#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#define SERVER_ADDRESS "127.0.0.1"
#define SERVER_PORT 7780
#define CLIENT_FILE_PATH "clrepository/file.bin"
void handleTimeout(int signal);
int gClientSocket;
int main(int argc, char** argv)
{
if (argc < 2)
{
fprintf(stderr, "-USAGE- %s <bytes>\n", argv[0]);
printf("-USAGE- <bytes> represents the number of bytes you want to receive from the server");
exit(EXIT_FAILURE);
}
if (atoi(argv[1]) > 65507)
{
fprintf(stderr, "-ERROR- The download rate is too high, please reconsider its size!\n");
exit(EXIT_FAILURE);
}
struct sockaddr_in server;
socklen_t slen = sizeof server;
int requested_bytes = atoi(argv[1]), received_bytes;
int server_file_size;
if ((gClientSocket = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
perror("socket()");
exit(EXIT_FAILURE);
}
memset(&server, 0, slen);
server.sin_family = AF_INET;
server.sin_port = htons(SERVER_PORT);
server.sin_addr.s_addr = inet_addr(SERVER_ADDRESS);
if (inet_aton(SERVER_ADDRESS, &server.sin_addr) == 0)
{
perror("inet_aton()");
exit(EXIT_FAILURE);
}
sendto(gClientSocket, &requested_bytes, sizeof(int), 0, (struct sockaddr*) &server, slen);
if (recvfrom(gClientSocket, &server_file_size, sizeof(int), 0, (struct sockaddr*) &server, &slen) != 0)
{ }
if (server_file_size > 2048 * 1024)
printf("-WARNING- The file might be too large! (<2MB)\n");
if (requested_bytes > server_file_size)
{
printf("-ERROR- The number of bytes you want exceeds the size of the file!\n");
close(gClientSocket);
exit(EXIT_FAILURE);
}
FILE *pFile = fopen(CLIENT_FILE_PATH, "wb");
if (pFile == NULL)
{
perror("fopen()");
close(gClientSocket);
exit(EXIT_FAILURE);
}
int x = 0;
char* buffer = malloc(requested_bytes * sizeof(char));
int data_loss = server_file_size % requested_bytes;
printf("Download started. Estimated download time: %.2f seconds\n", 0.025 * (server_file_size / requested_bytes));
while (x < server_file_size)
{
if ((received_bytes = recvfrom(gClientSocket, buffer, requested_bytes, 0, (struct sockaddr*) &server, &slen)) > 0)
{
signal(SIGALRM, handleTimeout);
alarm(3);
fwrite(buffer, requested_bytes, 1, pFile);
x += received_bytes;
if (data_loss == server_file_size - x)
{
fwrite(buffer, data_loss, 1, pFile);
break;
}
}
else
{
perror("recvfrom()");
close(gClientSocket);
exit(EXIT_FAILURE);
}
}
printf("--------------------------------------------\n");
printf("The download has finished.\n");
printf("Download stats:\n- Downloaded/file size - %d/%d\n", x, server_file_size);
printf("- Data loss for %d bytes per packet: %d bytes\n", requested_bytes, data_loss);
if (data_loss != 0)
printf("- Writing the remaining %d bytes to the file...\n", data_loss);
printf("- All the information has been received from the server!\n"); if (buffer != NULL)
{
free(buffer);
buffer = NULL;
}
fclose(pFile);
close(gClientSocket);
exit(EXIT_SUCCESS);
}
void handleTimeout(int signal)
{
printf("--------------------------------------------\n");
printf("A timeout has occured!\nPlease check if your download rate\nis the same with the server's upload rate!\n");
close(gClientSocket);
exit(EXIT_FAILURE);
}