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/oauth2.go

@@ -0,0 +1,144 @@
+// 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 (
+	"net/http"
+	"strings"
+	"time"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/web/middleware"
+)
+
+// Ensure the struct implements the interface.
+var (
+	_ Auth = &OAuth2{}
+)
+
+// CheckOAuthAccessToken returns uid of user from oauth token
+func CheckOAuthAccessToken(accessToken string) int64 {
+	// JWT tokens require a "."
+	if !strings.Contains(accessToken, ".") {
+		return 0
+	}
+	token, err := models.ParseOAuth2Token(accessToken)
+	if err != nil {
+		log.Trace("ParseOAuth2Token: %v", err)
+		return 0
+	}
+	var grant *models.OAuth2Grant
+	if grant, err = models.GetOAuth2GrantByID(token.GrantID); err != nil || grant == nil {
+		return 0
+	}
+	if token.Type != models.TypeAccessToken {
+		return 0
+	}
+	if token.ExpiresAt < time.Now().Unix() || token.IssuedAt > time.Now().Unix() {
+		return 0
+	}
+	return grant.UserID
+}
+
+// OAuth2 implements the Auth interface and authenticates requests
+// (API requests only) by looking for an OAuth token in query parameters or the
+// "Authorization" header.
+type OAuth2 struct {
+}
+
+// Init does nothing as the OAuth2 implementation does not need to allocate any resources
+func (o *OAuth2) Init() error {
+	return nil
+}
+
+// Name represents the name of auth method
+func (o *OAuth2) Name() string {
+	return "oauth2"
+}
+
+// Free does nothing as the OAuth2 implementation does not have to release any resources
+func (o *OAuth2) Free() error {
+	return nil
+}
+
+// userIDFromToken returns the user id corresponding to the OAuth token.
+func (o *OAuth2) userIDFromToken(req *http.Request, store DataStore) int64 {
+	_ = req.ParseForm()
+
+	// Check access token.
+	tokenSHA := req.Form.Get("token")
+	if len(tokenSHA) == 0 {
+		tokenSHA = req.Form.Get("access_token")
+	}
+	if len(tokenSHA) == 0 {
+		// Well, check with header again.
+		auHead := req.Header.Get("Authorization")
+		if len(auHead) > 0 {
+			auths := strings.Fields(auHead)
+			if len(auths) == 2 && (auths[0] == "token" || strings.ToLower(auths[0]) == "bearer") {
+				tokenSHA = auths[1]
+			}
+		}
+	}
+	if len(tokenSHA) == 0 {
+		return 0
+	}
+
+	// Let's see if token is valid.
+	if strings.Contains(tokenSHA, ".") {
+		uid := CheckOAuthAccessToken(tokenSHA)
+		if uid != 0 {
+			store.GetData()["IsApiToken"] = true
+		}
+		return uid
+	}
+	t, err := models.GetAccessTokenBySHA(tokenSHA)
+	if err != nil {
+		if !models.IsErrAccessTokenNotExist(err) && !models.IsErrAccessTokenEmpty(err) {
+			log.Error("GetAccessTokenBySHA: %v", err)
+		}
+		return 0
+	}
+	t.UpdatedUnix = timeutil.TimeStampNow()
+	if err = models.UpdateAccessToken(t); err != nil {
+		log.Error("UpdateAccessToken: %v", err)
+	}
+	store.GetData()["IsApiToken"] = true
+	return t.UID
+}
+
+// Verify extracts the user ID from the OAuth token in the query parameters
+// or the "Authorization" header and returns the corresponding user object for that ID.
+// If verification is successful returns an existing user object.
+// Returns nil if verification fails.
+func (o *OAuth2) Verify(req *http.Request, w http.ResponseWriter, store DataStore, sess SessionStore) *models.User {
+	if !models.HasEngine {
+		return nil
+	}
+
+	if !middleware.IsAPIPath(req) && !isAttachmentDownload(req) {
+		return nil
+	}
+
+	id := o.userIDFromToken(req, store)
+	if id <= 0 {
+		return nil
+	}
+	log.Trace("OAuth2 Authorization: Found token for user[%d]", id)
+
+	user, err := models.GetUserByID(id)
+	if err != nil {
+		if !models.IsErrUserNotExist(err) {
+			log.Error("GetUserByName: %v", err)
+		}
+		return nil
+	}
+
+	log.Trace("OAuth2 Authorization: Logged in user %-v", user)
+	return user
+}