Add updates module and fix issues

updates/fetch.go

@@ -0,0 +1,122 @@
+package updates
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"time"
+
+	"github.com/google/renameio"
+
+	"github.com/Safing/portbase/log"
+)
+
+var (
+	updateURLs = []string{
+		"https://updates.safing.io",
+	}
+)
+
+func fetchFile(realFilepath, updateFilepath string, tries int) error {
+	// backoff when retrying
+	if tries > 0 {
+		time.Sleep(time.Duration(tries*tries) * time.Second)
+	}
+
+	// create URL
+	downloadURL, err := joinURLandPath(updateURLs[tries%len(updateURLs)], updateFilepath)
+	if err != nil {
+		return fmt.Errorf("error build url (%s + %s): %s", updateURLs[tries%len(updateURLs)], updateFilepath, err)
+	}
+
+	// create destination dir
+	dirPath := filepath.Dir(realFilepath)
+	err = os.MkdirAll(dirPath, 0755)
+	if err != nil {
+		return fmt.Errorf("updates: could not create updates folder: %s", dirPath)
+	}
+
+	// open file for writing
+	atomicFile, err := renameio.TempFile(filepath.Join(updateStoragePath, "tmp"), realFilepath)
+	if err != nil {
+		return fmt.Errorf("updates: could not create temp file for download: %s", err)
+	}
+	defer atomicFile.Cleanup()
+
+	// start file download
+	resp, err := http.Get(downloadURL)
+	if err != nil {
+		return fmt.Errorf("error fetching url (%s): %s", downloadURL, err)
+	}
+	defer resp.Body.Close()
+
+	// download and write file
+	n, err := io.Copy(atomicFile, resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed downloading %s: %s", downloadURL, err)
+	}
+	if resp.ContentLength != n {
+		return fmt.Errorf("download unfinished, written %d out of %d bytes.", n, resp.ContentLength)
+	}
+
+	// finalize file
+	err = atomicFile.CloseAtomicallyReplace()
+	if err != nil {
+		return fmt.Errorf("updates: failed to finalize file %s: %s", realFilepath, err)
+	}
+	// set permissions
+	err = os.Chmod(realFilepath, 0644)
+	if err != nil {
+		log.Warningf("updates: failed to set permissions on downloaded file %s: %s", realFilepath, err)
+	}
+
+	log.Infof("update: fetched %s (stored to %s)", downloadURL, realFilepath)
+	return nil
+}
+
+func fetchData(downloadPath string, tries int) ([]byte, error) {
+	// backoff when retrying
+	if tries > 0 {
+		time.Sleep(time.Duration(tries*tries) * time.Second)
+	}
+
+	// create URL
+	downloadURL, err := joinURLandPath(updateURLs[tries%len(updateURLs)], downloadPath)
+	if err != nil {
+		return nil, fmt.Errorf("error build url (%s + %s): %s", updateURLs[tries%len(updateURLs)], downloadPath, err)
+	}
+
+	// start file download
+	resp, err := http.Get(downloadURL)
+	if err != nil {
+		return nil, fmt.Errorf("error fetching url (%s): %s", downloadURL, err)
+	}
+	defer resp.Body.Close()
+
+	// download and write file
+	buf := bytes.NewBuffer(make([]byte, 0, resp.ContentLength))
+	n, err := io.Copy(buf, resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed downloading %s: %s", downloadURL, err)
+	}
+	if resp.ContentLength != n {
+		return nil, fmt.Errorf("download unfinished, written %d out of %d bytes.", n, resp.ContentLength)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func joinURLandPath(baseURL, urlPath string) (string, error) {
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return "", err
+	}
+
+	u.Path = path.Join(u.Path, urlPath)
+	return u.String(), nil
+}