Create a simple TCP echo server

1 files changed, 88 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..092aa20
--- /dev/null
+++ b/main.c
@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/socket.h>
+#include <string.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+#define SERVER_PORT 6667
+
+int main() {
+  struct sockaddr_in server;
+  int server_fd = socket(AF_INET, SOCK_STREAM, 0);
+
+  if (server_fd == -1) {
+    perror("Unable to create a socket");
+    return EXIT_FAILURE;
+  }
+
+  server.sin_addr.s_addr = htonl(INADDR_ANY);
+  server.sin_family = AF_INET;
+  server.sin_port = htons(SERVER_PORT);
+
+  int binderr = bind(server_fd, (struct sockaddr *) &server, sizeof(server));
+
+  if (binderr == -1) {
+    perror("Could not bind");
+    return EXIT_FAILURE;
+  }
+
+  int listenerr = listen(server_fd, SOMAXCONN);
+
+  if (listenerr == -1) {
+    perror("Could not listen");
+    return EXIT_FAILURE;
+  }
+
+  printf("Server listening at %d\n", SERVER_PORT);
+
+  struct sockaddr_in client;
+  socklen_t client_len = sizeof(client);
+
+  int client_fd = accept(server_fd, (struct sockaddr *)&client, &client_len);
+
+  if (client_fd == -1) {
+    perror("Could not accept connections");
+    exit(1);
+    return EXIT_FAILURE;
+  }
+
+  char exit[] = "EXIT\r\n";
+
+  while (true) {
+    char client_buf[1024];
+
+    memset(client_buf, 0, 1024);
+
+    read(client_fd, client_buf, 1024);
+
+    printf("RECEIVED: %s\n", client_buf);
+
+    for (int i=0; client_buf[i] != 0; i++) {
+      printf("%d-", (int) client_buf[i]);
+    }
+
+    putchar(0xa);
+
+    for (int i = 0; exit[i] != 0; i++) {
+      printf("%d-", (int)exit[i]);
+    }
+
+    putchar(0xa);
+
+    if (!strncmp(client_buf, exit, 4)) {
+      puts("Bye");
+
+      close(server_fd);
+      close(client_fd);
+
+      return EXIT_SUCCESS;
+    }
+
+    write(client_fd, client_buf, 1024);
+  }
+
+  return EXIT_SUCCESS;
+}