usr.bin/uudecode/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 <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 static const char *infile, *outfile;
  71 static FILE *infp, *outfp;
  72 static int base64, cflag, iflag, oflag, pflag, rflag, sflag;
  73
  74 static void     usage(void);
  75 static int      decode(void);
  76 static int      decode2(void);
  77 static int      uu_decode(void);
  78 static int      base64_decode(void);
  79
  80 int
  81 main(int argc, char *argv[])
  82 {
  83         int rval, ch;
  84
  85         if (strcmp(basename(argv[0]), "b64decode") == 0)
  86                 base64 = 1;
  87
  88         while ((ch = getopt(argc, argv, "cimo:prs")) != -1) {
  89                 switch (ch) {
  90                 case 'c':
  91                         if (oflag || rflag)
  92                                 usage();
  93                         cflag = 1; /* multiple uudecode'd files */
  94                         break;
  95                 case 'i':
  96                         iflag = 1; /* ask before override files */
  97                         break;
  98                 case 'm':
  99                         base64 = 1;
 100                         break;
 101                 case 'o':
 102                         if (cflag || pflag || rflag || sflag)
 103                                 usage();
 104                         oflag = 1; /* output to the specified file */
 105                         sflag = 1; /* do not strip pathnames for output */
 106                         outfile = optarg; /* set the output filename */
 107                         break;
 108                 case 'p':
 109                         if (oflag)
 110                                 usage();
 111                         pflag = 1; /* print output to stdout */
 112                         break;
 113                 case 'r':
 114                         if (cflag || oflag)
 115                                 usage();
 116                         rflag = 1; /* decode raw data */
 117                         break;
 118                 case 's':
 119                         if (oflag)
 120                                 usage();
 121                         sflag = 1; /* do not strip pathnames for output */
 122                         break;
 123                 default:
 124                         usage();
 125                 }
 126         }
 127         argc -= optind;
 128         argv += optind;
 129
 130         if (*argv != NULL) {
 131                 rval = 0;
 132                 do {
 133                         infp = fopen(infile = *argv, "r");
 134                         if (infp == NULL) {
 135                                 warn("%s", *argv);
 136                                 rval = 1;
 137                                 continue;
 138                         }
 139                         rval |= decode();
 140                         fclose(infp);
 141                 } while (*++argv);
 142         } else {
 143                 infile = "stdin";
 144                 infp = stdin;
 145                 rval = decode();
 146         }
 147         exit(rval);
 148 }
 149
 150 static int
 151 decode(void)
 152 {
 153         int r, v;
 154
 155         if (rflag) {
 156                 /* relaxed alternative to decode2() */
 157                 outfile = "/dev/stdout";
 158                 outfp = stdout;
 159                 if (base64)
 160                         return (base64_decode());
 161                 else
 162                         return (uu_decode());
 163         }
 164         v = decode2();
 165         if (v == EOF) {
 166                 warnx("%s: missing or bad \"begin\" line", infile);
 167                 return (1);
 168         }
 169         for (r = v; cflag; r |= v) {
 170                 v = decode2();
 171                 if (v == EOF)
 172                         break;
 173         }
 174         return (r);
 175 }
 176
 177 static int
 178 decode2(void)
 179 {
 180         int flags, fd, mode;
 181         size_t n, m;
 182         char *p, *q;
 183         void *handle;
 184         struct passwd *pw;
 185         struct stat st;
 186         char buf[MAXPATHLEN + 1];
 187
 188         base64 = 0;
 189         /* search for header line */
 190         for (;;) {
 191                 if (fgets(buf, sizeof(buf), infp) == NULL)
 192                         return (EOF);
 193                 p = buf;
 194                 if (strncmp(p, "begin-base64 ", 13) == 0) {
 195                         base64 = 1;
 196                         p += 13;
 197                 } else if (strncmp(p, "begin ", 6) == 0)
 198                         p += 6;
 199                 else
 200                         continue;
 201                 /* p points to mode */
 202                 q = strchr(p, ' ');
 203                 if (q == NULL)
 204                         continue;
 205                 *q++ = '\0';
 206                 /* q points to filename */
 207                 n = strlen(q);
 208                 while (n > 0 && (q[n-1] == '\n' || q[n-1] == '\r'))
 209                         q[--n] = '\0';
 210                 /* found valid header? */
 211                 if (n > 0)
 212                         break;
 213         }
 214
 215         handle = setmode(p);
 216         if (handle == NULL) {
 217                 warnx("%s: unable to parse file mode", infile);
 218                 return (1);
 219         }
 220         mode = getmode(handle, 0) & 0666;
 221         free(handle);
 222
 223         if (sflag) {
 224                 /* don't strip, so try ~user/file expansion */
 225                 p = NULL;
 226                 pw = NULL;
 227                 if (*q == '~')
 228                         p = strchr(q, '/');
 229                 if (p != NULL) {
 230                         *p = '\0';
 231                         pw = getpwnam(q + 1);
 232                         *p = '/';
 233                 }
 234                 if (pw != NULL) {
 235                         n = strlen(pw->pw_dir);
 236                         if (buf + n > p) {
 237                                 /* make room */
 238                                 m = strlen(p);
 239                                 if (sizeof(buf) < n + m) {
 240                                         warnx("%s: bad output filename",
 241                                             infile);
 242                                         return (1);
 243                                 }
 244                                 p = memmove(buf + n, p, m);
 245                         }
 246                         q = memcpy(p - n, pw->pw_dir, n);
 247                 }
 248         } else {
 249                 /* strip down to leaf name */
 250                 p = strrchr(q, '/');
 251                 if (p != NULL)
 252                         q = p + 1;
 253         }
 254         if (!oflag)
 255                 outfile = q;
 256
 257         /* POSIX says "/dev/stdout" is a 'magic cookie' not a special file. */
 258         if (pflag || strcmp(outfile, "/dev/stdout") == 0)
 259                 outfp = stdout;
 260         else {
 261                 flags = O_WRONLY | O_CREAT | O_EXCL;
 262                 if (lstat(outfile, &st) == 0) {
 263                         if (iflag) {
 264                                 warnc(EEXIST, "%s: %s", infile, outfile);
 265                                 return (0);
 266                         }
 267                         switch (st.st_mode & S_IFMT) {
 268                         case S_IFREG:
 269                         case S_IFLNK:
 270                                 /* avoid symlink attacks */
 271                                 if (unlink(outfile) == 0 || errno == ENOENT)
 272                                         break;
 273                                 warn("%s: unlink %s", infile, outfile);
 274                                 return (1);
 275                         case S_IFDIR:
 276                                 warnc(EISDIR, "%s: %s", infile, outfile);
 277                                 return (1);
 278                         default:
 279                                 if (oflag) {
 280                                         /* trust command-line names */
 281                                         flags &= ~O_EXCL;
 282                                         break;
 283                                 }
 284                                 warnc(EEXIST, "%s: %s", infile, outfile);
 285                                 return (1);
 286                         }
 287                 } else if (errno != ENOENT) {
 288                         warn("%s: %s", infile, outfile);
 289                         return (1);
 290                 }
 291                 if ((fd = open(outfile, flags, mode)) < 0 ||
 292                     (outfp = fdopen(fd, "w")) == NULL) {
 293                         warn("%s: %s", infile, outfile);
 294                         return (1);
 295                 }
 296         }
 297
 298         if (base64)
 299                 return (base64_decode());
 300         else
 301                 return (uu_decode());
 302 }
 303
 304 static int
 305 get_line(char *buf, size_t size)
 306 {
 307
 308         if (fgets(buf, size, infp) != NULL)
 309                 return (2);
 310         if (rflag)
 311                 return (0);
 312         warnx("%s: %s: short file", infile, outfile);
 313         return (1);
 314 }
 315
 316 static int
 317 checkend(const char *ptr, const char *end, const char *msg)
 318 {
 319         size_t n;
 320
 321         n = strlen(end);
 322         if (strncmp(ptr, end, n) != 0 ||
 323             strspn(ptr + n, " \t\r\n") != strlen(ptr + n)) {
 324                 warnx("%s: %s: %s", infile, outfile, msg);
 325                 return (1);
 326         }
 327         if (fclose(outfp) != 0) {
 328                 warn("%s: %s", infile, outfile);
 329                 return (1);
 330         }
 331         return (0);
 332 }
 333
 334 static int
 335 uu_decode(void)
 336 {
 337         int i, ch;
 338         char *p;
 339         char buf[MAXPATHLEN+1];
 340
 341         /* for each input line */
 342         for (;;) {
 343                 switch (get_line(buf, sizeof(buf))) {
 344                 case 0:
 345                         return (0);
 346                 case 1:
 347                         return (1);
 348                 }
 349
 350 #define DEC(c)          (((c) - ' ') & 077)     /* single character decode */
 351 #define IS_DEC(c)        ( (((c) - ' ') >= 0) && (((c) - ' ') <= 077 + 1) )
 352
 353 #define OUT_OF_RANGE do {                                               \
 354         warnx("%s: %s: character out of range: [%d-%d]",                \
 355             infile, outfile, 1 + ' ', 077 + ' ' + 1);                   \
 356         return (1);                                                     \
 357 } while (0)
 358
 359                 /*
 360                  * `i' is used to avoid writing out all the characters
 361                  * at the end of the file.
 362                  */
 363                 p = buf;
 364                 if ((i = DEC(*p)) <= 0)
 365                         break;
 366                 for (++p; i > 0; p += 4, i -= 3)
 367                         if (i >= 3) {
 368                                 if (!(IS_DEC(*p) && IS_DEC(*(p + 1)) &&
 369                                     IS_DEC(*(p + 2)) && IS_DEC(*(p + 3))))
 370                                         OUT_OF_RANGE;
 371
 372                                 ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 373                                 putc(ch, outfp);
 374                                 ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 375                                 putc(ch, outfp);
 376                                 ch = DEC(p[2]) << 6 | DEC(p[3]);
 377                                 putc(ch, outfp);
 378                         } else {
 379                                 if (i >= 1) {
 380                                         if (!(IS_DEC(*p) && IS_DEC(*(p + 1))))
 381                                                 OUT_OF_RANGE;
 382                                         ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 383                                         putc(ch, outfp);
 384                                 }
 385                                 if (i >= 2) {
 386                                         if (!(IS_DEC(*(p + 1)) &&
 387                                             IS_DEC(*(p + 2))))
 388                                                 OUT_OF_RANGE;
 389
 390                                         ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 391                                         putc(ch, outfp);
 392                                 }
 393                                 if (i >= 3) {
 394                                         if (!(IS_DEC(*(p + 2)) &&
 395                                             IS_DEC(*(p + 3))))
 396                                                 OUT_OF_RANGE;
 397                                         ch = DEC(p[2]) << 6 | DEC(p[3]);
 398                                         putc(ch, outfp);
 399                                 }
 400                         }
 401         }
 402         switch (get_line(buf, sizeof(buf))) {
 403         case 0:
 404                 return (0);
 405         case 1:
 406                 return (1);
 407         default:
 408                 return (checkend(buf, "end", "no \"end\" line"));
 409         }
 410 }
 411
 412 static int
 413 base64_decode(void)
 414 {
 415         int n, count, count4;
 416         char inbuf[MAXPATHLEN + 1], *p;
 417         unsigned char outbuf[MAXPATHLEN * 4];
 418         char leftover[MAXPATHLEN + 1];
 419
 420         leftover[0] = '\0';
 421         for (;;) {
 422                 strcpy(inbuf, leftover);
 423                 switch (get_line(inbuf + strlen(inbuf),
 424                     sizeof(inbuf) - strlen(inbuf))) {
 425                 case 0:
 426                         return (0);
 427                 case 1:
 428                         return (1);
 429                 }
 430
 431                 count = 0;
 432                 count4 = -1;
 433                 p = inbuf;
 434                 while (*p != '\0') {
 435                         /*
 436                          * Base64 encoded strings have the following
 437                          * characters in them: A-Z, a-z, 0-9 and +, / and =
 438                          */
 439                         if (isalnum(*p) || *p == '+' || *p == '/' || *p == '=')
 440                                 count++;
 441                         if (count % 4 == 0)
 442                                 count4 = p - inbuf;
 443                         p++;
 444                 }
 445
 446                 strcpy(leftover, inbuf + count4 + 1);
 447                 inbuf[count4 + 1] = 0;
 448
 449                 n = b64_pton(inbuf, outbuf, sizeof(outbuf));
 450
 451                 if (n < 0)
 452                         break;
 453                 fwrite(outbuf, 1, n, outfp);
 454         }
 455         return (checkend(inbuf, "====", "error decoding base64 input stream"));
 456 }
 457
 458 static void
 459 usage(void)
 460 {
 461
 462         (void)fprintf(stderr,
 463             "usage: uudecode [-cimprs] [file ...]\n"
 464             "       uudecode [-i] -o output_file [file]\n"
 465             "       b64decode [-cimprs] [file ...]\n"
 466             "       b64decode [-i] -o output_file [file]\n");
 467         exit(1);
 468 }