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/app/download.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/pkg/errors"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/server/channels/utils"
+)
+
+const (
+	// HTTPRequestTimeout defines a high timeout for downloading large files
+	// from an external URL to avoid slow connections from failing to install.
+	HTTPRequestTimeout = 1 * time.Hour
+)
+
+func (a *App) DownloadFromURL(downloadURL string) ([]byte, error) {
+	return a.Srv().downloadFromURL(downloadURL)
+}
+
+func (s *Server) downloadFromURL(downloadURL string) ([]byte, error) {
+	if !model.IsValidHTTPURL(downloadURL) {
+		return nil, errors.Errorf("invalid url %s", downloadURL)
+	}
+
+	u, err := url.ParseRequestURI(downloadURL)
+	if err != nil {
+		return nil, errors.Errorf("failed to parse url %s", downloadURL)
+	}
+	if !*s.platform.Config().PluginSettings.AllowInsecureDownloadURL && u.Scheme != "https" {
+		return nil, errors.Errorf("insecure url not allowed %s", downloadURL)
+	}
+
+	client := s.HTTPService().MakeClient(true)
+	client.Timeout = HTTPRequestTimeout
+
+	var resp *http.Response
+	err = utils.ProgressiveRetry(func() error {
+		resp, err = client.Get(downloadURL)
+
+		if err != nil {
+			return errors.Wrapf(err, "failed to fetch from %s", downloadURL)
+		}
+
+		if !(resp.StatusCode >= 200 && resp.StatusCode < 300) {
+			_, _ = io.Copy(io.Discard, resp.Body)
+			_ = resp.Body.Close()
+			return errors.Errorf("failed to fetch from %s", downloadURL)
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "download failed after multiple retries.")
+	}
+
+	defer resp.Body.Close()
+
+	return io.ReadAll(resp.Body)
+}