Fixed #454, Fixed #274

Signed-off-by: Vishal Rana <vr@labstack.com>

echo.go

@@ -152,20 +152,29 @@ const (
 
 // Headers
 const (
-	HeaderAcceptEncoding     = "Accept-Encoding"
+	HeaderAcceptEncoding                = "Accept-Encoding"
-	HeaderAuthorization      = "Authorization"
+	HeaderAuthorization                 = "Authorization"
-	HeaderContentDisposition = "Content-Disposition"
+	HeaderContentDisposition            = "Content-Disposition"
-	HeaderContentEncoding    = "Content-Encoding"
+	HeaderContentEncoding               = "Content-Encoding"
-	HeaderContentLength      = "Content-Length"
+	HeaderContentLength                 = "Content-Length"
-	HeaderContentType        = "Content-Type"
+	HeaderContentType                   = "Content-Type"
-	HeaderIfModifiedSince    = "If-Modified-Since"
+	HeaderIfModifiedSince               = "If-Modified-Since"
-	HeaderLastModified       = "Last-Modified"
+	HeaderLastModified                  = "Last-Modified"
-	HeaderLocation           = "Location"
+	HeaderLocation                      = "Location"
-	HeaderUpgrade            = "Upgrade"
+	HeaderUpgrade                       = "Upgrade"
-	HeaderVary               = "Vary"
+	HeaderVary                          = "Vary"
-	HeaderWWWAuthenticate    = "WWW-Authenticate"
+	HeaderWWWAuthenticate               = "WWW-Authenticate"
-	HeaderXForwardedFor      = "X-Forwarded-For"
+	HeaderXForwardedFor                 = "X-Forwarded-For"
-	HeaderXRealIP            = "X-Real-IP"
+	HeaderXRealIP                       = "X-Real-IP"
+	HeaderOrigin                        = "Origin"
+	HeaderAccessControlRequestMethod    = "Access-Control-Request-Method"
+	HeaderAccessControlRequestHeaders   = "Access-Control-Request-Headers"
+	HeaderAccessControlAllowOrigin      = "Access-Control-Allow-Origin"
+	HeaderAccessControlAllowMethods     = "Access-Control-Allow-Methods"
+	HeaderAccessControlAllowHeaders     = "Access-Control-Allow-Headers"
+	HeaderAccessControlAllowCredentials = "Access-Control-Allow-Credentials"
+	HeaderAccessControlExposeHeaders    = "Access-Control-Expose-Headers"
+	HeaderAccessControlMaxAge           = "Access-Control-Max-Age"
 )
 
 var (

middleware/cors.go

@@ -0,0 +1,133 @@
+package middleware
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/labstack/echo"
+)
+
+type (
+	// CORSConfig defines the config for CORS middleware.
+	CORSConfig struct {
+		// AllowOrigin defines a list of origins that may access the resource.
+		// Optional with default value as []string{"*"}.
+		AllowOrigins []string
+
+		// AllowMethods defines a list methods allowed when accessing the resource.
+		// This is used in response to a preflight request.
+		// Optional with default value as `DefaultCORSConfig.AllowMethods`.
+		AllowMethods []string
+
+		// AllowHeaders defines a list of request headers that can be used when
+		// making the actual request. This in response to a preflight request.
+		// Optional with default value as []string{}.
+		AllowHeaders []string
+
+		// AllowCredentials indicates whether or not the response to the request
+		// can be exposed when the credentials flag is true. When used as part of
+		// a response to a preflight request, this indicates whether or not the
+		// actual request can be made using credentials.
+		// Optional with default value as false.
+		AllowCredentials bool
+
+		// ExposeHeaders defines a whitelist headers that clients are allowed to
+		// access.
+		// Optional with default value as []string{}.
+		ExposeHeaders []string
+
+		// MaxAge indicates how long (in seconds) the results of a preflight request
+		// can be cached.
+		// Optional with default value as 0.
+		MaxAge int
+	}
+)
+
+var (
+	// DefaultCORSConfig is the default CORS middleware config.
+	DefaultCORSConfig = CORSConfig{
+		AllowOrigins: []string{"*"},
+		AllowMethods: []string{echo.GET, echo.HEAD, echo.PUT, echo.POST, echo.DELETE},
+	}
+)
+
+// CORS returns a cross-origin HTTP request (CORS) middleware.
+// See https://developer.mozilla.org/en/docs/Web/HTTP/Access_control_CORS
+func CORS() echo.MiddlewareFunc {
+	return CORSFromConfig(DefaultCORSConfig)
+}
+
+// CORSFromConfig returns a CORS middleware from config.
+// See `CORS()`.
+func CORSFromConfig(config CORSConfig) echo.MiddlewareFunc {
+	// Defaults
+	if len(config.AllowOrigins) == 0 {
+		config.AllowOrigins = DefaultCORSConfig.AllowOrigins
+	}
+	if len(config.AllowMethods) == 0 {
+		config.AllowMethods = DefaultCORSConfig.AllowMethods
+	}
+	allowMethods := strings.Join(config.AllowMethods, ",")
+	allowHeaders := strings.Join(config.AllowHeaders, ",")
+	exposeHeaders := strings.Join(config.ExposeHeaders, ",")
+	maxAge := strconv.Itoa(config.MaxAge)
+
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			rq := c.Request()
+			origin := c.Request().Header().Get(echo.HeaderOrigin)
+			header := c.Response().Header()
+
+			// Check allowed origins
+			allowedOrigin := ""
+			for _, o := range config.AllowOrigins {
+				if o == "*" || o == origin {
+					allowedOrigin = o
+					break
+				}
+			}
+
+			// Simple request
+			if rq.Method() != echo.OPTIONS {
+				header.Add(echo.HeaderVary, echo.HeaderOrigin)
+				if origin == "" || allowedOrigin == "" {
+					return next(c)
+				}
+				header.Set(echo.HeaderAccessControlAllowOrigin, allowedOrigin)
+				if config.AllowCredentials {
+					header.Set(echo.HeaderAccessControlAllowCredentials, "true")
+				}
+				if exposeHeaders != "" {
+					header.Set(echo.HeaderAccessControlExposeHeaders, exposeHeaders)
+				}
+				return next(c)
+			}
+
+			// Preflight request
+			header.Add(echo.HeaderVary, echo.HeaderOrigin)
+			header.Add(echo.HeaderVary, echo.HeaderAccessControlRequestMethod)
+			header.Add(echo.HeaderVary, echo.HeaderAccessControlRequestHeaders)
+			if origin == "" || allowedOrigin == "" {
+				return next(c)
+			}
+			header.Set(echo.HeaderAccessControlAllowOrigin, allowedOrigin)
+			header.Set(echo.HeaderAccessControlAllowMethods, allowMethods)
+			if config.AllowCredentials {
+				header.Set(echo.HeaderAccessControlAllowCredentials, "true")
+			}
+			if allowHeaders != "" {
+				header.Set(echo.HeaderAccessControlAllowHeaders, allowHeaders)
+			} else {
+				h := rq.Header().Get(echo.HeaderAccessControlRequestHeaders)
+				if h != "" {
+					header.Set(echo.HeaderAccessControlAllowHeaders, h)
+				}
+			}
+			if config.MaxAge > 0 {
+				header.Set(echo.HeaderAccessControlMaxAge, maxAge)
+			}
+			return c.NoContent(http.StatusNoContent)
+		}
+	}
+}

middleware/cors_test.go

@@ -0,0 +1,63 @@
+package middleware
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/labstack/echo"
+	"github.com/labstack/echo/test"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCORS(t *testing.T) {
+	e := echo.New()
+	rq := test.NewRequest(echo.GET, "/", nil)
+	rc := test.NewResponseRecorder()
+	c := echo.NewContext(rq, rc, e)
+	cors := CORSFromConfig(CORSConfig{
+		AllowCredentials: true,
+	})
+	h := cors(func(c echo.Context) error {
+		return c.String(http.StatusOK, "test")
+	})
+
+	// No origin header
+	h(c)
+	assert.Equal(t, "", rc.Header().Get(echo.HeaderAccessControlAllowOrigin))
+
+	// Wildcard origin
+	rq = test.NewRequest(echo.GET, "/", nil)
+	rc = test.NewResponseRecorder()
+	c = echo.NewContext(rq, rc, e)
+	rq.Header().Set(echo.HeaderOrigin, "localhost")
+	h(c)
+	assert.Equal(t, "*", rc.Header().Get(echo.HeaderAccessControlAllowOrigin))
+
+	// Simple request
+	rq = test.NewRequest(echo.GET, "/", nil)
+	rc = test.NewResponseRecorder()
+	c = echo.NewContext(rq, rc, e)
+	rq.Header().Set(echo.HeaderOrigin, "localhost")
+	cors = CORSFromConfig(CORSConfig{
+		AllowOrigins:     []string{"localhost"},
+		AllowCredentials: true,
+		MaxAge:           3600,
+	})
+	h = cors(func(c echo.Context) error {
+		return c.String(http.StatusOK, "test")
+	})
+	h(c)
+	assert.Equal(t, "localhost", rc.Header().Get(echo.HeaderAccessControlAllowOrigin))
+
+	// Preflight request
+	rq = test.NewRequest(echo.OPTIONS, "/", nil)
+	rc = test.NewResponseRecorder()
+	c = echo.NewContext(rq, rc, e)
+	rq.Header().Set(echo.HeaderOrigin, "localhost")
+	rq.Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSON)
+	h(c)
+	assert.Equal(t, "localhost", rc.Header().Get(echo.HeaderAccessControlAllowOrigin))
+	assert.NotEmpty(t, rc.Header().Get(echo.HeaderAccessControlAllowMethods))
+	assert.Equal(t, "true", rc.Header().Get(echo.HeaderAccessControlAllowCredentials))
+	assert.Equal(t, "3600", rc.Header().Get(echo.HeaderAccessControlMaxAge))
+}

middleware/static_test.go

@@ -0,0 +1 @@
+package middleware