From 9dbd73cc8c22cda9d2239719e4e550ac372874b8 Mon Sep 17 00:00:00 2001
From: Chrysanthes <juflowers@163.com>
Date: Wed, 20 Mar 2019 14:18:07 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BB=A5UDP=E5=B9=BF=E6=92=AD=E7=9A=84?=
 =?UTF-8?q?=E6=96=B9=E5=BC=8F=E5=AE=9E=E7=8E=B0=E4=BA=86=E8=87=AA=E5=8A=A8?=
 =?UTF-8?q?=E8=BF=9E=E6=8E=A5=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 Messenger.cs | 99 ++++++++++++++++++++++++++++++++++++++++++++++++----
 Program.cs   | 54 +++++++++++-----------------
 2 files changed, 113 insertions(+), 40 deletions(-)

diff --git a/Messenger.cs b/Messenger.cs
index 28fc796..9922bf0 100644
--- a/Messenger.cs
+++ b/Messenger.cs
@@ -4,13 +4,24 @@
 using System.Net;
 using System.Net.Sockets;
 using System.Text;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace SocketSingleSend
 {
     class Messenger
     {
+        class StateObject
+        {
+            public Socket workSocket;
+            public byte[] dataByte;
+            public IPEndPoint ipe;
+        }
+
+
         public const int MAX_BYTE_SIZE = 512;
+        public const int MIN_BYTE_SIZE = 64;
+        public const int BROADCAST_INTERVAL = 3000;
 
         private Socket socket;
 
@@ -101,10 +112,10 @@ public bool UDPSend(byte[] strByte, EndPoint targetIPE, bool firstSend = true)
                         return true;
                 }
             }
-            catch (Exception ex)
+            catch (SocketException ex)
             {
 #if DEBUG
-                Console.WriteLine(ex.Message);
+                Console.WriteLine(ex.Message + " errorCode: " + ex.ErrorCode);
 #endif
             }
             return false;
@@ -128,6 +139,53 @@ public bool SteadySend(string str, EndPoint targetIPE)
             return false;
         }
 
+        private void BroadcastCallback(IAsyncResult ar)
+        {
+            StateObject stateObj = (StateObject)ar.AsyncState;
+            try
+            {
+                int sendLen = stateObj.workSocket.EndSendTo(ar);
+#if DEBUG
+                Console.WriteLine("<<<<<<<<send one broadcast");
+#endif
+                if (sendLen == stateObj.dataByte.Length)
+                    Thread.Sleep(BROADCAST_INTERVAL);
+                stateObj.workSocket.BeginSendTo(stateObj.dataByte, 0, stateObj.dataByte.Length,
+                    SocketFlags.None, stateObj.ipe, BroadcastCallback, stateObj);
+            }
+            catch (SocketException ex)
+            {
+#if DEBUG
+                Console.WriteLine(ex.Message + " errorCode: " + ex.ErrorCode);
+#endif
+            }
+        }
+
+        public void Broadcasting(string bcStr, int bc_port)
+        {
+            if (!socket.EnableBroadcast)
+                socket.EnableBroadcast = true;
+            byte[] bcByte = CryptoUtil.StrToByte(CryptoUtil.Encrypt(bcStr));
+            IPEndPoint bcIPE = new IPEndPoint(IPAddress.Broadcast, bc_port);
+            StateObject stateObj = new StateObject()
+            {
+                dataByte = bcByte,
+                ipe = bcIPE,
+                workSocket = socket
+            };
+            try
+            {
+                socket.BeginSendTo(bcByte, 0, bcByte.Length, SocketFlags.None,
+                    bcIPE, new AsyncCallback(BroadcastCallback), stateObj);
+            }
+            catch (SocketException ex)
+            {
+#if DEBUG
+                Console.WriteLine(ex.Message + " errorCode: " + ex.ErrorCode);
+#endif
+            }
+        }
+
 
         public byte[] UDPReceive(ref EndPoint remoteIPE, int byteSize)
         {
@@ -155,17 +213,18 @@ public byte[] UDPReceive(ref EndPoint remoteIPE, int byteSize)
                         byte[] remainByte = UDPReceive(ref remoteIPE, remainLen);
                         IPAddress afterIP = ((IPEndPoint)remoteIPE).Address;
                         if (!beforeIP.Equals(afterIP))
-                            throw new Exception("Information confusion between different senders");
+                            throw new Exception(
+                                "Information confusion between different senders");
                         else
                             strByte = ConcatByte(strByte, remainByte);
                     }
                     return strByte;
                 }
             }
-            catch (Exception ex)
+            catch (SocketException ex)
             {
 #if DEBUG
-                Console.WriteLine(ex.Message);
+                Console.WriteLine(ex.Message + " errorCode: " + ex.ErrorCode);
 #endif
             }
             return null;
@@ -232,7 +291,35 @@ public void FlushReceiveBuf()
             }
         }
 
-
+        public string ReceiveBroadcast(ref EndPoint remoteIPE)
+        {
+            if (!socket.EnableBroadcast)
+                socket.EnableBroadcast = true;
+            try
+            {
+                int byteSize = (MAX_BYTE_SIZE < MIN_BYTE_SIZE) ? MIN_BYTE_SIZE : MAX_BYTE_SIZE;
+                byte[] receiveByte = new byte[byteSize];
+                int receiveLen = socket.ReceiveFrom(receiveByte,
+                    SocketFlags.None, ref remoteIPE);
+                if (receiveLen > 0)
+                {
+                    string bcMsg = CryptoUtil.Decrypt(CryptoUtil.ByteToStr(
+                        receiveByte, receiveLen));
+#if DEBUG
+                    Console.WriteLine(">>>>>>>>get broadcast '{0}' from: {1}",
+                        bcMsg, remoteIPE);
+#endif
+                    return bcMsg;
+                }
+            }
+            catch (SocketException ex)
+            {
+#if DEBUG
+                Console.WriteLine(ex.Message + " errorCode: " + ex.ErrorCode);
+#endif
+            }
+            return null;
+        }
 
 
     }
diff --git a/Program.cs b/Program.cs
index 21f171a..4b7fdd1 100644
--- a/Program.cs
+++ b/Program.cs
@@ -2,8 +2,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Net;
-using System.Net.NetworkInformation;
-using System.Net.Sockets;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -20,10 +18,7 @@ class Program
         private const int AS_PORT = 11019;
         private const int BC_PORT = 19019;
         static readonly IPAddress localIP = Dns.GetHostAddresses(Dns.GetHostName()).Last();
-        //实现加密广播自动连接 Ipv4
-        //实现不定长数据发送
-        //重构 抽出Socket通信类
-        //answer使用hash值作对比
+
         static bool sendFail = true;
         static Messenger udpSender;
         static Messenger udpReceiver;
@@ -60,36 +55,13 @@ static EndPoint CreateEmptyEP()
 
         static void Main(string[] args)
         {
-            //while (true)
-            //{
-            //    string str = Console.ReadLine();
-            //    string key = "SimpleSocketChat";
-            //    //string iv = key;
-            //    //CryptoUtil.Init(key, iv);
-            //    //string enStr = CryptoUtil.Encrypt(str);
-            //    //Console.WriteLine(enStr);
-            //    //string deStr = CryptoUtil.Decrypt(enStr);
-            //    //Console.WriteLine(deStr);
-            //    //string hashStr = CryptoUtil.SHA256Hash(str);
-            //    //Console.WriteLine(hashStr);
-            //    byte[] a = CryptoUtil.StrToByte(str);
-            //    byte[] b = CryptoUtil.StrToByte(key);
-            //    b = Messenger.ConcatByte(a, b);
-            //    a = Messenger.SplitByte(b, a.Length, out b);
-            //    Console.WriteLine(CryptoUtil.ByteToStr(a));
-            //    Console.WriteLine(CryptoUtil.ByteToStr(b));
-            //    Console.WriteLine("-----------------------------");
-            //}
-
-
-
             Console.WriteLine("1. Send ;\r\n2. Receive ;");
 #if DEBUG
             Console.WriteLine("3. Loop Send ;");
 #endif
             Console.WriteLine("Make a choice to do(1 or 2):");
 
-            string choice = Console.ReadLine();
+            string choice = Console.ReadLine().Trim();
             if (choice == "1")
             {
                 //do Send
@@ -97,21 +69,33 @@ static void Main(string[] args)
                 IPAddress targetIP = null;
                 while (targetIP == null)
                 {
-                    Console.WriteLine("Enter the other side's IP:");
-                    targetIP = StrToIP(Console.ReadLine().Trim());
+                    Console.WriteLine("Enter the other side's IP or press Enter directly:");
+                    string ipStr = Console.ReadLine().Trim();
+                    if (string.IsNullOrEmpty(ipStr))
+                    {
+                        Console.WriteLine("Waiting to auto connect...");
+                        EndPoint remoteIPE = CreateEmptyEP();
+                        ipStr = broadcaster.ReceiveBroadcast(ref remoteIPE);
+                        if (ipStr != null && ipStr.StartsWith(IP_FLAG))
+                            ipStr = ipStr.Substring(IP_FLAG.Length);
+                    }
+                    targetIP = StrToIP(ipStr);
                 }
+                Console.WriteLine("Connect to Receiver: {0}", targetIP);
                 Console.WriteLine("Write down your text:");
                 Console.WriteLine("-----------------------------------");
                 string str = null;
                 do
                 {
                     str = Console.ReadLine();
-                    if (str.Length > MAX_STR_LEN)
+                    if (str == null)
+                        break;
+                    else if (str.Length > MAX_STR_LEN)
                     {
                         Console.WriteLine("<<<<<<<<<<<Too Long!");
                         continue;
                     }
-                    if (str.Length == 0)
+                    else if (str.Length == 0)
                     {
                         Console.WriteLine("<<<<<<<<<<<Can not be empty!");
                         continue;
@@ -126,6 +110,7 @@ static void Main(string[] args)
                 InitMessenger(true, false);
                 Console.WriteLine("Local IP is: " + localIP);
                 Console.WriteLine("Waiting to receive the Msg...");
+                broadcaster.Broadcasting(IP_FLAG + localIP, BC_PORT);
                 Console.WriteLine("-----------------------------------");
                 string msg = null;
                 do
@@ -159,6 +144,7 @@ static void Main(string[] args)
                 }
             }
 #endif
+            broadcaster?.Close();
             udpReceiver?.Close();
             udpSender?.Close();
         }