route-proxy: a second authority for internal names, and a target a route names the scheme of

Internal aliases were served over plain HTTP only — correctly refused a
public certificate (no public CA can validate a private name), and then
left with nothing. The mesh has two authorities for its two name spaces
(08-connectivity §2), so the proxy now takes an optional internal ACME
directory and dispatches at the handshake by the same question HostPolicy
already answers: which authority may certify this name at all.

A route may also say its target speaks https, with insecure for a backend
whose own certificate nothing would trust — the shape Mailu's webmail
front needs, and the exception: everything else the mesh hands this proxy
stays plain http on the private network.

examples/route-proxy/routes_test.go

@@ -130,6 +130,68 @@ func TestAContributionMissingWhatARouteNeedsIsSkipped(t *testing.T) {
 	}
 }
 
+// A route may name a target reached over https, for a backend that terminates its own TLS — the
+// shape Mailu's webmail front needs, which this proxy reaches as a plain workload otherwise.
+func TestARouteMayTargetHttps(t *testing.T) {
+	routes, _, err := routesFrom(write(t, `{"given":[
+	  {"from":"mail","node":"anchor","at":"anchor.internal",
+	   "values":{"name":"mail.example","port":7443,"scheme":"https","insecure":true}}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if targetOf(routes, "mail.example") != "https://anchor.internal:7443" {
+		t.Fatalf("an https target was not built as one: %v", routes)
+	}
+	if !routes["mail.example"][0].insecure {
+		t.Fatal("insecure was declared and not carried onto the rule")
+	}
+}
+
+// A scheme that is neither http nor https is refused rather than guessed at.
+func TestARouteWithAnUnknownSchemeIsSkipped(t *testing.T) {
+	routes, _, err := routesFrom(write(t, `{"given":[
+	  {"from":"a","node":"n","at":"n.internal","values":{"name":"bad.example","port":80,"scheme":"ftp"}}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 0 {
+		t.Fatalf("a route with an unusable scheme was served: %v", routes)
+	}
+}
+
+// End to end: a backend terminating TLS with a certificate nothing would ordinarily trust is still
+// reached when the route declared `insecure`, and the response comes back through unmodified.
+func TestTheProxyReachesAnInsecureHttpsBackend(t *testing.T) {
+	workload := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("the workload, over its own TLS"))
+	}))
+	defer workload.Close()
+	target := strings.TrimPrefix(workload.URL, "https://")
+
+	held := newTable()
+	routes := map[string][]rule{"mail.example": {{target: "https://" + target, insecure: true}}}
+	held.set(routes, allPublic(routes))
+
+	proxy := httptest.NewServer(handler(held))
+	defer proxy.Close()
+
+	asked, err := http.NewRequest(http.MethodGet, proxy.URL, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	asked.Host = "mail.example"
+	answer, err := http.DefaultClient.Do(asked)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer answer.Body.Close()
+	if answer.StatusCode != http.StatusOK {
+		t.Fatalf("an insecure https backend was not reached: %d", answer.StatusCode)
+	}
+}
+
 // End to end through the proxy itself: a request for the name reaches the workload, and a name
 // nobody asked for is refused in a way that says what IS served.
 func TestTheProxyReachesTheWorkloadAndNamesWhatItServes(t *testing.T) {
@@ -271,6 +333,31 @@ func TestNoCertificateIsAskedForOnAnInternalAlias(t *testing.T) {
 	}
 }
 
+// A certificate is asked of the *internal* authority only for a name that is routed here and is
+// not a route's own public name — the internal-network alias, never the route it accompanies.
+func TestTheInternalAuthorityOnlyCertifiesInternalOnlyAliases(t *testing.T) {
+	routes, public, err := routesFrom(write(t, `{"given":[
+	  {"from":"app","node":"anchor","at":"anchor.internal",
+	   "values":{"name":"app.example","internal-name":"app.anchor.internal","port":8080}}
+	]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	held := newTable()
+	held.set(routes, public)
+	policy := onlyInternalNamesTheMeshSaid(held)
+
+	if err := policy(context.Background(), "app.anchor.internal"); err != nil {
+		t.Errorf("the internal alias was refused by its own authority: %v", err)
+	}
+	if err := policy(context.Background(), "app.example"); err == nil {
+		t.Error("the internal authority certified a route's public name, which the public authority already covers")
+	}
+	if err := policy(context.Background(), "unrouted.internal"); err == nil {
+		t.Error("the internal authority certified a name nobody routed here")
+	}
+}
+
 // A route withdrawn stops being certifiable, without the proxy restarting.
 func TestWithdrawingARouteWithdrawsItsCertificate(t *testing.T) {
 	held := newTable()