From c48cc08de2517a8faa273a9e0674c32f2e540ace Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Fri, 4 Oct 2024 18:20:06 -0700
Subject: [PATCH] wgengine: stop conntrack log spam about Canonical net probes

Like we do for the ones on iOS.

As a bonus, this removes a caller of tsaddr.IsTailscaleIP which we
want to revamp/remove soonish.

Updates #13687

Change-Id: Iab576a0c48e9005c7844ab52a0aba5ba343b750e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
---
 wgengine/pendopen.go | 69 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 58 insertions(+), 11 deletions(-)

diff --git a/wgengine/pendopen.go b/wgengine/pendopen.go
index 59b1fccda..340c7e0f3 100644
--- a/wgengine/pendopen.go
+++ b/wgengine/pendopen.go
@@ -5,14 +5,17 @@ package wgengine
 
 import (
 	"fmt"
+	"net/netip"
 	"runtime"
+	"strings"
 	"time"
 
+	"github.com/gaissmai/bart"
 	"tailscale.com/net/flowtrack"
 	"tailscale.com/net/packet"
-	"tailscale.com/net/tsaddr"
 	"tailscale.com/net/tstun"
 	"tailscale.com/types/ipproto"
+	"tailscale.com/types/lazy"
 	"tailscale.com/util/mak"
 	"tailscale.com/wgengine/filter"
 )
@@ -86,6 +89,57 @@ func (e *userspaceEngine) trackOpenPreFilterIn(pp *packet.Parsed, t *tstun.Wrapp
 	return
 }
 
+var (
+	appleIPRange = netip.MustParsePrefix("17.0.0.0/8")
+	canonicalIPs = lazy.SyncFunc(func() (checkIPFunc func(netip.Addr) bool) {
+		// https://bgp.he.net/AS41231#_prefixes
+		t := &bart.Table[bool]{}
+		for _, s := range strings.Fields(`
+			91.189.89.0/24
+			91.189.91.0/24
+			91.189.92.0/24
+			91.189.93.0/24
+			91.189.94.0/24
+			91.189.95.0/24
+			162.213.32.0/24
+			162.213.34.0/24
+			162.213.35.0/24
+			185.125.188.0/23
+			185.125.190.0/24
+			194.169.254.0/24`) {
+			t.Insert(netip.MustParsePrefix(s), true)
+		}
+		return func(ip netip.Addr) bool {
+			v, _ := t.Lookup(ip)
+			return v
+		}
+	})
+)
+
+// isOSNetworkProbe reports whether the target is likely a network
+// connectivity probe target from e.g. iOS or Ubuntu network-manager.
+//
+// iOS likes to probe Apple IPs on all interfaces to check for connectivity.
+// Don't start timers tracking those. They won't succeed anyway. Avoids log
+// spam like:
+func (e *userspaceEngine) isOSNetworkProbe(dst netip.AddrPort) bool {
+	// iOS had log spam like:
+	// open-conn-track: timeout opening (100.115.73.60:52501 => 17.125.252.5:443); no associated peer node
+	if runtime.GOOS == "ios" && dst.Port() == 443 && appleIPRange.Contains(dst.Addr()) {
+		if _, ok := e.PeerForIP(dst.Addr()); !ok {
+			return true
+		}
+	}
+	// NetworkManager; https://github.com/tailscale/tailscale/issues/13687
+	// open-conn-track: timeout opening (TCP 100.96.229.119:42798 => 185.125.190.49:80); no associated peer node
+	if runtime.GOOS == "linux" && dst.Port() == 80 && canonicalIPs()(dst.Addr()) {
+		if _, ok := e.PeerForIP(dst.Addr()); !ok {
+			return true
+		}
+	}
+	return false
+}
+
 func (e *userspaceEngine) trackOpenPostFilterOut(pp *packet.Parsed, t *tstun.Wrapper) (res filter.Response) {
 	res = filter.Accept // always
 
@@ -95,19 +149,12 @@ func (e *userspaceEngine) trackOpenPostFilterOut(pp *packet.Parsed, t *tstun.Wra
 		pp.TCPFlags&packet.TCPSyn == 0 {
 		return
 	}
+	if e.isOSNetworkProbe(pp.Dst) {
+		return
+	}
 
 	flow := flowtrack.MakeTuple(pp.IPProto, pp.Src, pp.Dst)
 
-	// iOS likes to probe Apple IPs on all interfaces to check for connectivity.
-	// Don't start timers tracking those. They won't succeed anyway. Avoids log spam
-	// like:
-	//    open-conn-track: timeout opening (100.115.73.60:52501 => 17.125.252.5:443); no associated peer node
-	if runtime.GOOS == "ios" && flow.DstPort() == 443 && !tsaddr.IsTailscaleIP(flow.DstAddr()) {
-		if _, ok := e.PeerForIP(flow.DstAddr()); !ok {
-			return
-		}
-	}
-
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	if _, dup := e.pendOpen[flow]; dup {