Make HTTP middleware easier to use

server/auth/context.go

Index: server/auth/context.go
diff --git a/server/auth/context.go b/server/auth/context.go
index 035d59fb1472ae58d5c8b58da3e21409c92e40fe..0599dd98927bdfab7ea38975cac78315eee6ae69 100644
--- a/server/auth/context.go
+++ b/server/auth/context.go
@@ -1,28 +1,27 @@
 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package auth
 
 import (
 	"fmt"
 	"net/http"
 
-	"github.com/julienschmidt/httprouter"
 	"golang.org/x/net/context"
 
 	"github.com/luci/luci-go/common/errors"
 	"github.com/luci/luci-go/common/logging"
 
 	"github.com/luci/luci-go/server/auth/identity"
-	"github.com/luci/luci-go/server/middleware"
+	"github.com/luci/luci-go/server/router"
 )
 
 type authenticatorKey int
 
 // SetAuthenticator injects copy of Authenticator (list of auth methods) into
 // the context to use by default in LoginURL, LogoutURL and Authenticate.
 // Usually installed into the context by some base middleware.
 func SetAuthenticator(c context.Context, a Authenticator) context.Context {
 	return context.WithValue(c, authenticatorKey(0), append(Authenticator(nil), a...))
 }
@@ -30,101 +29,100 @@ func SetAuthenticator(c context.Context, a Authenticator) context.Context {
 // GetAuthenticator extracts instance of Authenticator (list of auth methods)
 // from the context. Returns nil if no authenticator is set.
 func GetAuthenticator(c context.Context) Authenticator {
 	if a, ok := c.Value(authenticatorKey(0)).(Authenticator); ok {
 		return a
 	}
 	return nil
 }
 
 // Use is a middleware that simply puts given Authenticator into the context.
-func Use(h middleware.Handler, a Authenticator) middleware.Handler {
-	return func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-		h(SetAuthenticator(c, a), rw, r, p)
+func Use(a Authenticator) router.Middleware {
+	return func(c *router.Context, next router.Handler) {
+		c.Context = SetAuthenticator(c.Context, a)
+		next(c)
 	}
 }
 
 // LoginURL returns a URL that, when visited, prompts the user to sign in,
 // then redirects the user to the URL specified by dest. It is wrapper around
 // LoginURL method of Authenticator in the context.
 func LoginURL(c context.Context, dest string) (string, error) {
 	return GetAuthenticator(c).LoginURL(c, dest)
 }
 
 // LogoutURL returns a URL that, when visited, signs the user out,
 // then redirects the user to the URL specified by dest. It is wrapper around
 // LogoutURL method of Authenticator in the context.
 func LogoutURL(c context.Context, dest string) (string, error) {
 	return GetAuthenticator(c).LogoutURL(c, dest)
 }
 
-// Authenticate returns a wrapper around middleware.Handler that performs
-// authentication (using Authenticator in the context) and calls `h`.
-func Authenticate(h middleware.Handler) middleware.Handler {
-	return func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-		a := GetAuthenticator(c)
-		if a == nil {
-			replyError(c, rw, 500, "Authentication middleware is not configured")
-			return
-		}
-		ctx, err := a.Authenticate(c, r)
-		switch {
-		case errors.IsTransient(err):
-			replyError(c, rw, 500, fmt.Sprintf("Transient error during authentication - %s", err))
-		case err != nil:
-			replyError(c, rw, 401, fmt.Sprintf("Authentication error - %s", err))
-		default:
-			h(ctx, rw, r, p)
-		}
+// Authenticate is a middleware that performs authentication (using Authenticator
+// in the context) and calls next handler.
+func Authenticate(c *router.Context, next router.Handler) {
+	a := GetAuthenticator(c.Context)
+	if a == nil {
+		replyError(c.Context, c.Writer, 500, "Authentication middleware is not configured")
+		return
+	}
+	ctx, err := a.Authenticate(c.Context, c.Request)
+	switch {
+	case errors.IsTransient(err):
+		replyError(c.Context, c.Writer, 500, fmt.Sprintf("Transient error during authentication - %s", err))
+	case err != nil:
+		replyError(c.Context, c.Writer, 401, fmt.Sprintf("Authentication error - %s", err))
+	default:
+		c.Context = ctx
+		next(c)
 	}
 }
 
 // Autologin is a middleware that redirects the user to login page if the user
 // is not signed in yet or authentication methods do not recognize user
 // credentials. Uses Authenticator instance in the context.
-func Autologin(h middleware.Handler) middleware.Handler {
-	return func(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
-		a := GetAuthenticator(c)
-		if a == nil {
-			replyError(c, rw, 500, "Authentication middleware is not configured")
-			return
+func Autologin(c *router.Context, next router.Handler) {
+	a := GetAuthenticator(c.Context)
+	if a == nil {
+		replyError(c.Context, c.Writer, 500, "Authentication middleware is not configured")
+		return
+	}
+	ctx, err := a.Authenticate(c.Context, c.Request)
+
+	switch {
+	case errors.IsTransient(err):
+		replyError(c.Context, c.Writer, 500, fmt.Sprintf("Transient error during authentication - %s", err))
+
+	case err != nil:
+		replyError(c.Context, c.Writer, 401, fmt.Sprintf("Authentication error - %s", err))
+
+	case CurrentIdentity(ctx).Kind() == identity.Anonymous:
+		dest := c.Request.RequestURI
+		if dest == "" {
+			// Make r.URL relative.
+			destURL := *c.Request.URL
+			destURL.Host = ""
+			destURL.Scheme = ""
+			dest = destURL.String()
 		}
-		ctx, err := a.Authenticate(c, r)
-
-		switch {
-		case errors.IsTransient(err):
-			replyError(c, rw, 500, fmt.Sprintf("Transient error during authentication - %s", err))
-
-		case err != nil:
-			replyError(c, rw, 401, fmt.Sprintf("Authentication error - %s", err))
-
-		case CurrentIdentity(ctx).Kind() == identity.Anonymous:
-			dest := r.RequestURI
-			if dest == "" {
-				// Make r.URL relative.
-				destURL := *r.URL
-				destURL.Host = ""
-				destURL.Scheme = ""
-				dest = destURL.String()
-			}
-			url, err := a.LoginURL(c, dest)
-			if err != nil {
-				if errors.IsTransient(err) {
-					replyError(c, rw, 500, fmt.Sprintf("Transient error during authentication - %s", err))
-				} else {
-					replyError(c, rw, 401, fmt.Sprintf("Authentication error - %s", err))
-				}
-				return
+		url, err := a.LoginURL(c.Context, dest)
+		if err != nil {
+			if errors.IsTransient(err) {
+				replyError(c.Context, c.Writer, 500, fmt.Sprintf("Transient error during authentication - %s", err))
+			} else {
+				replyError(c.Context, c.Writer, 401, fmt.Sprintf("Authentication error - %s", err))
 			}
-			http.Redirect(rw, r, url, 302)
-
-		default:
-			h(ctx, rw, r, p)
+			return
 		}
+		http.Redirect(c.Writer, c.Request, url, 302)
+
+	default:
+		c.Context = ctx
+		next(c)
 	}
 }
 
 // replyError logs the error and writes it to ResponseWriter.
 func replyError(c context.Context, rw http.ResponseWriter, code int, msg string) {
 	logging.Errorf(c, "HTTP %d: %s", code, msg)
 	http.Error(rw, msg, code)
 }