2. 首先生成一个叫sock_fd的socket描述符,用于监听端口。
4. 处理fdsr中可以接收数据的连接。如果是sock_fd,表明有新连接加入,将新加入连接的socket描述符放置到fd_A。
#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>
int conn_amount; // current connection amount
{
int i;
printf("client amount: %d\n", conn_amount);
for (i = 0; i < BACKLOG; i++) {
printf("[%d]:%d ", i, fd_A[i]);
}
printf("\n\n");
}
{
int sock_fd, new_fd; // listen on sock_fd, new connection on new_fd
struct sockaddr_in server_addr; // server address information
struct sockaddr_in client_addr; // connector's address information
socklen_t sin_size;
int yes = 1;
char buf[BUF_SIZE];
int ret;
int i;
perror("socket");
exit(1);
}
perror("setsockopt");
exit(1);
}
server_addr.sin_family = AF_INET; // host byte order
server_addr.sin_port = htons(MYPORT); // short, network byte order
server_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
memset(server_addr.sin_zero, '\0', sizeof(server_addr.sin_zero));
perror("bind");
exit(1);
}
perror("listen");
exit(1);
}
int maxsock;
struct timeval tv;
sin_size = sizeof(client_addr);
maxsock = sock_fd;
while (1) {
// initialize file descriptor set
FD_ZERO(&fdsr);
FD_SET(sock_fd, &fdsr);
tv.tv_sec = 30;
tv.tv_usec = 0;
for (i = 0; i < BACKLOG; i++) {
if (fd_A[i] != 0) {
FD_SET(fd_A[i], &fdsr);
}
}
if (ret < 0) {
perror("select");
break;
} else if (ret == 0) {
printf("timeout\n");
continue;
}
for (i = 0; i < conn_amount; i++) {
if (FD_ISSET(fd_A[i], &fdsr)) {
ret = recv(fd_A[i], buf, sizeof(buf), 0);
if (ret <= 0) { // client close
printf("client[%d] close\n", i);
close(fd_A[i]);
FD_CLR(fd_A[i], &fdsr);
fd_A[i] = 0;
} else { // receive data
if (ret < BUF_SIZE)
memset(&buf[ret], '\0', 1);
printf("client[%d] send:%s\n", i, buf);
}
}
}
if (FD_ISSET(sock_fd, &fdsr)) {
new_fd = accept(sock_fd, (struct sockaddr *)&client_addr, &sin_size);
if (new_fd <= 0) {
perror("accept");
continue;
}
if (conn_amount < BACKLOG) {
fd_A[conn_amount++] = new_fd;
printf("new connection client[%d] %s:%d\n", conn_amount,
inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
if (new_fd > maxsock)
maxsock = new_fd;
}
else {
printf("max connections arrive, exit\n");
send(new_fd, "bye", 4, 0);
close(new_fd);
break;
}
}
showclient();
}
for (i = 0; i < BACKLOG; i++) {
if (fd_A[i] != 0) {
close(fd_A[i]);
}
}
}
for(i = 0;i < MAXCLIENT;i++)
{
if(fd[i] == 0)
{
fd[i] = new_fd;
break;
}
conn_amount++;
这样就可以重复利用fd[i]的空间;
另外在recv返回值<=0的时候,加一句conn_amount++;
还有一点,超过最大连接数的时候break应该为continue,这样会更人性化一点,客户端太多关闭它的请求就行了,没必要自毁,这样整个系统就可以动态与客户端实现连接,很感谢楼主的贡献,使我少走了很多弯路,现在在楼主的基础上,我基本上已经实现了多用户访问的服务器端程序,而且还加上了数据库,我觉得这个世界是这么的美妙!
这些代码,经过长时间测试,没有出现问题,朋友们如果有什么更简洁高效的方法,一定要共享出来哦!
{
char msg[BUF_SIZE];
int Listen_socket,ret,on;
struct sockaddr_in local_addr;
struct sockaddr_in client_addr;
int i;
fd_set fdsr; //文件描述符集的定义
socklen_t addr_size;
addr_size = sizeof(struct sockaddr_in);
int new_fd;
struct timeval tv;
if( (Listen_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
{
emit err_msg_signal("failed create socket");
}
on = 1;
ret = setsockopt( Listen_socket, SOL_SOCKET, SO_REUSEADDR,
&on, sizeof(on) );
//设置发送时限
setsockopt(Listen_socket,SOL_SOCKET,SO_SNDTIMEO,(char *)&nNetTimeout,sizeof(int) );
//设置接收时限
setsockopt(Listen_socket,SOL_SOCKET,SO_RCVTIMEO,(char *)&nNetTimeout,sizeof(int));
local_addr.sin_family = AF_INET;
local_addr.sin_port = htons(port);
local_addr.sin_addr.s_addr = INADDR_ANY;
//绑定本机IP和端口号
if(bind(Listen_socket, (struct sockaddr*)&local_addr, sizeof(struct sockaddr)) == -1)
{
emit err_msg_signal("failed bind");
}
if(listen(Listen_socket, 8) == -1)
{
emit err_msg_signal("failed listen");
}
QTime current_time;
current_time = QTime::currentTime();
int flag_minutechange = 0,lastminute = current_time.currentTime().minute();
int maxsock = Listen_socket;
以下为并发连接处理,系统关键部分
***************************************/
{
{
lastminute = current_time.currentTime().minute();
flag_minutechange = 1;
}
FD_SET(Listen_socket, &fdsr);
for (i = 0; i < MAXCLIENT; i++) //将存在的套接字加入描述符集
{
if (fd[i] != 0)
{
FD_SET(fd[i], &fdsr);
if(flag_minutechange == 1)
{
con_time[i]--;
if(con_time[i] <= 0)
{
close(fd[i]);
FD_CLR(fd[i], &fdsr);
fd[i] = 0;
conn_amount--;
}
}
}
flag_minutechange = 0;
tv.tv_sec = 1;
tv.tv_usec = 0;
ret = select(maxsock + 1, &fdsr, NULL, NULL,&tv); //关键的select()函数,用来探测各套接字的异常
//如果在文件描述符集中有连接请求或发送请求,会作相应处理,
//从而成功的解决了单线程情况下阻塞进程的情况,实现多用户连接与通信
{
qDebug()<<"failed select\n";
break;
}
else if (ret == 0) //=0表示超时,下一轮循环
{
//qDebug()<<"timeout\n";
continue;
}
for (i = 0; i < conn_amount; i++)
{
if (FD_ISSET(fd[i], &fdsr))
{
ret = recv(fd[i], msg, BUF_SIZE, 0);
if (ret <= 0) // recv<=0,表明客户端关闭连接,服务器也关闭相应连接,并把连接套接子从文件描述符集中清除
{
qDebug("client[%d] close\n", i);
close(fd[i]);
FD_CLR(fd[i], &fdsr);
fd[i] = 0;
conn_amount--;
}
else //否则表明客户端有数据发送过来,作相应接受处理
{
con_time[i] = MAX_IDLECONNCTIME; //重新写入fd[i]的超时数,再此之后如果MAX_IDLECONNCTIME分钟内此连接无反应,服务器会关闭该连接
if (ret < BUF_SIZE)
emit err_msg_signal("client ip: " + QString::fromLatin1(inet_ntoa(client_addr.sin_addr)) +
" port: " + QString::number(ntohs(client_addr.sin_port))+" coming data");
qDebug("client[%d] send:%s\n", i, msg);
msg[ret] = '\0';
emit recv_msg_signal(QString::fromLatin1(msg),fd[i]);
//send(fd[i],msg,ret,0);
}
}
}
// 以下说明异常有来自客户端的连接请求
if (FD_ISSET(Listen_socket, &fdsr))
{
new_fd = accept(Listen_socket, (struct sockaddr *)&client_addr, &addr_size);
if (new_fd <= 0)
{
qDebug("failed accept");
continue;
}
if (conn_amount < MAXCLIENT)
{
for(i = 0;i < MAXCLIENT;i++)
{
if(fd[i] == 0)
{
con_time[i] = MAX_IDLECONNCTIME; //每次新建立连接,设置该连接的超时数,如果此连接此后MAX_IDLECONNCTIME分钟内无反应,关闭该连接
break;
}
conn_amount++;
//fd[conn_amount++] = new_fd;
qDebug("new connection client[%d] %s:%d\n", conn_amount,
inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
emit err_msg_signal("client ip: " + QString::fromLatin1(inet_ntoa(client_addr.sin_addr)) +
" port: " + QString::number(ntohs(client_addr.sin_port)));
if (new_fd > maxsock)
maxsock = new_fd;
}
else
{
qDebug("MAXCLIENT arrive, exit\n");
send(new_fd, "over MAXCLIENT\n", 25, 0);
close(new_fd);
continue;
}
}
}