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; }