[英]Implement Digest authentication via HttpWebRequest in C#
有誰知道如何篩選使用摘要式 http 身份驗證的抓取網站? 我使用這樣的代碼:
var request = (HttpWebRequest)WebRequest.Create(SiteUrl);
request.Credentials=new NetworkCredential(Login, Password)
我能夠訪問該站點的主頁,但是當我嘗試瀏覽任何其他頁面(使用具有相同憑據的另一個請求)時,我收到“HTTP/1.1 400 錯誤請求”錯誤。
我使用 Fiddler 將我的 C# 應用程序的請求與 Mozilla Firefox 請求進行比較。
我嘗試訪問的 2 個 URL 是: https://mysiteurl/forum/index.php https://mysiteurl/forum/viewforum.php?f=4&sid=d104363e563968b4e4c07e04f4a15203
這是我的 C# 應用程序的 2 個請求 ():
Authorization: Digest username="xxx",realm="abc",nonce="NXa26+NjBAA=747dfd1776c9d585bd388377ef3160f1ff265429",uri="/forum/index.php",algorithm="MD5",cnonce="89179bf17dd27785aa1c88ad976817c9",nc=00000001,qop="auth",response="3088821620d9cbbf71e775fddbacfb6d"
Authorization: Digest username="xxx",realm="abc",nonce="1h7T6+NjBAA=4fed4d804d0edcb54bf4c2f912246330d96afa76",uri="/forum/viewforum.php",algorithm="MD5",cnonce="bb990b0516a371549401c0289fbacc7c",nc=00000001,qop="auth",response="1ddb95a45fd7ea8dbefd37a2db705e3a"
這就是 Firefox 發送到服務器的內容:
Authorization: Digest username="xxx", realm="abc", nonce="T9ICNeRjBAA=4fbb28d42db044e182116ac27176e81d067a313c", uri="/forum/", algorithm=MD5, response="33f29dcc5d70b61be18eaddfca9bd601", qop=auth, nc=00000001, cnonce="ab96bbe39d8d776d"
Authorization: Digest username="xxx", realm="abc", nonce="T9ICNeRjBAA=4fbb28d42db044e182116ac27176e81d067a313c", uri="/forum/viewforum.php?f=4&sid=d104363e563968b4e4c07e04f4a15203", algorithm=MD5, response="a996dae9368a79d49f2f29ea7a327cd5", qop=auth, nc=00000002, cnonce="e233ae90908860e1"
所以在我的應用程序中,我在“nonce”字段中有不同的值,而在 Firefox 中這個字段是相同的。 另一方面,我在“nc”字段中有相同的值,而 Firefox 會增加這個字段。
此外,當我的應用程序嘗試訪問 Fiddler 中的站點頁面時,我可以看到它總是收到響應“HTTP/1.1 401 需要授權”,而 Firefox 僅授權一次。 我試圖設置 request.PreAuthenticate = true; 但是好像沒什么效果……
我的問題是:如何使用 C# 正確實現摘要認證? 是否有任何標准方法或我必須從頭開始? 提前致謝。
創建一個類 Digest.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Text.RegularExpressions;
using System.Net;
using System.IO;
namespace NUI
{
public class DigestAuthFixer
{
private static string _host;
private static string _user;
private static string _password;
private static string _realm;
private static string _nonce;
private static string _qop;
private static string _cnonce;
private static DateTime _cnonceDate;
private static int _nc;
public DigestAuthFixer(string host, string user, string password)
{
// TODO: Complete member initialization
_host = host;
_user = user;
_password = password;
}
private string CalculateMd5Hash(
string input)
{
var inputBytes = Encoding.ASCII.GetBytes(input);
var hash = MD5.Create().ComputeHash(inputBytes);
var sb = new StringBuilder();
foreach (var b in hash)
sb.Append(b.ToString("x2"));
return sb.ToString();
}
private string GrabHeaderVar(
string varName,
string header)
{
var regHeader = new Regex(string.Format(@"{0}=""([^""]*)""", varName));
var matchHeader = regHeader.Match(header);
if (matchHeader.Success)
return matchHeader.Groups[1].Value;
throw new ApplicationException(string.Format("Header {0} not found", varName));
}
private string GetDigestHeader(
string dir)
{
_nc = _nc + 1;
var ha1 = CalculateMd5Hash(string.Format("{0}:{1}:{2}", _user, _realm, _password));
var ha2 = CalculateMd5Hash(string.Format("{0}:{1}", "GET", dir));
var digestResponse =
CalculateMd5Hash(string.Format("{0}:{1}:{2:00000000}:{3}:{4}:{5}", ha1, _nonce, _nc, _cnonce, _qop, ha2));
return string.Format("Digest username=\"{0}\", realm=\"{1}\", nonce=\"{2}\", uri=\"{3}\", " +
"algorithm=MD5, response=\"{4}\", qop={5}, nc={6:00000000}, cnonce=\"{7}\"",
_user, _realm, _nonce, dir, digestResponse, _qop, _nc, _cnonce);
}
public string GrabResponse(
string dir)
{
var url = _host + dir;
var uri = new Uri(url);
var request = (HttpWebRequest)WebRequest.Create(uri);
// If we've got a recent Auth header, re-use it!
if (!string.IsNullOrEmpty(_cnonce) &&
DateTime.Now.Subtract(_cnonceDate).TotalHours < 1.0)
{
request.Headers.Add("Authorization", GetDigestHeader(dir));
}
HttpWebResponse response;
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (WebException ex)
{
// Try to fix a 401 exception by adding a Authorization header
if (ex.Response == null || ((HttpWebResponse)ex.Response).StatusCode != HttpStatusCode.Unauthorized)
throw;
var wwwAuthenticateHeader = ex.Response.Headers["WWW-Authenticate"];
_realm = GrabHeaderVar("realm", wwwAuthenticateHeader);
_nonce = GrabHeaderVar("nonce", wwwAuthenticateHeader);
_qop = GrabHeaderVar("qop", wwwAuthenticateHeader);
_nc = 0;
_cnonce = new Random().Next(123400, 9999999).ToString();
_cnonceDate = DateTime.Now;
var request2 = (HttpWebRequest)WebRequest.Create(uri);
request2.Headers.Add("Authorization", GetDigestHeader(dir));
response = (HttpWebResponse)request2.GetResponse();
}
var reader = new StreamReader(response.GetResponseStream());
return reader.ReadToEnd();
}
}
}
現在在您的應用程序中,您可以使用以下代碼:
DigestAuthFixer digest = new DigestAuthFixer(url, username, password);
string strReturn = digest.GrabResponse(url);
來自4GuysFromRolla的這篇文章似乎是您正在尋找的:
我目前正在觀察同樣的問題,盡管我正在測試的網絡服務器是我自己的。 服務器日志顯示:
Digest: uri mismatch - </var/path/some.jpg> does not match request-uri
</var/path/some.jpg?parameter=123456789>
我嘗試從 URL 中刪除參數(因為這似乎有所不同),但錯誤仍然像以前一樣發生。
我的結論是 URL 參數也必須包含在摘要哈希中,並且HttpWebRequest
出於某種原因將其刪除。
基於@kitwalker 的出色工作,這是我為 DotNetCore 3 編寫的委托處理程序。
/// <summary>
/// Respond to a Digest auth challenge and retry the request.
/// See <c>https://en.wikipedia.org/wiki/Digest_access_authentication</c>.
/// </summary>
/// <example>
/// Example response header with challenge details:
/// header: www-authenticate
/// value: <c>Digest realm="Signaling Controller", charset="UTF-8", algorithm=MD5, nonce="6088c71a:a699df7b2e03c53cfe06f8d070f4345c", qop="auth"</c>
/// </example>
public class DigestAuthenticationHandler : DelegatingHandler
{
private readonly ILogger _logger;
private readonly CredentialSettings _settings;
public DigestAuthenticationHandler(ILogger<DigestAuthenticationHandler> logger, CredentialSettings settings)
{
_logger = logger;
_settings = settings;
}
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
CancellationToken cancellationToken)
{
var username = _settings?.Username;
var password = _settings?.Password;
if (string.IsNullOrEmpty(username))
{
throw new ArgumentNullException(nameof(username), "Missing credentials.");
}
if (string.IsNullOrEmpty(password))
{
throw new ArgumentNullException(nameof(password), "Missing credentials.");
}
var response = await base.SendAsync(request, cancellationToken);
if (response.StatusCode == HttpStatusCode.Unauthorized)
{
var header = response.Headers.WwwAuthenticate;
var value = header.FirstOrDefault();
_logger.LogDebug("Challenged with scheme: '{Scheme}'", value?.Scheme ?? "(unknown)");
if (string.Compare(value?.Scheme, "Digest", StringComparison.OrdinalIgnoreCase) != 0)
{
_logger.LogDebug("Authentication challenge is not of type 'Digest' - give up");
return response;
}
var details = new DigestAuthenticationDetails(value?.Parameter);
_logger.LogDebug("Authentication challenge details: {Details}", details);
var qop = details["qop"];
var realm = details["realm"];
var nonce = details["nonce"];
var algorithm = details["algorithm"];
if (algorithm != "MD5")
{
_logger.LogError("Algorithm '{Algorithm}' unsupported; cannot respond to Digest auth challenge - give up", algorithm);
return response;
}
var cnonce = new Random().Next(123400, 9999999).ToString();
var nc = 1;
var uri = request.RequestUri.PathAndQuery;
var digest = BuildDigestHeader(username, password, request.Method, uri, realm, algorithm, nonce, cnonce, qop, nc);
request.Headers.Add("Authorization", digest);
var retry = await base.SendAsync(request, cancellationToken);
return retry;
}
return response;
}
private static string BuildDigestHeader(
string username,
string password,
HttpMethod method,
string uri,
string realm,
string algorithm,
string nonce,
string cnonce,
string qop,
int nc)
{
static string CalculateMd5Hash(string input)
{
var bytes = Encoding.ASCII.GetBytes(input);
var hash = MD5.Create().ComputeHash(bytes);
var builder = new StringBuilder();
foreach (var b in hash)
{
builder.Append(b.ToString("x2"));
}
return builder.ToString();
}
var ha1 = CalculateMd5Hash($"{username}:{realm}:{password}");
var ha2 = CalculateMd5Hash($"{method}:{uri}");
var digestResponse = CalculateMd5Hash($"{ha1}:{nonce}:{nc:00000000}:{cnonce}:{qop}:{ha2}");
return "Digest "
+ $"username=\"{username}\", "
+ $"realm=\"{realm}\", "
+ $"nonce=\"{nonce}\", "
+ $"uri=\"{uri}\", "
+ $"algorithm=\"{algorithm}\", "
+ $"response=\"{digestResponse}\", "
+ $"qop={qop}, "
+ $"nc={nc:00000000}, "
+ $"cnonce=\"{cnonce}\"";
}
private class DigestAuthenticationDetails
{
private readonly Dictionary<string, string?> _values;
public DigestAuthenticationDetails(string? authentication)
{
_values = new Dictionary<string, string?>();
if (authentication != null)
{
foreach (var pair in authentication.Split(","))
{
var item = pair.Split("=");
string? key = null;
string? value = null;
if (item.Length == 1)
{
key = item.ElementAt(0);
}
else
{
key = item.ElementAt(0);
value = item.ElementAt(1);
}
key = key
.Trim()
.Replace("\"", "")
.Replace("'", "")
.ToLower();
value = value
?.Trim()
.Replace("\"", "")
.Replace("'", "");
_values.Add(key, value);
}
}
}
public string this[string key] => GetValueOrThrow(key);
public override string ToString()
{
var builder = new StringBuilder();
foreach (var (key, value) in _values)
{
builder.Append($"'{key}'='{value}' ");
}
return builder.ToString();
}
private string GetValueOrThrow(string key)
{
if (_values.TryGetValue(key, out var value))
{
if (value != null)
{
return value;
}
throw new ArgumentNullException(nameof(value), $"No value for key '{key}'.");
}
throw new ArgumentOutOfRangeException(nameof(key), $"Key '{key}' was not found in Digest auth challenge.");
}
}
}
然后,無論您在何處注冊服務,都將委托處理程序添加到需要摘要身份驗證功能的HttpClient
中:
services.AddTransient<DigestAuthenticationHandler>();
services.AddHttpClient<ServiceThatNeedsHttpClient>()
.AddHttpMessageHandler<DigestAuthenticationHandler>();
注意:不支持緩存以前使用的摘要標頭。
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