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socket多人聊天程序C语言版(一)

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首先,不要一步登天直接解决多人聊天这个问题,先把问题化简。
1.多人聊天的核心问题是服务器如何标识不同的客户端,如何根据客户端的需求转发消息给指定客户端。
2.多人聊天转化为C-C聊天,但是不再是直接C-C,而是通过server转发消息,所以变成==>C-S-C。
3.server如何允许2个client同时连接,设置listen函数的第二个参数,最大连接数。
4.server如何标识两个client,用一个结构体数组来存放两个client的信息。
5.server如何转发消息给client,很简单,先接收到的发送给还没接收到的。如图:


6.server如何管理两个client的连接状态,连接成功很简单,就是accpet成功后就是连接成功了。但是怎么判断连接断开呢?这个涉及到的select函数的使用,有点复杂~,所以我就简单的用了一个send函数发送一个空消息来判断是否断开连接,这个不严谨,容易出BUG,但是实践起来简单就使用了它。
7.要用线程来管理接收消息、发送消息、接受请求、管理连接状态。

技术要点:C语言线程函数的使用。

_beginthreadex函数原型

_ACRTIMP uintptr_t __cdecl _beginthreadex
( _In_opt_ void* _Security,//安全属性,NULL为默认安全属性
 _In_ unsigned _StackSize,//线程堆栈的大小。如果为0,则线程堆栈大小和创建它的线程的相同。一般用0 
 _In_ _beginthreadex_proc_type _StartAddress, //线程函数的地址
 _In_opt_ void* _ArgList, //传进线程的函数
 _In_ unsigned _InitFlag, //线程初始状态,0:立即运行;CREATE_SUSPEND:悬挂(如果出事状态定义为悬挂,就要调用ResumeThread(HANDLE) 来激活线程的运行) 
 _Out_opt_ unsigned* _ThrdAddr //用于记录线程ID的地址
 )



例子:

#include <process.h>
#include <stdio.h>

unsigned __stdcall Thread(void* param)
{
  printf("%d\n", *(int*)param); //这里必须先要强行转换为int*,不然void* 直接解引用会出错。
  return 0;
}

int main()
{
  int i = 0;
  _beginthreadex(NULL, 0, Thread, &i, 0, NULL);
  return 0;
}


1V1,C-S-C聊天例子:
编写环境:win10,VS2015

效果图:

server code:

#include <WinSock2.h>
#include <process.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib,"ws2_32.lib")

#define SEND_OVER 1             //已经转发消息
#define SEND_YET 0             //还没转发消息

int g_iStatus = SEND_YET;
SOCKET g_ServerSocket = INVALID_SOCKET;   //服务端套接字
SOCKADDR_IN g_ClientAddr = { 0 };      //客户端地址
int g_iClientAddrLen = sizeof(g_ClientAddr);
bool g_bCheckConnect = false;        //检查连接情况
HANDLE g_hRecv1 = NULL;
HANDLE g_hRecv2 = NULL;
//客户端信息结构体
typedef struct _Client
{
  SOCKET sClient;   //客户端套接字
  char buf[128];    //数据缓冲区
  char userName[16];  //客户端用户名
  char IP[20];     //客户端IP
  UINT_PTR flag;    //标记客户端,用来区分不同的客户端
}Client;

Client g_Client[2] = { 0 };         //创建一个客户端结构体

//发送数据线程
unsigned __stdcall ThreadSend(void* param)
{
  int ret = 0;
  int flag = *(int*)param;
  SOCKET client = INVALID_SOCKET;         //创建一个临时套接字来存放要转发的客户端套接字
  char temp[128] = { 0 };             //创建一个临时的数据缓冲区,用来存放接收到的数据
  memcpy(temp, g_Client[!flag].buf, sizeof(temp));
  sprintf(g_Client[flag].buf, "%s: %s", g_Client[!flag].userName, temp);//添加一个用户名头

  if (strlen(temp) != 0 && g_iStatus == SEND_YET) //如果数据不为空且还没转发则转发
    ret = send(g_Client[flag].sClient, g_Client[flag].buf, sizeof(g_Client[flag].buf), 0);
  if (ret == SOCKET_ERROR)
    return 1;
  g_iStatus = SEND_OVER;  //转发成功后设置状态为已转发
  return 0;
}

//接受数据
unsigned __stdcall ThreadRecv(void* param)
{
  SOCKET client = INVALID_SOCKET;
  int flag = 0; 
  if (*(int*)param == g_Client[0].flag)      //判断是哪个客户端发来的消息
  {
    client = g_Client[0].sClient;
    flag = 0;
  }  
  else if (*(int*)param == g_Client[1].flag)
  {
    client = g_Client[1].sClient;
    flag = 1;
  }
  char temp[128] = { 0 }; //临时数据缓冲区
  while (1)
  {
    memset(temp, 0, sizeof(temp));
    int ret = recv(client, temp, sizeof(temp), 0); //接收数据
    if (ret == SOCKET_ERROR)
      continue;
    g_iStatus = SEND_YET;                //设置转发状态为未转发
    flag = client == g_Client[0].sClient ? 1 : 0;    //这个要设置,否则会出现自己给自己发消息的BUG
    memcpy(g_Client[!flag].buf, temp, sizeof(g_Client[!flag].buf));
    _beginthreadex(NULL, 0, ThreadSend, &flag, 0, NULL); //开启一个转发线程,flag标记着要转发给哪个客户端
    //这里也可能是导致CPU使用率上升的原因。
  }

  return 0;
}

//管理连接
unsigned __stdcall ThreadManager(void* param)
{
  while (1)
  {
    if (send(g_Client[0].sClient, "", sizeof(""), 0) == SOCKET_ERROR)
    {
      if (g_Client[0].sClient != 0)
      {
        CloseHandle(g_hRecv1); //这里关闭了线程句柄,但是测试结果断开连C/S接后CPU仍然疯涨
        CloseHandle(g_hRecv2);
        printf("Disconnect from IP: %s,UserName: %s\n", g_Client[0].IP, g_Client[0].userName);
        closesocket(g_Client[0].sClient);  //这里简单的判断:若发送消息失败,则认为连接中断(其原因有多种),关闭该套接字
        g_Client[0] = { 0 };
      }
    }
    if (send(g_Client[1].sClient, "", sizeof(""), 0) == SOCKET_ERROR)
    {
      if (g_Client[1].sClient != 0)
      {
        CloseHandle(g_hRecv1);
        CloseHandle(g_hRecv2);
        printf("Disconnect from IP: %s,UserName: %s\n", g_Client[1].IP, g_Client[1].userName);
        closesocket(g_Client[1].sClient);
        g_Client[1] = { 0 };
      }
    }
    Sleep(2000); //2s检查一次
  }

  return 0;
}

//接受请求
unsigned __stdcall ThreadAccept(void* param)
{

  int i = 0;
  int temp1 = 0, temp2 = 0;
  _beginthreadex(NULL, 0, ThreadManager, NULL, 0, NULL);
  while (1)
  {
    while (i < 2)
    {
      if (g_Client[i].flag != 0)
      {
        ++i;
        continue;
      }
      //如果有客户端申请连接就接受连接
      if ((g_Client[i].sClient = accept(g_ServerSocket, (SOCKADDR*)&g_ClientAddr, &g_iClientAddrLen)) == INVALID_SOCKET)
      {
        printf("accept failed with error code: %d\n", WSAGetLastError());
        closesocket(g_ServerSocket);
        WSACleanup();
        return -1;
      }
      recv(g_Client[i].sClient, g_Client[i].userName, sizeof(g_Client[i].userName), 0); //接收用户名
      printf("Successfuuly got a connection from IP:%s ,Port: %d,UerName: %s\n",
        inet_ntoa(g_ClientAddr.sin_addr), htons(g_ClientAddr.sin_port), g_Client[i].userName);
      memcpy(g_Client[i].IP, inet_ntoa(g_ClientAddr.sin_addr), sizeof(g_Client[i].IP)); //记录客户端IP
      g_Client[i].flag = g_Client[i].sClient; //不同的socke有不同UINT_PTR类型的数字来标识
      i++;
    }
    i = 0;

    if (g_Client[0].flag != 0 && g_Client[1].flag != 0)         //当两个用户都连接上服务器后才进行消息转发
    {
      if (g_Client[0].flag != temp1)   //每次断开一个连接后再次连上会新开一个线程,导致cpu使用率上升,所以要关掉旧的
      {
        if (g_hRecv1)         //这里关闭了线程句柄,但是测试结果断开连C/S接后CPU仍然疯涨
          CloseHandle(g_hRecv1);
        g_hRecv1 = (HANDLE)_beginthreadex(NULL, 0, ThreadRecv, &g_Client[0].flag, 0, NULL); //开启2个接收消息的线程
      }  
      if (g_Client[1].flag != temp2)
      {
        if (g_hRecv2)
          CloseHandle(g_hRecv2);
        g_hRecv2 = (HANDLE)_beginthreadex(NULL, 0, ThreadRecv, &g_Client[1].flag, 0, NULL);
      }    
    }

    temp1 = g_Client[0].flag; //防止ThreadRecv线程多次开启
    temp2 = g_Client[1].flag;

    Sleep(3000);
  }

  return 0;
}

//启动服务器
int StartServer()
{
  //存放套接字信息的结构
  WSADATA wsaData = { 0 };
  SOCKADDR_IN ServerAddr = { 0 };       //服务端地址
  USHORT uPort = 18000;            //服务器监听端口

  //初始化套接字
  if (WSAStartup(MAKEWORD(2, 2), &wsaData))
  {
    printf("WSAStartup failed with error code: %d\n", WSAGetLastError());
    return -1;
  }
  //判断版本
  if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2)
  {
    printf("wVersion was not 2.2\n");
    return -1;
  }
  //创建套接字
  g_ServerSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (g_ServerSocket == INVALID_SOCKET)
  {
    printf("socket failed with error code: %d\n", WSAGetLastError());
    return -1;
  }

  //设置服务器地址
  ServerAddr.sin_family = AF_INET;//连接方式
  ServerAddr.sin_port = htons(uPort);//服务器监听端口
  ServerAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);//任何客户端都能连接这个服务器

  //绑定服务器
  if (SOCKET_ERROR == bind(g_ServerSocket, (SOCKADDR*)&ServerAddr, sizeof(ServerAddr)))
  {
    printf("bind failed with error code: %d\n", WSAGetLastError());
    closesocket(g_ServerSocket);
    return -1;
  }
  //设置监听客户端连接数
  if (SOCKET_ERROR == listen(g_ServerSocket, 20000))
  {
    printf("listen failed with error code: %d\n", WSAGetLastError());
    closesocket(g_ServerSocket);
    WSACleanup();
    return -1;
  }

  _beginthreadex(NULL, 0, ThreadAccept, NULL, 0, 0);
  for (int k = 0;k < 100;k++) //让主线程休眠,不让它关闭TCP连接.
    Sleep(10000000);

  //关闭套接字
  for (int j = 0;j < 2;j++)
  {
    if (g_Client[j].sClient != INVALID_SOCKET)
      closesocket(g_Client[j].sClient);
  }
  closesocket(g_ServerSocket);
  WSACleanup();
  return 0;
}

int main()
{
  StartServer(); //启动服务器

  return 0;
}

client code:

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <WinSock2.h>
#include <process.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#pragma comment(lib,"ws2_32.lib")
#define RECV_OVER 1
#define RECV_YET 0
char userName[16] = { 0 };
int iStatus = RECV_YET;
//接受数据
unsigned __stdcall ThreadRecv(void* param)
{
  char buf[128] = { 0 };
  while (1)
  {
    int ret = recv(*(SOCKET*)param, buf, sizeof(buf), 0);
    if (ret == SOCKET_ERROR)
    {
      Sleep(500);
      continue;
    }
    if (strlen(buf) != 0)
    {
      printf("%s\n", buf);
      iStatus = RECV_OVER;
    }
    else
      Sleep(100);  


  }
  return 0;
}

//发送数据
unsigned __stdcall ThreadSend(void* param)
{
  char buf[128] = { 0 };
  int ret = 0;
  while (1)
  {
    int c = getch();
    if(c == 72 || c == 0 || c == 68)//为了显示美观,加一个无回显的读取字符函数
      continue;          //getch返回值我是经过实验得出如果是返回这几个值,则getch就会自动跳过,具体我也不懂。
    printf("%s: ", userName);
    gets_s(buf);
    ret = send(*(SOCKET*)param, buf, sizeof(buf), 0);
    if (ret == SOCKET_ERROR)
      return 1;
  }
  return 0;
}

//连接服务器
int ConnectServer()
{
  WSADATA wsaData = { 0 };//存放套接字信息
  SOCKET ClientSocket = INVALID_SOCKET;//客户端套接字
  SOCKADDR_IN ServerAddr = { 0 };//服务端地址
  USHORT uPort = 18000;//服务端端口
             //初始化套接字
  if (WSAStartup(MAKEWORD(2, 2), &wsaData))
  {
    printf("WSAStartup failed with error code: %d\n", WSAGetLastError());
    return -1;
  }
  //判断套接字版本
  if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2)
  {
    printf("wVersion was not 2.2\n");
    return -1;
  }
  //创建套接字
  ClientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (ClientSocket == INVALID_SOCKET)
  {
    printf("socket failed with error code: %d\n", WSAGetLastError());
    return -1;
  }
  //输入服务器IP
  printf("Please input server IP:");
  char IP[32] = { 0 };
  gets_s(IP);
  //设置服务器地址
  ServerAddr.sin_family = AF_INET;
  ServerAddr.sin_port = htons(uPort);//服务器端口
  ServerAddr.sin_addr.S_un.S_addr = inet_addr(IP);//服务器地址

  printf("connecting......\n");
  //连接服务器
  if (SOCKET_ERROR == connect(ClientSocket, (SOCKADDR*)&ServerAddr, sizeof(ServerAddr)))
  {
    printf("connect failed with error code: %d\n", WSAGetLastError());
    closesocket(ClientSocket);
    WSACleanup();
    return -1;
  }
  printf("Connecting server successfully IP:%s Port:%d\n",
    IP, htons(ServerAddr.sin_port));
  printf("Please input your UserName: ");
  gets_s(userName);
  send(ClientSocket, userName, sizeof(userName), 0);
  printf("\n\n");
  _beginthreadex(NULL, 0, ThreadRecv, &ClientSocket, 0, NULL); //启动接收和发送消息线程
  _beginthreadex(NULL, 0, ThreadSend, &ClientSocket, 0, NULL);
  for (int k = 0;k < 1000;k++)
    Sleep(10000000);
  closesocket(ClientSocket);
  WSACleanup();
  return 0;
}

int main()
{
  ConnectServer(); //连接服务器
  return 0;
}

这程序还有一些BUG,其中最大的就是关掉一个连接后CPU使用率疯涨,我测试过我想到的可能,还是找不到结果~,希望有大神懂的告知一下。

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