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| #define _GNU_SOURCE 1
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <poll.h>
#define USER_LIMIT 5
#define BUFFER_SIZE 64
#define FD_LIMIT 65535
struct client_data
{
sockaddr_in address;
char* write_buf;
char buf[BUFFER_SIZE];
};
int setnonblocking(int fd)
{
int old_option = fcntl(fd, F_GETFL);
int new_option = old_option | O_NONBLOCK;
fcntl(fd, F_SETFL, new_option);
return old_option;
}
int main(int argc, char* argv[])
{
if (argc <= 2)
{
printf("usage: %s ip_address port_number\n", basename(argv[0]));
return 1;
}
const char* ip = argv[1];
int port = atoi(argv[2]);
int ret = 0;
struct sockaddr_in address;
bzero(&address, sizeof(address));
address.sin_family = AF_INET;
inet_pton(AF_INET, ip, &address.sin_addr);
address.sin_port = htons(port);
int listenfd = socket(PF_INET, SOCK_STREAM, 0);
assert(listenfd >= 0);
ret = bind(listenfd, (struct sockaddr*)&address, sizeof(address));
assert(ret != -1);
ret = listen(listenfd, 5);
assert(ret != -1);
client_data* users = new client_data[FD_LIMIT];
pollfd fds[USER_LIMIT + 1];
int user_counter = 0;
for (int i = 1; i <= USER_LIMIT; ++i)
{
fds[i].fd = -1;
fds[i].events = 0;
}
fds[0].fd = listenfd;
fds[0].events = POLLIN | POLLERR;
fds[0].revents = 0;
while (1)
{
ret = poll(fds, user_counter + 1, -1);
if (ret < 0)
{
printf("poll failure\n");
break;
}
for (int i = 0; i < user_counter + 1; ++i)
{
if ((fds[i].fd == listenfd) && (fds[i].revents & POLLIN))
{
struct sockaddr_in client_address;
socklen_t client_addrlength = sizeof(client_address);
int connfd = accept(listenfd, (struct sockaddr*)&client_address, &client_addrlength);
if (connfd < 0)
{
printf("errno is: %d\n", errno);
continue;
}
if (user_counter >= USER_LIMIT)
{
const char* info = "too many users\n";
printf("%s", info);
send(connfd, info, strlen(info), 0);
close(connfd);
continue;
}
user_counter++;
users[connfd].address = client_address;
setnonblocking(connfd);
fds[user_counter].fd = connfd;
fds[user_counter].events = POLLIN | POLLRDHUP | POLLERR;
fds[user_counter].revents = 0;
printf("comes a new user, now have %d users\n", user_counter);
}
else if (fds[i].revents & POLLERR)
{
printf("get an error from %d\n", fds[i].fd);
char errors[100];
memset(errors, '\0', 100);
socklen_t length = sizeof(errors);
if (getsockopt(fds[i].fd, SOL_SOCKET, SO_ERROR, &errors, &length) < 0)
{
printf("get socket option failed\n");
}
continue;
}
else if (fds[i].revents & POLLRDHUP)
{
users[fds[i].fd] = users[fds[user_counter].fd];
close(fds[i].fd);
fds[i] = fds[user_counter];
i--;
user_counter--;
printf("a client left\n");
}
else if (fds[i].revents & POLLIN)
{
int connfd = fds[i].fd;
memset(users[connfd].buf, '\0', BUFFER_SIZE);
ret = recv(connfd, users[connfd].buf, BUFFER_SIZE - 1, 0);
printf("get %d bytes of client data %s from %d\n", ret, users[connfd].buf, connfd);
if (ret < 0)
{
if (errno != EAGAIN)
{
close(connfd);
users[fds[i].fd] = users[fds[user_counter].fd];
fds[i] = fds[user_counter];
i--;
user_counter--;
}
}
else if (ret == 0)
{
printf("code should not come to here\n");
}
else
{
for (int j = 1; j <= user_counter; ++j)
{
if (fds[j].fd == connfd)
{
continue;
}
fds[j].events |= ~POLLIN;
fds[j].events |= POLLOUT;
users[fds[j].fd].write_buf = users[connfd].buf;
}
}
}
else if (fds[i].revents & POLLOUT)
{
int connfd = fds[i].fd;
if (!users[connfd].write_buf)
{
continue;
}
ret = send(connfd, users[connfd].write_buf, strlen(users[connfd].write_buf), 0);
users[connfd].write_buf = NULL;
fds[i].events |= ~POLLOUT;
fds[i].events |= POLLIN;
}
}
}
delete[] users;
close(listenfd);
return 0;
}
|