proxy.cs

using System;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using System.Net.Http.Headers;

namespace DAI.Edit.Backend.WebApi.Controllers
{
    [Authorize]
    [Route("proxy")]
    [ApiController]
    public class Proxy : ControllerBase
    {
        public Proxy() { }

        private async Task DoProxyRequest(Func<HttpClient, Task<HttpResponseMessage>> doProxyRequest)
        {
            using (var httpClient = new HttpClient())
            {
                var response = await doProxyRequest(httpClient);
                Response.StatusCode = (int)response.StatusCode;
                Response.ContentType = response.Content.Headers.ContentType.ToString();
                Response.ContentLength = response.Content.Headers.ContentLength;
                await response.Content.CopyToAsync(Response.Body, null);
                await Response.CompleteAsync();
            }
        }

        [HttpGet]
        public async Task Get([FromQuery(Name = "url")] string url) =>
            await DoProxyRequest(async (httpClient) =>
            {
                var proxyRequest = new HttpRequestMessage(HttpMethod.Get, new Uri(url));
                return await httpClient.SendAsync(proxyRequest, HttpCompletionOption.ResponseHeadersRead);
            });

        [HttpPost]
        public async Task PostStatement([FromQuery(Name = "url")] string url) =>
            await DoProxyRequest(async (httpClient) =>
            {
                var proxyRequest = new HttpRequestMessage(HttpMethod.Post, new Uri(url));
                proxyRequest.Content = new StreamContent(Request.Body);
                proxyRequest.Content.Headers.ContentType = new MediaTypeHeaderValue(Request.ContentType);
                return await httpClient.SendAsync(proxyRequest, HttpCompletionOption.ResponseHeadersRead);
            });
    }
}