Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/api4/image.go

@@ -0,0 +1,46 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package api4
+
+import (
+	"net/http"
+	"net/url"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+)
+
+func (api *API) InitImage() {
+	api.BaseRoutes.Image.Handle("", api.APISessionRequiredTrustRequester(getImage)).Methods("GET")
+}
+
+func getImage(c *Context, w http.ResponseWriter, r *http.Request) {
+	actualURL := r.URL.Query().Get("url")
+	parsedURL, err := url.Parse(actualURL)
+	if err != nil {
+		c.Err = model.NewAppError("getImage", "api.image.get.app_error", nil, err.Error(), http.StatusBadRequest)
+		return
+	} else if parsedURL.Opaque != "" {
+		c.Err = model.NewAppError("getImage", "api.image.get.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+	siteURL, err := url.Parse(*c.App.Config().ServiceSettings.SiteURL)
+	if err != nil {
+		c.Err = model.NewAppError("getImage", "model.config.is_valid.site_url.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if parsedURL.Scheme == "" {
+		parsedURL.Scheme = siteURL.Scheme
+	}
+	if parsedURL.Host == "" {
+		parsedURL.Host = siteURL.Host
+	}
+
+	// in case image proxy is enabled and we are fetching a remote image (NOT static or served by plugins), pass request to proxy
+	if *c.App.Config().ImageProxySettings.Enable && parsedURL.Host != siteURL.Host {
+		c.App.ImageProxy().GetImage(w, r, parsedURL.String())
+	} else {
+		http.Redirect(w, r, parsedURL.String(), http.StatusFound)
+	}
+}