From 37d03d25eb072b93de0842f9fa6f37a5db65e9a4 Mon Sep 17 00:00:00 2001
From: Alex Macocian <amacocian@yahoo.com>
Date: Mon, 29 Jul 2019 15:57:34 +0300
Subject: [PATCH] Beta implementation for a form parser in case of POST HTTP
 request.

---
 MTSC-TestServer/Program.cs                   |   3 +-
 MTSC/Common/Http/HttpMessage.cs              |   9 ++
 MTSC/Common/Http/ServerModules/PostModule.cs | 120 +++++++++++++++++++
 MTSC/Server/Handlers/HttpHandler.cs          |   2 +
 4 files changed, 133 insertions(+), 1 deletion(-)
 create mode 100644 MTSC/Common/Http/ServerModules/PostModule.cs

diff --git a/MTSC-TestServer/Program.cs b/MTSC-TestServer/Program.cs
index ed19a33..63c0be1 100644
--- a/MTSC-TestServer/Program.cs
+++ b/MTSC-TestServer/Program.cs
@@ -28,7 +28,8 @@ namespace MTSC_TestServer
                 .AddExceptionHandler(new ExceptionConsoleLogger())
                 //.AddHandler(new BroadcastHandler())
                 .AddHandler(new WebsocketHandler().AddWebsocketHandler(new BroadcastModule()))
-                .AddHandler(new HttpHandler().AddHttpModule(new FileServerModule()))
+                .AddHandler(new HttpHandler().AddHttpModule(new FileServerModule())
+                                            .AddHttpModule(new PostModule()))
                 .Run();
         }
 
diff --git a/MTSC/Common/Http/HttpMessage.cs b/MTSC/Common/Http/HttpMessage.cs
index f243d60..19b997c 100644
--- a/MTSC/Common/Http/HttpMessage.cs
+++ b/MTSC/Common/Http/HttpMessage.cs
@@ -486,6 +486,15 @@ namespace MTSC.Common.Http
         /// </summary>
         /// <param name="header">Key of the header.</param>
         /// <returns>True if the message contains a header with the provided key.</returns>
+        public bool ContainsHeader(EntityHeadersEnum header)
+        {
+            return ContainsHeader(entityHeaders[(int)header]);
+        }
+        /// <summary>
+        /// Check if the message contains a header.
+        /// </summary>
+        /// <param name="header">Key of the header.</param>
+        /// <returns>True if the message contains a header with the provided key.</returns>
         public bool ContainsHeader(string header)
         {
             return headers.ContainsKey(header);
diff --git a/MTSC/Common/Http/ServerModules/PostModule.cs b/MTSC/Common/Http/ServerModules/PostModule.cs
new file mode 100644
index 0000000..ed9615e
--- /dev/null
+++ b/MTSC/Common/Http/ServerModules/PostModule.cs
@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using MTSC.Exceptions;
+using MTSC.Server;
+using MTSC.Server.Handlers;
+
+namespace MTSC.Common.Http.ServerModules
+{
+    public class PostModule : IHttpModule
+    {
+        private static string urlEncodedHeader = "application/x-www-form-urlencoded";
+        private static string multipartHeader = "multipart/form-data";
+
+        public event EventHandler<Dictionary<string, string>> FormReceived;
+
+        #region Private Methods
+        private Dictionary<string, string> ParseFormUrlEncoded(HttpMessage request)
+        {
+            if (!request.ContainsHeader(HttpMessage.EntityHeadersEnum.ContentLength))
+            {
+                throw new InvalidPostFormException("Form is missing content-length header!");
+            }
+            else
+            {
+                Dictionary<string, string> formData = new Dictionary<string, string>();
+                int length = int.Parse(request[HttpMessage.EntityHeadersEnum.ContentLength]);
+                int step = 0, parsedLength = 0;
+                StringBuilder fieldBuilder = new StringBuilder();
+                StringBuilder valueBuilder = new StringBuilder();
+                /*
+                 * Parse request body to obtain the form data.
+                 * Example of a form: field1=value1&field2=value2
+                 */
+                for (int i = 0; i < request.Body.Length; i++)
+                {
+                    if(request.Body[i] == '\n')
+                    {
+                        continue;
+                    }
+                    else if(step == 0)
+                    {
+                        parsedLength++;
+                        if(request.Body[i] == '=')
+                        {
+                            step = 1;
+                        }
+                        else
+                        {
+                            fieldBuilder.Append((char)request.Body[i]);
+                        }
+                    }
+                    else
+                    {
+                        parsedLength++;
+                        if(request.Body[i] == '&')
+                        {
+                            step = 0;
+                            formData[fieldBuilder.ToString()] = valueBuilder.ToString();
+                            fieldBuilder.Clear();
+                            valueBuilder.Clear();
+                        }
+                        else
+                        {
+                            valueBuilder.Append((char)request.Body[i]);
+                            if(parsedLength == length)
+                            {
+                                formData[fieldBuilder.ToString()] = valueBuilder.ToString();
+                            }
+                        }
+                    }
+                }
+                return formData;
+            }
+        }
+
+        private Dictionary<string, string> ParseFormMultipart(HttpMessage request)
+        {
+            throw new NotImplementedException("Multipart form parsing not implemented yet.");
+        }
+        #endregion
+
+        #region Interface Implementation
+        bool IHttpModule.HandleRequest(Server.Server server, HttpHandler handler, ClientData client, HttpMessage request, ref HttpMessage response)
+        {
+            if(request.Method == HttpMessage.MethodEnum.Post &&
+               request.ContainsHeader(HttpMessage.EntityHeadersEnum.ContentType))
+            {
+                if (request[HttpMessage.EntityHeadersEnum.ContentType].Contains(urlEncodedHeader))
+                {
+                    Dictionary<string, string> form = ParseFormUrlEncoded(request);
+                    FormReceived?.Invoke(this, form);
+                    server.LogDebug("Received POST form of " + form.Keys.Count + " keys!");
+                    return true;
+                }
+                else if (request[HttpMessage.EntityHeadersEnum.ContentType].Contains(multipartHeader))
+                {
+                    Dictionary<string, string> form = ParseFormMultipart(request);
+                    FormReceived?.Invoke(this, form);
+                    server.LogDebug("Received POST form of " + form.Keys.Count + " keys!");
+                    return true;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        void IHttpModule.Tick(Server.Server server, HttpHandler handler)
+        {
+            
+        }
+        #endregion
+    }
+}
diff --git a/MTSC/Server/Handlers/HttpHandler.cs b/MTSC/Server/Handlers/HttpHandler.cs
index 11871de..25394b5 100644
--- a/MTSC/Server/Handlers/HttpHandler.cs
+++ b/MTSC/Server/Handlers/HttpHandler.cs
@@ -14,6 +14,8 @@ namespace MTSC.Server.Handlers
     /// </summary>
     public class HttpHandler : IHandler
     {
+        private static string urlEncodedHeader = "application/x-www-form-urlencoded";
+        private static string multipartHeader = "multipart/form-data";
         #region Fields
         List<IHttpModule> httpModules = new List<IHttpModule>();
         ConcurrentQueue<Tuple<ClientData,HttpMessage>> messageQueue = new ConcurrentQueue<Tuple<ClientData, HttpMessage>>();