public override async Task TransformResponseTrailersAsync(HttpContext httpContext, HttpResponseMessage proxyResponse)
{
if (ShouldCopyResponseTrailers.GetValueOrDefault(true))
{
await base.TransformResponseTrailersAsync(httpContext, proxyResponse);
}
if (ResponseTrailerTransforms.Count == 0)
{
return;
}
// Only run the transforms if trailers are actually supported by the client response.
var responseTrailersFeature = httpContext.Features.Get <IHttpResponseTrailersFeature>();
var outgoingTrailers = responseTrailersFeature?.Trailers;
if (outgoingTrailers != null && !outgoingTrailers.IsReadOnly)
{
var transformContext = new ResponseTrailersTransformContext()
{
HttpContext = httpContext,
ProxyResponse = proxyResponse,
HeadersCopied = ShouldCopyResponseTrailers.GetValueOrDefault(true),
};
foreach (var responseTrailerTransform in ResponseTrailerTransforms)
{
await responseTrailerTransform.ApplyAsync(transformContext);
}
}
}
/// <summary>
/// Sets the given trailer on the HttpResponse.
/// </summary>
public static void SetHeader(ResponseTrailersTransformContext context, string headerName, StringValues values)
{
var responseTrailersFeature = context.HttpContext.Features.Get <IHttpResponseTrailersFeature>();
var responseTrailers = responseTrailersFeature.Trailers;
// Support should have already been checked by the caller.
Debug.Assert(responseTrailers != null);
Debug.Assert(!responseTrailers.IsReadOnly);
responseTrailers[headerName] = values;
}
public async Task AddResponseTrailer_Success(string startValue, int status, string value, bool append, bool always, string expected)
{
var httpContext = new DefaultHttpContext();
var trailerFeature = new TestTrailersFeature();
httpContext.Features.Set <IHttpResponseTrailersFeature>(trailerFeature);
trailerFeature.Trailers["name"] = startValue.Split(";", System.StringSplitOptions.RemoveEmptyEntries);
httpContext.Response.StatusCode = status;
var transformContext = new ResponseTrailersTransformContext()
{
HttpContext = httpContext,
ProxyResponse = new HttpResponseMessage(),
HeadersCopied = true,
};
var transform = new ResponseTrailerValueTransform("name", value, append, always);
await transform.ApplyAsync(transformContext);
Assert.Equal(expected.Split(";", System.StringSplitOptions.RemoveEmptyEntries), trailerFeature.Trailers["name"]);
}
// Assumes the response status code has been set on the HttpContext already.
/// <inheritdoc/>
public override ValueTask ApplyAsync(ResponseTrailersTransformContext context)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
if (Always || Success(context))
{
var existingHeader = TakeHeader(context, HeaderName);
if (Append)
{
var value = StringValues.Concat(existingHeader, Value);
SetHeader(context, HeaderName, value);
}
else if (!string.IsNullOrEmpty(Value))
{
SetHeader(context, HeaderName, Value);
}
// If the given value is empty, any existing header is removed.
}
return(default);
/// <summary>
/// Removes and returns the current trailer value by first checking the HttpResponse
/// and falling back to the value from HttpResponseMessage only if
/// <see cref="ResponseTrailersTransformContext.HeadersCopied"/> is not set.
/// This ordering allows multiple transforms to mutate the same header.
/// </summary>
/// <param name="headerName">The name of the header to take.</param>
/// <returns>The response header value, or StringValues.Empty if none.</returns>
public static StringValues TakeHeader(ResponseTrailersTransformContext context, string headerName)
{
var existingValues = StringValues.Empty;
var responseTrailersFeature = context.HttpContext.Features.Get <IHttpResponseTrailersFeature>();
var responseTrailers = responseTrailersFeature.Trailers;
// Support should have already been checked by the caller.
Debug.Assert(responseTrailers != null);
Debug.Assert(!responseTrailers.IsReadOnly);
if (responseTrailers.TryGetValue(headerName, out var responseValues))
{
responseTrailers.Remove(headerName);
existingValues = responseValues;
}
else if (!context.HeadersCopied &&
context.ProxyResponse.TrailingHeaders.TryGetValues(headerName, out var values))
{
existingValues = (string[])values;
}
return(existingValues);
}
/// <inheritdoc/>
public override ValueTask ApplyAsync(ResponseTrailersTransformContext context)
{
return(_func(context));
}
/// <summary> /// Transforms the given response trailers. The trailers will have (optionally) already been /// copied to the <see cref="HttpResponse"/> and any changes should be made there. /// </summary> public abstract Task ApplyAsync(ResponseTrailersTransformContext context);
private static bool Success(ResponseTrailersTransformContext context)
{
// TODO: How complex should this get? Compare with http://nginx.org/en/docs/http/ngx_http_headers_module.html#add_header
return(context.HttpContext.Response.StatusCode < 400);
}