udp_server.c

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

#define PORT 8888
#define MAXLINE 1024

int sockfd;

static void signal_handler(int signum) {
	if (signum == SIGINT || signum == SIGTERM) {
		printf("\n\nSignal %d received, preparing to exit...\n", signum);
        close(sockfd);
        exit(0);
	}
}

int main() { 
    char buffer[MAXLINE];
    struct sockaddr_in servaddr, cliaddr;
    socklen_t len;

    signal(SIGINT, signal_handler);
    signal(SIGTERM, signal_handler);

    // Create a UDP socket
    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket creation failed");
        exit(EXIT_FAILURE);
    }

    memset(&servaddr, 0, sizeof(servaddr));
    memset(&cliaddr, 0, sizeof(cliaddr));

    // Server information
    servaddr.sin_family = AF_INET; // IPv4
    servaddr.sin_addr.s_addr = INADDR_ANY; // Accept packets on any interface
    servaddr.sin_port = htons(PORT); // Server port

    // Bind the socket to the server address
    if (bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

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

    while (1) {
        // Receive a UDP packet
        len = sizeof(cliaddr);
        int n = recvfrom(sockfd, (char *)buffer, MAXLINE, 0, (struct sockaddr *)&cliaddr, &len);

        // Print the received packet
        if (n > 0) {
            buffer[n] = '\0'; // Null-terminate the received data
            printf("Received packet from %s:%d: %s\n", inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port), buffer);
        } else {
            perror("Error receiving packet");
        }

        // Clear the buffer for the next packet
        memset(buffer, 0, sizeof(buffer));
    }

    // Close the socket
    close(sockfd);

    return 0;
}