tun2socks: panic at random api for testing

intra/dnsx/cacher.go

@@ -330,8 +330,8 @@ func (t *ctransport) hangoverCheckpoint() {
 
 func (t *ctransport) fetch(network string, q *dns.Msg, summary *x.DNSSummary, cb *cache, key string) (*dns.Msg, error) {
 	sendRequest := func(fsmm *x.DNSSummary) (*dns.Msg, error) {
-		if false && settings.Debug && rand10pc() {
-			panic("test crash")
+		if settings.PanicAtRandom.Load() && rand10pc() {
+			panic("dns: cache: fetch: rand10pc")
 		}
 
 		fsmm.QName = summary.QName

intra/netstack/forwarders.go

@@ -173,7 +173,7 @@ func (p *processor) deliverPackets() {
 			pkt.DecRef()
 		}
 		p.mu.Lock()
-		if false && settings.Debug && rand10pc() {
+		if settings.PanicAtRandom.Load() && rand10pc() {
 			panic("ns: tun: forwarder: deliverPackets rand10pc")
 		}
 	}

intra/settings/config.go

@@ -107,6 +107,10 @@ var SystemDNSForUndelegatedDomains = atomic.Bool{}
 // to "Intra".
 var SetUserAgentForDoH = atomic.Bool{}
 
+// PanicAtRandom is a global flag to panic the network engine
+// every once in a while (for testing).
+var PanicAtRandom = atomic.Bool{}
+
 // L3 returns the string'd repr of engine.
 func L3(engine int) string {
 	switch engine {

intra/tun2socks.go

@@ -155,6 +155,13 @@ func PrintStack(onConsole bool) {
 	}
 }
 
+// PanicAtRandom instruct portions under test of the network engine
+// to panic at random.
+func PanicAtRandom(y bool) {
+	settings.PanicAtRandom.Store(y)
+	log.I("tun: panic at random? %t", y)
+}
+
 // SetCrashFd sets output file to go runtime crashes to.
 func SetCrashFd(fp string) (ok bool) {
 	defer func() {