gitea/modules/httplib/url.go

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// 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 guessRequestScheme(req *http.Request, def string) 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 def
}
func guessForwardedHost(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 host := guessForwardedHost(req); host != "" {
// if it is behind a reverse proxy, use "https" as default scheme in case the site admin forgets to set the correct forwarded-protocol headers
return guessRequestScheme(req, "https") + "://" + host + setting.AppSubURL + "/"
} else if req.Host != "" {
// if it is not behind a reverse proxy, use the scheme from config options, meanwhile use "https" as much as possible
defaultScheme := util.Iif(setting.Protocol == "http", "http", "https")
return guessRequestScheme(req, defaultScheme) + "://" + req.Host + setting.AppSubURL + "/"
}
return setting.AppURL
}
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)))
}