also configure acme validation with http-01, and fix a bug that caused tls cert refresh at startup to not always run

we already do acme tls-alpn-01 validation, and still require it (we could relax
this at some point). http-01 is easy to add.

the bug was that the list of acme managers and hosts to refresh was overwritten
by another listener. the listeners are a map, and we range over it, so the
order we handle them is random. if the public listener was handled first, and
an internal handler later, the list was reset again.

autotls/autotls.go

@@ -2,11 +2,9 @@
 // requesting certificates with ACME, typically from Let's Encrypt.
 package autotls
 
-// We only do tls-alpn-01. For http-01, we would have to start another
-// listener. For DNS we would need a third party tool with an API that can make
-// the DNS changes, as we don't want to link in dozens of bespoke API's for DNS
-// record manipulation into mox. We can do http-01 relatively easily. It could
-// be useful to not depend on a single mechanism.
+// We do tls-alpn-01, and also http-01. For DNS we would need a third party tool
+// with an API that can make the DNS changes, as we don't want to link in dozens of
+// bespoke API's for DNS record manipulation into mox.
 
 import (
 	"bytes"
@@ -272,6 +270,12 @@ func (m *Manager) HostPolicy(ctx context.Context, host string) (rerr error) {
 	default:
 	}
 
+	xhost, _, err := net.SplitHostPort(host)
+	if err == nil {
+		// For http-01, host may include a port number.
+		host = xhost
+	}
+
 	d, err := dns.ParseDomain(host)
 	if err != nil {
 		return fmt.Errorf("invalid host: %v", err)

autotls/autotls_test.go

@@ -36,6 +36,9 @@ func TestAutotls(t *testing.T) {
 	if err := m.HostPolicy(context.Background(), "mox.example"); err != nil {
 		t.Fatalf("hostpolicy, got err %v, expected no error", err)
 	}
+	if err := m.HostPolicy(context.Background(), "mox.example:80"); err != nil {
+		t.Fatalf("hostpolicy, got err %v, expected no error", err)
+	}
 	if err := m.HostPolicy(context.Background(), "other.mox.example"); err == nil || !errors.Is(err, errHostNotAllowed) {
 		t.Fatalf("hostpolicy, got err %v, expected errHostNotAllowed", err)
 	}

http/web.go

@@ -189,7 +189,7 @@ type pathHandler struct {
 	Handle    http.HandlerFunc
 }
 type serve struct {
-	Kinds        []string // Type of handler and protocol (http/https).
+	Kinds        []string // Type of handler and protocol (e.g. acme-tls-alpn-01, account-http, admin-https).
 	TLSConfig    *tls.Config
 	PathHandlers []pathHandler // Sorted, longest first.
 	Webserver    bool          // Whether serving WebHandler. PathHandlers are always evaluated before WebHandlers.
@@ -319,7 +319,7 @@ func Listen() {
 
 		if l.TLS != nil && l.TLS.ACME != "" && (l.SMTP.Enabled && !l.SMTP.NoSTARTTLS || l.Submissions.Enabled || l.IMAPS.Enabled) {
 			port := config.Port(mox.Conf.Static.ACME[l.TLS.ACME].Port, 443)
-			ensureServe(true, port, "acme-tls-alpn01")
+			ensureServe(true, port, "acme-tls-alpn-01")
 		}
 
 		if l.AccountHTTP.Enabled {
@@ -405,16 +405,16 @@ func Listen() {
 			srv.Webserver = true
 		}
 
-		// We'll explicitly ensure these TLS certs exist (e.g. are created with ACME)
-		// immediately after startup. We only do so for our explicit listener hostnames,
-		// not for mta-sts DNS records, it can be requested on demand (perhaps never). We
-		// do request autoconfig, otherwise clients may run into their timeouts waiting for
-		// the certificate to be given during the first https connection.
-		ensureManagerHosts = map[*autotls.Manager]map[dns.Domain]struct{}{}
-
 		if l.TLS != nil && l.TLS.ACME != "" {
 			m := mox.Conf.Static.ACME[l.TLS.ACME].Manager
 
+			// If we are listening on port 80 for plain http, also register acme http-01
+			// validation handler.
+			if srv, ok := portServe[80]; ok && srv.TLSConfig == nil {
+				srv.Kinds = append(srv.Kinds, "acme-http-01")
+				srv.HandleFunc("acme-http-01", nil, "/.well-known/acme-challenge/", m.Manager.HTTPHandler(nil).ServeHTTP)
+			}
+
 			hosts := map[dns.Domain]struct{}{
 				mox.Conf.Static.HostnameDomain: {},
 			}
@@ -467,7 +467,13 @@ func adminIndex(w http.ResponseWriter, r *http.Request) {
 
 // functions to be launched in goroutine that will serve on a listener.
 var servers []func()
-var ensureManagerHosts map[*autotls.Manager]map[dns.Domain]struct{}
+
+// We'll explicitly ensure these TLS certs exist (e.g. are created with ACME)
+// immediately after startup. We only do so for our explicit listener hostnames,
+// not for mta-sts DNS records, it can be requested on demand (perhaps never). We
+// do request autoconfig, otherwise clients may run into their timeouts waiting for
+// the certificate to be given during the first https connection.
+var ensureManagerHosts = map[*autotls.Manager]map[dns.Domain]struct{}{}
 
 // listen prepares a listener, and adds it to "servers", to be launched (if not running as root) through Serve.
 func listen1(ip string, port int, tlsConfig *tls.Config, name string, kinds []string, handler http.Handler) {