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#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.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 BUFFER_SIZE 512
#define lengthof(X) (sizeof(X) / sizeof(*(X)))
int main(int argc, char **argv)
{
struct sockaddr_in addr = {.sin_family = AF_INET};
int peers[SOCKETS_MAX] = {0}, res;
struct pollfd ppeers[SOCKETS_MAX] = {0};
char buf[BUFFER_SIZE] = {0};
addr.sin_port = htons(8604);
if (argc >= 2)
addr.sin_port = htons(atoi(argv[1]));
addr.sin_addr = (struct in_addr){.s_addr = INADDR_ANY};
if (argc >= 3)
{
res = inet_pton(AF_INET, argv[2], &addr.sin_addr);
if (res == -1)
err(1, "inet_pton()");
}
peers[0] = socket(AF_INET, SOCK_STREAM, 0);
if (peers[0] == -1)
err(1, "socket()");
res = setsockopt(peers[0], SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof(int));
if (res == -1)
err(1, "setsockopt()");
res = bind(peers[0], (void *)&addr, sizeof(addr));
if (res == -1)
err(1, "bind()");
res = listen(peers[0], 16);
if (res == -1)
err(1, "listen()");
signal(SIGPIPE, SIG_IGN);
for (;;)
{
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, -1);
if (res == -1)
err(1, "poll");
if (ppeers[0].revents & POLLIN)
{
int client = accept(peers[0], NULL, NULL);
if (client == -1)
{
warn("accept()");
goto after;
}
for (size_t i = 1; i < lengthof(peers); ++i)
if (!peers[i])
{
peers[i] = client;
goto after;
}
warnx("dropping %d as peer list is full", client);
close(client);
}
after:
for (size_t i = 1; i < written; ++i)
{
if (!(ppeers[i].revents & POLLIN))
continue;
ssize_t reads = read(ppeers[i].fd, buf, sizeof(buf));
if (reads == -1 || !reads)
{
for (size_t j = 1; j < lengthof(peers); ++j)
if (ppeers[i].fd == peers[j])
{
close(peers[j]);
peers[j] = 0;
break;
}
continue;
}
for (size_t j = 1; j < lengthof(peers); ++j)
{
if (!peers[j] || i == j)
continue;
size_t writtenall = 0;
while (writtenall < reads)
{
ssize_t written = write(peers[j], buf + writtenall, reads - writtenall);
if (written == -1)
break;
else
writtenall += written;
}
}
}
}
}
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