网络编程 笔记（八） I/O复用

select函数调用示例

#include <stdio.h>#include <unistd.h>#include <sys/time.h>#include <sys/select.h>#define BUF_SIZE 30int main(int argc, char *argv[]){    fd_set reads, temps;    int result;    long str_len;    char buf[BUF_SIZE];    struct timeval timeout;    FD_ZERO(&reads);    FD_SET(0, &reads);    while (1) {        temps = reads;        timeout.tv_sec = 5;        timeout.tv_usec = 0;        result = select(1, &temps, 0, 0, &timeout);        if (result == -1) {            puts("select() error");            break;        }        else if(result == 0){            puts("time out");        }        else{            if (FD_ISSET(0, &temps)) {                str_len = read(0, buf, BUF_SIZE);                buf[str_len] = 0 ;                printf("message from console : %s", buf);            }        }    }    return  0;}

基于Windows实现I/O复用服务器端

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <WinSock2.h>#define BUF_SIZE 1024void ErrorHandling(char *message);int main(int argc, char *argv[]){    WSADATA wsaData;    SOCKET hServSock, hClntSock;    SOCKADDR_IN servAdr, clntAdr;    TIMEVAL timeout;    fd_set reads, cpyReads;    int adrSz;    int strLen, fdNum, i;    char buf[BUF_SIZE];    if (argc != 2)    {        printf("Usage : %s <port> \n", argv[0]);        exit(1);    }    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)    {        ErrorHandling("WSAStartup() error!");    }    hServSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);    if (hServSock == INVALID_SOCKET)    {        ErrorHandling("socket() error!");    }    memset(&servAdr, 0, sizeof(servAdr));    servAdr.sin_family = AF_INET;    servAdr.sin_addr.s_addr = htonl(INADDR_ANY);    servAdr.sin_port = htons(atoi(argv[1]));    if (bind(hServSock, (SOCKADDR *) &servAdr, sizeof(servAdr)) == SOCKET_ERROR)    {        ErrorHandling("bind() error!");    }    if (listen(hServSock, 5) == SOCKET_ERROR)    {        ErrorHandling("listen() error!");    }    FD_ZERO(&reads);    FD_SET(hServSock, &reads);    while (1)    {        cpyReads = reads;        timeout.tv_sec = 5;        timeout.tv_usec = 5000;        if ((fdNum = select(0, &cpyReads, 0, 0, &timeout)) == SOCKET_ERROR)        {            break;        }        if (fdNum == 0)        {            continue;        }        for (i = 0; i < reads.fd_count; i++)        {            if (FD_ISSET(reads.fd_array[i], &cpyReads))            {                if (reads.fd_array[i] == hServSock)                {                    adrSz = sizeof(clntAdr);                    hClntSock = accept(hServSock, (SOCKADDR *)&clntAdr, &adrSz);                    if (hClntSock == INVALID_SOCKET)                    {                        ErrorHandling("accept() error!");                    }                    FD_SET(hClntSock, &reads);                    printf("connected client : %d \n", hClntSock);                }                else                {                    strLen = recv(reads.fd_array[i], buf, BUF_SIZE - 1, 0);                    if (strLen == 0)                    {                        FD_CLR(reads.fd_array[i], &reads);                        closesocket(cpyReads.fd_array[i]);                        printf("closed client : %d \n", cpyReads.fd_array[i]);                    }                    else                    {                        send(reads.fd_array[i], buf, strLen, 0);                    }                }            }        }    }    closesocket(hServSock);    WSACleanup();    system("PAUSE");    return 0;}void ErrorHandling(char *message){    fputs(message, stderr);    fputc('\n', stderr);    exit(1);}

基于Linux客户端

////  main.c//  echo_client////  Created by wu on 15/10/16.//  Copyright (c) 2015年 template. All rights reserved.//#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <arpa/inet.h>#include <sys/socket.h>#define BUF_SIZE 1024void error_handing(char *message);void echo_client(int argc, const char * argv[]);void test_gethostbyname();int main(int argc, const char * argv[]){    echo_client(argc,  argv);    return 0;}void error_handing(char *message){    fputs(message, stderr);    fputc('\n', stderr);    exit(1);}void echo_client(int argc, const char * argv[]){    // 套接字文件描述符号    int sock;    // 接收信息的BUF    char message[BUF_SIZE];    long str_len, recv_len, recv_cnt;    // 套接字地址信息    struct sockaddr_in serv_adr;    if (argc != 3)    {        printf("Usage : %s <port>\n", argv[0]);        exit(1);    }    // 创建客户端套接字，参数含义为：    // PF_INET 表示IPv4    // SOCK_STREAM 表示以流方式传输    // IPPROTO_TCP 表示使用tcp协议    sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);    if (sock == -1)    {        error_handing("socket() error");    }    //组织服务器地址信息    memset(&serv_adr, 0, sizeof(serv_adr));    serv_adr.sin_family = PF_INET;    serv_adr.sin_addr.s_addr = inet_addr(argv[1]);    serv_adr.sin_port = htons(atoi(argv[2]));    //向服务器发起连接    if (connect(sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr)))    {        error_handing("connect() error");    }    else    {        puts("Connected..........");    }    while (1)    {        fputs("Input message(Q to quit) : ", stdout);        fgets(message, BUF_SIZE, stdin);        if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))        {            break;        }        str_len = write(sock, message, strlen(message));        recv_len = 0;        while (recv_len < str_len) {            recv_cnt = read(sock, message, BUF_SIZE-1);            if (recv_cnt == -1) {                error_handing("read() error");            }            recv_len += recv_cnt;        }        message[str_len] = 0;        printf("Message from server: %s", message);    }    close(sock);}