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client_goback.c
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client_goback.c
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// client code for UDP socket programming
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#define IP_PROTOCOL 0
#define LEN 512
#define KEY 'H'
#define TRUE 1
#define FALSE 0
#define SUCCESS 0
#define FAILURE 1
#define RRQ 1
#define DATA 2
#define ACK 3
#define ERROR 4
#define TYPE_INDEX 0
#define WINDOW_SIZE_INDEX 1
#define SEQ_NUM_INDEX 1
#define FILE_NAME_INDEX 2
#define RED printf("\033[0;31m");
#define GREEN printf("\033[0;32m");
#define DEFAULT printf("\033[0m");
// please first look at server's code.
int getType(char packet[LEN]){
return packet[TYPE_INDEX]-'0';
}
int getWindowSize(char packet[LEN]){
return packet[WINDOW_SIZE_INDEX]-'0';
}
char getSeqNum(char packet[LEN]){
return packet[SEQ_NUM_INDEX];
}
char* getFileName(char packet[LEN]){
char* file_name = malloc(20);
for(int i=0;i<20;i++){
file_name[i] = packet[FILE_NAME_INDEX + i];
}
file_name[19]='\0';
printf("File in func %s\n", file_name );
return file_name;
}
void flush_packet(char packet[LEN]){
int i = 0;
for(i=0;i<LEN;i++){
packet[i]='\0';
}
}
void show_data(char packet[LEN]){
for(int i=2;i<LEN;i++){
printf("%c", packet[i]);
}
return;
}
// to send ack to server of given seq_num
int send_ack(int sockfd, struct sockaddr_in my_addr, char seq_num){
char packet[LEN];
flush_packet(packet);
// '3' = ACK
packet[0] = '3';//packet type
packet[1] = seq_num;
int len = sizeof(my_addr);
int sendBits = sendto(sockfd, packet, LEN, 0, (struct sockaddr*)&my_addr, len);
if(sendBits<=0){
RED printf("Error while writing...\n"); DEFAULT
return FAILURE;
}
return SUCCESS;
}
void receive_file_go_back_n(int sockfd, struct sockaddr_in my_addr){
int addrlen = sizeof(my_addr);
int req_seq_num = 0;
while(TRUE){
char packet[LEN];
int read_bits = recvfrom(sockfd, packet, LEN, 0, (struct sockaddr*)&my_addr, &addrlen);
if(read_bits<=0){
printf("Error in reading...\n");
return;
}
int type = getType(packet);
if(type == ERROR){
printf("File Not Found !!!\n");
return;
}else if(type != DATA){
continue;
}
int seq_num = getSeqNum(packet);
if(seq_num == req_seq_num){
GREEN printf("Recieved Packet of seq_num : %d\n", seq_num); DEFAULT
printf("Sending ACK of seq_num : %d\n", req_seq_num);
if(send_ack(sockfd, my_addr, req_seq_num)==FAILURE){
RED printf("ACK was not sent successfully...\n"); DEFAULT
}else{
printf("ACK Sent Successfully\n");
}
req_seq_num++;
}else{
RED printf("Recieved Packet of seq_num : %d\n But Required was %d\n", seq_num, req_seq_num); DEFAULT
}
}
}
void sendRequest(int sockfd, struct sockaddr_in my_addr, char file_name[20]){
// type + window_size + name
// 1 + 1 + 20 = 22
char packet[22];
int window_size = 1;
packet[0]='1';
packet[1]=window_size;
int i;
for(i=2;i<22;i++){
packet[i] = file_name[i-2];
}
int addrlen = sizeof(my_addr);
int sendBits = sendto(sockfd, packet, 22, 0, (struct sockaddr*)&my_addr, addrlen);
if(sendBits <= 0){
RED printf("Error in sending....\n"); DEFAULT
}
}
// driver code
int main(int argc, char *argv[])
{
if(argc != 3){
fprintf(stderr,"Usage: %s hostname port\n", argv[0]); //Validating cmd arguments
}
// ######################### Initialization #########################
int PORT_NO = atoi(argv[2]);
char IP_ADDRESS[50];
strcpy(IP_ADDRESS, argv[1]);
struct sockaddr_in my_addr;
int addrlen = sizeof(my_addr);
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(PORT_NO);
my_addr.sin_addr.s_addr = inet_addr(IP_ADDRESS);
// ##################################################################
// ###################### Create Socket #############################
int sockfd = socket(AF_INET, SOCK_DGRAM,
IP_PROTOCOL);
if (sockfd < 0)
printf("\nfile descriptor not received!!\n");
else
printf("\nfile descriptor %d received\n", sockfd);
// ##################################################################
while (1) {
char file_name[20];
printf("\nPlease enter file name to receive:\n");
scanf("%s", file_name);
sendRequest(sockfd, my_addr, file_name);
receive_file_go_back_n(sockfd, my_addr);
}
return 0;
}