#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/tcp.h>
#include <sys/socket.h>

#define PORT 9090
#define BUF_SIZE 1024

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[BUF_SIZE] = {0};
    int rcvbuf, len;

    // Create socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // Set receive buffer size
    rcvbuf = 32768;  // 32 KB
    if (setsockopt(server_fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf)) < 0) {
        perror("setsockopt SO_RCVBUF failed");
        exit(EXIT_FAILURE);
    }

    // Verify buffer size
    len = sizeof(rcvbuf);
    getsockopt(server_fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, &len);
    printf("Server receive buffer size = %d bytes\n", rcvbuf);

    // Bind socket
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    listen(server_fd, 3);

    printf("Server listening on port %d...\n", PORT);

    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t *)&addrlen)) < 0) {
        perror("accept failed");
        exit(EXIT_FAILURE);
    }

    int valread = read(new_socket, buffer, BUF_SIZE);
    printf("Server received: %s\n", buffer);

    close(new_socket);
    close(server_fd);
    return 0;
}