UDP Program Checking Attendance Status (Computer Networks)

UDP Program Checking Attendance Status (Computer Networks)

21:36

Description:    This UDP program checks attendance status of a person.

Following is the summary of the program:

          i) Create a UDP client and server.

         ii) Client sends packet of information (containing Roll No. & Name) to the server

        iii) Server must respond with the message “<Roll No.> Welcome Aboard!”

        iv) Client must again send the packet “CHECK: <Roll No.>”

         v) Server must respond “[<Roll No.>] you have checked in already!” or “You haven’t checked in yet!” depending on the roll number.

C Code (Server)

#include<stdio.h>

#include<unistd.h>

#include<sys/types.h>

#include<sys/socket.h>

#include<netinet/in.h>

#define PORT_NO 8888

#define IP "127.0.0.1"

int main() {

     int msg_len = 100, i, j, count = 0;

     char *msg_send = (char*)malloc(msg_len);

     char *msg_rec = (char*)malloc(msg_len);

     char LIST[100][10];

     struct sockaddr_in serv_addr;

     int sock = socket(AF_INET, SOCK_DGRAM, 0);

     serv_addr.sin_family = AF_INET;

     serv_addr.sin_port = htons(PORT_NO);

     serv_addr.sin_addr.s_addr = inet_addr(IP);

     int sockaddr_len = sizeof(serv_addr);

     bind(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

     while (1) {

           recvfrom(sock, msg_rec, msg_len, 0, (struct sockaddr*)&serv_addr, &sockaddr_len);

          

           for (i = 0;msg_rec[i] != ' ';i++)

                msg_send[i] = msg_rec[i];

           msg_send[i] = '\0';

           strcat(msg_send, " Welcome Aboard!\n");

           sendto(sock, msg_send, msg_len, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

           recvfrom(sock, msg_rec, msg_len, 0, (struct sockaddr*)&serv_addr, &sockaddr_len);

          

           for (i = 0;msg_rec[i] != ' ';i++);

           char rollNo[10];

           for (i++, j = 0;msg_rec[i] != '\0';i++, j++)

                rollNo[j] = msg_rec[i];

           rollNo[j] = '\0';

          

           printf("\n\tCURRENT LIST CONTAINS %i ROLL NOS\n ", count);

           for (i = 0;i < count;i++)

                printf("\n#%i %s", i + 1, LIST[i]);

           for (i = 0;i < count;i++)

                if (strcmp(rollNo, LIST[i]) == 0) {

                     msg_send[0] = '\0';

                     strcpy(msg_send, "[");

                     strcat(msg_send, rollNo);

                     strcat(msg_send, "] You've checked in already!");

                     sendto(sock, msg_send, msg_len, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

                     break;

                }

           if (i == count) {

                strcpy(LIST[count], rollNo);

                count++;

                msg_send[0] = '\0';

                strcpy(msg_send, "[");

                strcat(msg_send, rollNo);

                strcat(msg_send, "] You haven't checked in yet!");

                sendto(sock, msg_send, msg_len, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

           }

           printf("\n\n");

     }

}

C Code (Client)

#include<stdio.h>

#include<unistd.h>

#include<sys/types.h>

#include<sys/socket.h>

#include<netinet/in.h>

#define PORT_NO 8888

#define IP "127.0.0.1"

int main() {

     int msg_len = 100, i;

     char *msg_send = (char*)malloc(msg_len);

     char *msg_rec = (char*)malloc(msg_len);

     char *input = (char*)malloc(msg_len);

     char rollNo[10];

     struct sockaddr_in serv_addr;

     int sock = socket(AF_INET, SOCK_DGRAM, 0);

     serv_addr.sin_family = AF_INET;

     serv_addr.sin_port = htons(PORT_NO);

     serv_addr.sin_addr.s_addr = inet_addr(IP);

     int sockaddr_len = sizeof(serv_addr);

     bind(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

     while (1) {

           printf("Enter Input (ROLL NO NAME): ");

           gets(input);

           strcpy(msg_send, input);

           sendto(sock, msg_send, msg_len, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

           recvfrom(sock, msg_rec, msg_len, 0, (struct sockaddr*)&serv_addr, &sockaddr_len);

           printf("\n%s\n", msg_rec);

           for (i = 0;input[i] != ' ';i++)

                rollNo[i] = input[i];

           rollNo[i] = '\0';

           msg_send[0] = '\0';

           strcpy(msg_send, "CHECK: ");

           strcat(msg_send, rollNo);

           sendto(sock, msg_send, msg_len, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

           recvfrom(sock, msg_rec, msg_len, 0, (struct sockaddr*)&serv_addr, &sockaddr_len);

           printf("%s\n", msg_rec);

          

           printf("\n\n");

     }

}