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 30

int 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 1024
void 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 1024
void 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);

}