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#include <errno.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>
#include <fcntl.h>
#include <poll.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#define SOCKETS_MAX 128
#define POLL_WAITMS 1000
#define BUFFER_SIZE 512
#define lengthof(X) (sizeof(X) / sizeof(*(X)))
int main(int argc, char **argv)
{
int res;
int peers[SOCKETS_MAX] = {0};
struct pollfd ppeers[SOCKETS_MAX] = {0};
char buf[BUFFER_SIZE] = {0};
int port = 8604;
if (argc >= 2)
port = atoi(argv[1]);
struct in_addr inaddr = (struct in_addr)
{ .s_addr = INADDR_ANY };
if (argc >= 3)
{
res = inet_pton(AF_INET, argv[2], &inaddr);
if (res == -1)
err(1, "inet_pton()");
}
int sock = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
if (sock == -1)
err(1, "socket()");
res = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof(int));
if (res == -1)
err(1, "setsockopt()");
struct sockaddr_in addr = (struct sockaddr_in)
{
.sin_family = AF_INET,
.sin_port = htons(port),
.sin_addr = inaddr,
};
res = bind(sock, (void *)&addr, sizeof(addr));
if (res == -1)
err(1, "bind()");
res = listen(sock, 16);
if (res == -1)
err(1, "listen()");
signal(SIGPIPE, SIG_IGN);
for (;;)
{
int client = accept(sock, NULL, NULL);
if (client > 0)
{
for (size_t i = 0; i < lengthof(peers); ++i)
if (!peers[i])
{
res = fcntl(client, F_SETFL, fcntl(client, F_GETFL, 0) | O_NONBLOCK);
if (res == -1)
{
warn("fcntl()");
goto accept_err;
}
peers[i] = client;
goto accept_end;
}
warnx("dropping %d as peer list is full", client);
accept_err:
close(client);
}
accept_end:
nfds_t written = 0;
for (size_t i = 0; i < lengthof(peers); ++i)
if (peers[i])
ppeers[written++] = (struct pollfd)
{
.fd = peers[i],
.events = POLLIN,
};
res = poll(ppeers, written, POLL_WAITMS);
if (res == -1)
err(1, "poll");
if (!res)
continue;
for (size_t i = 0; i < lengthof(peers); ++i)
{
if (!peers[i])
continue;
errno = 0;
ssize_t reads = read(peers[i], buf, sizeof(buf));
if (reads == -1 || !reads)
{
if (errno != EAGAIN && errno != EWOULDBLOCK)
{
close(peers[i]);
peers[i] = 0;
}
continue;
}
for (size_t j = 0; j < lengthof(peers); ++j)
if (peers[j] && i != j)
write(peers[j], buf, reads);
}
}
}
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