + tcpForwarderTemplate.Execute(w, &data) +} |