Override host of webapi odata links

Question

I\'m using WebAPI 2.2 and Microsoft.AspNet.OData 5.7.0 to create an OData service that supports paging.

When hosted in the production environment, the WebAPI lives o

Answer 1

The answer by lencharest is promising, but I found an improvement on his method. Rather than using the UrlHelper, I created a class derived from System.Net.Http.DelegatingHandler. This class is inserted (first) into the message handling pipeline and thus has a crack at altering the incoming HttpRequestMessage. It's an improvement over the above solution because in addition to altering the controller-specific URLs (as the UrlHelper does, e,g, https://data.contoso.com/odata/MyController), it also alters the url that appears as the xml:base in the OData service document (e.g., https://data.contoso.com/odata).

My particular application was to host an OData service behind a proxy server, and I wanted all the URLs presented by the server to be the externally-visible URLs, not the internally-visible ones. And, I didn't want to have to rely on annotations for this; I wanted it to be fully automatic.

The message handler looks like this:

    public class BehindProxyMessageHandler : DelegatingHandler
    {
        protected async override Task SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
        {
            var builder = new UriBuilder(request.RequestUri);
            var visibleHost = builder.Host;
            var visibleScheme = builder.Scheme;
            var visiblePort = builder.Port;

            if (request.Headers.Contains("X-Forwarded-Host"))
            {
                string[] forwardedHosts = request.Headers.GetValues("X-Forwarded-Host").First().Split(new char[] { ',' });
                visibleHost = forwardedHosts[0].Trim();
            }

            if (request.Headers.Contains("X-Forwarded-Proto"))
            {
                visibleScheme = request.Headers.GetValues("X-Forwarded-Proto").First();
            }

            if (request.Headers.Contains("X-Forwarded-Port"))
            {
                try
                {
                    visiblePort = int.Parse(request.Headers.GetValues("X-Forwarded-Port").First());
                }
                catch (Exception)
                { }
            }

            builder.Host = visibleHost;
            builder.Scheme = visibleScheme;
            builder.Port = visiblePort;

            request.RequestUri = builder.Uri;
            var response = await base.SendAsync(request, cancellationToken);
            return response;
        }
    }

You wire the handler up in WebApiConfig.cs:

    config.Routes.MapODataServiceRoute(
        routeName: "odata",
        routePrefix: "odata",
        model: builder.GetEdmModel(),
        pathHandler: new DefaultODataPathHandler(),
        routingConventions: ODataRoutingConventions.CreateDefault()
    );
    config.MessageHandlers.Insert(0, new BehindProxyMessageHandler());