srv.c

在Linux环境下运行

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>

#define SERVPORT 3000
#define BUFFER_SIZE 128
#define BACKLOG 10

struct MSG
{
uint32_t dest_addr;
uint32_t head_addr;
char buf[BUFFER_SIZE];
int imsglen;
};

int cln_num=0,cln_sck_fd[BACKLOG];
struct sockaddr_in cln_addr[BACKLOG];
struct sockaddr_in srv_addr;
/*接收*/
void * msg_rcv(void * Parm)
{
         int i,rcvBytes;
         struct MSG msg_buf;
         int sck_fd = *((int*)Parm);
         while(1)
	    {
	     if ((rcvBytes = recv(sck_fd,(char *)&msg_buf,sizeof(struct MSG),0)) ==-1) 
	        {
			perror("recv error！");
			return NULL;
		}else if(rcvBytes==0)
		{
			printf("recv error！\n");
			return NULL;
		}
		msg_buf.buf[msg_buf.imsglen]=0;

		if(msg_buf.dest_addr==srv_addr.sin_addr.s_addr)//在键盘输入的IP与检测连接的IP一致时则显示接收消息
		{
			printf("Received Msg from %s: %s\n",inet_ntoa(msg_buf.head_addr),msg_buf.buf);
			continue;
		}
                /*将消息通过服务端转发给另外一个客户端*/
		for(i=0;i<cln_num;i++)//当客户端接收到消息就退出
		{
		    if(cln_addr[i].sin_addr.s_addr==msg_buf.dest_addr)
		     {
			if(send(cln_sck_fd[i],(char *)&msg_buf,sizeof(struct MSG),0)==-1)
			{
				perror("sand");
              		exit(1);
			}
			break;
		     }
		}
		if(i==cln_num)//提示消息不能到达
		{
			strcpy(msg_buf.buf,"Aim host unreachable!");
			msg_buf.dest_addr=msg_buf.head_addr;
			msg_buf.head_addr=srv_addr.sin_addr.s_addr;
			msg_buf.imsglen = strlen(msg_buf.buf);
			if(send(sck_fd,(char *)&msg_buf,sizeof(struct MSG),0)==-1)
			{
				perror("send");
              		exit(1);
			}
		}
	}
	return NULL;
}

     /*发送*/
void * msg_send(void)
{
	
	struct MSG msg_buf;
	int i,len=0;

	while(1)
	{
		memset(&msg_buf,0,sizeof(struct MSG));		
		scanf("%s",msg_buf.buf);
		msg_buf.head_addr=srv_addr.sin_addr.s_addr;
		msg_buf.imsglen = strlen(msg_buf.buf);
		
		if(msg_buf.imsglen<=0)
		{
			printf("[host addr] [msg]\n");
			continue;
		}
		for(i=0;i<cln_num;i++)
		{
			msg_buf.dest_addr=cln_addr[cln_num].sin_addr.s_addr;
			if(send(cln_sck_fd[i],(char *)&msg_buf,sizeof(struct MSG),0)==-1)
			{
				printf("Send error!\n");
				exit(1);
			}
		}		   
	}
}

int main()
{
	int srv_sck_fd,iSize;
	pthread_t pThreadID;
	int iRet;

	if((srv_sck_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) 
	{
		perror("socket error！");
		exit(1);
	}
	srv_addr.sin_family=AF_INET;//使用Internet协议族
	srv_addr.sin_port=htons(SERVPORT);//指定端口号
	srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);//使用所有的网络接口
	//srv_addr.sin_addr.s_addr = inet_addr("192.168.1.5");
	bzero(&(srv_addr.sin_zero),8);
              /*绑定*/
	if (bind(srv_sck_fd, (struct sockaddr *)&srv_addr, sizeof(struct sockaddr)) == -1) 
	{
		perror("bind error！");
		exit(1);
	}
             /*监听*/
	if (listen(srv_sck_fd,10) == -1) 
	{
		perror("listen error！");
		exit(1);
	}

	iSize = sizeof(struct sockaddr_in);
	iRet = pthread_create(&pThreadID,NULL,msg_send,NULL);//创建发送线程
         /*接收*/
	while(1)
	{
		if ((cln_sck_fd[cln_num] = accept(srv_sck_fd, (struct sockaddr *)&cln_addr[cln_num],&iSize)) == -1)
		{
			perror("accept error");
			continue;
		}
		
		iRet = pthread_create(&pThreadID,NULL,msg_rcv,(void *)&cln_sck_fd[cln_num]);
		
		printf("received a connection from %s\n", inet_ntoa(cln_addr[cln_num].sin_addr));
		cln_num++;
	}
}