fix(rewriter): prevent mixing of cached rule engines (#44)

internal/proxy/director/layer/authn/layer.go

@@ -10,6 +10,9 @@ import (
 	"forge.cadoles.com/Cadoles/go-proxy"
 	"forge.cadoles.com/Cadoles/go-proxy/wildcard"
 	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
+	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director/layer/util"
+	"forge.cadoles.com/cadoles/bouncer/internal/rule"
+	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
 	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/Masterminds/sprig/v3"
 	"github.com/pkg/errors"
@@ -21,6 +24,8 @@ type Layer struct {
 	auth      Authenticator
 	debug     bool
 
+	ruleEngineCache *util.RuleEngineCache[*Vars, *LayerOptions]
+
 	templateDir string
 }
 
@@ -74,7 +79,7 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 				return
 			}
 
-			if err := l.applyRules(ctx, r, options, user); err != nil {
+			if err := l.applyRules(ctx, r, layer, options, user); err != nil {
 				if errors.Is(err, ErrForbidden) {
 					l.renderForbiddenPage(w, r, layer, options, user)
 					return
@@ -189,6 +194,18 @@ func NewLayer(layerType store.LayerType, auth Authenticator, funcs ...OptionFunc
 	opts := NewOptions(funcs...)
 
 	return &Layer{
+		ruleEngineCache: util.NewInMemoryRuleEngineCache[*Vars, *LayerOptions](func(options *LayerOptions) (*rule.Engine[*Vars], error) {
+			engine, err := rule.NewEngine[*Vars](
+				rule.WithRules(options.Rules...),
+				rule.WithExpr(getAuthnAPI()...),
+				ruleHTTP.WithRequestFuncs(),
+			)
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			return engine, nil
+		}),
 		layerType:   layerType,
 		auth:        auth,
 		templateDir: opts.TemplateDir,

internal/proxy/director/layer/authn/layer_options.go

@@ -28,12 +28,13 @@ func DefaultLayerOptions() LayerOptions {
 	return LayerOptions{
 		MatchURLs: []string{"*"},
 		Rules: []string{
-			"del_headers('Remote-*')",
+			"del_headers(ctx, 'Remote-*')",
-			"set_header('Remote-User', user.subject)",
+			"set_header(ctx,'Remote-User', vars.user.subject)",
 			`map(
-				toPairs(user.attrs), {
+				toPairs(vars.user.attrs), {
 					let name = replace(lower(string(get(#, 0))), '_', '-');
 					set_header(
+						ctx,
 						'Remote-User-Attr-' + name, 
 						get(#, 1)
 					) 

internal/proxy/director/layer/authn/rules.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"net/http"
 
-	"forge.cadoles.com/cadoles/bouncer/internal/rule"
 	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
+	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/expr-lang/expr"
 	"github.com/pkg/errors"
 )
@@ -14,17 +14,11 @@ type Vars struct {
 	User *User `expr:"user"`
 }
 
-func (l *Layer) applyRules(ctx context.Context, r *http.Request, options *LayerOptions, user *User) error {
+func (l *Layer) applyRules(ctx context.Context, r *http.Request, layer *store.Layer, options *LayerOptions, user *User) error {
-	rules := options.Rules
+	key := string(layer.Proxy) + "-" + string(layer.Name)
-	if len(rules) == 0 {
+	revisionedEngine := l.ruleEngineCache.Get(key)
-		return nil
-	}
 
-	engine, err := rule.NewEngine[*Vars](
+	engine, err := revisionedEngine.Get(ctx, layer.Revision, options)
-		rule.WithRules(options.Rules...),
-		rule.WithExpr(getAuthnAPI()...),
-		ruleHTTP.WithRequestFuncs(),
-	)
 	if err != nil {
 		return errors.WithStack(err)
 	}

internal/proxy/director/layer/rewriter/layer.go

@@ -16,8 +16,8 @@ import (
 const LayerType store.LayerType = "rewriter"
 
 type Layer struct {
-	requestRuleEngine  *util.RevisionedRuleEngine[*RequestVars, *LayerOptions]
+	requestRuleEngineCache  *util.RuleEngineCache[*RequestVars, *LayerOptions]
-	responseRuleEngine *util.RevisionedRuleEngine[*ResponseVars, *LayerOptions]
+	responseRuleEngineCache *util.RuleEngineCache[*ResponseVars, *LayerOptions]
 }
 
 func (l *Layer) LayerType() store.LayerType {
@@ -42,7 +42,7 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 				return
 			}
 
-			if err := l.applyRequestRules(ctx, r, layer.Revision, options); err != nil {
+			if err := l.applyRequestRules(ctx, r, layer, options); err != nil {
 				var redirect *errRedirect
 				if errors.As(err, &redirect) {
 					http.Redirect(w, r, redirect.URL(), redirect.StatusCode())
@@ -76,7 +76,7 @@ func (l *Layer) ResponseTransformer(layer *store.Layer) proxy.ResponseTransforme
 
 		ctx := r.Request.Context()
 
-		if err := l.applyResponseRules(ctx, r, layer.Revision, options); err != nil {
+		if err := l.applyResponseRules(ctx, r, layer, options); err != nil {
 			return errors.WithStack(err)
 		}
 
@@ -86,7 +86,7 @@ func (l *Layer) ResponseTransformer(layer *store.Layer) proxy.ResponseTransforme
 
 func New(funcs ...OptionFunc) *Layer {
 	return &Layer{
-		requestRuleEngine: util.NewRevisionedRuleEngine(func(options *LayerOptions) (*rule.Engine[*RequestVars], error) {
+		requestRuleEngineCache: util.NewInMemoryRuleEngineCache(func(options *LayerOptions) (*rule.Engine[*RequestVars], error) {
 			engine, err := rule.NewEngine[*RequestVars](
 				rule.WithRules(options.Rules.Request...),
 				ruleHTTP.WithRequestFuncs(),
@@ -98,7 +98,7 @@ func New(funcs ...OptionFunc) *Layer {
 
 			return engine, nil
 		}),
-		responseRuleEngine: util.NewRevisionedRuleEngine(func(options *LayerOptions) (*rule.Engine[*ResponseVars], error) {
+		responseRuleEngineCache: util.NewInMemoryRuleEngineCache(func(options *LayerOptions) (*rule.Engine[*ResponseVars], error) {
 			engine, err := rule.NewEngine[*ResponseVars](
 				rule.WithRules(options.Rules.Response...),
 				ruleHTTP.WithResponseFuncs(),

internal/proxy/director/layer/rewriter/rules.go

@@ -8,6 +8,7 @@ import (
 	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
 	"forge.cadoles.com/cadoles/bouncer/internal/rule"
 	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
+	"forge.cadoles.com/cadoles/bouncer/internal/store"
 	"github.com/pkg/errors"
 )
 
@@ -87,13 +88,13 @@ func fromRequest(r *http.Request) RequestVar {
 	}
 }
 
-func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layerRevision int, options *LayerOptions) error {
+func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layer *store.Layer, options *LayerOptions) error {
 	rules := options.Rules.Request
 	if len(rules) == 0 {
 		return nil
 	}
 
-	engine, err := l.getRequestRuleEngine(ctx, layerRevision, options)
+	engine, err := l.getRequestRuleEngine(ctx, layer, options)
 	if err != nil {
 		return errors.WithStack(err)
 	}
@@ -117,8 +118,11 @@ func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layerRev
 	return nil
 }
 
-func (l *Layer) getRequestRuleEngine(ctx context.Context, layerRevision int, options *LayerOptions) (*rule.Engine[*RequestVars], error) {
+func (l *Layer) getRequestRuleEngine(ctx context.Context, layer *store.Layer, options *LayerOptions) (*rule.Engine[*RequestVars], error) {
-	engine, err := l.requestRuleEngine.Get(ctx, layerRevision, options)
+	key := string(layer.Proxy) + "-" + string(layer.Name)
+	revisionedEngine := l.requestRuleEngineCache.Get(key)
+
+	engine, err := revisionedEngine.Get(ctx, layer.Revision, options)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
@@ -145,13 +149,13 @@ type ResponseVar struct {
 	Trailer          map[string][]string `expr:"trailer"`
 }
 
-func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layerRevision int, options *LayerOptions) error {
+func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layer *store.Layer, options *LayerOptions) error {
 	rules := options.Rules.Response
 	if len(rules) == 0 {
 		return nil
 	}
 
-	engine, err := l.getResponseRuleEngine(ctx, layerRevision, options)
+	engine, err := l.getResponseRuleEngine(ctx, layer, options)
 	if err != nil {
 		return errors.WithStack(err)
 	}
@@ -187,8 +191,11 @@ func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layerR
 	return nil
 }
 
-func (l *Layer) getResponseRuleEngine(ctx context.Context, layerRevision int, options *LayerOptions) (*rule.Engine[*ResponseVars], error) {
+func (l *Layer) getResponseRuleEngine(ctx context.Context, layer *store.Layer, options *LayerOptions) (*rule.Engine[*ResponseVars], error) {
-	engine, err := l.responseRuleEngine.Get(ctx, layerRevision, options)
+	key := string(layer.Proxy) + "-" + string(layer.Name)
+	revisionedEngine := l.responseRuleEngineCache.Get(key)
+
+	engine, err := revisionedEngine.Get(ctx, layer.Revision, options)
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}

internal/proxy/director/layer/util/rule_engine_cache.go

@@ -0,0 +1,28 @@
+package util
+
+import (
+	"forge.cadoles.com/cadoles/bouncer/internal/cache"
+	"forge.cadoles.com/cadoles/bouncer/internal/cache/memory"
+)
+
+type RuleEngineCache[V any, O any] struct {
+	cache   cache.Cache[string, *RevisionedRuleEngine[V, O]]
+	factory RuleEngineFactoryFunc[V, O]
+}
+
+func (c *RuleEngineCache[V, O]) Get(key string) *RevisionedRuleEngine[V, O] {
+	revisionedRuleEngine, exists := c.cache.Get(key)
+	if !exists {
+		revisionedRuleEngine = NewRevisionedRuleEngine(c.factory)
+		c.cache.Set(key, revisionedRuleEngine)
+	}
+
+	return revisionedRuleEngine
+}
+
+func NewInMemoryRuleEngineCache[V any, O any](factory RuleEngineFactoryFunc[V, O]) *RuleEngineCache[V, O] {
+	return &RuleEngineCache[V, O]{
+		factory: factory,
+		cache:   memory.NewCache[string, *RevisionedRuleEngine[V, O]](),
+	}
+}