root: introduce down-propagating Helper.BlockState for other directives/plugins to use (#7594)

* add 'root' key to Helper.State for access in frankenphp's `php_server` directive

* clone state before passing it to child directives, but keep sharing it among sibling directives

* propagate named route state from children to parent

* use BlockState to set "root" instead

* gofmt -w .

* go fmt ./...

* here we go

caddyconfig/httpcaddyfile/builtins.go

@@ -668,6 +668,8 @@ func parseRoot(h Helper) ([]ConfigValue, error) {
 		if !h.NextArg() {
 			return nil, h.ArgErr()
 		}
+		// store the unmatched root in block state so sibling directives can access it
+		h.BlockState["root"] = h.Val()
 		return h.NewRoute(nil, caddyhttp.VarsMiddleware{"root": h.Val()}), nil
 	}
 
@@ -682,6 +684,10 @@ func parseRoot(h Helper) ([]ConfigValue, error) {
 	if !h.NextArg() {
 		return nil, h.ArgErr()
 	}
+	// store the unmatched root in state so sibling/child directives can access it
+	if userMatcherSet == nil {
+		h.BlockState["root"] = h.Val()
+	}
 	// make the route with the matcher
 	return h.NewRoute(userMatcherSet, caddyhttp.VarsMiddleware{"root": h.Val()}), nil
 }

caddyconfig/httpcaddyfile/directives.go

@@ -202,7 +202,10 @@ func RegisterGlobalOption(opt string, setupFunc UnmarshalGlobalFunc) {
 type Helper struct {
 	*caddyfile.Dispenser
 	// State stores intermediate variables during caddyfile adaptation.
-	State        map[string]any
+	State map[string]any
+	// BlockState stores intermediate variables scoped to the current block.
+	// It propagates down, but unlike state not back up from child to parent.
+	BlockState   map[string]any
 	options      map[string]any
 	warnings     *[]caddyconfig.Warning
 	matcherDefs  map[string]caddy.ModuleMap
@@ -385,6 +388,11 @@ func parseSegmentAsConfig(h Helper) ([]ConfigValue, error) {
 			}
 		}
 
+		// clone BlockState once for the entire block so sibling directives
+		// can share state, but changes don't leak to the parent scope
+		subBlockState := make(map[string]any, len(h.BlockState))
+		maps.Copy(subBlockState, h.BlockState)
+
 		// with matchers ready to go, evaluate each directive's segment
 		for _, seg := range segments {
 			dir := seg.Directive()
@@ -396,6 +404,7 @@ func parseSegmentAsConfig(h Helper) ([]ConfigValue, error) {
 			subHelper := h
 			subHelper.Dispenser = caddyfile.NewDispenser(seg)
 			subHelper.matcherDefs = matcherDefs
+			subHelper.BlockState = subBlockState
 
 			results, err := dirFunc(subHelper)
 			if err != nil {

caddyconfig/httpcaddyfile/httptype.go

@@ -143,6 +143,7 @@ func (st ServerType) Setup(
 				parentBlock:  sb.block,
 				groupCounter: gc,
 				State:        state,
+				BlockState:   state,
 			}
 
 			results, err := dirFunc(h)
@@ -504,6 +505,7 @@ func (ServerType) extractNamedRoutes(
 			parentBlock:  sb.block,
 			groupCounter: gc,
 			State:        state,
+			BlockState:   state,
 		}
 
 		handler, err := ParseSegmentAsSubroute(h)

caddytest/integration/forwardauth_test.go

@@ -190,7 +190,7 @@ func TestForwardAuthCopyHeadersAuthResponseWins(t *testing.T) {
 	// its own values. The backend must receive the auth service values.
 	req, _ := http.NewRequest(http.MethodGet, "http://localhost:9080/", nil)
 	req.Header.Set("Authorization", "Bearer token123")
-	req.Header.Set("X-User-Id", "forged-id")   // must be overwritten
+	req.Header.Set("X-User-Id", "forged-id")     // must be overwritten
 	req.Header.Set("X-User-Role", "forged-role") // must be overwritten
 	tester.AssertResponse(req, http.StatusOK, "ok")
 

modules/caddyhttp/reverseproxy/httptransport_test.go

@@ -129,11 +129,11 @@ func TestHTTPTransport_DialTLSContext_ProxyProtocol(t *testing.T) {
 	defer cancel()
 
 	tests := []struct {
-		name                    string
-		tls                     *TLSConfig
-		proxyProtocol           string
+		name                     string
+		tls                      *TLSConfig
+		proxyProtocol            string
 		serverNameHasPlaceholder bool
-		expectDialTLSContext    bool
+		expectDialTLSContext     bool
 	}{
 		{
 			name:                 "no TLS, no proxy protocol",
@@ -194,4 +194,3 @@ func TestHTTPTransport_DialTLSContext_ProxyProtocol(t *testing.T) {
 		})
 	}
 }
-