code.gitea.io/gitea@v1.19.3/modules/markup/camo.go (about)

     1  // Copyright 2022 The Gitea Authors. All rights reserved.
     2  // SPDX-License-Identifier: MIT
     3  
     4  package markup
     5  
     6  import (
     7  	"crypto/hmac"
     8  	"crypto/sha1"
     9  	"encoding/base64"
    10  	"net/url"
    11  	"strings"
    12  
    13  	"code.gitea.io/gitea/modules/setting"
    14  	"code.gitea.io/gitea/modules/util"
    15  )
    16  
    17  // CamoEncode encodes a lnk to fit with the go-camo and camo proxy links. The purposes of camo-proxy are:
    18  // 1. Allow accessing "http://" images on a HTTPS site by using the "https://" URLs provided by camo-proxy.
    19  // 2. Hide the visitor's real IP (protect privacy) when accessing external images.
    20  func CamoEncode(link string) string {
    21  	if strings.HasPrefix(link, setting.Camo.ServerURL) {
    22  		return link
    23  	}
    24  
    25  	mac := hmac.New(sha1.New, []byte(setting.Camo.HMACKey))
    26  	_, _ = mac.Write([]byte(link)) // hmac does not return errors
    27  	macSum := b64encode(mac.Sum(nil))
    28  	encodedURL := b64encode([]byte(link))
    29  
    30  	return util.URLJoin(setting.Camo.ServerURL, macSum, encodedURL)
    31  }
    32  
    33  func b64encode(data []byte) string {
    34  	return strings.TrimRight(base64.URLEncoding.EncodeToString(data), "=")
    35  }
    36  
    37  func camoHandleLink(link string) string {
    38  	if setting.Camo.Enabled {
    39  		lnkURL, err := url.Parse(link)
    40  		if err == nil && lnkURL.IsAbs() && !strings.HasPrefix(link, setting.AppURL) &&
    41  			(setting.Camo.Allways || lnkURL.Scheme != "https") {
    42  			return CamoEncode(link)
    43  		}
    44  	}
    45  	return link
    46  }