linux下socket通讯

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <sys/types.h> #include <unistd.h> #include <fcntl.h> //socket #include <sys/socket.h> #include <netinet/in.h> int sock_count=0; int ListenSockfd=0; //for listen int ConnSockfd; //for do something fd_set fds; fd_set fds_for_Comm; int addr_len; int ret; struct timeval tv={1,0}; struct timeval tv1={0,100}; struct sockaddr_in serveraddr; struct sockaddr_in clientaddr; int main() { pid_t pid;//for fork char i=0; char buf[1024]; ssize_t recvlen=0; //填充地址结构 memset(&serveraddr,0,sizeof(serveraddr)); serveraddr.sin_family=AF_INET; serveraddr.sin_addr.s_addr=htonl(INADDR_ANY); serveraddr.sin_port=htons(6666); //建立socket用于侦听 if((ListenSockfd=socket(AF_INET,SOCK_STREAM,0))==-1) { printf("create socket error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } //将socke设置为非堵塞 fcntl(ListenSockfd,F_SETFL,O_NONBLOCK); //绑定地址到侦听socket if(bind(ListenSockfd,(struct sockaddr *)&serveraddr,sizeof(serveraddr))==-1) { printf("create socket error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } //侦听socket if(listen(ListenSockfd,10)==-1) { printf("create socket error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } addr_len=sizeof(struct sockaddr_in); while(1) { int fd[2];//管道文件描述符 //清空描述符集 FD_ZERO(&fds); //将侦听socket放置于描述符集 FD_SET(ListenSockfd,&fds); //进行轮询 ret=select(ListenSockfd+1,&fds,NULL,NULL,&tv); //轮询出错 if(ret<0) { printf("select socket error: %s(errno: %d)\n",strerror(errno),errno); break; } //轮询超时 else if(ret==0) { continue; } //检查侦听socket是否可读 if(FD_ISSET(ListenSockfd,&fds)) { if(i<10)//判断连接数是否大于10 { //建立连接并生成用于通信的socket ConnSockfd=accept(ListenSockfd,(struct sockaddr*)&clientaddr,&addr_len); if(ConnSockfd<0) { printf("accept error\n"); continue; } //在建立新连接时建立管道，以为在下面要为每一个子进程建立一个管道，因此管道的声名和建立应该放在while循环中 if(pipe(fd)<0) { printf("create pipe error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } //打印客户端信息，并发送欢迎信息 printf("new connection client[%d] %s:%d\n",sock_count,inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port)); send(ConnSockfd,"welcome to the file transfer\n",sizeof("welcome to the file transfer\n"),0); i++; } else { send(ConnSockfd,"Server is over MaxNum\n",sizeof("Server is over MaxNum\n"),0); } } //建立子进程 if((pid=fork())>0)//如果是父进程 { //关闭管道读端 close(fd[0]); //向管道写入连接到服务端的客户的顺序编号 if(write(fd[1],(char *)&i,1)==-1) printf("write error: %s(errno: %d)\n",strerror(errno),errno); } else if(pid==0)//如果是子进程 { char i_c; int ret; int maxId; close(fd[1]);//关闭管道写入端 while(1) { //建立select轮询 FD_ZERO(&fds_for_Comm); FD_SET(fd[0],&fds_for_Comm); FD_SET(ConnSockfd,&fds_for_Comm); maxId= fd[0]>ConnSockfd ? fd[0] : ConnSockfd ; ret=select(maxId+1,&fds_for_Comm,NULL,NULL,&tv1); if(ret<0) { printf("select error: %s(errno: %d)\n",strerror(errno),errno); exit(0); } else if(ret==0) { continue; } //判断管道是否可读 if(FD_ISSET(fd[0],&fds_for_Comm)) { read(fd[0],(char *)&i_c,1); //block printf(">>>>>>>>>>>%d\n",i_c); } //判断socket是否可读 if(FD_ISSET(ConnSockfd,&fds_for_Comm)) { memset(buf,0,1024); recvlen=recv(ConnSockfd, buf, 1024, 0); printf("from client[%d]: %s\n",i_c,buf); } } } } exit(0); }