CSRF Support

modules/csrf/app/csrf.go

@@ -0,0 +1,116 @@
+package csrf
+
+import (
+	"crypto/rand"
+	"crypto/subtle"
+	"encoding/hex"
+	"html/template"
+	"io"
+	"math"
+	"net/url"
+
+	"github.com/revel/revel"
+)
+
+// allowMethods are HTTP methods that do NOT require a token
+var allowedMethods = map[string]bool{
+	"GET":     true,
+	"HEAD":    true,
+	"OPTIONS": true,
+	"TRACE":   true,
+}
+
+func RandomString(length int) (string, error) {
+	buffer := make([]byte, int(math.Ceil(float64(length)/2)))
+	if _, err := io.ReadFull(rand.Reader, buffer); err != nil {
+		return "", nil
+	}
+	str := hex.EncodeToString(buffer)
+	return str[:length], nil
+}
+
+func RefreshToken(c *revel.Controller) {
+	token, err := RandomString(64)
+	if err != nil {
+		panic(err)
+	}
+	c.Session["csrf_token"] = token
+}
+
+func CsrfFilter(c *revel.Controller, fc []revel.Filter) {
+	token, foundToken := c.Session["csrf_token"]
+
+	if !foundToken {
+		RefreshToken(c)
+	}
+
+	referer, refErr := url.Parse(c.Request.Header.Get("Referer"))
+	isSameOrigin := sameOrigin(c.Request.URL, referer)
+
+	// If the Request method isn't in the white listed methods
+	if !allowedMethods[c.Request.Method] && !IsExempt(c) {
+		// Token wasn't present at all
+		if !foundToken {
+			c.Result = c.Forbidden("REVEL CSRF: Session token missing.")
+			return
+		}
+
+		// Referer header is invalid
+		if refErr != nil {
+			c.Result = c.Forbidden("REVEL CSRF: HTTP Referer malformed.")
+			return
+		}
+
+		// Same origin
+		if !isSameOrigin {
+			c.Result = c.Forbidden("REVEL CSRF: Same origin mismatch.")
+			return
+		}
+
+		var requestToken string
+		// First check for token in post data
+		if c.Request.Method == "POST" {
+			requestToken = c.Request.FormValue("csrftoken")
+		}
+
+		// Then check for token in custom headers, as with AJAX
+		if requestToken == "" {
+			requestToken = c.Request.Header.Get("X-CSRFToken")
+		}
+
+		if requestToken == "" || !compareToken(requestToken, token) {
+			c.Result = c.Forbidden("REVEL CSRF: Invalid token.")
+			return
+		}
+	}
+
+	fc[0](c, fc[1:])
+
+	// Only add token to RenderArgs if the request is: not AJAX, not missing referer header, and is same origin.
+	if c.Request.Header.Get("X-CSRFToken") == "" && isSameOrigin {
+		c.RenderArgs["_csrftoken"] = token
+	}
+}
+
+func compareToken(requestToken, token string) bool {
+	// ConstantTimeCompare will panic if the []byte aren't the same length
+	if len(requestToken) != len(token) {
+		return false
+	}
+	return subtle.ConstantTimeCompare([]byte(requestToken), []byte(token)) == 1
+}
+
+// Validates same origin policy
+func sameOrigin(u1, u2 *url.URL) bool {
+	return u1.Scheme == u2.Scheme && u1.Host == u2.Host
+}
+
+func init() {
+	revel.TemplateFuncs["csrftoken"] = func(renderArgs map[string]interface{}) template.HTML {
+		if tokenFunc, ok := renderArgs["_csrftoken"]; !ok {
+			panic("REVEL CSRF: _csrftoken missing from RenderArgs.")
+		} else {
+			return template.HTML(tokenFunc.(func() string)())
+		}
+	}
+}

modules/csrf/app/csrf_test.go

@@ -0,0 +1,169 @@
+package csrf
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strconv"
+	"testing"
+
+	"github.com/revel/revel"
+)
+
+var testFilters = []revel.Filter{
+	CsrfFilter,
+	func(c *revel.Controller, fc []revel.Filter) {
+		c.RenderHtml("{{ csrftoken . }}")
+	},
+}
+
+func TestTokenInSession(t *testing.T) {
+	resp := httptest.NewRecorder()
+	getRequest, _ := http.NewRequest("GET", "http://www.example.com/", nil)
+	c := revel.NewController(revel.NewRequest(getRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	testFilters[0](c, testFilters)
+
+	if _, ok := c.Session["csrf_token"]; !ok {
+		t.Fatal("token should be present in session")
+	}
+}
+
+func TestPostWithoutToken(t *testing.T) {
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status != 403 {
+		t.Fatal("post without token should be forbidden")
+	}
+}
+
+func TestNoReferrer(t *testing.T) {
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	RefreshToken(c)
+	token := c.Session["csrf_token"]
+
+	// make a new request with the token
+	data := url.Values{}
+	data.Set("csrftoken", token)
+	formPostRequest, _ := http.NewRequest("POST", "http://www.example.com/", bytes.NewBufferString(data.Encode()))
+	formPostRequest.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+	formPostRequest.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))
+
+	// and replace the old request
+	c.Request = revel.NewRequest(formPostRequest)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status != 403 {
+		t.Fatal("post without referer should be forbidden")
+	}
+}
+
+func TestRefererHttps(t *testing.T) {
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+
+	c.Session = make(revel.Session)
+
+	RefreshToken(c)
+	token := c.Session["csrf_token"]
+
+	// make a new request with the token
+	data := url.Values{}
+	data.Set("csrftoken", token)
+	formPostRequest, _ := http.NewRequest("POST", "https://www.example.com/", bytes.NewBufferString(data.Encode()))
+	formPostRequest.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+	formPostRequest.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))
+	formPostRequest.Header.Add("Referer", "http://www.example.com/")
+
+	// and replace the old request
+	c.Request = revel.NewRequest(formPostRequest)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status != 403 {
+		t.Fatal("posts to https should have an https referer")
+	}
+}
+
+func TestHeaderWithToken(t *testing.T) {
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+
+	c.Session = make(revel.Session)
+
+	RefreshToken(c)
+	token := c.Session["csrf_token"]
+
+	// make a new request with the token
+	formPostRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+	formPostRequest.Header.Add("X-CSRFToken", token)
+	formPostRequest.Header.Add("Referer", "http://www.example.com/")
+
+	// and replace the old request
+	c.Request = revel.NewRequest(formPostRequest)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status == 403 {
+		t.Fatal("post with http header token should be allowed")
+	}
+}
+
+func TestFormPostWithToken(t *testing.T) {
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+
+	c.Session = make(revel.Session)
+
+	RefreshToken(c)
+	token := c.Session["csrf_token"]
+
+	// make a new request with the token
+	data := url.Values{}
+	data.Set("csrftoken", token)
+	formPostRequest, _ := http.NewRequest("POST", "http://www.example.com/", bytes.NewBufferString(data.Encode()))
+	formPostRequest.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+	formPostRequest.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))
+	formPostRequest.Header.Add("Referer", "http://www.example.com/")
+
+	// and replace the old request
+	c.Request = revel.NewRequest(formPostRequest)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status == 403 {
+		t.Fatal("form post with token should be allowed")
+	}
+}
+
+func TestNoTokenInArgsWhenCORs(t *testing.T) {
+	resp := httptest.NewRecorder()
+
+	getRequest, _ := http.NewRequest("GET", "http://www.example1.com/", nil)
+	getRequest.Header.Add("Referer", "http://www.example2.com/")
+
+	c := revel.NewController(revel.NewRequest(getRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	testFilters[0](c, testFilters)
+
+	if _, ok := c.RenderArgs["_csrftoken"]; ok {
+		t.Fatal("RenderArgs should not contain token when not same origin")
+	}
+}

modules/csrf/app/exempt.go

@@ -0,0 +1,36 @@
+package csrf
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/revel/revel"
+)
+
+var (
+	exemptPath   = make(map[string]bool)
+	exemptAction = make(map[string]bool)
+)
+
+func MarkExempt(route string) {
+	if strings.HasPrefix(route, "/") {
+		// e.g. "/controller/action"
+		exemptPath[strings.ToLower(route)] = true
+	} else if routeParts := strings.Split(route, "."); len(routeParts) == 2 {
+		// e.g. "ControllerName.ActionName"
+		exemptAction[route] = true
+	} else {
+		err := fmt.Sprintf("csrf.MarkExempt() received invalid argument \"%v\". Either provide a path prefixed with \"/\" or controller action in the form of \"ControllerName.ActionName\".", route)
+		panic(err)
+	}
+}
+
+func IsExempt(c *revel.Controller) bool {
+	if _, ok := exemptPath[strings.ToLower(c.Request.Request.URL.Path)]; ok {
+		return true
+	} else if _, ok := exemptAction[c.Action]; ok {
+		return true
+	}
+
+	return false
+}

modules/csrf/app/exempt_test.go

@@ -0,0 +1,55 @@
+package csrf
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/revel/revel"
+)
+
+func TestExemptPath(t *testing.T) {
+	MarkExempt("/Controller/Action")
+
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/Controller/Action", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status == 403 {
+		t.Fatal("post to csrf exempt action should pass")
+	}
+}
+
+func TestExemptPathCaseInsensitive(t *testing.T) {
+	MarkExempt("/Controller/Action")
+
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/controller/action", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status == 403 {
+		t.Fatal("post to csrf exempt action should pass")
+	}
+}
+
+func TestExemptAction(t *testing.T) {
+	MarkExempt("Controller.Action")
+
+	resp := httptest.NewRecorder()
+	postRequest, _ := http.NewRequest("POST", "http://www.example.com/Controller/Action", nil)
+	c := revel.NewController(revel.NewRequest(postRequest), revel.NewResponse(resp))
+	c.Session = make(revel.Session)
+	c.Action = "Controller.Action"
+
+	testFilters[0](c, testFilters)
+
+	if c.Response.Status == 403 {
+		t.Fatal("post to csrf exempt action should pass")
+	}
+}