UDP_datetime:

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

#define PORT     8080
#define MAXLINE 1024

int main() {
    int sockfd;
    char buffer[MAXLINE];
    char *hello = "Hello from server";
    struct sockaddr_in servaddr, cliaddr;

    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));

    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = INADDR_ANY;
    servaddr.sin_port = htons(PORT);

    if (bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    int len, n;

    len = sizeof(cliaddr);

    n = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, (struct sockaddr *)&cliaddr, &len);
    buffer[n] = '\0';
    printf("Client : %s\n", buffer);

    time_t rawtime;
    struct tm *timeinfo;
    time(&rawtime);
    timeinfo = localtime(&rawtime);
    char datetime[MAXLINE];
    strftime(datetime, MAXLINE, "%Y-%m-%d %H:%M:%S", timeinfo);

    size_t response_length = strlen(hello) + strlen(datetime) + 4;
    if (response_length >= MAXLINE) {
        fprintf(stderr, "Response length exceeds buffer size\n");
        exit(EXIT_FAILURE);
    }

    char response[MAXLINE];
    if (snprintf(response, MAXLINE, "%s - %s", hello, datetime) >= MAXLINE) {
        fprintf(stderr, "Response truncated due to buffer size\n");
        exit(EXIT_FAILURE);
    }

    sendto(sockfd, (const char *)response, strlen(response), MSG_CONFIRM, (const struct sockaddr *)&cliaddr, len);
    printf("Hello message sent.\n");

    return 0;
}


//UDP_CLIENT_datetime:



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

#define PORT     8080
#define MAXLINE 1024

int main() {
    int sockfd;
    char buffer[MAXLINE];
    char *hello = "Hello from client";
    struct sockaddr_in servaddr;

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

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

    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);
    servaddr.sin_addr.s_addr = INADDR_ANY;

    int n, len;

    time_t rawtime;
    struct tm *timeinfo;
    time(&rawtime);
    timeinfo = localtime(&rawtime);
    char datetime[MAXLINE];
    strftime(datetime, MAXLINE, "%Y-%m-%d %H:%M:%S", timeinfo);

    size_t message_length = strlen(hello) + strlen(datetime) + 4;
    if (message_length > MAXLINE) {
        fprintf(stderr, "Message length exceeds buffer size\n");
        exit(EXIT_FAILURE);
    }

    char message[MAXLINE];
    if (snprintf(message, MAXLINE, "%s - %s", hello, datetime) >= MAXLINE) {
        fprintf(stderr, "Message truncated due to buffer size\n");
        exit(EXIT_FAILURE);
    }

    sendto(sockfd, (const char *)message, strlen(message),
        MSG_CONFIRM, (const struct sockaddr *)&servaddr,
            sizeof(servaddr));
    printf("Hello message sent.\n");

    n = recvfrom(sockfd, (char *)buffer, MAXLINE,
                MSG_WAITALL, (struct sockaddr *)&servaddr,
                &len);
    buffer[n] = '\0';
    printf("Server : %s\n", buffer);

    close(sockfd);
    return 0;
}