URL rewrite for https and www in ASPNET Core (Solved)

If you want to url rewrite to both https and www using ASP.NET Core 2.0, here is some pretty straight-forward C# you can add to your Startup.cs.

Woo-hoo!

// ...

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        // ...
    }
    else
    {
        // url rewrite; do this before UseStaticFiles
        var options = new RewriteOptions().Add(
            new RedirectRules(rewriteHttps: true, rewriteWww: true));
        app.UseRewriter(options);
    }

    // ...
}

// ...

public class RedirectRules : Microsoft.AspNetCore.Rewrite.IRule
{
    private readonly bool _rewriteHttps;
    private readonly bool _rewriteWww;

    public RedirectRules(bool rewriteHttps, bool rewriteWww)
    {
        _rewriteHttps = rewriteHttps;
        _rewriteWww = rewriteWww;
    }

    public void ApplyRule(RewriteContext context)
    {
        //
        // redirect two ways
        //    - http to https (if enabled)
        //    - non-www host to www host (if enabled)
        //

        const string hostRoot = "mydomain.com";
        var request = context.HttpContext.Request;
        var currentHost = request.Host;
        HostString newHost;

        // do we need to rewrite from http to https
        var isNewProtocol = _rewriteHttps && request.Scheme.ToLower() == "http";

        // do we need to rewrite from non-www host to www host
        if (_rewriteWww && currentHost.Host == hostRoot)
            newHost = new HostString($"www.{hostRoot}", currentHost.Port ?? 80);

        // if either rewrite done, create a new url
        if (isNewProtocol || newHost.HasValue)
        {
            var newUrl = new StringBuilder()
                .Append(isNewProtocol ? "https" : request.Scheme)
                .Append("://")
                .Append(newHost.HasValue ? newHost : currentHost)
                .Append(request.PathBase)
                .Append(request.Path)
                .Append(request.QueryString);
            context.HttpContext.Response.Redirect(newUrl.ToString(), permanent: true);
            context.Result = RuleResult.EndResponse;
        }
    }
}