MM-14686 Send all image proxy requests through /api/v4/image (#10775)

* MM-14686 Implement /api/v4/image when proxy is disabled

* MM-14686 Send all image proxy requests through /api/v4/image

* Update unit tests

services/imageproxy/imageproxy.go

@@ -7,6 +7,8 @@ import (
 	"errors"
 	"io"
 	"net/http"
+	"net/url"
+	"strings"
 	"sync"
 
 	"github.com/mattermost/mattermost-server/mlog"
@@ -39,13 +41,6 @@ type ImageProxyBackend interface {
 
 	// GetImageDirect returns a proxied image along with its content type.
 	GetImageDirect(imageURL string) (io.ReadCloser, string, error)
-
-	// GetProxiedImageURL returns the URL to access a given image through the image proxy, whether the image proxy is
-	// running externally or as part of the Mattermost server itself.
-	GetProxiedImageURL(imageURL string) string
-
-	// GetUnproxiedImageURL returns the original URL of an image from one that has been directed at the image proxy.
-	GetUnproxiedImageURL(proxiedURL string) string
 }
 
 func MakeImageProxy(configService configservice.ConfigService, httpService httpservice.HTTPService, logger *mlog.Logger) *ImageProxy {
@@ -123,24 +118,36 @@ func (proxy *ImageProxy) GetImageDirect(imageURL string) (io.ReadCloser, string,
 // GetProxiedImageURL takes the URL of an image and returns a URL that can be used to view that image through the
 // image proxy.
 func (proxy *ImageProxy) GetProxiedImageURL(imageURL string) string {
-	proxy.lock.RLock()
-	defer proxy.lock.RUnlock()
+	return getProxiedImageURL(imageURL, *proxy.ConfigService.Config().ServiceSettings.SiteURL)
+}
 
-	if proxy.backend == nil {
+func getProxiedImageURL(imageURL, siteURL string) string {
+	if imageURL == "" || imageURL[0] == '/' || strings.HasPrefix(imageURL, siteURL) {
 		return imageURL
 	}
 
-	return proxy.backend.GetProxiedImageURL(imageURL)
+	return siteURL + "/api/v4/image?url=" + url.QueryEscape(imageURL)
 }
 
 // GetUnproxiedImageURL takes the URL of an image on the image proxy and returns the original URL of the image.
 func (proxy *ImageProxy) GetUnproxiedImageURL(proxiedURL string) string {
-	proxy.lock.RLock()
-	defer proxy.lock.RUnlock()
+	return getUnproxiedImageURL(proxiedURL, *proxy.ConfigService.Config().ServiceSettings.SiteURL)
+}
 
-	if proxy.backend == nil {
+func getUnproxiedImageURL(proxiedURL, siteURL string) string {
+	if !strings.HasPrefix(proxiedURL, siteURL+"/api/v4/image?url=") {
 		return proxiedURL
 	}
 
-	return proxy.backend.GetUnproxiedImageURL(proxiedURL)
+	parsed, err := url.Parse(proxiedURL)
+	if err != nil {
+		return proxiedURL
+	}
+
+	u := parsed.Query()["url"]
+	if len(u) == 0 {
+		return proxiedURL
+	}
+
+	return u[0]
 }