tools/gpgsplit.c

   1 /* gpgsplit.c - An OpenPGP packet splitting tool
   2  * Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <ctype.h>
  26 #include <unistd.h>
  27 #include <assert.h>
  28 #include <sys/types.h>
  29 #ifdef HAVE_DOSISH_SYSTEM
  30 # include <fcntl.h> /* for setmode() */
  31 #endif
  32 #include <zlib.h>
  33 #ifdef HAVE_BZIP2
  34 #include <bzlib.h>
  35 #endif /* HAVE_BZIP2 */
  36 #if defined(__riscos__) && defined(USE_ZLIBRISCOS)
  37 # include "zlib-riscos.h"
  38 #endif
  39
  40 #define INCLUDED_BY_MAIN_MODULE 1
  41 #include "util.h"
  42 #include "openpgpdefs.h"
  43
  44 static int opt_verbose;
  45 static const char *opt_prefix = "";
  46 static int opt_uncompress;
  47 static int opt_secret_to_public;
  48 static int opt_no_split;
  49
  50 static void g10_exit( int rc );
  51 static void split_packets (const char *fname);
  52
  53
  54 enum cmd_and_opt_values {
  55   aNull = 0,
  56   oVerbose        = 'v',
  57   oPrefix       = 'p',
  58   oUncompress   = 500,
  59   oSecretToPublic,
  60   oNoSplit,
  61
  62   aTest
  63 };
  64
  65
  66 static ARGPARSE_OPTS opts[] = {
  67
  68     { 301, NULL, 0, "@Options:\n " },
  69
  70     { oVerbose, "verbose",   0, "verbose" },
  71     { oPrefix,  "prefix",    2, "|STRING|Prepend filenames with STRING" },
  72     { oUncompress, "uncompress", 0, "uncompress a packet"},
  73     { oSecretToPublic, "secret-to-public", 0, "convert secret keys to public keys"},
  74     { oNoSplit, "no-split", 0, "write to stdout and don't actually split"},
  75 {0} };
  76
  77
  78 static const char *
  79 my_strusage (int level)
  80 {
  81   const char *p;
  82   switch (level)
  83     {
  84     case 11: p = "gpgsplit (GnuPG)";
  85       break;
  86     case 13: p = VERSION; break;
  87     case 17: p = PRINTABLE_OS_NAME; break;
  88     case 19: p =
  89                "Please report bugs to <bug-gnupg@gnu.org>.\n";
  90     break;
  91     case 1:
  92     case 40:    p =
  93                   "Usage: gpgsplit [options] [files] (-h for help)";
  94     break;
  95     case 41:    p =
  96                   "Syntax: gpgsplit [options] [files]\n"
  97                   "Split an OpenPGP message into packets\n";
  98     break;
  99
 100     default:    p = NULL;
 101     }
 102   return p;
 103 }
 104
 105
 106
 107 int
 108 main (int argc, char **argv)
 109 {
 110   ARGPARSE_ARGS pargs;
 111
 112 #ifdef HAVE_DOSISH_SYSTEM
 113   setmode( fileno(stdin), O_BINARY );
 114   setmode( fileno(stdout), O_BINARY );
 115 #endif
 116   log_set_prefix ("gpgsplit", JNLIB_LOG_WITH_PREFIX);
 117   set_strusage (my_strusage);
 118
 119   pargs.argc = &argc;
 120   pargs.argv = &argv;
 121   pargs.flags=  1;  /* do not remove the args */
 122   while (optfile_parse( NULL, NULL, NULL, &pargs, opts))
 123     {
 124       switch (pargs.r_opt)
 125         {
 126         case oVerbose: opt_verbose = 1; break;
 127         case oPrefix: opt_prefix = pargs.r.ret_str; break;
 128         case oUncompress: opt_uncompress = 1; break;
 129         case oSecretToPublic: opt_secret_to_public = 1; break;
 130         case oNoSplit: opt_no_split = 1; break;
 131         default : pargs.err = 2; break;
 132         }
 133     }
 134
 135   if (log_get_errorcount(0))
 136     g10_exit (2);
 137
 138   if (!argc)
 139     split_packets (NULL);
 140   else
 141     {
 142       for ( ;argc; argc--, argv++)
 143         split_packets (*argv);
 144     }
 145
 146   g10_exit (0);
 147   return 0;
 148 }
 149
 150
 151 static void
 152 g10_exit (int rc)
 153 {
 154   rc = rc? rc : log_get_errorcount(0)? 2 : 0;
 155   exit(rc );
 156 }
 157
 158 static const char *
 159 pkttype_to_string (int pkttype)
 160 {
 161   const char *s;
 162
 163   switch (pkttype)
 164     {
 165     case PKT_PUBKEY_ENC    : s = "pk_enc"; break;
 166     case PKT_SIGNATURE     : s = "sig"; break;
 167     case PKT_SYMKEY_ENC    : s = "sym_enc"; break;
 168     case PKT_ONEPASS_SIG   : s = "onepass_sig"; break;
 169     case PKT_SECRET_KEY    : s = "secret_key"; break;
 170     case PKT_PUBLIC_KEY    : s = "public_key"; break;
 171     case PKT_SECRET_SUBKEY : s = "secret_subkey"; break;
 172     case PKT_COMPRESSED    :
 173       s = opt_uncompress? "uncompressed":"compressed";
 174       break;
 175     case PKT_ENCRYPTED     : s = "encrypted"; break;
 176     case PKT_MARKER            : s = "marker"; break;
 177     case PKT_PLAINTEXT     : s = "plaintext"; break;
 178     case PKT_RING_TRUST    : s = "ring_trust"; break;
 179     case PKT_USER_ID       : s = "user_id"; break;
 180     case PKT_PUBLIC_SUBKEY : s = "public_subkey"; break;
 181     case PKT_OLD_COMMENT   : s = "old_comment"; break;
 182     case PKT_ATTRIBUTE     : s = "attribute"; break;
 183     case PKT_ENCRYPTED_MDC : s = "encrypted_mdc"; break;
 184     case PKT_MDC               : s = "mdc"; break;
 185     case PKT_COMMENT       : s = "comment"; break;
 186     case PKT_GPG_CONTROL   : s = "gpg_control"; break;
 187     default: s = "unknown"; break;
 188     }
 189   return s;
 190 }
 191
 192
 193 /*
 194  * Create a new filename and a return a pointer to a statically
 195  * allocated buffer
 196  */
 197 static char *
 198 create_filename (int pkttype)
 199 {
 200   static unsigned int partno = 0;
 201   static char *name;
 202
 203   if (!name)
 204     name = xmalloc (strlen (opt_prefix) + 100 );
 205
 206   assert (pkttype < 1000 && pkttype >= 0 );
 207   partno++;
 208   sprintf (name, "%s%06u-%03d" EXTSEP_S "%.40s",
 209            opt_prefix, partno, pkttype, pkttype_to_string (pkttype));
 210   return name;
 211 }
 212
 213 static int
 214 read_u16 (FILE *fp, size_t *rn)
 215 {
 216   int c;
 217
 218   if ( (c = getc (fp)) == EOF )
 219     return -1;
 220   *rn = c << 8;
 221   if ( (c = getc (fp)) == EOF )
 222     return -1;
 223   *rn |= c;
 224   return 0;
 225 }
 226
 227 static int
 228 read_u32 (FILE *fp, unsigned long *rn)
 229 {
 230   size_t tmp;
 231
 232   if (read_u16 (fp, &tmp))
 233     return -1;
 234   *rn = tmp << 16;
 235   if (read_u16 (fp, &tmp))
 236     return -1;
 237   *rn |= tmp;
 238   return 0;
 239 }
 240
 241 static int
 242 write_old_header (FILE *fp, int pkttype, unsigned int len)
 243 {
 244   int ctb = (0x80 | ((pkttype & 15)<<2));
 245
 246   if (len < 256)
 247     ;
 248   else if (len < 65536)
 249     ctb |= 1;
 250   else
 251     ctb |= 2;
 252
 253   if ( putc ( ctb, fp) == EOF )
 254     return -1;
 255
 256   if ( (ctb & 2) )
 257     {
 258       if (putc ((len>>24), fp) == EOF)
 259         return -1;
 260       if (putc ((len>>16), fp) == EOF)
 261         return -1;
 262     }
 263   if ( (ctb & 3) )
 264     {
 265       if (putc ((len>>8), fp) == EOF)
 266         return -1;
 267     }
 268   if (putc ((len&0xff), fp) == EOF)
 269     return -1;
 270   return 0;
 271 }
 272
 273 static int
 274 write_new_header (FILE *fp, int pkttype, unsigned int len)
 275 {
 276   if ( putc ((0xc0 | (pkttype & 0x3f)), fp) == EOF )
 277     return -1;
 278
 279   if (len < 192)
 280     {
 281       if (putc (len, fp) == EOF)
 282         return -1;
 283     }
 284   else if (len < 8384)
 285     {
 286       len -= 192;
 287       if (putc ((len/256)+192, fp) == EOF)
 288         return -1;
 289       if (putc ((len%256), fp) == EOF)
 290         return -1;
 291     }
 292   else
 293     {
 294       if (putc ( 0xff, fp) == EOF)
 295         return -1;
 296       if (putc ( (len >> 24), fp) == EOF)
 297         return -1;
 298       if (putc ( (len >> 16), fp) == EOF)
 299         return -1;
 300       if (putc ( (len >> 8), fp) == EOF)
 301         return -1;
 302       if (putc ( (len & 0xff), fp) == EOF)
 303         return -1;
 304     }
 305   return 0;
 306 }
 307
 308 /* Return the length of the public key given BUF of BUFLEN with a
 309    secret key. */
 310 static int
 311 public_key_length (const unsigned char *buf, size_t buflen)
 312 {
 313   const unsigned char *s;
 314   int nmpis;
 315
 316   /*   byte version number (3 or 4)
 317        u32  creation time
 318        [u16  valid days (version 3 only)]
 319        byte algorithm
 320        n    MPIs (n and e) */
 321   if (!buflen)
 322     return 0;
 323   if (buf[0] < 2 || buf[0] > 4)
 324     return 0; /* wrong version number */
 325   if (buflen < (buf[0] == 4? 6:8))
 326     return 0;
 327   s = buf + (buf[0] == 4? 6:8);
 328   buflen -= (buf[0] == 4? 6:8);
 329   switch (s[-1])
 330     {
 331     case 1:
 332     case 2:
 333     case 3:
 334       nmpis = 2;
 335       break;
 336     case 16:
 337     case 20:
 338       nmpis = 3;
 339       break;
 340     case 17:
 341       nmpis = 4;
 342       break;
 343     default:
 344       return 0;
 345     }
 346
 347   for (; nmpis; nmpis--)
 348     {
 349       unsigned int nbits, nbytes;
 350
 351       if (buflen < 2)
 352         return 0;
 353       nbits = (s[0] << 8) | s[1];
 354       s += 2; buflen -= 2;
 355       nbytes = (nbits+7) / 8;
 356       if (buflen < nbytes)
 357         return 0;
 358       s += nbytes; buflen -= nbytes;
 359     }
 360
 361   return s - buf;
 362 }
 363
 364 static int
 365 handle_zlib(int algo,FILE *fpin,FILE *fpout)
 366 {
 367   z_stream zs;
 368   byte *inbuf, *outbuf;
 369   unsigned int inbufsize, outbufsize;
 370   int c,zinit_done, zrc, nread, count;
 371   size_t n;
 372
 373   memset (&zs, 0, sizeof zs);
 374   inbufsize = 2048;
 375   inbuf = xmalloc (inbufsize);
 376   outbufsize = 8192;
 377   outbuf = xmalloc (outbufsize);
 378   zs.avail_in = 0;
 379   zinit_done = 0;
 380
 381   do
 382     {
 383       if (zs.avail_in < inbufsize)
 384         {
 385           n = zs.avail_in;
 386           if (!n)
 387             zs.next_in = (Bytef *) inbuf;
 388           count = inbufsize - n;
 389           for (nread=0;
 390                nread < count && (c=getc (fpin)) != EOF;
 391                nread++)
 392             inbuf[n+nread] = c;
 393
 394           n += nread;
 395           if (nread < count && algo == 1)
 396             {
 397               inbuf[n] = 0xFF; /* chew dummy byte */
 398               n++;
 399             }
 400           zs.avail_in = n;
 401         }
 402       zs.next_out = (Bytef *) outbuf;
 403       zs.avail_out = outbufsize;
 404
 405       if (!zinit_done)
 406         {
 407           zrc = (algo == 1? inflateInit2 ( &zs, -13)
 408                  : inflateInit ( &zs ));
 409           if (zrc != Z_OK)
 410             {
 411               log_fatal ("zlib problem: %s\n", zs.msg? zs.msg :
 412                          zrc == Z_MEM_ERROR ? "out of core" :
 413                          zrc == Z_VERSION_ERROR ?
 414                          "invalid lib version" :
 415                          "unknown error" );
 416             }
 417           zinit_done = 1;
 418         }
 419       else
 420         {
 421 #ifdef Z_SYNC_FLUSH
 422           zrc = inflate (&zs, Z_SYNC_FLUSH);
 423 #else
 424           zrc = inflate (&zs, Z_PARTIAL_FLUSH);
 425 #endif
 426           if (zrc == Z_STREAM_END)
 427             ; /* eof */
 428           else if (zrc != Z_OK && zrc != Z_BUF_ERROR)
 429             {
 430               if (zs.msg)
 431                 log_fatal ("zlib inflate problem: %s\n", zs.msg );
 432               else
 433                 log_fatal ("zlib inflate problem: rc=%d\n", zrc );
 434             }
 435           for (n=0; n < outbufsize - zs.avail_out; n++)
 436             {
 437               if (putc (outbuf[n], fpout) == EOF )
 438                 return 1;
 439             }
 440         }
 441     }
 442   while (zrc != Z_STREAM_END && zrc != Z_BUF_ERROR);
 443   {
 444     int i;
 445
 446     fputs ("Left over bytes:", stderr);
 447     for (i=0; i < zs.avail_in; i++)
 448       fprintf (stderr, " %02X", zs.next_in[i]);
 449     putc ('\n', stderr);
 450
 451   }
 452   inflateEnd (&zs);
 453
 454   return 0;
 455 }
 456
 457 #ifdef HAVE_BZIP2
 458 static int
 459 handle_bzip2(int algo,FILE *fpin,FILE *fpout)
 460 {
 461   bz_stream bzs;
 462   byte *inbuf, *outbuf;
 463   unsigned int inbufsize, outbufsize;
 464   int c,zinit_done, zrc, nread, count;
 465   size_t n;
 466
 467   memset (&bzs, 0, sizeof bzs);
 468   inbufsize = 2048;
 469   inbuf = xmalloc (inbufsize);
 470   outbufsize = 8192;
 471   outbuf = xmalloc (outbufsize);
 472   bzs.avail_in = 0;
 473   zinit_done = 0;
 474
 475   do
 476     {
 477       if (bzs.avail_in < inbufsize)
 478         {
 479           n = bzs.avail_in;
 480           if (!n)
 481             bzs.next_in = inbuf;
 482           count = inbufsize - n;
 483           for (nread=0;
 484                nread < count && (c=getc (fpin)) != EOF;
 485                nread++)
 486             inbuf[n+nread] = c;
 487
 488           n += nread;
 489           if (nread < count && algo == 1)
 490             {
 491               inbuf[n] = 0xFF; /* chew dummy byte */
 492               n++;
 493             }
 494           bzs.avail_in = n;
 495         }
 496       bzs.next_out = outbuf;
 497       bzs.avail_out = outbufsize;
 498
 499       if (!zinit_done)
 500         {
 501           zrc = BZ2_bzDecompressInit(&bzs,0,0);
 502           if (zrc != BZ_OK)
 503             log_fatal ("bz2lib problem: %d\n",zrc);
 504           zinit_done = 1;
 505         }
 506       else
 507         {
 508           zrc = BZ2_bzDecompress(&bzs);
 509           if (zrc == BZ_STREAM_END)
 510             ; /* eof */
 511           else if (zrc != BZ_OK && zrc != BZ_PARAM_ERROR)
 512             log_fatal ("bz2lib inflate problem: %d\n", zrc );
 513           for (n=0; n < outbufsize - bzs.avail_out; n++)
 514             {
 515               if (putc (outbuf[n], fpout) == EOF )
 516                 return 1;
 517             }
 518         }
 519     }
 520   while (zrc != BZ_STREAM_END && zrc != BZ_PARAM_ERROR);
 521   BZ2_bzDecompressEnd(&bzs);
 522
 523   return 0;
 524 }
 525 #endif /* HAVE_BZIP2 */
 526
 527 /* hdr must point to a buffer large enough to hold all header bytes */
 528 static int
 529 write_part (FILE *fpin, unsigned long pktlen,
 530             int pkttype, int partial, unsigned char *hdr, size_t hdrlen)
 531 {
 532   FILE *fpout;
 533   int c, first;
 534   unsigned char *p;
 535   const char *outname = create_filename (pkttype);
 536
 537 #if defined(__riscos__) && defined(USE_ZLIBRISCOS)
 538   static int initialized = 0;
 539
 540   if (!initialized)
 541       initialized = riscos_load_module("ZLib", zlib_path, 1);
 542 #endif
 543   if (opt_no_split)
 544     fpout = stdout;
 545   else
 546     {
 547       if (opt_verbose)
 548         log_info ("writing `%s'\n", outname);
 549       fpout = fopen (outname, "wb");
 550       if (!fpout)
 551         {
 552           log_error ("error creating `%s': %s\n", outname, strerror(errno));
 553           /* stop right now, otherwise we would mess up the sequence
 554              of the part numbers */
 555           g10_exit (1);
 556         }
 557     }
 558
 559   if (opt_secret_to_public
 560       && (pkttype == PKT_SECRET_KEY || pkttype == PKT_SECRET_SUBKEY))
 561     {
 562       unsigned char *blob = xmalloc (pktlen);
 563       int i, len;
 564
 565       pkttype = pkttype == PKT_SECRET_KEY? PKT_PUBLIC_KEY:PKT_PUBLIC_SUBKEY;
 566
 567       for (i=0; i < pktlen; i++)
 568         {
 569           c = getc (fpin);
 570           if (c == EOF)
 571             goto read_error;
 572           blob[i] = c;
 573         }
 574       len = public_key_length (blob, pktlen);
 575       if (!len)
 576         {
 577           log_error ("error calcualting public key length\n");
 578           g10_exit (1);
 579         }
 580       if ( (hdr[0] & 0x40) )
 581         {
 582           if (write_new_header (fpout, pkttype, len))
 583             goto write_error;
 584         }
 585       else
 586         {
 587           if (write_old_header (fpout, pkttype, len))
 588             goto write_error;
 589         }
 590
 591       for (i=0; i < len; i++)
 592         {
 593           if ( putc (blob[i], fpout) == EOF )
 594             goto write_error;
 595         }
 596
 597       goto ready;
 598     }
 599
 600
 601   if (!opt_uncompress)
 602     {
 603       for (p=hdr; hdrlen; p++, hdrlen--)
 604         {
 605           if ( putc (*p, fpout) == EOF )
 606             goto write_error;
 607         }
 608     }
 609
 610   first = 1;
 611   while (partial)
 612     {
 613       size_t partlen;
 614
 615       if (partial == 1)
 616         { /* openpgp */
 617           if (first )
 618             {
 619               c = pktlen;
 620               assert( c >= 224 && c < 255 );
 621               first = 0;
 622             }
 623           else if ((c = getc (fpin)) == EOF )
 624             goto read_error;
 625           else
 626             hdr[hdrlen++] = c;
 627
 628           if (c < 192)
 629             {
 630               pktlen = c;
 631               partial = 0; /* (last segment may follow) */
 632             }
 633           else if (c < 224 )
 634             {
 635               pktlen = (c - 192) * 256;
 636               if ((c = getc (fpin)) == EOF)
 637                 goto read_error;
 638               hdr[hdrlen++] = c;
 639               pktlen += c + 192;
 640               partial = 0;
 641             }
 642           else if (c == 255)
 643             {
 644               if (read_u32 (fpin, &pktlen))
 645                 goto read_error;
 646               hdr[hdrlen++] = pktlen >> 24;
 647               hdr[hdrlen++] = pktlen >> 16;
 648               hdr[hdrlen++] = pktlen >> 8;
 649               hdr[hdrlen++] = pktlen;
 650               partial = 0;
 651             }
 652           else
 653             { /* next partial body length */
 654               for (p=hdr; hdrlen; p++, hdrlen--)
 655                 {
 656                   if ( putc (*p, fpout) == EOF )
 657                     goto write_error;
 658                 }
 659               partlen = 1 << (c & 0x1f);
 660               for (; partlen; partlen--)
 661                 {
 662                   if ((c = getc (fpin)) == EOF)
 663                     goto read_error;
 664                   if ( putc (c, fpout) == EOF )
 665                     goto write_error;
 666                 }
 667             }
 668         }
 669       else if (partial == 2)
 670         { /* old gnupg */
 671           assert (!pktlen);
 672           if ( read_u16 (fpin, &partlen) )
 673             goto read_error;
 674           hdr[hdrlen++] = partlen >> 8;
 675           hdr[hdrlen++] = partlen;
 676           for (p=hdr; hdrlen; p++, hdrlen--)
 677             {
 678               if ( putc (*p, fpout) == EOF )
 679                 goto write_error;
 680             }
 681           if (!partlen)
 682             partial = 0; /* end of packet */
 683           for (; partlen; partlen--)
 684             {
 685               c = getc (fpin);
 686               if (c == EOF)
 687                 goto read_error;
 688               if ( putc (c, fpout) == EOF )
 689                 goto write_error;
 690             }
 691         }
 692       else
 693         { /* compressed: read to end */
 694           pktlen = 0;
 695           partial = 0;
 696           hdrlen = 0;
 697           if (opt_uncompress)
 698             {
 699               if ((c = getc (fpin)) == EOF)
 700                 goto read_error;
 701
 702               if(c==1 || c==2)
 703                 {
 704                   if(handle_zlib(c,fpin,fpout))
 705                     goto write_error;
 706                 }
 707 #ifdef HAVE_BZIP2
 708               else if(c==3)
 709                 {
 710                   if(handle_bzip2(c,fpin,fpout))
 711                     goto write_error;
 712                 }
 713 #endif /* HAVE_BZIP2 */
 714               else
 715                 {
 716                   log_error("invalid compression algorithm (%d)\n",c);
 717                   goto read_error;
 718                 }
 719             }
 720           else
 721             {
 722               while ( (c=getc (fpin)) != EOF )
 723                 {
 724                   if ( putc (c, fpout) == EOF )
 725                     goto write_error;
 726                 }
 727             }
 728           if (!feof (fpin))
 729             goto read_error;
 730         }
 731     }
 732
 733   for (p=hdr; hdrlen; p++, hdrlen--)
 734     {
 735       if ( putc (*p, fpout) == EOF )
 736         goto write_error;
 737     }
 738
 739   /* standard packet or last segment of partial length encoded packet */
 740   for (; pktlen; pktlen--)
 741     {
 742       c = getc (fpin);
 743       if (c == EOF)
 744         goto read_error;
 745       if ( putc (c, fpout) == EOF )
 746         goto write_error;
 747     }
 748
 749  ready:
 750   if ( !opt_no_split && fclose (fpout) )
 751     log_error ("error closing `%s': %s\n", outname, strerror (errno));
 752   return 0;
 753
 754  write_error:
 755   log_error ("error writing `%s': %s\n", outname, strerror (errno));
 756   if (!opt_no_split)
 757     fclose (fpout);
 758   return 2;
 759
 760  read_error:
 761   if (!opt_no_split)
 762     {
 763       int save = errno;
 764       fclose (fpout);
 765       errno = save;
 766     }
 767   return -1;
 768 }
 769
 770
 771
 772 static int
 773 do_split (FILE *fp)
 774 {
 775   int c, ctb, pkttype;
 776   unsigned long pktlen = 0;
 777   int partial = 0;
 778   unsigned char header[20];
 779   int header_idx = 0;
 780
 781   ctb = getc (fp);
 782   if (ctb == EOF)
 783     return 3; /* ready */
 784   header[header_idx++] = ctb;
 785
 786   if (!(ctb & 0x80))
 787     {
 788       log_error("invalid CTB %02x\n", ctb );
 789       return 1;
 790     }
 791   if ( (ctb & 0x40) )
 792     { /* new CTB */
 793       pkttype =  (ctb & 0x3f);
 794       if( (c = getc (fp)) == EOF )
 795         return -1;
 796       header[header_idx++] = c;
 797
 798       if ( c < 192 )
 799         pktlen = c;
 800       else if ( c < 224 )
 801         {
 802           pktlen = (c - 192) * 256;
 803           if( (c = getc (fp)) == EOF )
 804             return -1;
 805           header[header_idx++] = c;
 806           pktlen += c + 192;
 807         }
 808       else if ( c == 255 )
 809         {
 810           if (read_u32 (fp, &pktlen))
 811             return -1;
 812           header[header_idx++] = pktlen >> 24;
 813           header[header_idx++] = pktlen >> 16;
 814           header[header_idx++] = pktlen >> 8;
 815           header[header_idx++] = pktlen;
 816         }
 817       else
 818         { /* partial body length */
 819           pktlen = c;
 820           partial = 1;
 821         }
 822     }
 823   else
 824     {
 825       int lenbytes;
 826
 827       pkttype = (ctb>>2)&0xf;
 828       lenbytes = ((ctb&3)==3)? 0 : (1<<(ctb & 3));
 829       if (!lenbytes )
 830         {
 831           pktlen = 0; /* don't know the value */
 832           if( pkttype == PKT_COMPRESSED )
 833             partial = 3;
 834           else
 835             partial = 2; /* the old GnuPG partial length encoding */
 836         }
 837       else
 838         {
 839           for ( ; lenbytes; lenbytes-- )
 840             {
 841               pktlen <<= 8;
 842               if( (c = getc (fp)) == EOF )
 843                 return -1;
 844               header[header_idx++] = c;
 845
 846               pktlen |= c;
 847             }
 848         }
 849     }
 850
 851   return write_part (fp, pktlen, pkttype, partial, header, header_idx);
 852 }
 853
 854
 855 static void
 856 split_packets (const char *fname)
 857 {
 858   FILE *fp;
 859   int rc;
 860
 861   if (!fname || !strcmp (fname, "-"))
 862     {
 863       fp = stdin;
 864       fname = "-";
 865     }
 866   else if ( !(fp = fopen (fname,"rb")) )
 867     {
 868       log_error ("can't open `%s': %s\n", fname, strerror (errno));
 869       return;
 870     }
 871
 872   while ( !(rc = do_split (fp)) )
 873     ;
 874   if ( rc > 0 )
 875     ; /* error already handled */
 876   else if ( ferror (fp) )
 877     log_error ("error reading `%s': %s\n", fname, strerror (errno));
 878   else
 879     log_error ("premature EOF while reading `%s'\n", fname );
 880
 881   if ( fp != stdin )
 882     fclose (fp);
 883 }