Add sso.Group, context.Auth, context.APIAuth to allow auth special routes (#16086)

* Add sso.Group, context.Auth, context.APIAuth to allow auth special routes

* Remove unnecessary check

* Rename sso -> auth

* remove unused method of Auth interface

services/auth/auth.go

@@ -0,0 +1,130 @@
+// Copyright 2014 The Gogs Authors. All rights reserved.
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package auth
+
+import (
+	"fmt"
+	"net/http"
+	"reflect"
+	"regexp"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/web/middleware"
+)
+
+// authMethods contains the list of authentication plugins in the order they are expected to be
+// executed.
+//
+// The OAuth2 plugin is expected to be executed first, as it must ignore the user id stored
+// in the session (if there is a user id stored in session other plugins might return the user
+// object for that id).
+//
+// The Session plugin is expected to be executed second, in order to skip authentication
+// for users that have already signed in.
+var authMethods = []Auth{
+	&OAuth2{},
+	&Basic{},
+	&Session{},
+}
+
+// The purpose of the following three function variables is to let the linter know that
+// those functions are not dead code and are actually being used
+var (
+	_ = handleSignIn
+)
+
+// Methods returns the instances of all registered methods
+func Methods() []Auth {
+	return authMethods
+}
+
+// Register adds the specified instance to the list of available methods
+func Register(method Auth) {
+	authMethods = append(authMethods, method)
+}
+
+// Init should be called exactly once when the application starts to allow plugins
+// to allocate necessary resources
+func Init() {
+	if setting.Service.EnableReverseProxyAuth {
+		Register(&ReverseProxy{})
+	}
+	specialInit()
+	for _, method := range Methods() {
+		err := method.Init()
+		if err != nil {
+			log.Error("Could not initialize '%s' auth method, error: %s", reflect.TypeOf(method).String(), err)
+		}
+	}
+}
+
+// Free should be called exactly once when the application is terminating to allow Auth plugins
+// to release necessary resources
+func Free() {
+	for _, method := range Methods() {
+		err := method.Free()
+		if err != nil {
+			log.Error("Could not free '%s' auth method, error: %s", reflect.TypeOf(method).String(), err)
+		}
+	}
+}
+
+// isAttachmentDownload check if request is a file download (GET) with URL to an attachment
+func isAttachmentDownload(req *http.Request) bool {
+	return strings.HasPrefix(req.URL.Path, "/attachments/") && req.Method == "GET"
+}
+
+var gitRawPathRe = regexp.MustCompile(`^/[a-zA-Z0-9_.-]+/[a-zA-Z0-9_.-]+/(?:(?:git-(?:(?:upload)|(?:receive))-pack$)|(?:info/refs$)|(?:HEAD$)|(?:objects/)|raw/)`)
+var lfsPathRe = regexp.MustCompile(`^/[a-zA-Z0-9_.-]+/[a-zA-Z0-9_.-]+/info/lfs/`)
+
+func isGitRawOrLFSPath(req *http.Request) bool {
+	if gitRawPathRe.MatchString(req.URL.Path) {
+		return true
+	}
+	if setting.LFS.StartServer {
+		return lfsPathRe.MatchString(req.URL.Path)
+	}
+	return false
+}
+
+// handleSignIn clears existing session variables and stores new ones for the specified user object
+func handleSignIn(resp http.ResponseWriter, req *http.Request, sess SessionStore, user *models.User) {
+	_ = sess.Delete("openid_verified_uri")
+	_ = sess.Delete("openid_signin_remember")
+	_ = sess.Delete("openid_determined_email")
+	_ = sess.Delete("openid_determined_username")
+	_ = sess.Delete("twofaUid")
+	_ = sess.Delete("twofaRemember")
+	_ = sess.Delete("u2fChallenge")
+	_ = sess.Delete("linkAccount")
+	err := sess.Set("uid", user.ID)
+	if err != nil {
+		log.Error(fmt.Sprintf("Error setting session: %v", err))
+	}
+	err = sess.Set("uname", user.Name)
+	if err != nil {
+		log.Error(fmt.Sprintf("Error setting session: %v", err))
+	}
+
+	// Language setting of the user overwrites the one previously set
+	// If the user does not have a locale set, we save the current one.
+	if len(user.Language) == 0 {
+		lc := middleware.Locale(resp, req)
+		user.Language = lc.Language()
+		if err := models.UpdateUserCols(user, "language"); err != nil {
+			log.Error(fmt.Sprintf("Error updating user language [user: %d, locale: %s]", user.ID, user.Language))
+			return
+		}
+	}
+
+	middleware.SetLocaleCookie(resp, user.Language, 0)
+
+	// Clear whatever CSRF has right now, force to generate a new one
+	middleware.DeleteCSRFCookie(resp)
+}