CRC Client Code in c

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <unistd.h>

#include <arpa/inet.h>

#include "crc_gen_fn.c"

#define RESET(buff) \

for (i = 0; i < 100; i++) \

buff[i] = '\0';

void error(const char *msg)

{

perror(msg);

exit(1);

}

int main(int argc, char const *argv[])

{

int sockfd, i,j;

struct sockaddr_in serv_addr;

char buff[100], key[100], data[100];

char *res=malloc(30);

//Checking the provided port no

if (argc < 3)

error("Port No not provided");

serv_addr.sin_family = AF_INET;

serv_addr.sin_addr.s_addr = inet_addr(argv[1]);

serv_addr.sin_port = htons(atoi(argv[2]));

//Socket

if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)

error("Error in Socket");

//Connect

if( connect(sockfd , (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)

error("Error in connecting");

//sending the data

RESET(buff)

recv(sockfd , buff, 100, 0);

printf(" %s ",buff);

scanf("%s",data);

RESET(buff)

strcpy(buff,data);

send(sockfd , buff, 100, 0);

//Sending the key

RESET(buff)

recv(sockfd, buff, 100, 0);

printf("%s",buff);

scanf("%s",key);

RESET(buff)

strcpy(buff,key);

send(sockfd, buff, 100, 0);

//Get the crc from server

RESET(buff)

recv(sockfd , buff, 100, 0);

printf("From The server : %s \n",buff);

//Check the crc at receiver side

res = crc(buff,key);

printf("\nAt the receiver End : \n");

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

printf("%c",res[i]);

for(i=strlen(res) - 1 ,j=1 ; j < strlen(key) ; i--,j++)

{

if(res[i]=='1')

break;

}

if(j<strlen(key))

send(sockfd, "Error", 100, 0);

else

{

send(sockfd, "OKAY ",100,0);

}

close(sockfd);

printf("\n");

return 0 ;

}