caddyhttp: Implement auto_https prefer_wildcard option (#6146)

* Allow specifying multiple `auto_https` options

* Implement `auto_https prefer_wildcard` option

* Adapt tests, add mock DNS module for config testing

* Rebase fix

caddyconfig/httpcaddyfile/httptype.go

@@ -534,8 +534,8 @@ func (st *ServerType) serversFromPairings(
 	if hsp, ok := options["https_port"].(int); ok {
 		httpsPort = strconv.Itoa(hsp)
 	}
-	autoHTTPS := "on"
-	if ah, ok := options["auto_https"].(string); ok {
+	autoHTTPS := []string{}
+	if ah, ok := options["auto_https"].([]string); ok {
 		autoHTTPS = ah
 	}
 
@@ -594,17 +594,37 @@ func (st *ServerType) serversFromPairings(
 		}
 
 		// handle the auto_https global option
-		if autoHTTPS != "on" {
-			srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
-			switch autoHTTPS {
+		for _, val := range autoHTTPS {
+			switch val {
 			case "off":
+				if srv.AutoHTTPS == nil {
+					srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
+				}
 				srv.AutoHTTPS.Disabled = true
+
 			case "disable_redirects":
+				if srv.AutoHTTPS == nil {
+					srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
+				}
 				srv.AutoHTTPS.DisableRedir = true
+
 			case "disable_certs":
+				if srv.AutoHTTPS == nil {
+					srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
+				}
 				srv.AutoHTTPS.DisableCerts = true
+
 			case "ignore_loaded_certs":
+				if srv.AutoHTTPS == nil {
+					srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
+				}
 				srv.AutoHTTPS.IgnoreLoadedCerts = true
+
+			case "prefer_wildcard":
+				if srv.AutoHTTPS == nil {
+					srv.AutoHTTPS = new(caddyhttp.AutoHTTPSConfig)
+				}
+				srv.AutoHTTPS.PreferWildcard = true
 			}
 		}
 
@@ -673,7 +693,7 @@ func (st *ServerType) serversFromPairings(
 		})
 
 		var hasCatchAllTLSConnPolicy, addressQualifiesForTLS bool
-		autoHTTPSWillAddConnPolicy := autoHTTPS != "off"
+		autoHTTPSWillAddConnPolicy := srv.AutoHTTPS == nil || !srv.AutoHTTPS.Disabled
 
 		// if needed, the ServerLogConfig is initialized beforehand so
 		// that all server blocks can populate it with data, even when not
@@ -757,6 +777,13 @@ func (st *ServerType) serversFromPairings(
 				}
 			}
 
+			wildcardHosts := []string{}
+			for _, addr := range sblock.parsedKeys {
+				if strings.HasPrefix(addr.Host, "*.") {
+					wildcardHosts = append(wildcardHosts, addr.Host[2:])
+				}
+			}
+
 			for _, addr := range sblock.parsedKeys {
 				// if server only uses HTTP port, auto-HTTPS will not apply
 				if listenersUseAnyPortOtherThan(srv.Listen, httpPort) {
@@ -772,6 +799,18 @@ func (st *ServerType) serversFromPairings(
 					}
 				}
 
+				// If prefer wildcard is enabled, then we add hosts that are
+				// already covered by the wildcard to the skip list
+				if srv.AutoHTTPS != nil && srv.AutoHTTPS.PreferWildcard && addr.Scheme == "https" {
+					baseDomain := addr.Host
+					if idx := strings.Index(baseDomain, "."); idx != -1 {
+						baseDomain = baseDomain[idx+1:]
+					}
+					if !strings.HasPrefix(addr.Host, "*.") && slices.Contains(wildcardHosts, baseDomain) {
+						srv.AutoHTTPS.Skip = append(srv.AutoHTTPS.Skip, addr.Host)
+					}
+				}
+
 				// If TLS is specified as directive, it will also result in 1 or more connection policy being created
 				// Thus, catch-all address with non-standard port, e.g. :8443, can have TLS enabled without
 				// specifying prefix "https://"
@@ -919,7 +958,10 @@ func (st *ServerType) serversFromPairings(
 		if addressQualifiesForTLS &&
 			!hasCatchAllTLSConnPolicy &&
 			(len(srv.TLSConnPolicies) > 0 || !autoHTTPSWillAddConnPolicy || defaultSNI != "" || fallbackSNI != "") {
-			srv.TLSConnPolicies = append(srv.TLSConnPolicies, &caddytls.ConnectionPolicy{DefaultSNI: defaultSNI, FallbackSNI: fallbackSNI})
+			srv.TLSConnPolicies = append(srv.TLSConnPolicies, &caddytls.ConnectionPolicy{
+				DefaultSNI:  defaultSNI,
+				FallbackSNI: fallbackSNI,
+			})
 		}
 
 		// tidy things up a bit

caddyconfig/httpcaddyfile/options.go

@@ -452,15 +452,22 @@ func parseOptPersistConfig(d *caddyfile.Dispenser, _ any) (any, error) {
 
 func parseOptAutoHTTPS(d *caddyfile.Dispenser, _ any) (any, error) {
 	d.Next() // consume option name
-	if !d.Next() {
+	val := d.RemainingArgs()
+	if len(val) == 0 {
 		return "", d.ArgErr()
 	}
-	val := d.Val()
-	if d.Next() {
-		return "", d.ArgErr()
-	}
-	if val != "off" && val != "disable_redirects" && val != "disable_certs" && val != "ignore_loaded_certs" {
-		return "", d.Errf("auto_https must be one of 'off', 'disable_redirects', 'disable_certs', or 'ignore_loaded_certs'")
+	for _, v := range val {
+		switch v {
+		case "off":
+		case "disable_redirects":
+		case "disable_certs":
+		case "ignore_loaded_certs":
+		case "prefer_wildcard":
+			break
+
+		default:
+			return "", d.Errf("auto_https must be one of 'off', 'disable_redirects', 'disable_certs', 'ignore_loaded_certs', or 'prefer_wildcard'")
+		}
 	}
 	return val, nil
 }

caddyconfig/httpcaddyfile/tlsapp.go

@@ -45,8 +45,8 @@ func (st ServerType) buildTLSApp(
 	if hp, ok := options["http_port"].(int); ok {
 		httpPort = strconv.Itoa(hp)
 	}
-	autoHTTPS := "on"
-	if ah, ok := options["auto_https"].(string); ok {
+	autoHTTPS := []string{}
+	if ah, ok := options["auto_https"].([]string); ok {
 		autoHTTPS = ah
 	}
 
@@ -54,13 +54,14 @@ func (st ServerType) buildTLSApp(
 	// key, so that they don't get forgotten/omitted by auto-HTTPS
 	// (since they won't appear in route matchers)
 	httpsHostsSharedWithHostlessKey := make(map[string]struct{})
-	if autoHTTPS != "off" {
+	if !slices.Contains(autoHTTPS, "off") {
 		for _, pair := range pairings {
 			for _, sb := range pair.serverBlocks {
 				for _, addr := range sb.parsedKeys {
 					if addr.Host != "" {
 						continue
 					}
+
 					// this server block has a hostless key, now
 					// go through and add all the hosts to the set
 					for _, otherAddr := range sb.parsedKeys {
@@ -350,7 +351,7 @@ func (st ServerType) buildTLSApp(
 	internalAP := &caddytls.AutomationPolicy{
 		IssuersRaw: []json.RawMessage{json.RawMessage(`{"module":"internal"}`)},
 	}
-	if autoHTTPS != "off" && autoHTTPS != "disable_certs" {
+	if !slices.Contains(autoHTTPS, "off") && !slices.Contains(autoHTTPS, "disable_certs") {
 		for h := range httpsHostsSharedWithHostlessKey {
 			al = append(al, h)
 			if !certmagic.SubjectQualifiesForPublicCert(h) {
@@ -417,7 +418,10 @@ func (st ServerType) buildTLSApp(
 		}
 
 		// consolidate automation policies that are the exact same
-		tlsApp.Automation.Policies = consolidateAutomationPolicies(tlsApp.Automation.Policies)
+		tlsApp.Automation.Policies = consolidateAutomationPolicies(
+			tlsApp.Automation.Policies,
+			slices.Contains(autoHTTPS, "prefer_wildcard"),
+		)
 
 		// ensure automation policies don't overlap subjects (this should be
 		// an error at provision-time as well, but catch it in the adapt phase
@@ -563,7 +567,7 @@ func newBaseAutomationPolicy(
 
 // consolidateAutomationPolicies combines automation policies that are the same,
 // for a cleaner overall output.
-func consolidateAutomationPolicies(aps []*caddytls.AutomationPolicy) []*caddytls.AutomationPolicy {
+func consolidateAutomationPolicies(aps []*caddytls.AutomationPolicy, preferWildcard bool) []*caddytls.AutomationPolicy {
 	// sort from most specific to least specific; we depend on this ordering
 	sort.SliceStable(aps, func(i, j int) bool {
 		if automationPolicyIsSubset(aps[i], aps[j]) {
@@ -648,6 +652,31 @@ outer:
 					j--
 				}
 			}
+
+			if preferWildcard {
+				// remove subjects from i if they're covered by a wildcard in j
+				iSubjs := aps[i].SubjectsRaw
+				for iSubj := 0; iSubj < len(iSubjs); iSubj++ {
+					for jSubj := range aps[j].SubjectsRaw {
+						if !strings.HasPrefix(aps[j].SubjectsRaw[jSubj], "*.") {
+							continue
+						}
+						if certmagic.MatchWildcard(aps[i].SubjectsRaw[iSubj], aps[j].SubjectsRaw[jSubj]) {
+							iSubjs = slices.Delete(iSubjs, iSubj, iSubj+1)
+							iSubj--
+							break
+						}
+					}
+				}
+				aps[i].SubjectsRaw = iSubjs
+
+				// remove i if it has no subjects left
+				if len(aps[i].SubjectsRaw) == 0 {
+					aps = slices.Delete(aps, i, i+1)
+					i--
+					continue outer
+				}
+			}
 		}
 	}
 

caddytest/integration/caddyfile_adapt/auto_https_prefer_wildcard.caddyfiletest

@@ -0,0 +1,106 @@
+{
+	auto_https prefer_wildcard
+}
+
+*.example.com {
+	tls {
+		dns mock
+	}
+	respond "fallback"
+}
+
+foo.example.com {
+	respond "foo"
+}
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":443"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"host": [
+										"foo.example.com"
+									]
+								}
+							],
+							"handle": [
+								{
+									"handler": "subroute",
+									"routes": [
+										{
+											"handle": [
+												{
+													"body": "foo",
+													"handler": "static_response"
+												}
+											]
+										}
+									]
+								}
+							],
+							"terminal": true
+						},
+						{
+							"match": [
+								{
+									"host": [
+										"*.example.com"
+									]
+								}
+							],
+							"handle": [
+								{
+									"handler": "subroute",
+									"routes": [
+										{
+											"handle": [
+												{
+													"body": "fallback",
+													"handler": "static_response"
+												}
+											]
+										}
+									]
+								}
+							],
+							"terminal": true
+						}
+					],
+					"automatic_https": {
+						"prefer_wildcard": true
+					}
+				}
+			}
+		},
+		"tls": {
+			"automation": {
+				"policies": [
+					{
+						"subjects": [
+							"*.example.com"
+						],
+						"issuers": [
+							{
+								"challenges": {
+									"dns": {
+										"provider": {
+											"name": "mock"
+										}
+									}
+								},
+								"module": "acme"
+							}
+						]
+					}
+				]
+			}
+		}
+	}
+}

caddytest/integration/caddyfile_adapt/wildcard_pattern.caddyfiletest

@@ -0,0 +1,157 @@
+*.example.com {
+	tls foo@example.com {
+		dns mock
+	}
+
+	@foo host foo.example.com
+	handle @foo {
+		respond "Foo!"
+	}
+
+	@bar host bar.example.com
+	handle @bar {
+		respond "Bar!"
+	}
+
+	# Fallback for otherwise unhandled domains
+	handle {
+		abort
+	}
+}
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":443"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"host": [
+										"*.example.com"
+									]
+								}
+							],
+							"handle": [
+								{
+									"handler": "subroute",
+									"routes": [
+										{
+											"group": "group3",
+											"handle": [
+												{
+													"handler": "subroute",
+													"routes": [
+														{
+															"handle": [
+																{
+																	"body": "Foo!",
+																	"handler": "static_response"
+																}
+															]
+														}
+													]
+												}
+											],
+											"match": [
+												{
+													"host": [
+														"foo.example.com"
+													]
+												}
+											]
+										},
+										{
+											"group": "group3",
+											"handle": [
+												{
+													"handler": "subroute",
+													"routes": [
+														{
+															"handle": [
+																{
+																	"body": "Bar!",
+																	"handler": "static_response"
+																}
+															]
+														}
+													]
+												}
+											],
+											"match": [
+												{
+													"host": [
+														"bar.example.com"
+													]
+												}
+											]
+										},
+										{
+											"group": "group3",
+											"handle": [
+												{
+													"handler": "subroute",
+													"routes": [
+														{
+															"handle": [
+																{
+																	"abort": true,
+																	"handler": "static_response"
+																}
+															]
+														}
+													]
+												}
+											]
+										}
+									]
+								}
+							],
+							"terminal": true
+						}
+					]
+				}
+			}
+		},
+		"tls": {
+			"automation": {
+				"policies": [
+					{
+						"subjects": [
+							"*.example.com"
+						],
+						"issuers": [
+							{
+								"challenges": {
+									"dns": {
+										"provider": {
+											"name": "mock"
+										}
+									}
+								},
+								"email": "foo@example.com",
+								"module": "acme"
+							},
+							{
+								"ca": "https://acme.zerossl.com/v2/DV90",
+								"challenges": {
+									"dns": {
+										"provider": {
+											"name": "mock"
+										}
+									}
+								},
+								"email": "foo@example.com",
+								"module": "acme"
+							}
+						]
+					}
+				]
+			}
+		}
+	}
+}

caddytest/integration/mockdns_test.go

@@ -0,0 +1,61 @@
+package integration
+
+import (
+	"context"
+
+	"github.com/caddyserver/caddy/v2"
+	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/caddyserver/certmagic"
+	"github.com/libdns/libdns"
+)
+
+func init() {
+	caddy.RegisterModule(MockDNSProvider{})
+}
+
+// MockDNSProvider is a mock DNS provider, for testing config with DNS modules.
+type MockDNSProvider struct{}
+
+// CaddyModule returns the Caddy module information.
+func (MockDNSProvider) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "dns.providers.mock",
+		New: func() caddy.Module { return new(MockDNSProvider) },
+	}
+}
+
+// Provision sets up the module.
+func (MockDNSProvider) Provision(ctx caddy.Context) error {
+	return nil
+}
+
+// UnmarshalCaddyfile sets up the module from Caddyfile tokens.
+func (MockDNSProvider) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+	return nil
+}
+
+// AppendsRecords appends DNS records to the zone.
+func (MockDNSProvider) AppendRecords(ctx context.Context, zone string, recs []libdns.Record) ([]libdns.Record, error) {
+	return nil, nil
+}
+
+// DeleteRecords deletes DNS records from the zone.
+func (MockDNSProvider) DeleteRecords(ctx context.Context, zone string, recs []libdns.Record) ([]libdns.Record, error) {
+	return nil, nil
+}
+
+// GetRecords gets DNS records from the zone.
+func (MockDNSProvider) GetRecords(ctx context.Context, zone string) ([]libdns.Record, error) {
+	return nil, nil
+}
+
+// SetRecords sets DNS records in the zone.
+func (MockDNSProvider) SetRecords(ctx context.Context, zone string, recs []libdns.Record) ([]libdns.Record, error) {
+	return nil, nil
+}
+
+// Interface guard
+var _ caddyfile.Unmarshaler = (*MockDNSProvider)(nil)
+var _ certmagic.DNSProvider = (*MockDNSProvider)(nil)
+var _ caddy.Provisioner = (*MockDNSProvider)(nil)
+var _ caddy.Module = (*MockDNSProvider)(nil)

modules/caddyhttp/autohttps.go

@@ -65,6 +65,12 @@ type AutoHTTPSConfig struct {
 	// enabled. To force automated certificate management
 	// regardless of loaded certificates, set this to true.
 	IgnoreLoadedCerts bool `json:"ignore_loaded_certificates,omitempty"`
+
+	// If true, automatic HTTPS will prefer wildcard names
+	// and ignore non-wildcard names if both are available.
+	// This allows for writing a config with top-level host
+	// matchers without having those names produce certificates.
+	PreferWildcard bool `json:"prefer_wildcard,omitempty"`
 }
 
 // automaticHTTPSPhase1 provisions all route matchers, determines
@@ -157,6 +163,27 @@ func (app *App) automaticHTTPSPhase1(ctx caddy.Context, repl *caddy.Replacer) er
 			}
 		}
 
+		if srv.AutoHTTPS.PreferWildcard {
+			wildcards := make(map[string]struct{})
+			for d := range serverDomainSet {
+				if strings.HasPrefix(d, "*.") {
+					wildcards[d[2:]] = struct{}{}
+				}
+			}
+			for d := range serverDomainSet {
+				if strings.HasPrefix(d, "*.") {
+					continue
+				}
+				base := d
+				if idx := strings.Index(d, "."); idx != -1 {
+					base = d[idx+1:]
+				}
+				if _, ok := wildcards[base]; ok {
+					delete(serverDomainSet, d)
+				}
+			}
+		}
+
 		// nothing more to do here if there are no domains that qualify for
 		// automatic HTTPS and there are no explicit TLS connection policies:
 		// if there is at least one domain but no TLS conn policy (F&&T), we'll