Kestrel 在处理流量时抛出 "Invalid Host header" 错误

Question

我们最近将 ASP.NET MVC 5 应用程序迁移到了 ASP.NET Core 2.2。

一切似乎都运行良好，但我们经常收到以下异常（大约每秒 3 次，稍后会详细介绍）：

BadHttpRequestException: Invalid Host header: '~^appname.*$'
  Module "Microsoft.AspNetCore.Server.Kestrel.Core.BadHttpRequestException", line 0, col 0, in Throw
    Void Throw(Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.RequestRejectionReason, System.String)
  Module "Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Http1Connection", line 95, col 0, in EnsureHostHeaderExists
    Void EnsureHostHeaderExists()
  Module "Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Http1Connection", line 196, col 0, in TryParseRequest
    Boolean TryParseRequest(System.IO.Pipelines.ReadResult, Boolean ByRef)
  Module "Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol+<ProcessRequests>d__185`1", line 170, col 0, in MoveNext
    Void MoveNext()
  Module "System.Runtime.ExceptionServices.ExceptionDispatchInfo", line 12, col 0, in Throw
    Void Throw()
  Module "System.Runtime.CompilerServices.TaskAwaiter", line 46, col 0, in HandleNonSuccessAndDebuggerNotification
    Void HandleNonSuccessAndDebuggerNotification(System.Threading.Tasks.Task)
  Module "Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol+<ProcessRequestsAsync>d__184`1", line 135, col 0, in MoveNext
    Void MoveNext()

在咨询我们的运营团队成员后，很明显我们有三个 HAProxy 实例，它们大约每秒检查一次我们应用程序的每个节点。

对该应用程序的每个请求都将按如下方式流动：

HAProxy -> Nginx -> Kestrel/ASP.NET Core 应用程序

我的问题是，我怎样才能确定这里发生了什么？

Answer 1

我猜你应该向那里传递一些有效的 Url、星号或正斜杠

负责解析的代码在这里https://github.com/aspnet/KestrelHttpServer/blob/b8a1c04ffbeee6c60a74766142ff3e2e6779d701/src/Kestrel.Core/Internal/Http/Http1Connection.cs

        public void OnStartLine(HttpMethod method, HttpVersion version, Span<byte> target, Span<byte> path, Span<byte> query, Span<byte> customMethod, bool pathEncoded)
        {
            Debug.Assert(target.Length != 0, "Request target must be non-zero length");

            var ch = target[0];
            if (ch == ByteForwardSlash)
            {
                // origin-form.
                // The most common form of request-target.
                // https://tools.ietf.org/html/rfc7230#section-5.3.1
                OnOriginFormTarget(method, version, target, path, query, customMethod, pathEncoded);
            }
            else if (ch == ByteAsterisk && target.Length == 1)
            {
                OnAsteriskFormTarget(method);
            }
            else if (target.GetKnownHttpScheme(out var scheme))
            {
                OnAbsoluteFormTarget(target, query);
            }
            else
            {
                // Assume anything else is considered authority form.
                // FYI: this should be an edge case. This should only happen when
                // a client mistakenly thinks this server is a proxy server.
                OnAuthorityFormTarget(method, target);
            }

            Method = method != HttpMethod.Custom
                ? HttpUtilities.MethodToString(method) ?? string.Empty
                : customMethod.GetAsciiStringNonNullCharacters();
            _httpVersion = version;

            Debug.Assert(RawTarget != null, "RawTarget was not set");
            Debug.Assert(Method != null, "Method was not set");
            Debug.Assert(Path != null, "Path was not set");
            Debug.Assert(QueryString != null, "QueryString was not set");
            Debug.Assert(HttpVersion != null, "HttpVersion was not set");
        }

例如，我们在 Host header 中发送 LoadBalancer 的主机，如 dc-lb.company-dc.lan，在你的场景中我猜它应该是你的 HAProxy 实例的主机名

Answer 2

当前版本的 Kestrel（我们使用 ASP.NET Core 2.2）不支持 HTTP 访问日志记录。

看到这个问题：Support access logging with Common Log Format/Extended Log Format

为了追查问题，我不得不让我们的运营团队查看我们的 nginx 日志（nginx 是我们正在使用的反向代理）以确定无效主机 header 的请求来自何处.

问题原来是 mal-configured 状态检查应用程序。

Kestrel 在处理流量时抛出 "Invalid Host header" 错误

Kestrel throwing "Invalid Host header" error while serving traffic

kestrel-http-server

asp.net-core