From 261b81eeaada702eb254e502462ac3a4d1249ec0 Mon Sep 17 00:00:00 2001
From: Raymaekers Luca <raymaekers.luca@gmail.com>
Date: Wed, 16 Oct 2024 02:18:30 +0200
Subject: Initial commit

---
 server.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 172 insertions(+)
 create mode 100644 server.c

(limited to 'server.c')

diff --git a/server.c b/server.c
new file mode 100644
index 0000000..63784d1
--- /dev/null
+++ b/server.c
@@ -0,0 +1,172 @@
+// 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
+
+// TODO: send message to all other clients
+// - implement different rooms
+// - implement history
+// - implement tls
+
+#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
+
+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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