c++下基于windows socket的服务器客户端程序(基于UDP协议)

前天写了一个基于tcp协议的服务器客户端程序,今天写了一个基于UDP协议的,由于在上一篇使用TCP协议的服务器中注释已经较为详细,且许多api的调用是相同的,故不再另外注释。

使用UDP协议需要注意几点：

①UDP是面向无连接的,客户端在于服务器通信前无须建立连接,且UDP协议不保证发出的消息是否被收到,是否有丢失。

②UDP的接收和发送信息使用recvfrom()与sendto()函数

代码如下:

服务器端:

 #include <iostream>
 #include "Ws2tcpip.h"
 #include "Winsock2.h"

 using std::cin;
 using std::cout;
 using std::cerr;
 using std::endl;

 #pragma comment(lib, "ws2_32.lib")

 int SOCKADDR_IN_SIZE = sizeof(SOCKADDR_IN);
 const u_short DEFAULT_PORT = ;
 const size_t MSG_BUF_SIZE = ;
 const size_t IP_BUF_SIZE = ;

 int main() {
     WSADATA wsa_data;
     SOCKET sock_serv = INVALID_SOCKET;
     SOCKADDR_IN addr_serv, addr_clt;
     char ip_buf[IP_BUF_SIZE];
     char msg_buf[MSG_BUF_SIZE];
     int ret_val = ;
     //
     ret_val = WSAStartup(MAKEWORD(, ), &wsa_data);
     if (ret_val != ) {
         cerr << "WSAStartup() function failed with error: " << WSAGetLastError() << "\n";
         system("pause");
         return ;
     }
     //
     //SecureZeroMemory(&addr_serv, SOCKADDR_IN_SIZE);
     addr_serv.sin_family = AF_INET;
     addr_serv.sin_port = htons(DEFAULT_PORT);
     addr_serv.sin_addr.S_un.S_addr = ADDR_ANY;
     //
     sock_serv = socket(addr_serv.sin_family, SOCK_DGRAM, IPPROTO_UDP);
     if (sock_serv == INVALID_SOCKET) {
         cerr << "socket() function failed with error: " << WSAGetLastError() << "\n";
         WSACleanup();
         system("pause");
         return ;
     }
     //
     ret_val = bind(sock_serv, (SOCKADDR*)&addr_serv, SOCKADDR_IN_SIZE);
     if (ret_val != ) {
         cerr << "bind() function failed with error: " << WSAGetLastError() << "\n";
         system("pause");
         return ;
     }
     cout << "A UDP server has started successfully..." << endl;
     //
     while (true) {
         SecureZeroMemory(msg_buf, MSG_BUF_SIZE);
         ret_val = recvfrom(sock_serv, msg_buf, MSG_BUF_SIZE, , (SOCKADDR*)&addr_clt, &SOCKADDR_IN_SIZE);
         if (ret_val > ) {
             inet_ntop(addr_clt.sin_family, &addr_clt, ip_buf, IP_BUF_SIZE);
             cout << "message from client " << ip_buf << ": " << msg_buf << endl;
             cout << "enter the message to response: ";
             cin.getline(msg_buf, MSG_BUF_SIZE);
             sendto(sock_serv, msg_buf, strlen(msg_buf), , (SOCKADDR*)&addr_clt, SOCKADDR_IN_SIZE);
         }
         else if (ret_val == ) {
             cout << "connection is closed..." << endl;
         }
         else {
             cerr << "recvfrom() function failed with error: " << WSAGetLastError() << "\n";
             closesocket(sock_serv);
             WSACleanup();
             system("pause");
             return ;
         }
     }
     ret_val = shutdown(sock_serv, SD_BOTH);
     if (ret_val == SOCKET_ERROR) {
         cerr << "shutdown() function failed with error: " << WSAGetLastError() << "\n";
         closesocket(sock_serv);
         WSACleanup();
         system("pause");
         return ;
     }
     closesocket(sock_serv);
     WSACleanup();
     cout << "server shutdown..." << endl;
     system("pause");
     return ;
 }

客户端:

 #include <Winsock2.h>
 #include <WS2tcpip.h>
 #include <iostream>

 using std::cout;
 using std::cin;
 using std::cerr;
 using std::endl;

 #pragma comment(lib, "ws2_32.lib")

 const int MSG_BUF_SIZE = ;
 int SOCKADDR_SIZE = sizeof(SOCKADDR);
 const int SERV_PORT = ;
 const char *SERV_IP = "127.0.0.1";

 int main() {
     WSADATA wsa_data;
     SOCKET sock_clt = INVALID_SOCKET;
     SOCKADDR_IN addr_serv;
     char msg_buf[MSG_BUF_SIZE];
     int ret_val = ;
     //
     ret_val = WSAStartup(MAKEWORD(, ), &wsa_data);
     if (ret_val != ) {
         cerr << "WSAStartup() function failed with error: " << WSAGetLastError() << "\n";
         system("pause");
         return ;
     }
     //
     sock_clt = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
     if (sock_clt == INVALID_SOCKET) {
         cerr << "socket() function failed with error: " << WSAGetLastError() << "\n";
         WSACleanup();
         system("pause");
         return ;
     }
     //
     addr_serv.sin_family = AF_INET;
     addr_serv.sin_port = htons(SERV_PORT);
     ret_val = InetPton(addr_serv.sin_family, SERV_IP, &addr_serv.sin_addr);
     if (ret_val != ) {
         cerr << "inet_pton() function failed with error: " << WSAGetLastError() << "\n";
         closesocket(sock_clt);
         WSACleanup();
         system("pause");
         return ;
     }
     //
     cout << "A UDP client has already started successfully..." << endl;
     //
     //SecureZeroMemory(msg_buf, MSG_BUF_SIZE);
     while (true) {
         cout << "enter the message you want to send: ";
         cin.getline(msg_buf, MSG_BUF_SIZE);
         ret_val = sendto(sock_clt, msg_buf, strlen(msg_buf), , (SOCKADDR*)&addr_serv, SOCKADDR_SIZE);
         if (ret_val == SOCKET_ERROR) {
             cerr << "sendto() function failed with error: " << WSAGetLastError() << "\n";
             closesocket(sock_clt);
             WSACleanup();
             system("pause");
             return ;
         }
         SecureZeroMemory(msg_buf, MSG_BUF_SIZE);
         ret_val = recvfrom(sock_clt, msg_buf, MSG_BUF_SIZE, , (SOCKADDR*)&addr_serv, &SOCKADDR_SIZE);
         if (ret_val > ) {
             cout << "feedback from the server: " << msg_buf << endl;
         }
         else if (ret_val == ) {
             cout << "connection is closed..." << endl;
         }
         else {
             cerr << "recvfrom() function failed with error: " << WSAGetLastError() << "\n";
             closesocket(sock_clt);
             WSACleanup();
             system("pause");
             return ;
         }
     }
     ret_val = shutdown(sock_clt, SD_BOTH);
     if (ret_val == SOCKET_ERROR) {
         cerr << "shutdown() function failed with error: " << WSAGetLastError() << "\n";
         closesocket(sock_clt);
         WSACleanup();
         system("pause");
         return ;
     }
     closesocket(sock_clt);
     WSACleanup();
     system("pause");
     return ;
 }