output.c

/*
This file is part of pmktorrent
Copyright (C) 2007, 2009 Emil Renner Berthing
Edited 2019-2020 xxkfqz <xxkfqz@gmail.com>

pmktorrent is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

pmktorrent is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
*/
#ifndef ALLINONE
#include <sys/types.h>    /* off_t */
#include <stdio.h>        /* printf() etc. */
#include <string.h>       /* strlen() etc. */
#include <time.h>         /* time() */
#include <stdlib.h>       /* free() */
#ifdef USE_OPENSSL
#include <openssl/sha.h>  /* SHA_DIGEST_LENGTH */
#else
#include <inttypes.h>
#include "sha1.h"
#endif

#include "pmktorrent.h"

#define EXPORT
#endif /* ALLINONE */

/*
 * I don’t know exactly how many files there should be, so that their
 * number causes problems for users of other clients.
 */
#define FILES_NUMBER_WARNING 10000000

/*
 * write announce list
 */
static void write_announce_list(FILE *f, llist_t *list)
{
    /* the announce list is a list of lists of urls */
    fprintf(f, "13:announce-listl");
    /* go through them all.. */
    for (; list; list = list->next)
    {
        slist_t *l;

        /* .. and print the lists */
        fprintf(f, "l");
        for (l = list->l; l; l = l->next)
            fprintf(f, "%lu:%s",
                    (unsigned long)strlen(l->s), l->s);
        fprintf(f, "e");
    }
    fprintf(f, "e");
}

/*
 * write file list
 */
static void write_file_list(FILE *f, flist_t *list)
{
    char *a, *b;

    fprintf(f, "5:filesl");

    /* go through all the files */
    for (; list; list = list->next)
    {
        /* the file list contains a dictionary for every file
           with entries for the length and path
           write the length first */
        fprintf(f, "d6:lengthi%" PRIoff "e4:pathl", list->size);
        /* the file path is written as a list of subdirectories
           and the last entry is the filename
           sorry this code is even uglier than the rest */
        a = list->path;
        /* while there are subdirectories before the filename.. */
        while ((b = strchr(a, DIRSEP_CHAR)) != NULL)
        {
            /* set the next DIRSEP_CHAR to '\0' so fprintf
               will only write the first subdirectory name */
            *b = '\0';
            /* print it bencoded */
            fprintf(f, "%lu:%s", (unsigned long)strlen(a), a);
            /* undo our alteration to the string */
            *b = DIRSEP_CHAR;
            /* and move a to the beginning of the next
               subdir or filename */
            a = b + 1;
        }
        /* now print the filename bencoded and end the
           path name list and file dictionary */
        fprintf(f, "%lu:%see", (unsigned long)strlen(a), a);
    }

    /* whew, now end the file list */
    fprintf(f, "e");
}

/*
 * write web seed list
 */
static void write_web_seed_list(FILE *f, slist_t *list)
{
    /* print the entry and start the list */
    fprintf(f, "8:url-listl");
    /* go through the list and write each URL */
    for (; list; list = list->next)
        fprintf(f, "%lu:%s", (unsigned long)strlen(list->s), list->s);
    /* end the list */
    fprintf(f, "e");
}

/*
 * write metainfo to the file stream using all the information
 * we've gathered so far and the hash string calculated
 */
EXPORT void write_metainfo(FILE *f, metafile_t *m, unsigned char *hash_string)
{
    if (!m->quiet)
    {
        fprintf(stderr, "Total number of files: %" PRIu64 "\n",
                m->file_count);
        if(m->file_count >= FILES_NUMBER_WARNING)
            fprintf(stderr,
                    "Warning: the current number of files can cause"
                    "problems on torrent clients");

        /* let the user know we've started writing the metainfo file */
        fprintf(stderr, "Writing metainfo file... ");
    }
    fflush(stdout);

    /* every metainfo file is one big dictonary */
    fprintf(f, "d");

    if (m->announce_list != NULL)
    {
        /* write the announce URL */
        fprintf(f, "8:announce%lu:%s",
                (unsigned long)strlen(m->announce_list->l->s),
                m->announce_list->l->s);
        /* write the announce-list entry if we have
           more than one announce URL */
        if (m->announce_list->next || m->announce_list->l->next)
            write_announce_list(f, m->announce_list);
    }

    /* add the comment if one is specified */
    if (m->comment != NULL)
        fprintf(f, "7:comment%lu:%s",
                (unsigned long)strlen(m->comment),
                m->comment);
    /* I made this! */
    fprintf(f, "10:created by%lu:%s", (unsigned long)strlen(m->created_by),
            m->created_by);
    /* add the creation date if specified */
    if (!m->no_creation_date)
        fprintf(f, "13:creation datei%lde", m->creation_date);

    /* now here comes the info section
       it is yet another dictionary */
    fprintf(f, "4:infod");
    /* first entry is either 'length', which specifies the length of a
       single file torrent, or a list of files and their respective sizes */
    if (!m->target_is_directory)
        fprintf(f, "6:lengthi%" PRIoff "e", m->file_list->size);
    else
        write_file_list(f, m->file_list);

    /* the info section also contains the name of the torrent,
       the piece length and the hash string */
    fprintf(f, "4:name%lu:%s12:piece lengthi%ue6:pieces%u:",
            (unsigned long)strlen(m->torrent_name), m->torrent_name,
            m->piece_length, m->pieces * SHA_DIGEST_LENGTH);
    fwrite(hash_string, 1, m->pieces * SHA_DIGEST_LENGTH, f);

    /* set the private flag */
    if (m->private)
        fprintf(f, "7:privatei1e");

    if (m->source)
        fprintf(f, "6:source%lu:%s", (unsigned long)strlen(m->source),
                m->source);

    /* end the info section */
    fprintf(f, "e");

    /* add url-list if one is specified */
    if (m->web_seed_list != NULL)
    {
        if (m->web_seed_list->next == NULL)
            fprintf(f, "8:url-list%lu:%s",
                    (unsigned long)strlen(m->web_seed_list->s),
                    m->web_seed_list->s);
        else
            write_web_seed_list(f, m->web_seed_list);
    }

    /* end the root dictionary */
    fprintf(f, "e");

    /* let the user know we're done already */
    if (!m->quiet)
        fprintf(stderr, "done.\n");
    fflush(stdout);
    free(hash_string);
}