linux c 简单聊天小程序

自己写的一个简单聊天小程序，运用了socket编程和多线程。服务端负责接收信息同时转发信息，客户端负责发送消息同时接收服务端发来的信息

**客户端**
	#include <stdio.h>
	#include <pthread.h>
	#include <string.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <unistd.h> 
	static int
	connect_to_server (struct in_addr *ipaddr)
	{
		int sock, ret;
		struct sockaddr_in addr;

		sock = socket (AF_INET, SOCK_STREAM, 0);
		if ( sock == -1 ) {
			printf ("ERROR: Cannot create server socket!\n");
			return -1;
		}
		memset (&addr, 0, sizeof (struct sockaddr_in));
		addr.sin_family = AF_INET;
		addr.sin_port = htons (7799);
		memcpy (&addr.sin_addr, ipaddr, sizeof (struct in_addr));

		ret = connect (sock, (struct sockaddr *)&addr,
					   sizeof (struct sockaddr_in));
		if ( ret == -1 ) {
			printf ("ERROR: Cannot connect to server!\n");
			close (sock);
			return -1;
		}
		return sock;
	}
	void* Revmeg(void* sock)
	{
		char buf[1024];
		int sock_id = *(int*)sock;
		while (1)
		{
			memset(buf, 0, sizeof(buf));
			int ret = recv(sock_id, buf, 1024, 0);
			if(ret>0)
			printf("Received data:%s\n", buf);
		}
	}
	int main (int argc, char *argv[])
	{
		int sock, ret;
		char rev[1024];
		char sen[1024];
		struct in_addr ipaddr;
		socklen_t recvlen;
		system("systemctl stop firewalld.service");//关闭防火墙
		if ( argc <= 1 ) {
			printf ("ERROR:Please input <IPADDR> \n");
			return 1;
		}

		ret = inet_aton (argv[1], &ipaddr);
		if ( ret == 0 ) {
			printf ("Usage: %s <IPADDR> <MESSAGE> ...\n", argv[0]);
			return 1;
		}
		
		sock = connect_to_server (&ipaddr);//创建客户端socket
		if ( sock == -1 )
			return 1;
		else
		printf ("Connect to server successfully.\n");
		pthread_t pid;
		pthread_create(&pid,NULL,Revmeg,&sock);
		while(1)
		{
			gets(sen);
			if (!strcmp(sen, "quit")){
				send(sock, sen, sizeof(sen), 0);
				break;	}
			send(sock, sen, sizeof(sen), 0);
		}
		close (sock);
		printf ("Connection closed.\n");
		return 0;
	}

**服务器**

```c
	#include <stdio.h>
	#include <pthread.h>
	#include <string.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <unistd.h> 
	#define MAXLINE 10//最大连接数为10
	int client[MAXLINE];//建立连接的client
	static int
	get_sersocket ()//创建服务器socket
	{
		int sock, ret;
		struct sockaddr_in addr;

		sock = socket (PF_INET, SOCK_STREAM, 0);
		if ( sock == -1 ) {
			printf ("ERROR: Cannot create server socket!\n");
			return -1;
		}

		memset (&addr, 0, sizeof (struct sockaddr_in));
		addr.sin_family = AF_INET;
		addr.sin_port = htons (7799);
		addr.sin_addr.s_addr = htonl (INADDR_ANY);

		ret = bind (sock, (struct sockaddr *)&addr, sizeof (struct sockaddr_in));
		if ( ret < 0 ) {
			printf ("ERROR: Cannot bind port to server socket!\n");
			close (sock);
			return -1;
		}
		return sock;
	}

	static int
	connect_with_client (int sersock)//建立连接
	{
		int commsock, ret;
		struct sockaddr_in caddr;
		socklen_t addrlen;

		ret = listen (sersock, MAXLINE);//监听连接请求
		if ( ret == -1 ) {
			printf ("ERROR: Cannot wait to connected.\n");
			return -1;
		}

		printf ("Waiting to connected...\n");

		addrlen = sizeof (struct sockaddr_in);
		commsock = accept (sersock, (struct sockaddr *)&caddr, &addrlen);//接收连接请求
		if ( commsock == -1 ) {
			printf ("ERROR: Connect with client failed!\n");
			return -1;
		}

		printf ("Connected with client %s:%d\n",
				inet_ntoa (caddr.sin_addr), ntohs (caddr.sin_port));

		return commsock;
	}
	void* clientmge(void* sock)接收客户端信息，并转发
	{
		char buf[1024]; 
		int socket_id = *(int*)sock;//客户端socket标识符
		while (1)
		{
			memset(buf, 0, sizeof(buf));
			int ret = recv(socket_id, buf, 1024, 0);
			if (ret > 0)
			{	if (!strcmp(buf, "quit")){
					close(socket_id);
					printf("One connection is closed\n");
			}
				printf("Received data：%s\n", buf);
				for (int i = 0; i < MAXLINE; i++)
				{
					send(client[i], buf, sizeof(buf), 0);
				}
			}
		}
	}
	int main ()
	{
		int sersock, commsock,n=1;
		char rev[1024] = { '\0' };
		socklen_t recvlen;
		system("systemctl stop firewalld.service");//关闭防火墙
		sersock = get_sersocket ();//创建服务器socket
		if ( sersock == -1 )
			return 1;
		while ( 1 ) {    
		client[n] = connect_with_client (sersock);//建立连接的client
		if ( client[n] == -1 ) {
			close (sersock);
			return 1;
			}
			pthread_t th;
			pthread_create(&th, NULL, clientmge, &client[n]);//接收客户端信息，并转发
			n++;
			if(n>MAXLINE){
				printf("The server is busy, please connect later");
				close (client[n]);
			}
	}
	for(int i=0;i<MAXLINE;i++)
		close (client[i]);
		close (sersock);
		return 0;

	}