/// <summary>
/// Removes and returns the current header value by first checking the HttpResponse
/// and falling back to the value from HttpResponseMessage or HttpContent only if
/// <see cref="ResponseTransformContext.HeadersCopied"/> is not set.
/// This ordering allows multiple transforms to mutate the same header.
/// </summary>
/// <param name="context">The transform context.</param>
/// <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(ResponseTransformContext context, string headerName)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
if (string.IsNullOrEmpty(headerName))
{
throw new ArgumentException($"'{nameof(headerName)}' cannot be null or empty.", nameof(headerName));
}
if (context.HttpContext.Response.Headers.TryGetValue(headerName, out var existingValues))
{
context.HttpContext.Response.Headers.Remove(headerName);
}
else if (context.ProxyResponse is { } proxyResponse&& !context.HeadersCopied)
{
if (!RequestUtilities.TryGetValues(proxyResponse.Headers, headerName, out existingValues))
{
RequestUtilities.TryGetValues(proxyResponse.Content.Headers, headerName, out existingValues);
}
}
return(existingValues);
}
/// <summary>
/// Removes and returns the current trailer value by first checking the HttpResponse
/// and falling back to the value from HttpResponseMessage only if
/// <see cref="ResponseTrailersTransformContext.HeadersCopied"/> is not set.
/// This ordering allows multiple transforms to mutate the same header.
/// </summary>
/// <param name="context">The transform context.</param>
/// <param name="headerName">The name of the header to take.</param>
/// <returns>The response header value, or StringValues.Empty if none.</returns>
public static StringValues TakeHeader(ResponseTrailersTransformContext context, string headerName)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
if (string.IsNullOrEmpty(headerName))
{
throw new ArgumentException($"'{nameof(headerName)}' cannot be null or empty.", nameof(headerName));
}
Debug.Assert(context.ProxyResponse is not null);
var responseTrailersFeature = context.HttpContext.Features.Get <IHttpResponseTrailersFeature>();
var responseTrailers = responseTrailersFeature?.Trailers;
// Support should have already been checked by the caller.
Debug.Assert(responseTrailers is not null);
Debug.Assert(!responseTrailers.IsReadOnly);
if (responseTrailers.TryGetValue(headerName, out var existingValues))
{
responseTrailers.Remove(headerName);
}
else if (!context.HeadersCopied)
{
RequestUtilities.TryGetValues(context.ProxyResponse.TrailingHeaders, headerName, out existingValues);
}
return(existingValues);
}
public void TryGetValues(params string[] headerValues)
{
var request = new HttpRequestMessage();
foreach (var value in headerValues)
{
request.Headers.TryAddWithoutValidation("foo", value);
}
request.Headers.TryAddWithoutValidation("bar", headerValues);
Assert.True(RequestUtilities.TryGetValues(request.Headers, "foo", out var actualValues));
Assert.Equal(headerValues, actualValues);
Assert.True(RequestUtilities.TryGetValues(request.Headers, "bar", out actualValues));
Assert.Equal(headerValues, actualValues);
}
/// <summary>
/// Removes and returns the current header value by first checking the HttpRequestMessage,
/// then the HttpContent, and falling back to the HttpContext only if
/// <see cref="RequestTransformContext.HeadersCopied"/> is not set.
/// This ordering allows multiple transforms to mutate the same header.
/// </summary>
/// <param name="context">The transform context.</param>
/// <param name="headerName">The name of the header to take.</param>
/// <returns>The requested header value, or StringValues.Empty if none.</returns>
public static StringValues TakeHeader(RequestTransformContext context, string headerName)
{
if (string.IsNullOrEmpty(headerName))
{
throw new ArgumentException($"'{nameof(headerName)}' cannot be null or empty.", nameof(headerName));
}
var proxyRequest = context.ProxyRequest;
if (RequestUtilities.TryGetValues(proxyRequest.Headers, headerName, out var existingValues))
{
proxyRequest.Headers.Remove(headerName);
}
else if (proxyRequest.Content is { } content&& RequestUtilities.TryGetValues(content.Headers, headerName, out existingValues))
{
content.Headers.Remove(headerName);
}
private static void RestoreUpgradeHeaders(HttpContext context, HttpResponseMessage response)
{
// We don't use NonValidated for the Connection header as we do want value validation.
// HttpHeaders.TryGetValues will handle the parsing and split the values for us.
if (RequestUtilities.TryGetValues(response.Headers, HeaderNames.Upgrade, out var upgradeValues) &&
response.Headers.TryGetValues(HeaderNames.Connection, out var connectionValues))
{
foreach (var value in connectionValues)
{
if (value.Equals("upgrade", StringComparison.OrdinalIgnoreCase))
{
context.Response.Headers.TryAdd(HeaderNames.Connection, value);
context.Response.Headers.TryAdd(HeaderNames.Upgrade, upgradeValues);
break;
}
}
}
}
