#ifndef _CONFIG_H
#define _CONFIG_H//用于控制输出的#define _DEBUG
#ifdef _DEBUG
#define TRACE(...) printf(__VA_ARGS__)
#else
#define TRACE(...)
#endif   #endif

#include "socketlib.h"
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>#define MYPORT 4444
#define BACKLOG 5
#define BUF_SIZE 200int fd_A[BACKLOG];
int conn_amount;int main()
{int nSocktfd, nNewSocktfd;int i,nRet,nMaxSock,nSockaddrLen;struct sockaddr_in client_addr;char szBuf[BUF_SIZE];fd_set fdRead;struct timeval tv;nSocktfd = ServerBuildSocket(MYPORT);if (nSocktfd < 0){TRACE("ServerBuildSocket faile.\n");exit(0);}conn_amount = 0;nSockaddrLen = sizeof(client_addr);nMaxSock = nSocktfd; while(1){FD_ZERO(&fdRead);FD_SET(nSocktfd,&fdRead);tv.tv_sec = 30;tv.tv_usec = 0;//add active connect to fd setfor (i = 0; i < BACKLOG; i++) {if (fd_A[i] != 0){FD_SET(fd_A[i],&fdRead);}}nRet = select(nMaxSock + 1, &fdRead, NULL, NULL, &tv);if (nRet < 0){TRACE("select failed.\n");break;}else if(nRet == 0){TRACE("timeout.\n");continue;}//check whether the connection have data to recieve for (i = 0; i < BACKLOG; i++){if (fd_A[i] && FD_ISSET(fd_A[i],&fdRead)){nRet = recv(fd_A[i],szBuf,sizeof(szBuf),0);if (nRet <= 0){TRACE("Client %d close\n",i);close(fd_A[i]);FD_CLR(fd_A[i],&fdRead);fd_A[i] = 0;conn_amount --;}else{if (nRet < BUF_SIZE)memset(&szBuf[nRet],'\0',1);TRACE("Client[%d] send: %s.\n",i,szBuf);}}}//for//check whether a new connection comesif (FD_ISSET(nSocktfd,&fdRead)){nNewSocktfd = accept(nSocktfd, (struct sockaddr *)&client_addr,&nSockaddrLen);if (nNewSocktfd <= 0){TRACE("accept failed.\n");continue;}if (conn_amount < BACKLOG -1){for(i = 0; i < BACKLOG; i++){if(fd_A[i] == 0){fd_A[i] = nNewSocktfd;conn_amount ++;break;}}TRACE("new connection client[%d] %s:%d\n", conn_amount,inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));if (nNewSocktfd > nMaxSock){nMaxSock = nNewSocktfd;}}else{TRACE("max connections arrive,exit\n");send(nNewSocktfd,"bye",4,0);close(nNewSocktfd);continue;}}}//while//close all connectionsfor (i = 0; i < BACKLOG; i++){if (fd_A[i] != 0){close(fd_A[i]);}}exit(0);}

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "config.h"
#include "socketlib.h"#define MYPORT 4444int main()
{int nSockFd;int nLen;char szBuf[1024];nSockFd = ConnectServer("127.0.0.1",MYPORT);if (nSockFd < 0){TRACE("ConnectServer failed.\n");exit(0);}while(fgets(nSockFd, 1024, stdin) != NULL){if(send(nSockFd,szBuf,strlen(szBuf),0) <= 0){TRACE("send failed.\n");exit(0);}}close(nSockFd);exit(0);}

#ifndef _SOCKETLIB_H
#define _SOCKETLIB_Hint ServerBuildSocket(unsigned int nPort);
int ConnectServer(const char *szIp,int nPort);#endif

#include "socketlib.h"
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>int ServerBuildSocket(unsigned int port)
{//Build socket for server ,bind and listen the portint sock_fd,BACKLOG = 5;int nOptVal = 1;struct sockaddr_in server_addr;if ((sock_fd = socket(AF_INET,SOCK_STREAM,0)) == -1){return -1; }if (setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR,&nOptVal,sizeof(int)) == -1){return -2;}server_addr.sin_family = AF_INET;server_addr.sin_port = htons(port);server_addr.sin_addr.s_addr = INADDR_ANY;if (bind(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1){return -3;}if (listen(sock_fd,BACKLOG) == -1){return -4;}return sock_fd;}int ConnectServer(const char *szIp, int nPort)
{int nSockFd;int nAddrLen;struct sockaddr_in addr;if ((nSockFd = socket(AF_INET, SOCK_STREAM, 0)) == -1){return -1;}addr.sin_family = AF_INET;addr.sin_port = htons(nPort);if (inet_aton(szIp, &addr.sin_addr) < 0){return -2;}nAddrLen = sizeof(addr);if (connect(nSockFd,(struct sockaddr *)&addr, nAddrLen) == -1){return -3;}return nSockFd;
}

server:select_server.o socketlib.o gcc -o server select_server.o socketlib.o
client:select_client.o socketlib.ogcc -o client select_client.o socketlib.o
select_server.o:select_server.c socketlib.hgcc -c select_server.c socketlib.h
select_client.o:select_client.c socketlib.hgcc -c select_client.c socketlib.h
socketlib.o:socketlib.c socketlib.hgcc -c socketlib.c socketlib.hclean:rm -f select_sever.o socketlib.o