/*-

 * Copyright (c) 2014 Michihiro NAKAJIMA

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "archive_platform.h"

#ifdef HAVE_ERRNO_H

#include <errno.h>

#endif

#include "archive_read_private.h"

static void

add_passphrase_to_tail(struct archive_read *a,

    struct archive_read_passphrase *p)

{

  *a->passphrases.last = p;

  a->passphrases.last = &p->next;

  p->next = NULL;

}

static struct archive_read_passphrase *

remove_passphrases_from_head(struct archive_read *a)

{

  struct archive_read_passphrase *p;

  p = a->passphrases.first;

  if (p != NULL)

    a->passphrases.first = p->next;

  return (p);

}

static void

insert_passphrase_to_head(struct archive_read *a,

    struct archive_read_passphrase *p)

{

  p->next = a->passphrases.first;

  a->passphrases.first = p;

  if (&a->passphrases.first == a->passphrases.last) {

    a->passphrases.last = &p->next;

    p->next = NULL;

  }

}

static struct archive_read_passphrase *

new_read_passphrase(struct archive_read *a, const char *passphrase)

{

  struct archive_read_passphrase *p;

  p = malloc(sizeof(*p));

  if (p == NULL) {

    archive_set_error(&a->archive, ENOMEM,

        "Can't allocate memory");

    return (NULL);

  }

  p->passphrase = strdup(passphrase);

  if (p->passphrase == NULL) {

    free(p);

    archive_set_error(&a->archive, ENOMEM,

        "Can't allocate memory");

    return (NULL);

  }

  return (p);

}

int

archive_read_add_passphrase(struct archive *_a, const char *passphrase)

{

  struct archive_read *a = (struct archive_read *)_a;

  struct archive_read_passphrase *p;

  archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,

    "archive_read_add_passphrase");

  if (passphrase == NULL || passphrase[0] == '\0') {

    archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,

        "Empty passphrase is unacceptable");

    return (ARCHIVE_FAILED);

  }

  p = new_read_passphrase(a, passphrase);

  if (p == NULL)

    return (ARCHIVE_FATAL);

  add_passphrase_to_tail(a, p);

  return (ARCHIVE_OK);

}

int

archive_read_set_passphrase_callback(struct archive *_a, void *client_data,

    archive_passphrase_callback *cb)

{

  struct archive_read *a = (struct archive_read *)_a;

  archive_check_magic(_a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW,

    "archive_read_set_passphrase_callback");

  a->passphrases.callback = cb;

  a->passphrases.client_data = client_data;

  return (ARCHIVE_OK);

}

/*

 * Call this in advance when you start to get a passphrase for decryption

 * for a entry.

 */

void

__archive_read_reset_passphrase(struct archive_read *a)

{

  a->passphrases.candidate = -1;

}

/*

 * Get a passphrase for decryption.

 */

const char *

__archive_read_next_passphrase(struct archive_read *a)

{

  struct archive_read_passphrase *p;

  const char *passphrase;

  if (a->passphrases.candidate < 0) {

    /* Count out how many passphrases we have. */

    int cnt = 0;

    for (p = a->passphrases.first; p != NULL; p = p->next)

      cnt++;

    a->passphrases.candidate = cnt;

    p = a->passphrases.first;

  } else if (a->passphrases.candidate > 1) {

    /* Rotate a passphrase list. */

    a->passphrases.candidate--;

    p = remove_passphrases_from_head(a);

    add_passphrase_to_tail(a, p);

    /* Pick a new passphrase candidate up. */

    p = a->passphrases.first;

  } else if (a->passphrases.candidate == 1) {

    /* This case is that all candidates failed to decrypt. */

    a->passphrases.candidate = 0;

    if (a->passphrases.first->next != NULL) {

      /* Rotate a passphrase list. */

      p = remove_passphrases_from_head(a);

      add_passphrase_to_tail(a, p);

    }

    p = NULL;

  } else  /* There is no passphrase candidate. */

    p = NULL;

  if (p != NULL)

    passphrase = p->passphrase;

  else if (a->passphrases.callback != NULL) {

    /* Get a passphrase through a call-back function

     * since we tried all passphrases out or we don't

     * have it. */

    passphrase = a->passphrases.callback(&a->archive,

        a->passphrases.client_data);

    if (passphrase != NULL) {

      p = new_read_passphrase(a, passphrase);

      if (p == NULL)

        return (NULL);

      insert_passphrase_to_head(a, p);

      a->passphrases.candidate = 1;

    }

  } else

    passphrase = NULL;

  return (passphrase);

}