概述
上文提到3.1版本默認沒有使用Hsts，但是使用了這個中間件。看名字就很好理解，https跳轉，顧名思義，就是跳轉到
https地址。
使用場景，當用戶使用http訪問網站時，自動跳轉到https地址。這樣更加安全，不需要用戶特意輸入https://協議。
具體做了些我們一起來看看。
app.UseHttpsRedirection();
使用方法
跟Hsts一樣，HttpsRedirection默認是不需要注入的，除非你需要修改默認配置。
services.AddHttpsRedirection(config =>
{
//https地址的端口號，默認null
config.HttpsPort = 12345;
//跳轉響應的狀態碼，默認307
config.RedirectStatusCode = 302;
});
直接使用中間件即可
app.UseHttpsRedirection();
源碼解析
源代碼很簡單，只有兩個類：HttpsRedirectionOptions配置類，HttpsRedirectionMiddleware中間件
HttpsRedirectionOptions就只有兩個配置項
/// <summary>
/// Options for the HttpsRedirection middleware
/// </summary>
public class HttpsRedirectionOptions
{
/// <summary>
/// The status code used for the redirect response. The default is 307.
/// </summary>
public int RedirectStatusCode { get; set; } = StatusCodes.Status307TemporaryRedirect;
/// <summary>
/// The HTTPS port to be added to the redirected URL.
/// </summary>
/// <remarks>
/// If the HttpsPort is not set, we will try to get the HttpsPort from the following:
/// 1. HTTPS_PORT environment variable
/// 2. IServerAddressesFeature
/// If that fails then the middleware will log a warning and turn off.
/// </remarks>
public int? HttpsPort { get; set; }
}
重點看下中間件做了些什么。代碼量很少，大體是這些邏輯。
- 如果請求是Https，跳過本中間件
- 中間件會依次嘗試從這三個地方取端口號：HttpsRedirectionOptions的配置，HttpsRedirectionOptions，HTTPS_PORT環境變量或配置，IServerAddressesFeature(如果Webhost上綁定了https地址，本中間件能夠解析出來端口號)。
- 如果沒有解析出來https的端口號，則跳過本中間件。
- 如果能夠解析出來https端口號，則拼接出來https地址，返回307跳轉響應報文（或者配置的其他狀態碼）。
注：3.1同時支持HTTPS_PORT和ANCM_HTTPS_PORT這兩個環境變量。
https://docs.microsoft.com/en-us/dotnet/core/compatibility/2.2-3.0
public class HttpsRedirectionMiddleware
{
private const int PortNotFound = -1;
private readonly RequestDelegate _next;
private readonly Lazy<int> _httpsPort;
private readonly int _statusCode;
private readonly IServerAddressesFeature _serverAddressesFeature;
private readonly IConfiguration _config;
private readonly ILogger _logger;
/// <summary>
/// Initializes the HttpsRedirectionMiddleware
/// </summary>
/// <param name="next"></param>
/// <param name="options"></param>
/// <param name="config"></param>
/// <param name="loggerFactory"></param>
public HttpsRedirectionMiddleware(RequestDelegate next, IOptions<HttpsRedirectionOptions> options, IConfiguration config, ILoggerFactory loggerFactory)
{
_next = next ?? throw new ArgumentNullException(nameof(next));
_config = config ?? throw new ArgumentNullException(nameof(config));
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
var httpsRedirectionOptions = options.Value;
if (httpsRedirectionOptions.HttpsPort.HasValue)
{
_httpsPort = new Lazy<int>(() => httpsRedirectionOptions.HttpsPort.Value);
}
else
{
_httpsPort = new Lazy<int>(TryGetHttpsPort);
}
_statusCode = httpsRedirectionOptions.RedirectStatusCode;
_logger = loggerFactory.CreateLogger<HttpsRedirectionMiddleware>();
}
/// <summary>
/// Initializes the HttpsRedirectionMiddleware
/// </summary>
/// <param name="next"></param>
/// <param name="options"></param>
/// <param name="config"></param>
/// <param name="loggerFactory"></param>
/// <param name="serverAddressesFeature">The</param>
public HttpsRedirectionMiddleware(RequestDelegate next, IOptions<HttpsRedirectionOptions> options, IConfiguration config, ILoggerFactory loggerFactory,
IServerAddressesFeature serverAddressesFeature)
: this(next, options, config, loggerFactory)
{
_serverAddressesFeature = serverAddressesFeature ?? throw new ArgumentNullException(nameof(serverAddressesFeature));
}
/// <summary>
/// Invokes the HttpsRedirectionMiddleware
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
public Task Invoke(HttpContext context)
{
if (context.Request.IsHttps)
{
return _next(context);
}
var port = _httpsPort.Value;
if (port == PortNotFound)
{
return _next(context);
}
var host = context.Request.Host;
if (port != 443)
{
host = new HostString(host.Host, port);
}
else
{
host = new HostString(host.Host);
}
var request = context.Request;
var redirectUrl = UriHelper.BuildAbsolute(
"https",
host,
request.PathBase,
request.Path,
request.QueryString);
context.Response.StatusCode = _statusCode;
context.Response.Headers[HeaderNames.Location] = redirectUrl;
_logger.RedirectingToHttps(redirectUrl);
return Task.CompletedTask;
}
// Returns PortNotFound (-1) if we were unable to determine the port.
private int TryGetHttpsPort()
{
// The IServerAddressesFeature will not be ready until the middleware is Invoked,
// Order for finding the HTTPS port:
// 1. Set in the HttpsRedirectionOptions
// 2. HTTPS_PORT environment variable
// 3. IServerAddressesFeature
// 4. Fail if not sets
var nullablePort = _config.GetValue<int?>("HTTPS_PORT") ?? _config.GetValue<int?>("ANCM_HTTPS_PORT");
if (nullablePort.HasValue)
{
var port = nullablePort.Value;
_logger.PortLoadedFromConfig(port);
return port;
}
if (_serverAddressesFeature == null)
{
_logger.FailedToDeterminePort();
return PortNotFound;
}
foreach (var address in _serverAddressesFeature.Addresses)
{
var bindingAddress = BindingAddress.Parse(address);
if (bindingAddress.Scheme.Equals("https", StringComparison.OrdinalIgnoreCase))
{
// If we find multiple different https ports specified, throw
if (nullablePort.HasValue && nullablePort != bindingAddress.Port)
{
_logger.FailedMultiplePorts();
return PortNotFound;
}
else
{
nullablePort = bindingAddress.Port;
}
}
}
if (nullablePort.HasValue)
{
var port = nullablePort.Value;
_logger.PortFromServer(port);
return port;
}
_logger.FailedToDeterminePort();
return PortNotFound;
}
}
OK，完成了。