服务器在写入响应头后关闭连接导致 HttpClient 异常

Question

我正在使用HttpClient通过PutAsync将数据放到HTTP服务器上。

当服务器返回错误代码（例如401 Unauthorized）时，它会关闭连接（在响应中提供Connection: close头）。此时，HttpClient会抛出System.Net.Http.HttpRequestException（在将内容复制到流中时出错），并列出以下内部异常。这似乎与写出数据有关（尽管它在BeginRead中），因为如果我说服服务器读取发送的所有数据，则不会引发异常。

我可以通过使用HttpClient.SendAsync执行相同任务，并使用HttpCompletionOption.ResponseHeadersRead参数来解决问题。在这种情况下，不会引发异常，我可以读取HttpResponseMessage.StatusCode。

我的问题是，这个异常正确吗？即服务器是否没有遵循关闭连接之前读取所有数据的标准？如果不是，那么PutAsync是否存在问题，因为它在这种情况下不允许访问返回的StatusCode？

示例代码：

using (FileStream stream = File.OpenRead(FilePath))
using (StreamContent content = new StreamContent(stream))
using (HttpRequestMessage req = new HttpRequestMessage
    {
        Method = HttpMethod.Put,
        RequestUri = new Uri(baseUri, Path),
        Content = content,
    })
using (HttpClient client = new HttpClient())
{
    req.Content.Headers.ContentType = new MediaTypeHeaderValue(FileContentType);
    // This version works:
    //using (HttpResponseMessage resp = await client.SendAsync(req,
    //    HttpCompletionOption.ResponseHeadersRead))
    // This version throws an exception:
    using (HttpResponseMessage resp = await client.PutAsync(
        new Uri(baseUri, Path), content))
    {
        if (resp.StatusCode == HttpStatusCode.Unauthorized)
        {
            // Try again with authorisation credentials based on resp.Headers.WwwAuthenticate
        }
    }
}

内部异常：System.IO.IOException（无法从传输连接中读取数据：远程主机强制关闭了现有的连接。）

at System.Net.Sockets.NetworkStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
at System.Net.PooledStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
at System.Net.ConnectStream.BeginReadWithoutValidation(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
at System.Net.ConnectStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state)
at System.Net.Http.StreamToStreamCopy.StartRead()

带有内部异常: System.Net.Sockets.SocketException（远程主机强制关闭了一个现有的连接）

at System.Net.Sockets.Socket.BeginReceive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags, AsyncCallback callback, Object state)
at System.Net.Sockets.NetworkStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)

- Nathan Phillips

Answer 1

如果符合您的需求，请尝试使用HTTP协议版本1.0：

using (HttpRequestMessage req = new HttpRequestMessage
    {
        Method = HttpMethod.Put,
        RequestUri = new Uri(baseUri, Path),
        Content = content,
        Version = HttpVersion.Version10
    })

- Oliver