Adding http forwarding support

Author: shibayan

src/Azure.WebJobs.Extensions.HttpApi/HttpFunctionBase.cs

@@ -57,10 +57,10 @@ protected IUrlHelper Url
             }
         }
 
-        public IObjectModelValidator ObjectValidator
+        protected IObjectModelValidator ObjectValidator
             => _objectModelValidator ??= HttpContext?.RequestServices?.GetRequiredService<IObjectModelValidator>();
 
-        public ProblemDetailsFactory ProblemDetailsFactory
+        protected ProblemDetailsFactory ProblemDetailsFactory
             => _problemDetailsFactory ??= HttpContext?.RequestServices?.GetRequiredService<ProblemDetailsFactory>();
 
         #region IActionResult helpers

src/Azure.WebJobs.Extensions.HttpApi/ProxyFunctionBase.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+using Microsoft.AspNetCore.Http;
+
+namespace Azure.WebJobs.Extensions.HttpApi
+{
+    public abstract class ProxyFunctionBase
+    {
+        protected ProxyFunctionBase(IHttpClientFactory httpClientFactory, IHttpContextAccessor httpContextAccessor)
+        {
+            _httpClient = httpClientFactory.CreateClient();
+            _httpContextAccessor = httpContextAccessor;
+        }
+
+        private readonly HttpClient _httpClient;
+        private readonly IHttpContextAccessor _httpContextAccessor;
+
+        protected async Task SendAsync(string destinationPrefix)
+        {
+            var context = _httpContextAccessor.HttpContext;
+
+            var request = new HttpRequestMessage();
+
+            request.Method = GetHttpMethod(context.Request.Method);
+
+            foreach (var (name, value) in context.Request.Headers)
+            {
+                request.Headers.TryAddWithoutValidation(name, (string)value);
+            }
+
+            var response = await _httpClient.SendAsync(request);
+        }
+
+        private static HttpMethod GetHttpMethod(string method)
+        {
+            return method switch
+            {
+                { } when HttpMethods.IsGet(method) => HttpMethod.Get,
+                { } when HttpMethods.IsPost(method) => HttpMethod.Post,
+                { } when HttpMethods.IsPut(method) => HttpMethod.Put,
+                { } when HttpMethods.IsDelete(method) => HttpMethod.Delete,
+                { } when HttpMethods.IsOptions(method) => HttpMethod.Options,
+                { } when HttpMethods.IsHead(method) => HttpMethod.Head,
+                { } when HttpMethods.IsPatch(method) => HttpMethod.Patch,
+                _ => throw new ArgumentOutOfRangeException(nameof(method), method, null)
+            };
+        }
+    }
+}