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#include <netinet/ip.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <poll.h>
#include <stdbool.h>
#include "config.h"
#define NS_TO_MS(X) ((long)(X) / (long)1000000)
#define S_TO_MS(X) ((long)(X) * (long)1000)
int get_socket() {
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
fprintf(stderr, "socket error: %s", strerror(errno));
exit(EXIT_FAILURE);
}
return sockfd;
}
size_t send_datagram(int sockfd, struct sockaddr_in server_address, char *buffer, size_t buffer_len) {
return sendto(sockfd, buffer, buffer_len, 0, (struct sockaddr*) &server_address, sizeof(server_address));
}
void send_data_request(int sockfd, struct sockaddr_in server_address, size_t pos, size_t bytes) {
char buffer[40];
sprintf(buffer, "GET %ld %ld\n", pos, bytes);
size_t buffer_len = strlen(buffer);
if (send_datagram(sockfd, server_address, buffer, buffer_len) != buffer_len) {
fprintf(stderr, "sendto error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
}
long get_time_interval(struct timespec start, struct timespec finish) {
return S_TO_MS(finish.tv_sec - start.tv_sec) + NS_TO_MS(finish.tv_nsec - start.tv_nsec);
}
int poll_socket_modify_timeout(int sockfd, int *timeout) {
if (*timeout < 0) {
*timeout = 0;
return 0;
}
struct pollfd fds;
struct timespec start;
struct timespec finish;
fds.fd = sockfd;
fds.events = POLLIN;
fds.revents = 0;
clock_gettime(CLOCK_REALTIME, &start);
int result = poll(&fds, 1, *timeout);
clock_gettime(CLOCK_REALTIME, &finish);
if (result == -1) {
fprintf(stderr, "poll error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
if (result == 0) {
*timeout = 0;
return 0;
}
*timeout -= get_time_interval(start, finish);
return result;
}
size_t recv_message(int sockfd, char *buffer, struct sockaddr_in *sender) {
socklen_t sender_len = sizeof(*sender);
bzero(buffer, HEADER_LEN + DATAGRAM_LEN);
bzero(sender, sizeof(*sender));
size_t datagram_len = recvfrom(sockfd, buffer, IP_MAXPACKET, 0,
(struct sockaddr*)sender, &sender_len);
if (datagram_len < 0) {
fprintf(stderr, "recvfrom error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
return datagram_len;
}
inline size_t min(size_t x, size_t y) { return (x<y ? x : y); }
void receive_file(int sockfd, struct sockaddr_in server_address, const char *file_name, size_t file_len) {
FILE *fd = fopen(file_name, "w");
if (!fd) {
fprintf(stderr, "fopen error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
size_t bytes_writen = 0;
size_t recv_pos, recv_len;
struct sockaddr_in sender;
char buffer[DATAGRAM_LEN + HEADER_LEN];
int prev_len = 0;
while (file_len) {
send_data_request(sockfd, server_address, bytes_writen, min(file_len, DATAGRAM_LEN));
int timeout = 10;
while (poll_socket_modify_timeout(sockfd, &timeout)) {
size_t received_bytes = recv_message(sockfd, buffer, &sender);
if (sender.sin_addr.s_addr != server_address.sin_addr.s_addr || sender.sin_port != server_address.sin_port) continue;
sscanf(buffer, "DATA %ld %ld\n", &recv_pos, &recv_len);
if (recv_pos != bytes_writen) continue;
fwrite(buffer + received_bytes - recv_len, sizeof(char), recv_len, fd);
file_len -= recv_len;
bytes_writen += recv_len;
break;
}
if (prev_len != bytes_writen) {
prev_len = bytes_writen;
printf("%.3f%%\n", 100.0 * (float)(bytes_writen) / (float)(file_len+bytes_writen));
}
}
fclose(fd);
}
int main(int argc, char *argv[]) {
if (argc != 5) {
printf("Usage:\n\t%s [server ip] [server port] [output file name] [file size]\n", argv[0]);
return -1;
}
int sockfd = get_socket();
struct sockaddr_in server_address;
bzero(&server_address, sizeof(server_address));
server_address.sin_family = AF_INET;
if (!inet_pton(AF_INET, argv[1], &server_address.sin_addr)) {
fprintf(stderr, "Invalid ip address: %s\n", argv[1]);
return -1;
}
server_address.sin_port = htons(atoi(argv[2]));
if (server_address.sin_port == 0) {
fprintf(stderr, "Invalid port: %s\n", argv[2]);
return -1;
}
size_t file_len = atoi(argv[4]);
if (file_len == 0) {
printf("File len is 0, nothing to do here.\n");
return 0;
}
receive_file(sockfd, server_address, argv[3], file_len);
}
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