.NET HTTP GET 请求问题（返回状态 200 OK 而不是 302 Found）答案

【问题标题】：.NET HTTP GET request problem (return state 200 OK instead of 302 Found).NET HTTP GET 请求问题（返回状态 200 OK 而不是 302 Found）
【发布时间】：2021-12-29 10:04:52
【问题描述】：

我正在运行以下代码，但收到的结果与从浏览器（例如 chrome）发出的调用不同。 .net 代码给我 200（OK），而 Chrome 302 带有重定向 url。谁能给我解释一下为什么？

System.Net.ServicePointManager.SecurityProtocol = Net.SecurityProtocolType.Tls12
Net.ServicePointManager.ServerCertificateValidationCallback = AddressOf certVerify

Dim client As New System.Net.Http.HttpClient
Dim requestMessage As New System.Net.Http.HttpRequestMessage
requestMessage.RequestUri = New Uri("https://iampe.agenziaentrate.gov.it/sam/UI/Logout?realm=/agenziaentrate")
requestMessage.Method = HttpMethod.Get
requestMessage.Headers.Accept.Add(New MediaTypeWithQualityHeaderValue("*/*"))
requestMessage.Headers.Host = "iampe.agenziaentrate.gov.it"
requestMessage.Headers.Add("Pragma", "no-cache")
requestMessage.Headers.Add("sec-ch-ua", """ Not A;Brand"";v=""99"", ""Chromium"";v=""96"", ""Google Chrome"";v=""96""")
requestMessage.Headers.Add("sec-ch-ua-mobile", "?0")
requestMessage.Headers.Add("sec-ch-ua-platform", """Windows""")
requestMessage.Headers.Add("Upgrade-Insecure-Requests", "1")
requestMessage.Headers.UserAgent.Add(New ProductInfoHeaderValue("ScraperBot", "1.0"))
requestMessage.Headers.Add("Accept", "*/*")
requestMessage.Headers.Add("Sec-Fetch-Site", "none")
requestMessage.Headers.Add("Sec-Fetch-Mode", "navigate")
requestMessage.Headers.Add("Sec-Fetch-User", "?1")
requestMessage.Headers.Add("Sec-Fetch-Dest", "document")
requestMessage.Headers.Add("Accept-Encoding", "gzip, deflate, br")
requestMessage.Headers.Add("Accept-Language", "it-IT,it;q=0.9")
Dim Risposta As System.Net.Http.HttpResponseMessage = client.SendAsync(requestMessage).Result



Public Function certVerify(se As Object, cert As System.Security.Cryptography.X509Certificates.X509Certificate, chain As System.Security.Cryptography.X509Certificates.X509Chain, sslerror As System.Net.Security.SslPolicyErrors)
        Return True
    End Function

enter image description here

【问题讨论】：

标签： .net httpclient tls1.2

【解决方案1】：

HttpClientHandler.AllowAutoRedirect 默认启用。 HttpClient 会自动跟随重定向并从重定向位置返回信息。

如果 AllowAutoRedirect 设置为 false，则所有 HTTP 状态代码为 300 到 399 的 HTTP 响应都将返回给应用程序。

我不是 VB 开发人员，因此无法真正向您展示如何在 VB 中执行此操作，但 docs page for HttpClientHandler 上的 C# 代码显示了如何通过在 HttpClientHandler 上传递一个实例来自定义 HttpClient 的行为。您应该能够根据自己的需要进行调整。

   // Create an HttpClientHandler that doesn't follow redirects
   HttpClientHandler handler = new HttpClientHandler();
   handler.AllowAutoRedirect = false;

   // Create an HttpClient object
   HttpClient client = new HttpClient(handler);

【讨论】：