usr.bin/bintrans/uudecode.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1983, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #if 0
  33 #ifndef lint
  34 static const char copyright[] =
  35 "@(#) Copyright (c) 1983, 1993\n\
  36         The Regents of the University of California.  All rights reserved.\n";
  37 #endif /* not lint */
  38
  39 #ifndef lint
  40 static char sccsid[] = "@(#)uudecode.c  8.2 (Berkeley) 4/2/94";
  41 #endif /* not lint */
  42 #endif
  43 #include <sys/cdefs.h>
  44 __FBSDID("$FreeBSD$");
  45
  46 /*
  47  * uudecode [file ...]
  48  *
  49  * create the specified file, decoding as you go.
  50  * used with uuencode.
  51  */
  52 #include <sys/param.h>
  53 #include <sys/socket.h>
  54 #include <sys/stat.h>
  55
  56 #include <netinet/in.h>
  57
  58 #include <ctype.h>
  59 #include <err.h>
  60 #include <errno.h>
  61 #include <fcntl.h>
  62 #include <libgen.h>
  63 #include <pwd.h>
  64 #include <resolv.h>
  65 #include <stdbool.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70
  71 extern int main_decode(int, char *[]);
  72
  73 static const char *infile, *outfile;
  74 static FILE *infp, *outfp;
  75 static bool base64, cflag, iflag, oflag, pflag, rflag, sflag;
  76
  77 static void     usage(void);
  78 static int      decode(void);
  79 static int      decode2(void);
  80 static int      uu_decode(void);
  81 static int      base64_decode(void);
  82
  83 int
  84 main_decode(int argc, char *argv[])
  85 {
  86         int rval, ch;
  87
  88         if (strcmp(basename(argv[0]), "b64decode") == 0)
  89                 base64 = true;
  90
  91         while ((ch = getopt(argc, argv, "cimo:prs")) != -1) {
  92                 switch (ch) {
  93                 case 'c':
  94                         if (oflag || rflag)
  95                                 usage();
  96                         cflag = true; /* multiple uudecode'd files */
  97                         break;
  98                 case 'i':
  99                         iflag = true; /* ask before override files */
 100                         break;
 101                 case 'm':
 102                         base64 = true;
 103                         break;
 104                 case 'o':
 105                         if (cflag || pflag || rflag || sflag)
 106                                 usage();
 107                         oflag = true; /* output to the specified file */
 108                         sflag = true; /* do not strip pathnames for output */
 109                         outfile = optarg; /* set the output filename */
 110                         break;
 111                 case 'p':
 112                         if (oflag)
 113                                 usage();
 114                         pflag = true; /* print output to stdout */
 115                         break;
 116                 case 'r':
 117                         if (cflag || oflag)
 118                                 usage();
 119                         rflag = true; /* decode raw data */
 120                         break;
 121                 case 's':
 122                         if (oflag)
 123                                 usage();
 124                         sflag = true; /* do not strip pathnames for output */
 125                         break;
 126                 default:
 127                         usage();
 128                 }
 129         }
 130         argc -= optind;
 131         argv += optind;
 132
 133         if (*argv != NULL) {
 134                 rval = 0;
 135                 do {
 136                         infp = fopen(infile = *argv, "r");
 137                         if (infp == NULL) {
 138                                 warn("%s", *argv);
 139                                 rval = 1;
 140                                 continue;
 141                         }
 142                         rval |= decode();
 143                         fclose(infp);
 144                 } while (*++argv);
 145         } else {
 146                 infile = "stdin";
 147                 infp = stdin;
 148                 rval = decode();
 149         }
 150         exit(rval);
 151 }
 152
 153 static int
 154 decode(void)
 155 {
 156         int r, v;
 157
 158         if (rflag) {
 159                 /* relaxed alternative to decode2() */
 160                 outfile = "/dev/stdout";
 161                 outfp = stdout;
 162                 if (base64)
 163                         return (base64_decode());
 164                 else
 165                         return (uu_decode());
 166         }
 167         v = decode2();
 168         if (v == EOF) {
 169                 warnx("%s: missing or bad \"begin\" line", infile);
 170                 return (1);
 171         }
 172         for (r = v; cflag; r |= v) {
 173                 v = decode2();
 174                 if (v == EOF)
 175                         break;
 176         }
 177         return (r);
 178 }
 179
 180 static int
 181 decode2(void)
 182 {
 183         int flags, fd, mode;
 184         size_t n, m;
 185         char *p, *q;
 186         void *handle;
 187         struct passwd *pw;
 188         struct stat st;
 189         char buf[MAXPATHLEN + 1];
 190
 191         base64 = false;
 192         /* search for header line */
 193         for (;;) {
 194                 if (fgets(buf, sizeof(buf), infp) == NULL)
 195                         return (EOF);
 196                 p = buf;
 197                 if (strncmp(p, "begin-base64 ", 13) == 0) {
 198                         base64 = true;
 199                         p += 13;
 200                 } else if (strncmp(p, "begin ", 6) == 0)
 201                         p += 6;
 202                 else
 203                         continue;
 204                 /* p points to mode */
 205                 q = strchr(p, ' ');
 206                 if (q == NULL)
 207                         continue;
 208                 *q++ = '\0';
 209                 /* q points to filename */
 210                 n = strlen(q);
 211                 while (n > 0 && (q[n-1] == '\n' || q[n-1] == '\r'))
 212                         q[--n] = '\0';
 213                 /* found valid header? */
 214                 if (n > 0)
 215                         break;
 216         }
 217
 218         handle = setmode(p);
 219         if (handle == NULL) {
 220                 warnx("%s: unable to parse file mode", infile);
 221                 return (1);
 222         }
 223         mode = getmode(handle, 0) & 0666;
 224         free(handle);
 225
 226         if (sflag) {
 227                 /* don't strip, so try ~user/file expansion */
 228                 p = NULL;
 229                 pw = NULL;
 230                 if (*q == '~')
 231                         p = strchr(q, '/');
 232                 if (p != NULL) {
 233                         *p = '\0';
 234                         pw = getpwnam(q + 1);
 235                         *p = '/';
 236                 }
 237                 if (pw != NULL) {
 238                         n = strlen(pw->pw_dir);
 239                         if (buf + n > p) {
 240                                 /* make room */
 241                                 m = strlen(p);
 242                                 if (sizeof(buf) < n + m) {
 243                                         warnx("%s: bad output filename",
 244                                             infile);
 245                                         return (1);
 246                                 }
 247                                 p = memmove(buf + n, p, m);
 248                         }
 249                         q = memcpy(p - n, pw->pw_dir, n);
 250                 }
 251         } else {
 252                 /* strip down to leaf name */
 253                 p = strrchr(q, '/');
 254                 if (p != NULL)
 255                         q = p + 1;
 256         }
 257         if (!oflag)
 258                 outfile = q;
 259
 260         /* POSIX says "/dev/stdout" is a 'magic cookie' not a special file. */
 261         if (pflag || strcmp(outfile, "/dev/stdout") == 0)
 262                 outfp = stdout;
 263         else {
 264                 flags = O_WRONLY | O_CREAT | O_EXCL;
 265                 if (lstat(outfile, &st) == 0) {
 266                         if (iflag) {
 267                                 warnc(EEXIST, "%s: %s", infile, outfile);
 268                                 return (0);
 269                         }
 270                         switch (st.st_mode & S_IFMT) {
 271                         case S_IFREG:
 272                         case S_IFLNK:
 273                                 /* avoid symlink attacks */
 274                                 if (unlink(outfile) == 0 || errno == ENOENT)
 275                                         break;
 276                                 warn("%s: unlink %s", infile, outfile);
 277                                 return (1);
 278                         case S_IFDIR:
 279                                 warnc(EISDIR, "%s: %s", infile, outfile);
 280                                 return (1);
 281                         default:
 282                                 if (oflag) {
 283                                         /* trust command-line names */
 284                                         flags &= ~O_EXCL;
 285                                         break;
 286                                 }
 287                                 warnc(EEXIST, "%s: %s", infile, outfile);
 288                                 return (1);
 289                         }
 290                 } else if (errno != ENOENT) {
 291                         warn("%s: %s", infile, outfile);
 292                         return (1);
 293                 }
 294                 if ((fd = open(outfile, flags, mode)) < 0 ||
 295                     (outfp = fdopen(fd, "w")) == NULL) {
 296                         warn("%s: %s", infile, outfile);
 297                         return (1);
 298                 }
 299         }
 300
 301         if (base64)
 302                 return (base64_decode());
 303         else
 304                 return (uu_decode());
 305 }
 306
 307 static int
 308 get_line(char *buf, size_t size)
 309 {
 310
 311         if (fgets(buf, size, infp) != NULL)
 312                 return (2);
 313         if (rflag)
 314                 return (0);
 315         warnx("%s: %s: short file", infile, outfile);
 316         return (1);
 317 }
 318
 319 static int
 320 checkend(const char *ptr, const char *end, const char *msg)
 321 {
 322         size_t n;
 323
 324         n = strlen(end);
 325         if (strncmp(ptr, end, n) != 0 ||
 326             strspn(ptr + n, " \t\r\n") != strlen(ptr + n)) {
 327                 warnx("%s: %s: %s", infile, outfile, msg);
 328                 return (1);
 329         }
 330         if (fclose(outfp) != 0) {
 331                 warn("%s: %s", infile, outfile);
 332                 return (1);
 333         }
 334         return (0);
 335 }
 336
 337 static int
 338 uu_decode(void)
 339 {
 340         int i, ch;
 341         char *p;
 342         char buf[MAXPATHLEN+1];
 343
 344         /* for each input line */
 345         for (;;) {
 346                 switch (get_line(buf, sizeof(buf))) {
 347                 case 0:
 348                         return (0);
 349                 case 1:
 350                         return (1);
 351                 }
 352
 353 #define DEC(c)          (((c) - ' ') & 077)     /* single character decode */
 354 #define IS_DEC(c)        ( (((c) - ' ') >= 0) && (((c) - ' ') <= 077 + 1) )
 355
 356 #define OUT_OF_RANGE do {                                               \
 357         warnx("%s: %s: character out of range: [%d-%d]",                \
 358             infile, outfile, ' ', 077 + ' ' + 1);                       \
 359         return (1);                                                     \
 360 } while (0)
 361
 362                 /*
 363                  * `i' is used to avoid writing out all the characters
 364                  * at the end of the file.
 365                  */
 366                 p = buf;
 367                 if ((i = DEC(*p)) <= 0)
 368                         break;
 369                 for (++p; i > 0; p += 4, i -= 3)
 370                         if (i >= 3) {
 371                                 if (!(IS_DEC(*p) && IS_DEC(*(p + 1)) &&
 372                                     IS_DEC(*(p + 2)) && IS_DEC(*(p + 3))))
 373                                         OUT_OF_RANGE;
 374
 375                                 ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 376                                 putc(ch, outfp);
 377                                 ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 378                                 putc(ch, outfp);
 379                                 ch = DEC(p[2]) << 6 | DEC(p[3]);
 380                                 putc(ch, outfp);
 381                         } else {
 382                                 if (i >= 1) {
 383                                         if (!(IS_DEC(*p) && IS_DEC(*(p + 1))))
 384                                                 OUT_OF_RANGE;
 385                                         ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 386                                         putc(ch, outfp);
 387                                 }
 388                                 if (i >= 2) {
 389                                         if (!(IS_DEC(*(p + 1)) &&
 390                                             IS_DEC(*(p + 2))))
 391                                                 OUT_OF_RANGE;
 392
 393                                         ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 394                                         putc(ch, outfp);
 395                                 }
 396                                 if (i >= 3) {
 397                                         if (!(IS_DEC(*(p + 2)) &&
 398                                             IS_DEC(*(p + 3))))
 399                                                 OUT_OF_RANGE;
 400                                         ch = DEC(p[2]) << 6 | DEC(p[3]);
 401                                         putc(ch, outfp);
 402                                 }
 403                         }
 404         }
 405         switch (get_line(buf, sizeof(buf))) {
 406         case 0:
 407                 return (0);
 408         case 1:
 409                 return (1);
 410         default:
 411                 return (checkend(buf, "end", "no \"end\" line"));
 412         }
 413 }
 414
 415 static int
 416 base64_decode(void)
 417 {
 418         int n, count, count4;
 419         char inbuf[MAXPATHLEN + 1], *p;
 420         unsigned char outbuf[MAXPATHLEN * 4];
 421         char leftover[MAXPATHLEN + 1];
 422
 423         leftover[0] = '\0';
 424         for (;;) {
 425                 strcpy(inbuf, leftover);
 426                 switch (get_line(inbuf + strlen(inbuf),
 427                     sizeof(inbuf) - strlen(inbuf))) {
 428                 case 0:
 429                         return (0);
 430                 case 1:
 431                         return (1);
 432                 }
 433
 434                 count = 0;
 435                 count4 = -1;
 436                 p = inbuf;
 437                 while (*p != '\0') {
 438                         /*
 439                          * Base64 encoded strings have the following
 440                          * characters in them: A-Z, a-z, 0-9 and +, / and =
 441                          */
 442                         if (isalnum(*p) || *p == '+' || *p == '/' || *p == '=')
 443                                 count++;
 444                         if (count % 4 == 0)
 445                                 count4 = p - inbuf;
 446                         p++;
 447                 }
 448
 449                 strcpy(leftover, inbuf + count4 + 1);
 450                 inbuf[count4 + 1] = 0;
 451
 452                 n = b64_pton(inbuf, outbuf, sizeof(outbuf));
 453
 454                 if (n < 0)
 455                         break;
 456                 fwrite(outbuf, 1, n, outfp);
 457         }
 458         return (checkend(inbuf, "====", "error decoding base64 input stream"));
 459 }
 460
 461 static void
 462 usage(void)
 463 {
 464
 465         (void)fprintf(stderr,
 466             "usage: uudecode [-cimprs] [file ...]\n"
 467             "       uudecode [-i] -o output_file [file]\n"
 468             "       b64decode [-cimprs] [file ...]\n"
 469             "       b64decode [-i] -o output_file [file]\n");
 470         exit(1);
 471 }