Make HTTP middleware easier to use

server/auth/openid/method.go

Index: server/auth/openid/method.go
diff --git a/server/auth/openid/method.go b/server/auth/openid/method.go
index f3f3d1207161b7ec6c709e809a77a298e87755cb..2e0db253a19f12d6bd875ac7d6131d6bac75259a 100644
--- a/server/auth/openid/method.go
+++ b/server/auth/openid/method.go
@@ -3,28 +3,27 @@
 // that can be found in the LICENSE file.
 
 package openid
 
 import (
 	"fmt"
 	"net/http"
 	"net/url"
 	"time"
 
-	"github.com/julienschmidt/httprouter"
 	"golang.org/x/net/context"
 
 	"github.com/luci/luci-go/common/clock"
 	"github.com/luci/luci-go/common/errors"
 	"github.com/luci/luci-go/common/logging"
 	"github.com/luci/luci-go/server/auth"
-	"github.com/luci/luci-go/server/middleware"
+	"github.com/luci/luci-go/server/router"
 )
 
 // These are installed into a HTTP router by AuthMethod.InstallHandlers(...).
 const (
 	loginURL    = "/auth/openid/login"
 	logoutURL   = "/auth/openid/logout"
 	callbackURL = "/auth/openid/callback"
 )
 
 // AuthMethod implements auth.Method and auth.UsersAPI and can be used as
@@ -45,24 +44,24 @@ type AuthMethod struct {
 	Insecure bool
 
 	// IncompatibleCookies is a list of cookies to remove when setting or clearing
 	// session cookie. It is useful to get rid of GAE cookies when OpenID cookies
 	// are being used. Having both is very confusing.
 	IncompatibleCookies []string
 }
 
 // InstallHandlers installs HTTP handlers used in OpenID protocol. Must be
 // installed in server HTTP router for OpenID authentication flow to work.
-func (m *AuthMethod) InstallHandlers(r *httprouter.Router, base middleware.Base) {
-	r.GET(loginURL, base(m.loginHandler))
-	r.GET(logoutURL, base(m.logoutHandler))
-	r.GET(callbackURL, base(m.callbackHandler))
+func (m *AuthMethod) InstallHandlers(r *router.Router, base router.MiddlewareChain) {
+	r.GET(loginURL, base, m.loginHandler)
+	r.GET(logoutURL, base, m.logoutHandler)
+	r.GET(callbackURL, base, m.callbackHandler)
 }
 
 // Warmup prepares local caches. It's optional.
 func (m *AuthMethod) Warmup(c context.Context) error {
 	cfg, err := fetchCachedSettings(c)
 	if err != nil {
 		return err
 	}
 	_, err = fetchDiscoveryDoc(c, cfg.DiscoveryURL)
 	return err
@@ -111,21 +110,23 @@ func (m *AuthMethod) LoginURL(c context.Context, dest string) (string, error) {
 func (m *AuthMethod) LogoutURL(c context.Context, dest string) (string, error) {
 	if m.SessionStore == nil {
 		return "", ErrNotConfigured
 	}
 	return makeRedirectURL(logoutURL, dest)
 }
 
 ////
 
 // loginHandler initiates login flow by redirecting user to OpenID login page.
-func (m *AuthMethod) loginHandler(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func (m *AuthMethod) loginHandler(ctx *router.Context) {
+	c, rw, r := ctx.Context, ctx.Writer, ctx.Request
+
 	dest, err := normalizeURL(r.URL.Query().Get("r"))
 	if err != nil {
 		replyError(c, rw, err, "Bad redirect URI (%q) - %s", dest, err)
 		return
 	}
 
 	cfg, err := fetchCachedSettings(c)
 	if err != nil {
 		replyError(c, rw, err, "Can't load OpenID settings - %s", err)
 		return
@@ -139,21 +140,23 @@ func (m *AuthMethod) loginHandler(c context.Context, rw http.ResponseWriter, r *
 	}
 	authURI, err := authenticationURI(c, cfg, state)
 	if err != nil {
 		replyError(c, rw, err, "Can't generate authentication URI - %s", err)
 		return
 	}
 	http.Redirect(rw, r, authURI, http.StatusFound)
 }
 
 // logoutHandler nukes active session and redirect back to destination URL.
-func (m *AuthMethod) logoutHandler(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func (m *AuthMethod) logoutHandler(ctx *router.Context) {
+	c, rw, r := ctx.Context, ctx.Writer, ctx.Request
+
 	dest, err := normalizeURL(r.URL.Query().Get("r"))
 	if err != nil {
 		replyError(c, rw, err, "Bad redirect URI (%q) - %s", dest, err)
 		return
 	}
 
 	// Close a session if there's one.
 	sid, err := decodeSessionCookie(c, r)
 	if err != nil {
 		replyError(c, rw, err, "Error when decoding session cookie - %s", err)
@@ -169,21 +172,23 @@ func (m *AuthMethod) logoutHandler(c context.Context, rw http.ResponseWriter, r
 	// Nuke all session cookies to get to a completely clean state.
 	removeCookie(rw, r, sessionCookieName)
 	m.removeIncompatibleCookies(rw, r)
 
 	// Redirect to the final destination.
 	http.Redirect(rw, r, dest, http.StatusFound)
 }
 
 // callbackHandler handles redirect from OpenID backend. Parameters contain
 // authorization code that can be exchanged for user profile.
-func (m *AuthMethod) callbackHandler(c context.Context, rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
+func (m *AuthMethod) callbackHandler(ctx *router.Context) {
+	c, rw, r := ctx.Context, ctx.Writer, ctx.Request
+
 	// This code path is hit when user clicks "Deny" on consent page.
 	q := r.URL.Query()
 	errorMsg := q.Get("error")
 	if errorMsg != "" {
 		replyError(c, rw, errors.New("login error"), "OpenID login error: %s", errorMsg)
 		return
 	}
 
 	// Validate inputs.
 	code := q.Get("code")