Implement OTS-CLI utility (#117)

cmd/ots-cli/cmd_fetch.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/Luzifer/ots/pkg/client"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+const storeFileMode = 0o600 // We assume the attached file to be a secret
+
+var fetchCmd = &cobra.Command{
+	Use:   "fetch url",
+	Short: "Retrieves a secret from the instance by its URL",
+	Long:  "",
+	Args:  cobra.ExactArgs(1),
+	RunE:  fetchRunE,
+}
+
+func init() {
+	fetchCmd.Flags().String("file-dir", ".", "Where to put files attached to the secret")
+	rootCmd.AddCommand(fetchCmd)
+}
+
+func checkDirWritable(dir string) error {
+	tmpFile := path.Join(dir, ".ots-cli.tmp")
+	if err := os.WriteFile(tmpFile, []byte(""), storeFileMode); err != nil {
+		return fmt.Errorf("writing tmp-file: %w", err)
+	}
+	defer os.Remove(tmpFile) //nolint:errcheck // We don't really care
+
+	return nil
+}
+
+func fetchRunE(cmd *cobra.Command, args []string) error {
+	fileDir, err := cmd.Flags().GetString("file-dir")
+	if err != nil {
+		return fmt.Errorf("getting file-dir parameter: %w", err)
+	}
+
+	// First lets check whether we potentially can write files
+	if err := checkDirWritable(fileDir); err != nil {
+		return fmt.Errorf("checking for directory write: %w", err)
+	}
+
+	logrus.Info("fetching secret...")
+	secret, err := client.Fetch(args[0])
+	if err != nil {
+		return fmt.Errorf("fetching secret")
+	}
+
+	for _, f := range secret.Attachments {
+		logrus.WithField("file", f.Name).Info("storing file...")
+		if err = storeAttachment(fileDir, f); err != nil {
+			return fmt.Errorf("saving file to disk: %w", err)
+		}
+	}
+
+	fmt.Println(secret.Secret) //nolint:forbidigo // Output intended for STDOUT
+
+	return nil
+}
+
+func storeAttachment(dir string, f client.SecretAttachment) error {
+	// First lets find a free file name to save the file as
+	var (
+		fileNameFragments = strings.SplitN(f.Name, ".", 2) //nolint:gomnd
+		i                 int
+		storeName         = path.Join(dir, f.Name)
+		storeNameTpl      string
+	)
+
+	if len(fileNameFragments) == 1 {
+		storeNameTpl = fmt.Sprintf("%s (%%d)", fileNameFragments[0])
+	} else {
+		storeNameTpl = fmt.Sprintf("%s (%%d).%s", fileNameFragments[0], fileNameFragments[1])
+	}
+
+	for _, err := os.Stat(storeName); !errors.Is(err, fs.ErrNotExist); _, err = os.Stat(storeName) {
+		i++
+		storeName = fmt.Sprintf(storeNameTpl, i)
+	}
+
+	// So we finally found a filename we can use
+	if err := os.WriteFile(storeName, f.Content, storeFileMode); err != nil {
+		return fmt.Errorf("writing file: %w", err)
+	}
+
+	return nil
+}