From b93ba7718cb58121ae791a9479b0466d05993eec Mon Sep 17 00:00:00 2001
From: Vladislav Yarmak <vladislav-ex-src@vm-0.com>
Date: Tue, 30 May 2023 21:43:36 +0300
Subject: [PATCH] improve chrome web store XML parsing

---
 extver.go | 14 ++++++++++++--
 main.go   |  2 +-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/extver.go b/extver.go
index 0002df4..397df6e 100644
--- a/extver.go
+++ b/extver.go
@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/xml"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -15,6 +16,10 @@ var (
 	defaultProdVersion = "113.0"
 )
 
+var (
+	ErrNoVerData = errors.New("no version data returned")
+)
+
 type StoreExtUpdateResponse struct {
 	XMLName xml.Name `xml:"gupdate"`
 	App     *struct {
@@ -85,7 +90,7 @@ func GetExtVer(ctx context.Context,
 	}
 
 	reader := io.LimitReader(resp.Body, 64*1024)
-	var respData StoreExtUpdateResponse
+	var respData *StoreExtUpdateResponse
 
 	dec := xml.NewDecoder(reader)
 	err = dec.Decode(&respData)
@@ -93,5 +98,10 @@ func GetExtVer(ctx context.Context,
 		return "", fmt.Errorf("unmarshaling of chrome web store response failed: %w", err)
 	}
 
-	return respData.App.UpdateCheck.Version, nil
+	if respData != nil && respData.App != nil &&
+		respData.App.UpdateCheck != nil && respData.App.UpdateCheck.Version != "" {
+		return respData.App.UpdateCheck.Version, nil
+	}
+
+	return "", ErrNoVerData
 }
diff --git a/main.go b/main.go
index 04158b9..fafc3a6 100644
--- a/main.go
+++ b/main.go
@@ -183,7 +183,7 @@ func run() int {
 		defer cl()
 		extVer, err := GetExtVer(ctx, nil, HolaExtStoreID, dialer)
 		if err != nil {
-			mainLogger.Critical("Can't detect latest API version. Try to specify -ext-ver parameter")
+			mainLogger.Critical("Can't detect latest API version. Try to specify -ext-ver parameter. Error: %v", err)
 			return 8
 		}
 		args.extVer = extVer