fix: runtime error: index out of range (0) with length 0 (#2328)

* Issue 2311: runtime error: index out of range [0] with length 0 while extracting state of of the csrf

---------

Co-authored-by: tuunit <jan@larwig.com>

pkg/cookies/csrf.go

@@ -72,9 +72,7 @@ func NewCSRF(opts *options.Cookie, codeVerifier string) (CSRF, error) {
 }
 
 // LoadCSRFCookie loads a CSRF object from a request's CSRF cookie
-func LoadCSRFCookie(req *http.Request, opts *options.Cookie) (CSRF, error) {
-	cookieName := GenerateCookieName(req, opts)
-
+func LoadCSRFCookie(req *http.Request, cookieName string, opts *options.Cookie) (CSRF, error) {
 	cookies := req.Cookies()
 	for _, cookie := range cookies {
 		if cookie.Name != cookieName {
@@ -89,17 +87,17 @@ func LoadCSRFCookie(req *http.Request, opts *options.Cookie) (CSRF, error) {
 		return csrf, nil
 	}
 
-	return nil, errors.New("CSRF cookie not found")
+	return nil, fmt.Errorf("CSRF cookie with name '%v' was not found", cookieName)
 }
 
 // GenerateCookieName in case cookie options state that CSRF cookie has fixed name then set fixed name, otherwise
 // build name based on the state
-func GenerateCookieName(req *http.Request, opts *options.Cookie) string {
+func GenerateCookieName(opts *options.Cookie, state string) string {
 	stateSubstring := ""
 	if opts.CSRFPerRequest {
 		// csrfCookieName will include a substring of the state to enable multiple csrf cookies
 		// in case of parallel requests
-		stateSubstring = ExtractStateSubstring(req)
+		stateSubstring = ExtractStateSubstring(state)
 	}
 	return csrfCookieName(opts, stateSubstring)
 }
@@ -218,20 +216,15 @@ func csrfCookieName(opts *options.Cookie, stateSubstring string) string {
 	if stateSubstring == "" {
 		return fmt.Sprintf("%v_csrf", opts.Name)
 	}
-	return fmt.Sprintf("%v_csrf_%v", opts.Name, stateSubstring)
+	return fmt.Sprintf("%v_%v_csrf", opts.Name, stateSubstring)
 }
 
 // ExtractStateSubstring extract the initial state characters, to add it to the CSRF cookie name
-func ExtractStateSubstring(req *http.Request) string {
+func ExtractStateSubstring(state string) string {
 	lastChar := csrfStateLength - 1
 	stateSubstring := ""
-
-	state := req.URL.Query()["state"]
-	if state[0] != "" {
-		state := state[0]
-		if lastChar <= len(state) {
-			stateSubstring = state[0:lastChar]
-		}
+	if lastChar <= len(state) {
+		stateSubstring = state[0:lastChar]
 	}
 	return stateSubstring
 }

pkg/cookies/csrf_test.go

@@ -19,6 +19,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 		cookieOpts  *options.Cookie
 		publicCSRF  CSRF
 		privateCSRF *csrf
+		csrfName    string
 	)
 
 	BeforeEach(func() {
@@ -39,6 +40,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 		Expect(err).ToNot(HaveOccurred())
 
 		privateCSRF = publicCSRF.(*csrf)
+		csrfName = GenerateCookieName(cookieOpts, csrfNonce)
 	})
 
 	Context("NewCSRF", func() {
@@ -175,7 +177,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 			})
 
 			It("should return error when no cookie is set", func() {
-				csrf, err := LoadCSRFCookie(req, cookieOpts)
+				csrf, err := LoadCSRFCookie(req, csrfName, cookieOpts)
 				Expect(err).To(HaveOccurred())
 				Expect(csrf).To(BeNil())
 			})
@@ -191,7 +193,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 					Value: encoded,
 				})
 
-				csrf, err := LoadCSRFCookie(req, cookieOpts)
+				csrf, err := LoadCSRFCookie(req, csrfName, cookieOpts)
 				Expect(err).ToNot(HaveOccurred())
 				Expect(csrf).ToNot(BeNil())
 			})
@@ -202,7 +204,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 					Value: "invalid",
 				})
 
-				csrf, err := LoadCSRFCookie(req, cookieOpts)
+				csrf, err := LoadCSRFCookie(req, csrfName, cookieOpts)
 				Expect(err).To(HaveOccurred())
 				Expect(csrf).To(BeNil())
 			})
@@ -223,7 +225,7 @@ var _ = Describe("CSRF Cookie Tests", func() {
 					Value: encoded,
 				})
 
-				csrf, err := LoadCSRFCookie(req, cookieOpts)
+				csrf, err := LoadCSRFCookie(req, csrfName, cookieOpts)
 				Expect(err).ToNot(HaveOccurred())
 				Expect(csrf).ToNot(BeNil())
 			})