gitea/modules/httplib/url.go

115 lines
3.8 KiB
Go

// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package httplib
import (
"context"
"net/http"
"net/url"
"strings"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
)
type RequestContextKeyStruct struct{}
var RequestContextKey = RequestContextKeyStruct{}
func urlIsRelative(s string, u *url.URL) bool {
// Unfortunately browsers consider a redirect Location with preceding "//", "\\", "/\" and "\/" as meaning redirect to "http(s)://REST_OF_PATH"
// Therefore we should ignore these redirect locations to prevent open redirects
if len(s) > 1 && (s[0] == '/' || s[0] == '\\') && (s[1] == '/' || s[1] == '\\') {
return false
}
return u != nil && u.Scheme == "" && u.Host == ""
}
// IsRelativeURL detects if a URL is relative (no scheme or host)
func IsRelativeURL(s string) bool {
u, err := url.Parse(s)
return err == nil && urlIsRelative(s, u)
}
func getRequestScheme(req *http.Request) string {
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Proto
if s := req.Header.Get("X-Forwarded-Proto"); s != "" {
return s
}
if s := req.Header.Get("X-Forwarded-Protocol"); s != "" {
return s
}
if s := req.Header.Get("X-Url-Scheme"); s != "" {
return s
}
if s := req.Header.Get("Front-End-Https"); s != "" {
return util.Iif(s == "on", "https", "http")
}
if s := req.Header.Get("X-Forwarded-Ssl"); s != "" {
return util.Iif(s == "on", "https", "http")
}
return ""
}
func getForwardedHost(req *http.Request) string {
// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host
return req.Header.Get("X-Forwarded-Host")
}
// GuessCurrentAppURL tries to guess the current full URL by http headers. It always has a '/' suffix, exactly the same as setting.AppURL
func GuessCurrentAppURL(ctx context.Context) string {
req, ok := ctx.Value(RequestContextKey).(*http.Request)
if !ok {
return setting.AppURL
}
// If no scheme provided by reverse proxy, then do not guess the AppURL, use the configured one.
// At the moment, if site admin doesn't configure the proxy headers correctly, then Gitea would guess wrong.
// There are some cases:
// 1. The reverse proxy is configured correctly, it passes "X-Forwarded-Proto/Host" headers. Perfect, Gitea can handle it correctly.
// 2. The reverse proxy is not configured correctly, doesn't pass "X-Forwarded-Proto/Host" headers, eg: only one "proxy_pass http://gitea:3000" in Nginx.
// 3. There is no reverse proxy.
// Without an extra config option, Gitea is impossible to distinguish between case 2 and case 3,
// then case 2 would result in wrong guess like guessed AppURL becomes "http://gitea:3000/", which is not accessible by end users.
// So in the future maybe it should introduce a new config option, to let site admin decide how to guess the AppURL.
reqScheme := getRequestScheme(req)
if reqScheme == "" {
return setting.AppURL
}
reqHost := getForwardedHost(req)
if reqHost == "" {
reqHost = req.Host
}
return reqScheme + "://" + reqHost + setting.AppSubURL + "/"
}
func MakeAbsoluteURL(ctx context.Context, s string) string {
if IsRelativeURL(s) {
return GuessCurrentAppURL(ctx) + strings.TrimPrefix(s, "/")
}
return s
}
func IsCurrentGiteaSiteURL(ctx context.Context, s string) bool {
u, err := url.Parse(s)
if err != nil {
return false
}
if u.Path != "" {
cleanedPath := util.PathJoinRelX(u.Path)
if cleanedPath == "" || cleanedPath == "." {
u.Path = "/"
} else {
u.Path += "/" + cleanedPath + "/"
}
}
if urlIsRelative(s, u) {
return u.Path == "" || strings.HasPrefix(strings.ToLower(u.Path), strings.ToLower(setting.AppSubURL+"/"))
}
if u.Path == "" {
u.Path = "/"
}
urlLower := strings.ToLower(u.String())
return strings.HasPrefix(urlLower, strings.ToLower(setting.AppURL)) || strings.HasPrefix(urlLower, strings.ToLower(GuessCurrentAppURL(ctx)))
}