U_CLIENT

/*
 * uclient.c
 *
 *  Created on: Mar 14, 2013
 *      Author: none
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <errno.h>

#define PORT        3666

void    addr_init(struct sockaddr_in *addr, int port, const char *IP){
    addr->sin_family    = AF_INET;
    addr->sin_port      = htons(port);
    inet_pton(AF_INET, IP, (void*)&addr->sin_addr);
}

void die(const char *type_error){
    printf("Error \"%s\" in %s\n", strerror(errno), type_error);
    exit(1);        //Remember: exit doesn't terminate current function but the entire program (closing and saving each file descriptor).
}

int main (int argc, char **argv){

    /*
     * Create principal socket members
     */
    int                 client_fd;
    struct sockaddr_in  server;
    socklen_t           addr_size = sizeof(struct sockaddr);

    char                buff_to_read[64];   //buff you'll use to read from server
    char                *file_name;         //a pointer to argv[2], your file name

    size_t              size_to_read = 0, size_read = 0;

    if (argc < 3){
        printf("Usage: <%s><IP-dest><FILE name>\n", argv[0]);
        exit(1);
    }

    if ( (client_fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0){
        die("socket()");
    }
    puts("socket()");

    server.sin_family = AF_INET;
    server.sin_port = htons(PORT);
    server.sin_addr.s_addr = inet_addr(argv[1]);
    file_name = argv[2];

    //SEND TO SERVER YOUR FILE NAME
    if ( (sendto(client_fd, file_name, strlen(file_name), 0, (struct sockaddr*)&server, addr_size)) < 0 ){
        printf("Error \"%s\" in sendto()\n", strerror(errno));
        exit(1);
    }
    puts("file name sent");

    //RECV FROM SERVER YOUR FILE SIZE
    if ( (recvfrom(client_fd, (size_t*)&size_to_read, sizeof(size_to_read), 0, NULL, NULL)) < 0){
        printf("Error \"%s\" in recvfrom()\n", strerror(errno));
        exit(1);
    }
    printf("Size of file: %lu\n", size_to_read);

    //IF FILE SIZE < 0: ERROR, EXIT(1)
    if (size_to_read < 0){
        printf("size_to_read < 0\n");
        exit(1);
    }

    //This commented region doesn't work, but meanwhile I'll try to fix it.
    /*
     *
    //READ UNTIL YOUR FILE SIZE IS > 0
    //size_to_read  = length of the message that is going to be sent from server
    //size_read     = length of each message received from server on each iteration
    while (size_to_read > 0){
        if ( (size_read = recvfrom(client_fd, buff_to_read, sizeof(buff_to_read), 0, NULL, NULL)) < 0){
            printf("Error \"%s\" in recvfrom()\n", strerror(errno));
            exit(1);
        }

        size_to_read -= size_read;
    }*/

    if ( (size_read = recvfrom(client_fd, buff_to_read, sizeof(buff_to_read), 0, NULL, NULL)) < 0){
        printf("Error \"%s\" in recvfrom()\n", strerror(errno));
        exit(1);
    }

    puts("file received");

    puts(buff_to_read);

    close(client_fd);
    return EXIT_SUCCESS;
}