与TCP协议下编写服务端程序代码类似，但因为是无连接的形式，所以不需要监听。
这次，我用了一点不同的想法：我建立一个服务端，用了两个端口和两个套接字，把服务端作为一个数据转发的中转站，使得客户机之间进行UDP协议下的通信。
服务端代码：
/**
* UDP/IP 服务器端 Server.c
*/
#include <winsock2.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#define true 1
#define false 0
#define BUFFSIZE 1024
int main(int argc, char**argv)
{
int Ret;
WSADATA wsaData;
SOCKET Socket_1;
SOCKET Socket_2;
SOCKADDR_IN ClientAddr_1;
int ClientAddr_1_Len = sizeof(ClientAddr_1);
SOCKADDR_IN ClientAddr_2;
int ClientAddr_2_Len = sizeof(ClientAddr_2);
unsigned short Port_1 = 5150;
unsigned short Port_2 = 8888;
char sendData[BUFFSIZE];
char recvData[BUFFSIZE];
if((Ret = WSAStartup(MAKEWORD(2,2), &wsaData)) != 0)
{
printf("WSASTARTUP_ERROR: %d\n", Ret);
exit(1);
}
if((Socket_1 = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == INVALID_SOCKET) {
printf("Socket_1_ERROR\n");
exit(1);
}
//将端口变量从主机字节顺序转换位网络字节顺序
ClientAddr_1.sin_family = AF_INET;
ClientAddr_1.sin_port = htons(Port_1);
ClientAddr_1.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
//使用bind将这个地址信息和套接字绑定起来
if(bind(Socket_1, (SOCKADDR *)&ClientAddr_1, ClientAddr_1_Len) == SOCKET_ERROR)
{
printf("BIND_SOCKET_1_ERROR: %d\n", SOCKET_ERROR);
exit(1);
}
if((Socket_2 = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == INVALID_SOCKET) {
printf("Socket_2_ERROR\n");
exit(1);
}
//将端口变量从主机字节顺序转换位网络字节顺序
ClientAddr_2.sin_family = AF_INET;
ClientAddr_2.sin_port = htons(Port_2);
ClientAddr_2.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
//使用bind将这个地址信息和套接字绑定起来
if(bind(Socket_2, (SOCKADDR *)&ClientAddr_2, ClientAddr_2_Len) == SOCKET_ERROR)
{
printf("BIND_SOCKET_2_ERROR: %d\n", SOCKET_ERROR);
exit(1);
}
printf("建立连接成功!");
//服务器作为中转站
//为两个IP之间互相转发消息
while(true)
{
//接收IP:192.168.1.2发送的数据
recvfrom(Socket_1, recvData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr_1, &ClientAddr_1_Len);
strcpy(sendData, recvData);
//转发数据给IP:192.168.1.6
if((Ret = sendto(Socket_2, sendData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr_2, ClientAddr_2_Len)) < 0)
printf("发送失败!\n");
//接收IP:192.168.1.6发送的数据
recvfrom(Socket_2, recvData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr_2, &ClientAddr_2_Len);
strcpy(sendData, recvData);
//转发数据给IP:192.168.1.2
if((Ret = sendto(Socket_1, sendData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr_1, ClientAddr_1_Len)) < 0)
printf("发送失败!\n");
}
closesocket(Socket_1);
closesocket(Socket_2);
//应用程序完成对接的处理后，调用WSACleanup
if(WSACleanup() == SOCKET_ERROR)
{
printf("WSACLEANUP_ERROR: %d\n", WSAGetLastError());
exit(1);
}
system("pause");
return 0;
}
但会有个小问题，首先发送数据的客户端的数据无法接收，而且要运行成功必须先发送一个信息，再打开第二个客户端（步骤貌似是这样，前段时间写的了，忘记了...= =）
客户端1代码：
/**
* UDP/IP 客户端 Client.c
*/
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define true 1
#define false 0
#define BUFFSIZE 1024
int main(int argc, char**argv)
{
int Ret;
WSADATA wsaData;
SOCKET SendSocket;
SOCKADDR_IN ClientAddr;
int ClientAddrLen = sizeof(ClientAddr);
unsigned short Port = 5150;
char sendData[BUFFSIZE];
char recvData[BUFFSIZE];
time_t rawtime;
if((Ret = WSAStartup(MAKEWORD(2,2), &wsaData)) != 0)
{
printf("WSASTARTUP_ERROR: %d\n", Ret);
exit(1);
}
if((SendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == INVALID_SOCKET) {
printf("SendSOCKET_ERROR\n");
exit(1);
}
ClientAddr.sin_family = AF_INET;
ClientAddr.sin_port = htons(Port);
ClientAddr.sin_addr.S_un.S_addr = inet_addr("192.168.1.2");//本机IPv4地址
printf("连接到IP:%s 端口:%d\n", inet_ntoa(ClientAddr.sin_addr), ntohs(ClientAddr.sin_port));
puts("-----开始聊天!-----");
//这样的循环聊天算法硬生生的把UDP协议弄得和前面TCP协议的聊天程序一样了。。。
//感觉并不太能表现UDP和TCP的区别。。。但我暂时没有好办法
while(true)
{
//发送数据
printf("\nC.C.:");
scanf("%s", sendData);
strcat(sendData, "\t____");
time(&rawtime);
strcat(sendData, ctime(&rawtime));
if((Ret = sendto(SendSocket, sendData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr, ClientAddrLen)) < 0)
printf("发送失败!\n");
//接收数据
if((Ret = recvfrom(SendSocket, recvData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr, &ClientAddrLen)) >= 0)
printf("鲁鲁:%s\n", recvData);
else
printf("接收失败!\n");
}
closesocket(SendSocket);
if(WSACleanup() == SOCKET_ERROR)
{
printf("WSACLEANUP_ERROR: %d\n", WSAGetLastError());
exit(1);
}
system("pause");
return 0;
}
按照思路即可编写客户端2的代码，代码也基本一样，就是端口号不能一样，需要对应服务端给定的另外一个端口号：
/**
* UDP/IP 客户端 Client.c
*/
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define true 1
#define false 0
#define BUFFSIZE 1024
int main(int argc, char**argv)
{
int Ret;
WSADATA wsaData;
SOCKET SendSocket;
SOCKADDR_IN ClientAddr;
int ClientAddrLen = sizeof(ClientAddr);
unsigned short Port = 8888;
char sendData[BUFFSIZE];
char recvData[BUFFSIZE];
time_t rawtime;
if((Ret = WSAStartup(MAKEWORD(2,2), &wsaData)) != 0)
{
printf("WSASTARTUP_ERROR: %d\n", Ret);
exit(1);
}
if((SendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == INVALID_SOCKET) {
printf("SendSOCKET_ERROR\n");
exit(1);
}
ClientAddr.sin_family = AF_INET;
ClientAddr.sin_port = htons(Port);
ClientAddr.sin_addr.S_un.S_addr = inet_addr("192.168.1.2");/**
* 服务端程序的计算机的IPv4地址
* 显然这整个聊天程序至少需要两台电脑，一台电脑可以为服务端和客户端，另外再一台电脑为客户端。或者有三台电脑就更不容易糊涂了，一台作为服务端，另外两台都是客户端。*/
printf("连接到IP:%s 端口:%d\n", inet_ntoa(ClientAddr.sin_addr), ntohs(ClientAddr.sin_port));
puts("-----开始聊天!-----");
while(true)
{
//接收数据
if((Ret = recvfrom(SendSocket, recvData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr, &ClientAddrLen)) >= 0)
printf("C.C.:%s\n", recvData);
else
printf("接收失败!\n");
//发送数据
printf("\n鲁鲁:");
scanf("%s", sendData);
strcat(sendData, "\t____");
time(&rawtime);
strcat(sendData, ctime(&rawtime));
if((Ret = sendto(SendSocket, sendData, BUFFSIZE, 0, (SOCKADDR*)&ClientAddr, ClientAddrLen)) < 0)
printf("发送失败!\n");
}
closesocket(SendSocket);
if(WSACleanup() == SOCKET_ERROR)
{
printf("WSACLEANUP_ERROR: %d\n", WSAGetLastError());
exit(1);
}
system("pause");
return 0;
}
