tcp/quic lab finished

network/tcpquiclab/tcp_server.c

@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+#define PORT 8080
+#define BUFFER_SIZE 1024
+
+int main() {
+    int server_fd, new_socket;
+    struct sockaddr_in address;
+    int opt = 1;
+    int addrlen = sizeof(address);
+    char buffer[BUFFER_SIZE] = {0};
+
+    // 1. Create socket file descriptor
+    // AF_INET: IPv4, SOCK_STREAM: TCP
+    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
+        perror("socket failed");
+        exit(EXIT_FAILURE);
+    }
+
+    // 2. Attach socket to the port 8080
+    // SO_REUSEADDR allows restarting the server immediately after closing
+    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
+        perror("setsockopt");
+        exit(EXIT_FAILURE);
+    }
+
+    address.sin_family = AF_INET;
+    address.sin_addr.s_addr = INADDR_ANY; // Listen on all interfaces
+    address.sin_port = htons(PORT);
+
+    // Bind
+    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
+        perror("bind failed");
+        exit(EXIT_FAILURE);
+    }
+
+    // 3. Listen for incoming connections
+    if (listen(server_fd, 3) < 0) {
+        perror("listen");
+        exit(EXIT_FAILURE);
+    }
+
+    printf("TCP Server listening on port %d...\n", PORT);
+
+    // 4. Accept connection
+    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
+        perror("accept");
+        exit(EXIT_FAILURE);
+    }
+
+    printf("Client connected.\n");
+
+    // 5. Receive data
+    int valread = read(new_socket, buffer, BUFFER_SIZE);
+    if (valread > 0) {
+        printf("Received %d bytes: %s\n", valread, buffer);
+        
+        // 6. Send response (Echo length or simple ack)
+        char response[BUFFER_SIZE];
+        snprintf(response, BUFFER_SIZE, "Server received %d bytes", valread);
+        send(new_socket, response, strlen(response), 0);
+        printf("Response sent to client.\n");
+    }
+
+    // 7. Close socket
+    close(new_socket);
+    close(server_fd);
+
+    return 0;
+}