1 files changed, 179 insertions, 0 deletions
diff --git a/services/auth/reverseproxy.go b/services/auth/reverseproxy.go
new file mode 100644
index 0000000..8a5a5dc
--- /dev/null
+++ b/services/auth/reverseproxy.go
@@ -0,0 +1,179 @@
+// Copyright 2014 The Gogs Authors. All rights reserved.
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"net/http"
+	"strings"
+
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/optional"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/web/middleware"
+
+	gouuid "github.com/google/uuid"
+)
+
+// Ensure the struct implements the interface.
+var (
+	_ Method = &ReverseProxy{}
+)
+
+// ReverseProxyMethodName is the constant name of the ReverseProxy authentication method
+const ReverseProxyMethodName = "reverse_proxy"
+
+// ReverseProxy implements the Auth interface, but actually relies on
+// a reverse proxy for authentication of users.
+// On successful authentication the proxy is expected to populate the username in the
+// "setting.ReverseProxyAuthUser" header. Optionally it can also populate the email of the
+// user in the "setting.ReverseProxyAuthEmail" header.
+type ReverseProxy struct{}
+
+// getUserName extracts the username from the "setting.ReverseProxyAuthUser" header
+func (r *ReverseProxy) getUserName(req *http.Request) string {
+	return strings.TrimSpace(req.Header.Get(setting.ReverseProxyAuthUser))
+}
+
+// Name represents the name of auth method
+func (r *ReverseProxy) Name() string {
+	return ReverseProxyMethodName
+}
+
+// getUserFromAuthUser extracts the username from the "setting.ReverseProxyAuthUser" header
+// of the request and returns the corresponding user object for that name.
+// Verification of header data is not performed as it should have already been done by
+// the reverse proxy.
+// If a username is available in the "setting.ReverseProxyAuthUser" header an existing
+// user object is returned (populated with username or email found in header).
+// Returns nil if header is empty.
+func (r *ReverseProxy) getUserFromAuthUser(req *http.Request) (*user_model.User, error) {
+	username := r.getUserName(req)
+	if len(username) == 0 {
+		return nil, nil
+	}
+	log.Trace("ReverseProxy Authorization: Found username: %s", username)
+
+	user, err := user_model.GetUserByName(req.Context(), username)
+	if err != nil {
+		if !user_model.IsErrUserNotExist(err) || !r.isAutoRegisterAllowed() {
+			log.Error("GetUserByName: %v", err)
+			return nil, err
+		}
+		user = r.newUser(req)
+	}
+	return user, nil
+}
+
+// getEmail extracts the email from the "setting.ReverseProxyAuthEmail" header
+func (r *ReverseProxy) getEmail(req *http.Request) string {
+	return strings.TrimSpace(req.Header.Get(setting.ReverseProxyAuthEmail))
+}
+
+// getUserFromAuthEmail extracts the username from the "setting.ReverseProxyAuthEmail" header
+// of the request and returns the corresponding user object for that email.
+// Verification of header data is not performed as it should have already been done by
+// the reverse proxy.
+// If an email is available in the "setting.ReverseProxyAuthEmail" header an existing
+// user object is returned (populated with the email found in header).
+// Returns nil if header is empty or if "setting.EnableReverseProxyEmail" is disabled.
+func (r *ReverseProxy) getUserFromAuthEmail(req *http.Request) *user_model.User {
+	if !setting.Service.EnableReverseProxyEmail {
+		return nil
+	}
+	email := r.getEmail(req)
+	if len(email) == 0 {
+		return nil
+	}
+	log.Trace("ReverseProxy Authorization: Found email: %s", email)
+
+	user, err := user_model.GetUserByEmail(req.Context(), email)
+	if err != nil {
+		// Do not allow auto-registration, we don't have a username here
+		if !user_model.IsErrUserNotExist(err) {
+			log.Error("GetUserByEmail: %v", err)
+		}
+		return nil
+	}
+	return user
+}
+
+// Verify attempts to load a user object based on headers sent by the reverse proxy.
+// First it will attempt to load it based on the username (see docs for getUserFromAuthUser),
+// and failing that it will attempt to load it based on the email (see docs for getUserFromAuthEmail).
+// Returns nil if the headers are empty or the user is not found.
+func (r *ReverseProxy) Verify(req *http.Request, w http.ResponseWriter, store DataStore, sess SessionStore) (*user_model.User, error) {
+	user, err := r.getUserFromAuthUser(req)
+	if err != nil {
+		return nil, err
+	}
+	if user == nil {
+		user = r.getUserFromAuthEmail(req)
+		if user == nil {
+			return nil, nil
+		}
+	}
+
+	// Make sure requests to API paths, attachment downloads, git and LFS do not create a new session
+	if !middleware.IsAPIPath(req) && !isAttachmentDownload(req) && !isGitRawOrAttachOrLFSPath(req) {
+		if sess != nil && (sess.Get("uid") == nil || sess.Get("uid").(int64) != user.ID) {
+			handleSignIn(w, req, sess, user)
+		}
+	}
+	store.GetData()["IsReverseProxy"] = true
+
+	log.Trace("ReverseProxy Authorization: Logged in user %-v", user)
+	return user, nil
+}
+
+// isAutoRegisterAllowed checks if EnableReverseProxyAutoRegister setting is true
+func (r *ReverseProxy) isAutoRegisterAllowed() bool {
+	return setting.Service.EnableReverseProxyAutoRegister
+}
+
+// newUser creates a new user object for the purpose of automatic registration
+// and populates its name and email with the information present in request headers.
+func (r *ReverseProxy) newUser(req *http.Request) *user_model.User {
+	username := r.getUserName(req)
+	if len(username) == 0 {
+		return nil
+	}
+
+	email := gouuid.New().String() + "@localhost"
+	if setting.Service.EnableReverseProxyEmail {
+		webAuthEmail := req.Header.Get(setting.ReverseProxyAuthEmail)
+		if len(webAuthEmail) > 0 {
+			email = webAuthEmail
+		}
+	}
+
+	var fullname string
+	if setting.Service.EnableReverseProxyFullName {
+		fullname = req.Header.Get(setting.ReverseProxyAuthFullName)
+	}
+
+	user := &user_model.User{
+		Name:     username,
+		Email:    email,
+		FullName: fullname,
+	}
+
+	overwriteDefault := user_model.CreateUserOverwriteOptions{
+		IsActive: optional.Some(true),
+	}
+
+	// The first user created should be an admin.
+	if user_model.CountUsers(req.Context(), nil) == 0 {
+		user.IsAdmin = true
+	}
+
+	if err := user_model.CreateUser(req.Context(), user, &overwriteDefault); err != nil {
+		// FIXME: should I create a system notice?
+		log.Error("CreateUser: %v", err)
+		return nil
+	}
+
+	return user
+}