feat(rewriter): add redirect(), get_cookie(), add_cookie() methods to rule engine (#36)

Reviewed-on: #35

doc/fr/references/layers/rewriter.md

@@ -38,6 +38,33 @@ Supprimer un ou plusieurs entêtes HTTP dont le nom correspond au patron `patter
 
 Le patron est défini par une chaîne comprenant un ou plusieurs caractères `*`, signifiant un ou plusieurs caractères arbitraires.
 
+##### `get_cookie(ctx, name string) Cookie`
+
+Récupère un cookie depuis la requête/réponse (en fonction du contexte d'utilisation).
+Retourne `nil` si le cookie n'existe pas.
+
+**Cookie**
+
+```js
+// Plus d'informations sur https://pkg.go.dev/net/http#Cookie
+{
+  name: "string", // Nom du cookie
+  value: "string", // Valeur associée au cookie
+  path: "string", // Chemin associé au cookie (présent uniquement dans un contexte de réponse)
+  domain: "string", // Domaine associé au cookie (présent uniquement dans un contexte de réponse)
+  expires: "string", // Date d'expiration du cookie (présent uniquement dans un contexte de réponse)
+  max_age: "string", // Age maximum du cookie (présent uniquement dans un contexte de réponse)
+  secure: "boolean", // Le cookie doit-il être présent uniquement en HTTPS ? (présent uniquement dans un contexte de réponse)
+  http_only: "boolean", // Le cookie est il accessible en Javascript ? (présent uniquement dans un contexte de réponse)
+  same_site: "int" // Voir https://pkg.go.dev/net/http#SameSite (présent uniquement dans un contexte de réponse)
+}
+```
+
+##### `set_cookie(ctx, cookie Cookie)`
+
+Définit un cookie sur la requête/réponse (en fonction du contexte d'utilisation).
+Voir la méthode `get_cookie()` pour voir les attributs potentiels.
+
 #### Requête
 
 ##### `set_host(ctx, host string)`
@@ -48,6 +75,12 @@ Modifier la valeur de l'entête `Host` de la requête.
 
 Modifier l'URL du serveur cible.
 
+##### `redirect(ctx, statusCode int, url string)`
+
+Interrompt la requête et retourne une redirection HTTP au client.
+
+Le code HTTP utilisé doit être supérieur ou égale à `300` et inférieur à `400` (non inclus).
+
 #### Réponse
 
 _Pas de fonctions spécifiques._
@@ -72,7 +105,7 @@ L'URL originale, avant réécriture du `Host` par Bouncer.
     },
     host: "string", // Nom d'hôte (<domaine>:<port>) de l'URL
     path: "string", // Chemin de l'URL (format assaini)
-    rawPath: "string", // Chemin de l'URL (format brut)
+    raw_path: "string", // Chemin de l'URL (format brut)
     raw_query: "string", // Variables d'URL (format brut)
     fragment : "string", // Fragment d'URL (format assaini)
     raw_fragment : "string" // Fragment d'URL (format brut)
@@ -96,7 +129,7 @@ La requête en cours de traitement.
         },
         host: "string", // Nom d'hôte (<domaine>:<port>) de l'URL
         path: "string", // Chemin de l'URL (format assaini)
-        rawPath: "string", // Chemin de l'URL (format brut)
+        raw_path: "string", // Chemin de l'URL (format brut)
         raw_query: "string", // Variables d'URL (format brut)
         fragment : "string", // Fragment d'URL (format assaini)
         raw_fragment : "string" // Fragment d'URL (format brut)

go.mod

@@ -1,8 +1,8 @@
 module forge.cadoles.com/cadoles/bouncer
 
-go 1.22
+go 1.23
 
-toolchain go1.22.0
+toolchain go1.23.0
 
 require (
 	forge.cadoles.com/Cadoles/go-proxy v0.0.0-20240626132607-e1db6466a926

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

@@ -39,6 +39,23 @@ func TestMatchAuthorizedCIDRs(t *testing.T) {
 			},
 			ExpectedResult: false,
 		},
+		{
+			RemoteHostPort: "192.168.1.15:43349",
+			AuthorizedCIDRs: []string{
+				"192.168.1.5/32",
+				"192.168.1.0/24",
+			},
+			ExpectedResult: true,
+		},
+		{
+			RemoteHostPort: "192.168.1.15:43349",
+			AuthorizedCIDRs: []string{
+				"192.168.1.5/32",
+				"192.168.1.6/32",
+				"192.168.1.7/32",
+			},
+			ExpectedResult: false,
+		},
 	}
 
 	auth := Authenticator{}

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

@@ -0,0 +1,79 @@
+package rewriter
+
+import (
+	"context"
+	"fmt"
+
+	"forge.cadoles.com/cadoles/bouncer/internal/rule"
+	"github.com/expr-lang/expr"
+	"github.com/pkg/errors"
+)
+
+type errRedirect struct {
+	statusCode int
+	url        string
+}
+
+func (e *errRedirect) StatusCode() int {
+	return e.statusCode
+}
+
+func (e *errRedirect) URL() string {
+	return e.url
+}
+
+func (e *errRedirect) Error() string {
+	return fmt.Sprintf("redirect %d %s", e.statusCode, e.url)
+}
+
+func newErrRedirect(statusCode int, url string) *errRedirect {
+	return &errRedirect{
+		url:        url,
+		statusCode: statusCode,
+	}
+}
+
+var _ error = &errRedirect{}
+
+func redirectFunc() expr.Option {
+	return expr.Function(
+		"redirect",
+		func(params ...any) (any, error) {
+			_, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			statusCode, err := rule.Assert[int](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			if statusCode < 300 || statusCode >= 400 {
+				return nil, errors.Errorf("unexpected redirect status code '%d'", statusCode)
+			}
+
+			url, err := rule.Assert[string](params[2])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			return nil, newErrRedirect(statusCode, url)
+		},
+		new(func(context.Context, int, string) bool),
+	)
+}
+
+func WithRewriterFuncs() rule.OptionFunc {
+	return func(opts *rule.Options) {
+		funcs := []expr.Option{
+			redirectFunc(),
+		}
+
+		if len(opts.Expr) == 0 {
+			opts.Expr = make([]expr.Option, 0)
+		}
+
+		opts.Expr = append(opts.Expr, funcs...)
+	}
+}

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

@@ -46,6 +46,12 @@ func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
 			}
 
 			if err := l.applyRequestRules(ctx, r, layer.Revision, options); err != nil {
+				var redirect *errRedirect
+				if errors.As(err, &redirect) {
+					http.Redirect(w, r, redirect.URL(), redirect.StatusCode())
+					return
+				}
+
 				logger.Error(ctx, "could not apply request rules", logger.E(errors.WithStack(err)))
 				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 
@@ -88,6 +94,7 @@ func New(funcs ...OptionFunc) *Layer {
 			engine, err := rule.NewEngine[*RequestVars](
 				rule.WithRules(options.Rules.Request...),
 				ruleHTTP.WithRequestFuncs(),
+				WithRewriterFuncs(),
 			)
 			if err != nil {
 				return nil, errors.WithStack(err)

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

@@ -3,6 +3,7 @@ package rewriter
 import (
 	"context"
 	"net/http"
+	"net/url"
 
 	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
 	"forge.cadoles.com/cadoles/bouncer/internal/rule"
@@ -27,6 +28,26 @@ type URLVar struct {
 	RawFragment string  `expr:"raw_fragment"`
 }
 
+func fromURL(url *url.URL) URLVar {
+	return URLVar{
+		Scheme: url.Scheme,
+		Opaque: url.Opaque,
+		User: UserVar{
+			Username: url.User.Username(),
+			Password: func() string {
+				passwd, _ := url.User.Password()
+				return passwd
+			}(),
+		},
+		Host:        url.Host,
+		Path:        url.Path,
+		RawPath:     url.RawPath,
+		RawQuery:    url.RawQuery,
+		Fragment:    url.Fragment,
+		RawFragment: url.RawFragment,
+	}
+}
+
 type UserVar struct {
 	Username string `expr:"username"`
 	Password string `expr:"password"`
@@ -48,6 +69,24 @@ type RequestVar struct {
 	RequestURI       string              `expr:"request_uri"`
 }
 
+func fromRequest(r *http.Request) RequestVar {
+	return RequestVar{
+		Method:           r.Method,
+		URL:              fromURL(r.URL),
+		RawURL:           r.URL.String(),
+		Proto:            r.Proto,
+		ProtoMajor:       r.ProtoMajor,
+		ProtoMinor:       r.ProtoMinor,
+		Header:           r.Header,
+		ContentLength:    r.ContentLength,
+		TransferEncoding: r.TransferEncoding,
+		Host:             r.Host,
+		Trailer:          r.Trailer,
+		RemoteAddr:       r.RemoteAddr,
+		RequestURI:       r.RequestURI,
+	}
+}
+
 func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layerRevision int, options *LayerOptions) error {
 	rules := options.Rules.Request
 	if len(rules) == 0 {
@@ -65,54 +104,8 @@ func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layerRev
 	}
 
 	vars := &RequestVars{
-		OriginalURL: URLVar{
+		OriginalURL: fromURL(originalURL),
-			Scheme: originalURL.Scheme,
+		Request:     fromRequest(r),
-			Opaque: originalURL.Opaque,
-			User: UserVar{
-				Username: originalURL.User.Username(),
-				Password: func() string {
-					passwd, _ := originalURL.User.Password()
-					return passwd
-				}(),
-			},
-			Host:        originalURL.Host,
-			Path:        originalURL.Path,
-			RawPath:     originalURL.RawPath,
-			RawQuery:    originalURL.RawQuery,
-			Fragment:    originalURL.Fragment,
-			RawFragment: originalURL.RawFragment,
-		},
-		Request: RequestVar{
-			Method: r.Method,
-			URL: URLVar{
-				Scheme: r.URL.Scheme,
-				Opaque: r.URL.Opaque,
-				User: UserVar{
-					Username: r.URL.User.Username(),
-					Password: func() string {
-						passwd, _ := r.URL.User.Password()
-						return passwd
-					}(),
-				},
-				Host:        r.URL.Host,
-				Path:        r.URL.Path,
-				RawPath:     r.URL.RawPath,
-				RawQuery:    r.URL.RawQuery,
-				Fragment:    r.URL.Fragment,
-				RawFragment: r.URL.RawFragment,
-			},
-			RawURL:           r.URL.String(),
-			Proto:            r.Proto,
-			ProtoMajor:       r.ProtoMajor,
-			ProtoMinor:       r.ProtoMinor,
-			Header:           r.Header,
-			ContentLength:    r.ContentLength,
-			TransferEncoding: r.TransferEncoding,
-			Host:             r.Host,
-			Trailer:          r.Trailer,
-			RemoteAddr:       r.RemoteAddr,
-			RequestURI:       r.RequestURI,
-		},
 	}
 
 	ctx = ruleHTTP.WithRequest(ctx, r)
@@ -169,54 +162,8 @@ func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layerR
 	}
 
 	vars := &ResponseVars{
-		OriginalURL: URLVar{
+		OriginalURL: fromURL(originalURL),
-			Scheme: originalURL.Scheme,
+		Request:     fromRequest(r.Request),
-			Opaque: originalURL.Opaque,
-			User: UserVar{
-				Username: originalURL.User.Username(),
-				Password: func() string {
-					passwd, _ := originalURL.User.Password()
-					return passwd
-				}(),
-			},
-			Host:        originalURL.Host,
-			Path:        originalURL.Path,
-			RawPath:     originalURL.RawPath,
-			RawQuery:    originalURL.RawQuery,
-			Fragment:    originalURL.Fragment,
-			RawFragment: originalURL.RawFragment,
-		},
-		Request: RequestVar{
-			Method: r.Request.Method,
-			URL: URLVar{
-				Scheme: r.Request.URL.Scheme,
-				Opaque: r.Request.URL.Opaque,
-				User: UserVar{
-					Username: r.Request.URL.User.Username(),
-					Password: func() string {
-						passwd, _ := r.Request.URL.User.Password()
-						return passwd
-					}(),
-				},
-				Host:        r.Request.URL.Host,
-				Path:        r.Request.URL.Path,
-				RawPath:     r.Request.URL.RawPath,
-				RawQuery:    r.Request.URL.RawQuery,
-				Fragment:    r.Request.URL.Fragment,
-				RawFragment: r.Request.URL.RawFragment,
-			},
-			RawURL:           r.Request.URL.String(),
-			Proto:            r.Request.Proto,
-			ProtoMajor:       r.Request.ProtoMajor,
-			ProtoMinor:       r.Request.ProtoMinor,
-			Header:           r.Request.Header,
-			ContentLength:    r.Request.ContentLength,
-			TransferEncoding: r.Request.TransferEncoding,
-			Host:             r.Request.Host,
-			Trailer:          r.Request.Trailer,
-			RemoteAddr:       r.Request.RemoteAddr,
-			RequestURI:       r.Request.RequestURI,
-		},
 		Response: ResponseVar{
 			Proto:            r.Proto,
 			ProtoMajor:       r.ProtoMajor,
@@ -231,6 +178,7 @@ func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layerR
 	}
 
 	ctx = ruleHTTP.WithResponse(ctx, r)
+	ctx = ruleHTTP.WithRequest(ctx, r.Request)
 
 	if _, err := engine.Apply(ctx, vars); err != nil {
 		return errors.WithStack(err)

internal/rule/http/context.go

@@ -22,10 +22,10 @@ func WithResponse(ctx context.Context, r *http.Response) context.Context {
 	return context.WithValue(ctx, contextKeyResponse, r)
 }
 
-func ctxRequest(ctx context.Context) (*http.Request, bool) {
+func CtxRequest(ctx context.Context) (*http.Request, bool) {
 	return rule.Context[*http.Request](ctx, contextKeyRequest)
 }
 
-func ctxResponse(ctx context.Context) (*http.Response, bool) {
+func CtxResponse(ctx context.Context) (*http.Response, bool) {
 	return rule.Context[*http.Response](ctx, contextKeyResponse)
 }

internal/rule/http/option.go

@@ -13,6 +13,8 @@ func WithRequestFuncs() rule.OptionFunc {
 			addRequestHeaderFunc(),
 			delRequestHeadersFunc(),
 			setRequestHostFunc(),
+			getRequestCookieFunc(),
+			addRequestCookieFunc(),
 		}
 
 		if len(opts.Expr) == 0 {
@@ -29,6 +31,8 @@ func WithResponseFuncs() rule.OptionFunc {
 			setResponseHeaderFunc(),
 			addResponseHeaderFunc(),
 			delResponseHeadersFunc(),
+			addResponseCookieFunc(),
+			getResponseCookieFunc(),
 		}
 
 		if len(opts.Expr) == 0 {

internal/rule/http/request.go

@@ -3,6 +3,7 @@ package http
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"net/url"
 	"strconv"
 	"strings"
@@ -28,7 +29,7 @@ func setRequestHostFunc() expr.Option {
 				return nil, errors.WithStack(err)
 			}
 
-			r, ok := ctxRequest(ctx)
+			r, ok := CtxRequest(ctx)
 			if !ok {
 				return nil, errors.New("could not find http request in context")
 			}
@@ -60,7 +61,7 @@ func setRequestURLFunc() expr.Option {
 				return false, errors.WithStack(err)
 			}
 
-			r, ok := ctxRequest(ctx)
+			r, ok := CtxRequest(ctx)
 			if !ok {
 				return nil, errors.New("could not find http request in context")
 			}
@@ -89,7 +90,7 @@ func addRequestHeaderFunc() expr.Option {
 
 			value := formatValue(params[2])
 
-			r, ok := ctxRequest(ctx)
+			r, ok := CtxRequest(ctx)
 			if !ok {
 				return nil, errors.New("could not find http request in context")
 			}
@@ -118,7 +119,7 @@ func setRequestHeaderFunc() expr.Option {
 
 			value := formatValue(params[2])
 
-			r, ok := ctxRequest(ctx)
+			r, ok := CtxRequest(ctx)
 			if !ok {
 				return nil, errors.New("could not find http request in context")
 			}
@@ -145,7 +146,7 @@ func delRequestHeadersFunc() expr.Option {
 				return nil, errors.WithStack(err)
 			}
 
-			r, ok := ctxRequest(ctx)
+			r, ok := CtxRequest(ctx)
 			if !ok {
 				return nil, errors.New("could not find http request in context")
 			}
@@ -167,6 +168,145 @@ func delRequestHeadersFunc() expr.Option {
 	)
 }
 
+type CookieVar struct {
+	Name     string        `expr:"name"`
+	Value    string        `expr:"value"`
+	Path     string        `expr:"path"`
+	Domain   string        `expr:"domain"`
+	Expires  time.Time     `expr:"expires"`
+	MaxAge   int           `expr:"max_age"`
+	Secure   bool          `expr:"secure"`
+	HttpOnly bool          `expr:"http_only"`
+	SameSite http.SameSite `expr:"same_site"`
+}
+
+func getRequestCookieFunc() expr.Option {
+	return expr.Function(
+		"get_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			name, err := rule.Assert[string](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			r, ok := CtxRequest(ctx)
+			if !ok {
+				return nil, errors.New("could not find http request in context")
+			}
+
+			cookie, err := r.Cookie(name)
+			if err != nil && !errors.Is(err, http.ErrNoCookie) {
+				return nil, errors.WithStack(err)
+			}
+
+			if cookie == nil {
+				return nil, nil
+			}
+
+			return CookieVar{
+				Name:     cookie.Name,
+				Value:    cookie.Value,
+				Path:     cookie.Path,
+				Domain:   cookie.Domain,
+				Expires:  cookie.Expires,
+				MaxAge:   cookie.MaxAge,
+				Secure:   cookie.Secure,
+				HttpOnly: cookie.HttpOnly,
+				SameSite: cookie.SameSite,
+			}, nil
+		},
+		new(func(context.Context, string) CookieVar),
+	)
+}
+
+func addRequestCookieFunc() expr.Option {
+	return expr.Function(
+		"add_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			values, err := rule.Assert[map[string]any](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			cookie, err := cookieFrom(values)
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			r, ok := CtxRequest(ctx)
+			if !ok {
+				return nil, errors.New("could not find http request in context")
+			}
+
+			r.AddCookie(cookie)
+
+			return true, nil
+		},
+		new(func(context.Context, map[string]any) bool),
+	)
+}
+
+func cookieFrom(values map[string]any) (*http.Cookie, error) {
+	cookie := &http.Cookie{}
+
+	if name, ok := values["name"].(string); ok {
+		cookie.Name = name
+	}
+
+	if value, ok := values["value"].(string); ok {
+		cookie.Value = value
+	}
+
+	if domain, ok := values["domain"].(string); ok {
+		cookie.Domain = domain
+	}
+
+	if path, ok := values["path"].(string); ok {
+		cookie.Path = path
+	}
+
+	if httpOnly, ok := values["http_only"].(bool); ok {
+		cookie.HttpOnly = httpOnly
+	}
+
+	if maxAge, ok := values["max_age"].(int); ok {
+		cookie.MaxAge = maxAge
+	}
+
+	if secure, ok := values["secure"].(bool); ok {
+		cookie.Secure = secure
+	}
+
+	if sameSite, ok := values["same_site"].(http.SameSite); ok {
+		cookie.SameSite = sameSite
+	} else if sameSite, ok := values["same_site"].(int); ok {
+		cookie.SameSite = http.SameSite(sameSite)
+	}
+
+	if expires, ok := values["expires"].(time.Time); ok {
+		cookie.Expires = expires
+	} else if rawExpires, ok := values["expires"].(string); ok {
+		expires, err := time.Parse(http.TimeFormat, rawExpires)
+		if err != nil {
+			return nil, errors.WithStack(err)
+		}
+
+		cookie.Expires = expires
+	}
+
+	return cookie, nil
+}
+
 func formatValue(v any) string {
 	var value string
 	switch v := v.(type) {

internal/rule/http/request_test.go

@@ -2,6 +2,7 @@ package http
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"testing"
 
@@ -185,6 +186,134 @@ func TestDelRequestHeaders(t *testing.T) {
 	}
 }
 
+func TestAddRequestCookie(t *testing.T) {
+	type TestCase struct {
+		Cookie     map[string]any
+		Check      func(t *testing.T, tc TestCase, req *http.Request)
+		ShouldFail bool
+	}
+
+	testCases := []TestCase{
+		{
+			Cookie: map[string]any{
+				"name": "test",
+			},
+			Check: func(t *testing.T, tc TestCase, req *http.Request) {
+				cookie, err := req.Cookie(tc.Cookie["name"].(string))
+				if err != nil {
+					t.Errorf("%+v", errors.WithStack(err))
+					return
+				}
+
+				if e, g := tc.Cookie["name"], cookie.Name; e != g {
+					t.Errorf("cookie.Name: expected '%v', got '%v'", e, g)
+				}
+			},
+		},
+		{
+			Cookie: map[string]any{
+				"name":  "foo",
+				"value": "test",
+			},
+			Check: func(t *testing.T, tc TestCase, req *http.Request) {
+				cookie, err := req.Cookie(tc.Cookie["name"].(string))
+				if err != nil {
+					t.Errorf("%+v", errors.WithStack(err))
+					return
+				}
+
+				if e, g := tc.Cookie["name"], cookie.Name; e != g {
+					t.Errorf("cookie.Name: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["value"], cookie.Value; e != g {
+					t.Errorf("cookie.Value: expected '%v', got '%v'", e, g)
+				}
+			},
+		},
+	}
+
+	for idx, tc := range testCases {
+		t.Run(fmt.Sprintf("Case_%d", idx), func(t *testing.T) {
+			type Vars struct {
+				NewCookie map[string]any `expr:"new_cookie"`
+			}
+
+			engine := createRuleEngine[Vars](t,
+				rule.WithExpr(addRequestCookieFunc()),
+				rule.WithRules(
+					`add_cookie(ctx, vars.new_cookie)`,
+				),
+			)
+
+			req, err := http.NewRequest("GET", "http://example.net", nil)
+			if err != nil {
+				t.Fatalf("%+v", errors.WithStack(err))
+			}
+
+			vars := Vars{
+				NewCookie: tc.Cookie,
+			}
+
+			ctx := context.Background()
+			ctx = WithRequest(ctx, req)
+
+			if _, err := engine.Apply(ctx, vars); err != nil {
+				t.Fatalf("%+v", errors.WithStack(err))
+			}
+
+			if tc.ShouldFail {
+				t.Error("engine.Apply() should have failed")
+			}
+
+			if tc.Check != nil {
+				tc.Check(t, tc, req)
+			}
+		})
+	}
+}
+
+func TestGetRequestCookie(t *testing.T) {
+	type Vars struct {
+		CookieName string `expr:"cookieName"`
+	}
+
+	engine := createRuleEngine[Vars](t,
+		rule.WithExpr(getRequestCookieFunc()),
+		rule.WithRules(
+			"let cookie = get_cookie(ctx, vars.cookieName); cookie.value",
+		),
+	)
+
+	req, err := http.NewRequest("GET", "http://example.net", nil)
+	if err != nil {
+		t.Fatalf("%+v", errors.WithStack(err))
+	}
+
+	vars := Vars{
+		CookieName: "foo",
+	}
+
+	cookie := &http.Cookie{
+		Name:  vars.CookieName,
+		Value: "bar",
+	}
+
+	req.AddCookie(cookie)
+
+	ctx := context.Background()
+	ctx = WithRequest(ctx, req)
+
+	results, err := engine.Apply(ctx, vars)
+	if err != nil {
+		t.Fatalf("%+v", errors.WithStack(err))
+	}
+
+	if e, g := cookie.Value, results[0]; e != g {
+		t.Errorf("result[0]: expected '%v', got '%v'", e, g)
+	}
+}
+
 func createRuleEngine[V any](t *testing.T, funcs ...rule.OptionFunc) *rule.Engine[V] {
 	engine, err := rule.NewEngine[V](funcs...)
 	if err != nil {

internal/rule/http/response.go

@@ -3,6 +3,7 @@ package http
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"strconv"
 	"strings"
 	"time"
@@ -41,7 +42,7 @@ func addResponseHeaderFunc() expr.Option {
 				value = fmt.Sprintf("%v", rawValue)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -82,7 +83,7 @@ func setResponseHeaderFunc() expr.Option {
 				value = fmt.Sprintf("%v", rawValue)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -109,7 +110,7 @@ func delResponseHeadersFunc() expr.Option {
 				return nil, errors.WithStack(err)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -130,3 +131,84 @@ func delResponseHeadersFunc() expr.Option {
 		new(func(context.Context, string) bool),
 	)
 }
+
+func addResponseCookieFunc() expr.Option {
+	return expr.Function(
+		"add_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			values, err := rule.Assert[map[string]any](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			cookie, err := cookieFrom(values)
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			r, ok := CtxResponse(ctx)
+			if !ok {
+				return nil, errors.New("could not find http request in context")
+			}
+
+			r.Header.Add("Set-Cookie", cookie.String())
+
+			return true, nil
+		},
+		new(func(context.Context, map[string]any) bool),
+	)
+}
+
+func getResponseCookieFunc() expr.Option {
+	return expr.Function(
+		"get_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			name, err := rule.Assert[string](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			res, ok := CtxResponse(ctx)
+			if !ok {
+				return nil, errors.New("could not find http response in context")
+			}
+
+			var cookie *http.Cookie
+			for _, c := range res.Cookies() {
+				if c.Name != name {
+					continue
+				}
+
+				cookie = c
+				break
+			}
+
+			if cookie == nil {
+				return nil, nil
+			}
+
+			return CookieVar{
+				Name:     cookie.Name,
+				Value:    cookie.Value,
+				Path:     cookie.Path,
+				Domain:   cookie.Domain,
+				Expires:  cookie.Expires,
+				MaxAge:   cookie.MaxAge,
+				Secure:   cookie.Secure,
+				HttpOnly: cookie.HttpOnly,
+				SameSite: cookie.SameSite,
+			}, nil
+		},
+		new(func(context.Context, string) CookieVar),
+	)
+}

internal/rule/http/response_test.go

@@ -2,9 +2,11 @@ package http
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"net/http"
 	"testing"
+	"time"
 
 	"forge.cadoles.com/cadoles/bouncer/internal/rule"
 	"github.com/pkg/errors"
@@ -124,6 +126,182 @@ func TestResponseDelHeaders(t *testing.T) {
 	}
 }
 
+func TestAddResponseCookie(t *testing.T) {
+	type TestCase struct {
+		Cookie     map[string]any
+		Check      func(t *testing.T, tc TestCase, res *http.Response)
+		ShouldFail bool
+	}
+
+	testCases := []TestCase{
+		{
+			Cookie: map[string]any{
+				"name":      "foo",
+				"value":     "test",
+				"domain":    "example.net",
+				"path":      "/custom",
+				"same_site": http.SameSiteStrictMode,
+				"http_only": true,
+				"secure":    false,
+				"expires":   time.Now().UTC().Truncate(time.Second),
+			},
+			Check: func(t *testing.T, tc TestCase, res *http.Response) {
+				var cookie *http.Cookie
+				for _, c := range res.Cookies() {
+					if c.Name == tc.Cookie["name"] {
+						cookie = c
+						break
+					}
+				}
+				if cookie == nil {
+					t.Errorf("could not find cookie '%s'", tc.Cookie["name"])
+					return
+				}
+
+				if e, g := tc.Cookie["name"], cookie.Name; e != g {
+					t.Errorf("cookie.Name: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["value"], cookie.Value; e != g {
+					t.Errorf("cookie.Value: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["domain"], cookie.Domain; e != g {
+					t.Errorf("cookie.Domain: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["path"], cookie.Path; e != g {
+					t.Errorf("cookie.Path: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["secure"], cookie.Secure; e != g {
+					t.Errorf("cookie.Secure: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["http_only"], cookie.HttpOnly; e != g {
+					t.Errorf("cookie.HttpOnly: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["same_site"], cookie.SameSite; e != g {
+					t.Errorf("cookie.SameSite: expected '%v', got '%v'", e, g)
+				}
+
+				if e, g := tc.Cookie["expires"], cookie.Expires; e != g {
+					t.Errorf("cookie.Expires: expected '%v', got '%v'", e, g)
+				}
+			},
+		},
+		{
+			Cookie: map[string]any{
+				"name":    "foo",
+				"expires": time.Now().UTC().Format(http.TimeFormat),
+			},
+			Check: func(t *testing.T, tc TestCase, res *http.Response) {
+				var cookie *http.Cookie
+				for _, c := range res.Cookies() {
+					if c.Name == tc.Cookie["name"] {
+						cookie = c
+						break
+					}
+				}
+				if cookie == nil {
+					t.Errorf("could not find cookie '%s'", tc.Cookie["name"])
+					return
+				}
+
+				if e, g := tc.Cookie["expires"], cookie.Expires.Format(http.TimeFormat); e != g {
+					t.Errorf("cookie.Expires: expected '%v', got '%v'", e, g)
+				}
+			},
+		},
+	}
+
+	for idx, tc := range testCases {
+		t.Run(fmt.Sprintf("Case_%d", idx), func(t *testing.T) {
+			type Vars struct {
+				NewCookie map[string]any `expr:"new_cookie"`
+			}
+
+			engine := createRuleEngine[Vars](t,
+				rule.WithExpr(addResponseCookieFunc()),
+				rule.WithRules(
+					`add_cookie(ctx, vars.new_cookie)`,
+				),
+			)
+
+			req, err := http.NewRequest("GET", "http://example.net", nil)
+			if err != nil {
+				t.Fatalf("%+v", errors.WithStack(err))
+			}
+
+			resp := createResponse(req, http.StatusOK, nil)
+
+			vars := Vars{
+				NewCookie: tc.Cookie,
+			}
+
+			ctx := context.Background()
+			ctx = WithRequest(ctx, req)
+			ctx = WithResponse(ctx, resp)
+
+			if _, err := engine.Apply(ctx, vars); err != nil {
+				t.Fatalf("%+v", errors.WithStack(err))
+			}
+
+			if tc.ShouldFail {
+				t.Error("engine.Apply() should have failed")
+			}
+
+			if tc.Check != nil {
+				tc.Check(t, tc, resp)
+			}
+		})
+	}
+}
+
+func TestGetResponseCookie(t *testing.T) {
+	type Vars struct {
+		CookieName string `expr:"cookieName"`
+	}
+
+	engine := createRuleEngine[Vars](t,
+		rule.WithExpr(getResponseCookieFunc()),
+		rule.WithRules(
+			"let cookie = get_cookie(ctx, vars.cookieName); cookie.value",
+		),
+	)
+
+	req, err := http.NewRequest("GET", "http://example.net", nil)
+	if err != nil {
+		t.Fatalf("%+v", errors.WithStack(err))
+	}
+
+	resp := createResponse(req, http.StatusOK, nil)
+
+	vars := Vars{
+		CookieName: "foo",
+	}
+
+	cookie := &http.Cookie{
+		Name:  vars.CookieName,
+		Value: "bar",
+	}
+
+	resp.Header.Add("Set-Cookie", cookie.String())
+
+	ctx := context.Background()
+	ctx = WithResponse(ctx, resp)
+
+	results, err := engine.Apply(ctx, vars)
+	if err != nil {
+		t.Fatalf("%+v", errors.WithStack(err))
+	}
+
+	if e, g := cookie.Value, results[0]; e != g {
+		t.Errorf("result[0]: expected '%v', got '%v'", e, g)
+	}
+}
+
 func createResponse(req *http.Request, statusCode int, body io.Reader) *http.Response {
 	return &http.Response{
 		Status:        http.StatusText(statusCode),