typedef struct{
    uint8_t ver : 2;
    uint8_t t : 2;
    uint8_t tkl : 4;
    uint8_t code;
    uint16_t id;
} coap_header;

typedef struct{
    coap_header hdr;
    coap_buffer tok;    //coap_buffer is another struct
    uint8_t numopt;
    coap_option opt[MAXOPT];    /coap_option is another struct
    coap_buffer payload;
} coap_packet;

#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 "coapHead.h"

#define PORT 8080
#define MAXLINE 1024

int main(){
    int sockfd;
    char buffer[MAXLINE];
    char *hello = "Hello from server. Packet Received.";
    struct sockaddr_in servaddr, cliaddr;
    struct coap_packet *temp = malloc(sizeof(coap_packet));

    //Creating socket file descriptor
    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));

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

    //Binding socket with server address
    if(bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
        perror("Binding Failed!");
        exit(EXIT_FAILURE);
    }

    int i=0;
    while(i<6){
    int n, len;
    n = recvfrom(sockfd, temp, sizeof(temp), MSG_WAITALL, (struct sockaddr *)&cliaddr, &len);
//  buffer[n] = '';
    printf("Client Packet received.nMessage ID: %dnMessage Type: %dn", (temp->hdr).id, (temp->hdr).t);
    sendto(sockfd, (const char*)hello, strlen(hello), MSG_CONFIRM,  (const struct sockaddr *)&cliaddr, len);
    printf("Hello message sent.n");
    i+=1;
    }

    return 0;
}