Modules/src/m_paper_key/restore.cpp

/*
 * Copyright (C) 2007, 2012 David Shaw <dshaw@jabberwocky.com>
 *
 * This program 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.
 *
 * This program 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
 */

#include "restore.h"

#include <cctype>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include "GFSDKBasic.h"
#include "output.h"
#include "packets.h"
#include "parse.h"

struct key {
  unsigned char fpr[20];
  struct packet *packet;
  struct key *next;
};

static auto extract_keys(struct packet *packet) -> struct key * {
  struct key *key = NULL;
  size_t idx = 1;

  /* Check the version */
  if (packet->len && packet->buf[0] != 0) {
    fprintf(stderr, "Cannot handle secrets file version %d\n", packet->buf[0]);
    return NULL;
  }

  while (idx < packet->len) {
    /* 1+20+2 == version + fingerprint + length */
    if (idx + 1 + 20 + 2 <= packet->len) {
      if (packet->buf[idx] == 4) {
        unsigned int len;
        struct key *newkey;

        newkey =
            static_cast<struct key *>(GFAllocateMemory(sizeof(struct key)));
        newkey->next = NULL;

        idx++;
        memcpy(newkey->fpr, &packet->buf[idx], 20);

        idx += 20;

        len = packet->buf[idx++] << 8;
        len |= packet->buf[idx++];

        if (idx + len <= packet->len) {
          newkey->packet = append_packet(NULL, &packet->buf[idx], len);
          idx += len;
        } else {
          fprintf(stderr, "Warning: Short data in secret image\n");
          free(newkey);
          break;
        }

        newkey->next = key;
        key = newkey;
      } else {
        fprintf(stderr, "Warning: Corrupt data in secret image\n");
        break;
      }
    } else {
      fprintf(stderr, "Warning: Short header in secret image\n");
      break;
    }
  }

  return key;
}

static void free_keys(struct key *key) {
  while (key) {
    struct key *keytmp = key;
    free_packet(key->packet);
    key = key->next;
    free(keytmp);
  }
}

auto restore(FILE *pubring, FILE *secrets, enum data_type input_type,
             const char *outname) -> int {
  struct packet *secret;

  if (input_type == AUTO) {
    int test = fgetc(secrets);

    if (test == EOF) {
      fprintf(stderr, "Unable to check type of secrets file\n");
      return 1;
    } else if (isascii(test) && isprint(test))
      input_type = BASE16;
    else
      input_type = RAW;

    ungetc(test, secrets);
  }

  secret = read_secrets_file(secrets, input_type);
  if (secret) {
    struct packet *pubkey;
    struct key *keys;
    int did_pubkey = 0;

    /* Build a list of all keys.  We need to do this since the
       public key we are transforming might have the subkeys in a
       different order than (or not match subkeys at all with) our
       secret data. */

    keys = extract_keys(secret);
    if (keys) {
      output_start(outname, RAW, NULL);

      while ((pubkey = parse(pubring, 0, 0))) {
        unsigned char ptag;

        if (pubkey->type == 6 || pubkey->type == 14) {
          /* Public key or subkey */
          unsigned char fpr[20];
          struct key *keyidx;

          if (pubkey->type == 6 && did_pubkey) break;

          calculate_fingerprint(pubkey, pubkey->len, fpr);

          /* Do we have a secret key that matches? */
          for (keyidx = keys; keyidx; keyidx = keyidx->next) {
            if (memcmp(fpr, keyidx->fpr, 20) == 0) {
              if (pubkey->type == 6) {
                ptag = 5;
                did_pubkey = 1;
              } else
                ptag = 7;

              /* Match, so create a secret key. */
              output_openpgp_header(ptag, pubkey->len + keyidx->packet->len);
              output_packet(pubkey);
              output_packet(keyidx->packet);
            }
          }
        } else if (did_pubkey) {
          /* Copy the usual user ID, sigs, etc, so the key is
             well-formed. */
          output_openpgp_header(pubkey->type, pubkey->len);
          output_packet(pubkey);
        }

        free_packet(pubkey);
      }

      free_keys(keys);
    } else {
      fprintf(stderr, "Unable to parse secret data\n");
      return 1;
    }
  } else {
    fprintf(stderr, "Unable to read secrets file\n");
    return 1;
  }

  return 0;
}