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// Server for chatty
// The idea is the following:
// - tcp server that you can send messages to
// - encrypted communication
// - history upon connecting
// - date of messages sent
// - author
// - fingeprint as ID for authorship
// - client for reading the messages and sending them at the same time
// TODO:
// - min height & width
// - wrapping input
// - max y for new messages and make them scroll
// - check resize event
// - asynchronously receive/send a message
// - fix receiving messages with arbitrary text length
// TODO: send message to all other clients
// - implement different rooms
// - implement history
// - implement tls
#include "common.h"
#include "config.h"
#include <arpa/inet.h>
#include <errno.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
#define MAX_CONNECTIONS 5
#define FD_MAX MAX_CONNECTIONS + 1
static const char *filename = "history.dat";
enum { FD_SERVER = 0 };
int serverfd;
void err_exit(const char *msg)
{
if (serverfd)
if (close(serverfd))
writef("Error while closing server socket. errno: %d\n", errno);
fprintf(stderr, "%s errno: %d\n", msg, errno);
_exit(1);
}
int main(void)
{
int clientfd;
int nclient = 0;
int on = 1;
struct message msg_recv = {0};
serverfd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
if (setsockopt(serverfd, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on)))
err_exit("Error while setting socket option.");
const struct sockaddr_in address = {
AF_INET,
htons(PORT),
{0},
};
if (bind(serverfd, (struct sockaddr *)&address, sizeof(address))) {
err_exit("Error while binding.");
}
if (listen(serverfd, BUF_MAX)) {
err_exit("Error while listening");
}
writef("Listening on localhost:%d\n", PORT);
struct pollfd fds[MAX_CONNECTIONS + 1] = {
{serverfd, POLLIN, 0}, // FD_SERVER
{ -1, POLLIN, 0},
{ -1, POLLIN, 0},
{ -1, POLLIN, 0},
{ -1, POLLIN, 0},
{ -1, POLLIN, 0},
};
for (;;) {
int ret = poll(fds, FD_MAX, 50000);
if (ret == -1)
err_exit("Error while polling");
else if (ret == 0) {
writef("polling timed out.\n");
continue;
}
// New client tries to connect to serverfd
if (fds[FD_SERVER].revents & POLLIN) {
clientfd = accept(serverfd, NULL, NULL);
// When MAX_CONNECTIONS is reached, close new clients trying to connect.
if (nclient == MAX_CONNECTIONS) {
writef("Max connections reached.\n");
if (send(clientfd, 0, 0, 0) == -1)
err_exit("Error while sending EOF to client socket.");
if (shutdown(clientfd, SHUT_RDWR))
err_exit("Error while shutting down client socket.");
if (close(clientfd))
err_exit("Error while closing client socket.");
} else if (clientfd != -1) {
nclient++;
// get a new available spot in the fds array
int i;
for (i = 0; i < MAX_CONNECTIONS; i++)
if (fds[i].fd == -1)
break;
fds[i].fd = clientfd;
writef("New client: %d, %d\n", i, clientfd);
} else {
writef("Could not accept client errno: %d\n", errno);
}
}
// Check for events on connected clients
for (int i = 1; i <= nclient; i++) {
if (!(fds[i].revents & POLLIN))
continue;
int nrecv;
clientfd = fds[i].fd;
nrecv = recv(clientfd, &msg_recv, sizeof(struct message), 0);
if (nrecv == 0) {
printf("client %d disconnected.\n", i);
fds[i].fd = -1;
fds[i].revents = 0;
if (shutdown(clientfd, SHUT_RDWR))
err_exit("Error while shutting down client %d socket.");
if (close(clientfd))
err_exit("Error while cloing client socket.");
nclient--;
break;
} else if (nrecv == -1) {
err_exit("Error while receiving from client socket.");
}
printf("client %d sent %d bytes.\n", i, nrecv);
// TODO:
for (int j = 1; j <= nclient; j++) {
// skip the client that sent the message
if (j == i)
continue;
if (send(fds[j].fd, &msg_recv, nrecv, 0) == -1)
printf("Error while sendig message to client %d. errno: %d\n", j, errno);
else
printf("Retransmitted message to client %d.\n", j);
}
// // TODO: check if bytes are correct
// FILE *f = fopen("srv_recv.bin", "wb");
// fwrite(&msg_recv, sizeof(struct message), 1, f);
// fclose(f);
//
// printf("written %lu bytes to srv_recv.bin\n", sizeof(msg_recv));
// return 0;
}
}
return 0;
}
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