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reliable_receiver.cpp
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reliable_receiver.cpp
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#include <iostream>
#include <vector>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <fcntl.h>
#include <algorithm>
#include <time.h>
#include <string>
#include <cstring>
#include <pthread.h>
#include <functional>
#include <queue>
#include <list>
#include <fstream>
#define MAX_BUFFER 2000
#define BUFFER_SIZE 1400
typedef struct message_struct{
char messages[BUFFER_SIZE];
int Sequence_number;
} message;
typedef struct ack_struct{
int request_sequence_number;
} ack;
int recv_sockfd;
struct addrinfo recv_hints, *recv_servinfo, *recv_p;
int recv_rv;
struct sockaddr_storage recv_their_addr; socklen_t recv_addr_len;
char recv_s[INET6_ADDRSTRLEN];
char myport[100];
char sender_ip[INET6_ADDRSTRLEN];
char receive_buffer[MAX_BUFFER][BUFFER_SIZE];
bool received_packet[MAX_BUFFER];
int Sequence_number;
char file_to_write[MAX_BUFFER][BUFFER_SIZE];
// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*)sa)->sin_addr);
}
return &(((struct sockaddr_in6*)sa)->sin6_addr);
}
int bind_udp(unsigned short int port){
sprintf(myport, "%d", port);
memset(&recv_hints, 0, sizeof recv_hints);
recv_hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4
recv_hints.ai_socktype = SOCK_DGRAM;
recv_hints.ai_flags = AI_PASSIVE; // use my IP
if ((recv_rv = getaddrinfo(NULL, myport, &recv_hints, &recv_servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(recv_rv));
return 1;
}
// loop through all the results and bind to the first we can
for(recv_p = recv_servinfo; recv_p != NULL; recv_p = recv_p->ai_next) {
if ((recv_sockfd = socket(recv_p->ai_family, recv_p->ai_socktype,
recv_p->ai_protocol)) == -1) {
perror("listener: socket");
continue;
}
if (bind(recv_sockfd, recv_p->ai_addr, recv_p->ai_addrlen) == -1) {
close(recv_sockfd);
perror("listener: bind");
continue;
}
break;
}
if (recv_p == NULL) {
fprintf(stderr, "listener: failed to bind socket\n");
return 2;
}
freeaddrinfo(recv_servinfo);
printf("listener: waiting to recvfrom...\n");
//fcntl(recv_sockfd, F_SETFL, fcntl(recv_sockfd, F_GETFL) | O_NONBLOCK);
return 0;
}
int recv_message(message* msg){
int ret = recvfrom(recv_sockfd, msg, sizeof(*msg), 0, (struct sockaddr *)&recv_their_addr, &recv_addr_len);
inet_ntop(recv_their_addr.ss_family, get_in_addr((struct sockaddr *)&recv_their_addr), sender_ip, sizeof sender_ip);
return ret;
}
int send_ack(char* hostname, unsigned short int hostUDPport, ack msg){
int sockfd;
struct addrinfo hints, *servinfo, *p;
int rv;
int numbytes;
char theirport[100];
sprintf(theirport, "%d", hostUDPport);
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
if ((rv = getaddrinfo("127.0.0.1", theirport, &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and make a socket
for(p = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("talker: socket");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "talker: failed to bind socket\n");
return 2;
}
if((numbytes = sendto(sockfd, &msg, sizeof(msg), 0, p->ai_addr, p->ai_addrlen)) == -1){
perror("talker: sendto");
exit(1);
}
freeaddrinfo(servinfo);
close(sockfd);
return numbytes;
}
void reliablyReceive(unsigned short int myUDPport, char* destinationFile){
/*FILE * pFile;
pFile = fopen (destinationFile, "wb");*/
std::ofstream outfile(destinationFile, std::ofstream::binary);
int i;
bool sentinal = true;
while(sentinal){
message msg;
recv_message(&msg);
//received the in order packet and the packet haven't been received before
if((msg.Sequence_number == Sequence_number) && (!received_packet[msg.Sequence_number]))
{
received_packet[Sequence_number/BUFFER_SIZE] = true;
//write the message to memory
for(i = 0; i < BUFFER_SIZE; i ++)
{
file_to_write[Sequence_number/BUFFER_SIZE][i] = msg.messages[i];
}
//not reaching end of file
if(msg.messages[BUFFER_SIZE-1] != '\0')
{
Sequence_number += BUFFER_SIZE;
//send ack for next packet
ack back_ack;
back_ack.request_sequence_number = Sequence_number;
send_ack(sender_ip, myUDPport-1, back_ack);
} else
//reaching end of file
{
sentinal = false;
}
// fwrite (msg.messages , sizeof(char), sizeof(msg.messages), pFile);
} else if(msg.Sequence_number > Sequence_number)
//packet is later packet, buffer those first
{
//buffer the message
for(i = 0; i < BUFFER_SIZE; i ++)
{
receive_buffer[msg.Sequence_number/BUFFER_SIZE][i] = msg.messages[i];
}
//send duplicate ack
ack back_ack;
back_ack.request_sequence_number = Sequence_number;
send_ack(sender_ip, myUDPport-1, back_ack);
}
//check the buffer if there is any packet buffered that can be delivered
while(receive_buffer[Sequence_number/BUFFER_SIZE][0]!= '\0')
{
received_packet[Sequence_number/BUFFER_SIZE] = true;
for(i = 0; i < BUFFER_SIZE; i++)
{
file_to_write[Sequence_number/BUFFER_SIZE][i] = receive_buffer[Sequence_number/BUFFER_SIZE][i];
}
//not reaching end of file
if(receive_buffer[Sequence_number/BUFFER_SIZE][BUFFER_SIZE-1] != '\0')
{
Sequence_number += BUFFER_SIZE;
} else
//reaching end of file
{
sentinal = false;
break;
}
// fwrite (receive_buffer[Sequence_number/BUFFER_SIZE] , sizeof(char), sizeof(receive_buffer[Sequence_number/BUFFER_SIZE]), pFile);
}
}
i = 0;
for(i = 0; i < Sequence_number/BUFFER_SIZE; i++){
//fwrite (file_to_write[i] , sizeof(char), sizeof(file_to_write[i]), pFile);
outfile.write(file_to_write[i], sizeof(file_to_write[i]));
}
int j = 0;
while(file_to_write[i][j] != '\0'){
j++;
}
outfile.write(file_to_write[i], j-1);
//printf("writing to file: %d\n", i);
//fclose (pFile);
}
//initialize all the variables
void init_variable()
{
int i,j;
Sequence_number = 0;
for(i = 0; i < MAX_BUFFER; i ++)
{
for(j = 0; j < BUFFER_SIZE; j ++)
{
receive_buffer[i][j] = '\0';
}
file_to_write[i][0] = '\0';
received_packet[i] = false;
}
}
int main(int argc, char** argv)
{
unsigned short int udpPort;
if(argc != 3)
{
fprintf(stderr, "usage: %s UDP_port filename_to_write\n\n", argv[0]);
exit(1);
}
init_variable();
udpPort = (unsigned short int)atoi(argv[1]);
bind_udp(udpPort);
reliablyReceive(udpPort, argv[2]);
}