HttpWebRequest在代碼中拋出異常但不是瀏覽器

Question

我目前正在編寫一個從銷售點系統的Web界面獲取數據的API。到目前爲止，我沒有任何問題登錄並生成報告以獲取數據，直到出現這種情況。

一般來說，我可以使用下面的方法返回一個HttpWebRequest對象，這個對象可以處理大多數請求到Web服務器的技巧。

private HttpWebRequest DefaultRequestObject(string path) 
{ 
    var request = (HttpWebRequest)WebRequest.Create(_baseUrl + path); 
    request.Method = "GET"; 
    request.Host = _baseUrl.Substring(8); // Cut off the https:// 
    request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0"; 
    request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"; 
    request.Headers.Add("Accept-Language", "en-US,en;q=0.5"); 
    request.Headers.Add("Accept-Encoding", "gzip, deflate"); 

    request.SendChunked = false; 
    request.AllowAutoRedirect = true; 

    request.ProtocolVersion = HttpVersion.Version11; 

    var sp = request.ServicePoint; 
    sp.Expect100Continue = false; 
    var prop = sp.GetType().GetProperty("HttpBehaviour", BindingFlags.Instance | BindingFlags.NonPublic); 
    prop.SetValue(sp, (byte)0, null); 

    request.CookieContainer = _cookieJar; 

    if (!String.IsNullOrEmpty(_cookieString)) 
     request.Headers.Add(HttpRequestHeader.Cookie, _cookieString); 

    return request; 
} 

當我發送一個GET請求，我用下面的方法：

public MgrngResponse GetContent(string serverPath, Dictionary<string, string> args) 
{ 
    if (!serverPath.StartsWith("/")) 
     serverPath = "/~pos/mgrng/" + serverPath; 

    var requestString = serverPath + "?" + HttpDataFormat(args); 
    var request = DefaultRequestObject(requestString); 

    try 
    { 
     var response = (HttpWebResponse)request.GetResponse(); 
     var mgrngResponse = new MgrngResponse(response); 

     if (!String.IsNullOrEmpty(mgrngResponse.HttpResponse.GetResponseHeader("Set-Cookie"))) 
      SaveMgrngResponseCookies(mgrngResponse); 

     _sessionExpiration = DateTime.Now.AddMinutes(15); 
     UpdateStatus(mgrngResponse.Content); 

     return mgrngResponse; 
    } 
    catch (WebException webException) 
    { 
     using (WebResponse response = webException.Response) 
     { 
      var httpResponse = (HttpWebResponse)response; 
      Console.WriteLine("Error code: {0}", httpResponse.StatusCode); 
      using (Stream data = response.GetResponseStream()) 
      using (var reader = new StreamReader(data)) 
      { 
       string text = reader.ReadToEnd(); 
       Console.WriteLine(text); 
      } 
     } 
     var eventArgs = new SessionUpdateEventArgs(SessionStatus.ConnectionError, "Unable to GET data"); 
     RaiseStatusChangeEvent(eventArgs); 
     return null; 
    } 
} 

這適用於所有到目前爲止，我已經嘗試了網頁，但我現在跑成當我嘗試獲取特定頁面的響應時出現新問題，該方法拋出一個帶有500內部服務器錯誤的WebException。

我用Fiddler來完全匹配瀏覽器的請求與我的（除了顯然的頭和cookie值的順序），但我仍然得到內部服務器錯誤。

以下是來自Fiddler的原始請求。第一個來自Firefox，第二個來自我的程序。

---

GET https://location.posprovider.com/~pos/mgrng/Report.php?boc_brand=7&csv_delimeter=csv_delimeter_comma&format=text&format1=csv&format1=txt&format1=pdf&format1=html HTTP/1.1 
Host: location.posprovider.com 
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0 
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 
Accept-Language: en-US,en;q=0.5 
Accept-Encoding: gzip, deflate 
Cookie: USER=af182fda473354eb3199522726ca61c9d5516c95f165cffd63b9522726ca61c9dc714cb52a46278e4399720706ea41e9dc714cb52a46278e4399720706ea41e9dc714cb52a46278e4399720706ea41e9dc714cb52a46278e4399720706ea41e9fc516c950a6607ae63b9522726ca61c9; PHPSESSID=9d7f54f9a1769a3e0572745fe0db3d97 
Connection: keep-alive 

---

GET https://location.posprovider.com/~pos/mgrng/Report.php?boc_brand=7&csv_delimeter=csv_delimeter_comma&format=text&format1=csv&format1=txt&format1=pdf&format1=html HTTP/1.1 
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0 
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 
Accept-Language: en-US,en;q=0.5 
Accept-Encoding: gzip, deflate 
Host: location.posprovider.com 
Cookie: PHPSESSID=16ad21c9d69fe85b3d185ab284f8620b; USER=30dca66f355e0ba89b6eda3c3e822ea24a95e5209e0f90bec94eda3c3e822ea243b5c500582b78cde96efa1c1ea20e8243b5c500582b78cde96efa1c1ea20e8243b5c500582b78cde96efa1c1ea20e8243b5c500582b78cde96efa1c1ea20e826395e520780b58edc94eda3c3e822ea2 
Connection: Keep-Alive 

---

我甚至嘗試登錄到Web界面，然後複製並粘貼我的生成請求字符串到瀏覽器中，我得到了所需的數據。

任何想法？

Answer 1

將您的節目請求拉入小提琴作曲家，並逐漸消除其餘的差異。你覺得怎麼做？

偉大的建議！顯然，我的cookie行有問題。 我複製並粘貼來自瀏覽器版本的cookie行到我的 ，它的工作。現在我只需要解決爲什麼我的餅乾不是 正確...

我同意這種診斷。誰知道服務器內部發生了什麼。可能有些脆弱的代碼需要非常精確的cookie字符串格式。