From 1cc2ef41d16ee9881def2cdc466c3b5400d04eac Mon Sep 17 00:00:00 2001
From: "Nikita Tyukalov, ASUS, Linux" <murkaTheGood@gmail.com>
Date: Tue, 24 Mar 2026 19:45:17 +0300
Subject: [PATCH] Implemented server

---
 main.c   | 45 ++++++++++++++++++++++++++++++
 server.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 server.h | 36 ++++++++++++++++++++++++
 3 files changed, 164 insertions(+)
 create mode 100644 server.c
 create mode 100644 server.h

diff --git a/main.c b/main.c
index 55c36f2..665cdee 100644
--- a/main.c
+++ b/main.c
@@ -8,12 +8,14 @@
 #include <sys/signalfd.h>
 
 #include "event_loop.h"
+#include "server.h"
 
 /*
  * Data
  */
 static bool _to_work = true;
 static int _sig_fd = -1;
+static int _server_fd = -1;
 
 /*
  * Private API
@@ -58,10 +60,40 @@ static bool signals_init() {
     return true;
 }
 
+// Finalize signals.
 static void signals_deinit() {
     close(_sig_fd);
 }
 
+// Initialize the server.
+// Returns:
+//  - true on success
+static bool server_init() {
+    _server_fd = server_open("0.0.0.0", 20070);
+    if (_server_fd == -1) {
+        return false;
+    }
+    struct epoll_event ev;
+    ev.data.fd = _server_fd;
+    ev.events = EPOLLIN;
+    bool loop_res = loop_ctl(
+        EPOLL_CTL_ADD,
+        _server_fd,
+        &ev
+    );
+    if (!loop_res) {
+        server_close();
+        printf("[!] loop_ctl failed\n");
+        return false;
+    }
+    return true;
+}
+
+// Finalize the server.
+static void server_deinit() {
+    server_close();
+}
+
 /*
  * Callbacks and main
  */
@@ -71,6 +103,13 @@ static void on_fd_event(int fd, uint32_t events) {
     if (fd == _sig_fd) {
         _to_work = false;
     }
+    // Server event
+    else if (fd == _server_fd) {
+        if (!server_event(_server_fd)) {
+            printf("[!] server_event failed\n");
+            _to_work = false;
+        }
+    }
     else {
         printf("[!] Event has happened on an unknown file descriptor\n");
     }
@@ -84,6 +123,11 @@ int main(int argc, char **argv) {
         loop_deinit();
         return 1;
     }
+    if (!server_init()) {
+        signals_deinit();
+        loop_deinit();
+        return 1;
+    }
 
     while (_to_work) {
         if (!loop_wait()) {
@@ -93,6 +137,7 @@ int main(int argc, char **argv) {
         printf("--- loop ---\n");
     }
     
+    server_close();
     signals_deinit();
     loop_deinit();
     return 0;
diff --git a/server.c b/server.c
new file mode 100644
index 0000000..8a2031a
--- /dev/null
+++ b/server.c
@@ -0,0 +1,83 @@
+#include "server.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#include <errno.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+/*
+ * Macros
+ */
+#define LISTEN_BACKLOG      (2048)
+
+/*
+ * Data
+ */
+static int _fd = -1;
+
+/*
+ * Private API
+ */
+bool _accept() {
+    close(accept(_fd, 0, 0));
+    return true;
+}
+
+/*
+ * Public API
+ */
+int server_open(const char* host, int port) {
+    struct hostent *he = gethostbyname(host);
+    if (!he) {
+        printf("[!] gethostbyname failed: %d (h_errno)\n", h_errno);
+        return -1;
+    }
+    _fd = socket(
+        AF_INET,
+        SOCK_STREAM | SOCK_NONBLOCK,
+        IPPROTO_TCP
+    );
+    if (_fd == -1) {
+        printf("[!] socket failed: %d\n", errno);
+        return -1;
+    }
+    const int opt = 1;
+    if (setsockopt(_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
+        close(_fd);
+        printf("[!] setsockopt failed: %d\n", errno);
+        return -1;
+    }
+    struct sockaddr_in addr;
+    addr.sin_family = AF_INET;
+    addr.sin_port = htobe16(port);
+    memcpy(&addr.sin_addr, he->h_addr, he->h_length);
+    if (bind(_fd, (const void *)&addr, sizeof(addr)) == -1) {
+        close(_fd);
+        printf("[!] bind failed: %d\n", errno);
+        return -1;
+    }
+    if (listen(_fd, LISTEN_BACKLOG) == -1) {
+        close(_fd);
+        printf("[!] listen failed: %d\n", errno);
+        return -1;
+    }
+    return _fd;
+}
+
+void server_close() {
+    shutdown(_fd, SHUT_RDWR);
+    close(_fd);
+}
+
+bool server_event(uint32_t events) {
+    if (events & EPOLLIN) {
+        return _accept();
+    }
+    // we assume any event other than EPOLLIN is error
+    return false;
+}
diff --git a/server.h b/server.h
new file mode 100644
index 0000000..0787b67
--- /dev/null
+++ b/server.h
@@ -0,0 +1,36 @@
+#ifndef __SERVER_H
+#define __SERVER_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+// Open the server.
+// Parameters:
+//  - host      - hostname or IP address (domain names are OK)
+//  - port      - port to use
+// Returns:
+//  - -1 on failure
+//  - file descriptor of the server on success
+// Remarks:
+//  - call only after server_init
+//  - you must add returned fd to epoll with EPOLLIN events
+int server_open(const char* host, int port);
+
+// Close the server.
+// Remarks:
+//  - the socket is automatically removed from epoll
+void server_close();
+
+// Notify the server that an event happened on its socket.
+// Returns:
+//  - true on success
+//  - false on failure
+// Remarks:
+//  - the server accepts the connection and starts managing
+//    it with connection.h
+//  - you should stop close the server if this function
+//    returns false
+bool server_event(uint32_t events);
+
+
+#endif