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 /*
  33  * uudecode [file ...]
  34  *
  35  * create the specified file, decoding as you go.
  36  * used with uuencode.
  37  */
  38 #include <sys/param.h>
  39 #include <sys/socket.h>
  40 #include <sys/stat.h>
  41
  42 #include <netinet/in.h>
  43
  44 #include <ctype.h>
  45 #include <err.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <libgen.h>
  49 #include <pwd.h>
  50 #include <resolv.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54 #include <unistd.h>
  55
  56 static const char *infile, *outfile;
  57 static FILE *infp, *outfp;
  58 static int base64, cflag, iflag, oflag, pflag, rflag, sflag;
  59
  60 static void     usage(void);
  61 static int      decode(void);
  62 static int      decode2(void);
  63 static int      uu_decode(void);
  64 static int      base64_decode(void);
  65
  66 int
  67 main(int argc, char *argv[])
  68 {
  69         int rval, ch;
  70
  71         if (strcmp(basename(argv[0]), "b64decode") == 0)
  72                 base64 = 1;
  73
  74         while ((ch = getopt(argc, argv, "cimo:prs")) != -1) {
  75                 switch (ch) {
  76                 case 'c':
  77                         if (oflag || rflag)
  78                                 usage();
  79                         cflag = 1; /* multiple uudecode'd files */
  80                         break;
  81                 case 'i':
  82                         iflag = 1; /* ask before override files */
  83                         break;
  84                 case 'm':
  85                         base64 = 1;
  86                         break;
  87                 case 'o':
  88                         if (cflag || pflag || rflag || sflag)
  89                                 usage();
  90                         oflag = 1; /* output to the specified file */
  91                         sflag = 1; /* do not strip pathnames for output */
  92                         outfile = optarg; /* set the output filename */
  93                         break;
  94                 case 'p':
  95                         if (oflag)
  96                                 usage();
  97                         pflag = 1; /* print output to stdout */
  98                         break;
  99                 case 'r':
 100                         if (cflag || oflag)
 101                                 usage();
 102                         rflag = 1; /* decode raw data */
 103                         break;
 104                 case 's':
 105                         if (oflag)
 106                                 usage();
 107                         sflag = 1; /* do not strip pathnames for output */
 108                         break;
 109                 default:
 110                         usage();
 111                 }
 112         }
 113         argc -= optind;
 114         argv += optind;
 115
 116         if (*argv != NULL) {
 117                 rval = 0;
 118                 do {
 119                         infp = fopen(infile = *argv, "r");
 120                         if (infp == NULL) {
 121                                 warn("%s", *argv);
 122                                 rval = 1;
 123                                 continue;
 124                         }
 125                         rval |= decode();
 126                         fclose(infp);
 127                 } while (*++argv);
 128         } else {
 129                 infile = "stdin";
 130                 infp = stdin;
 131                 rval = decode();
 132         }
 133         exit(rval);
 134 }
 135
 136 static int
 137 decode(void)
 138 {
 139         int r, v;
 140
 141         if (rflag) {
 142                 /* relaxed alternative to decode2() */
 143                 outfile = "/dev/stdout";
 144                 outfp = stdout;
 145                 if (base64)
 146                         return (base64_decode());
 147                 else
 148                         return (uu_decode());
 149         }
 150         v = decode2();
 151         if (v == EOF) {
 152                 warnx("%s: missing or bad \"begin\" line", infile);
 153                 return (1);
 154         }
 155         for (r = v; cflag; r |= v) {
 156                 v = decode2();
 157                 if (v == EOF)
 158                         break;
 159         }
 160         return (r);
 161 }
 162
 163 static int
 164 decode2(void)
 165 {
 166         int flags, fd, mode;
 167         size_t n, m;
 168         char *p, *q;
 169         void *handle;
 170         struct passwd *pw;
 171         struct stat st;
 172         char buf[MAXPATHLEN + 1];
 173
 174         base64 = 0;
 175         /* search for header line */
 176         for (;;) {
 177                 if (fgets(buf, sizeof(buf), infp) == NULL)
 178                         return (EOF);
 179                 p = buf;
 180                 if (strncmp(p, "begin-base64 ", 13) == 0) {
 181                         base64 = 1;
 182                         p += 13;
 183                 } else if (strncmp(p, "begin ", 6) == 0)
 184                         p += 6;
 185                 else
 186                         continue;
 187                 /* p points to mode */
 188                 q = strchr(p, ' ');
 189                 if (q == NULL)
 190                         continue;
 191                 *q++ = '\0';
 192                 /* q points to filename */
 193                 n = strlen(q);
 194                 while (n > 0 && (q[n-1] == '\n' || q[n-1] == '\r'))
 195                         q[--n] = '\0';
 196                 /* found valid header? */
 197                 if (n > 0)
 198                         break;
 199         }
 200
 201         handle = setmode(p);
 202         if (handle == NULL) {
 203                 warnx("%s: unable to parse file mode", infile);
 204                 return (1);
 205         }
 206         mode = getmode(handle, 0) & 0666;
 207         free(handle);
 208
 209         if (sflag) {
 210                 /* don't strip, so try ~user/file expansion */
 211                 p = NULL;
 212                 pw = NULL;
 213                 if (*q == '~')
 214                         p = strchr(q, '/');
 215                 if (p != NULL) {
 216                         *p = '\0';
 217                         pw = getpwnam(q + 1);
 218                         *p = '/';
 219                 }
 220                 if (pw != NULL) {
 221                         n = strlen(pw->pw_dir);
 222                         if (buf + n > p) {
 223                                 /* make room */
 224                                 m = strlen(p);
 225                                 if (sizeof(buf) < n + m) {
 226                                         warnx("%s: bad output filename",
 227                                             infile);
 228                                         return (1);
 229                                 }
 230                                 p = memmove(buf + n, p, m);
 231                         }
 232                         q = memcpy(p - n, pw->pw_dir, n);
 233                 }
 234         } else {
 235                 /* strip down to leaf name */
 236                 p = strrchr(q, '/');
 237                 if (p != NULL)
 238                         q = p + 1;
 239         }
 240         if (!oflag)
 241                 outfile = q;
 242
 243         /* POSIX says "/dev/stdout" is a 'magic cookie' not a special file. */
 244         if (pflag || strcmp(outfile, "/dev/stdout") == 0)
 245                 outfp = stdout;
 246         else {
 247                 flags = O_WRONLY | O_CREAT | O_EXCL;
 248                 if (lstat(outfile, &st) == 0) {
 249                         if (iflag) {
 250                                 warnc(EEXIST, "%s: %s", infile, outfile);
 251                                 return (0);
 252                         }
 253                         switch (st.st_mode & S_IFMT) {
 254                         case S_IFREG:
 255                         case S_IFLNK:
 256                                 /* avoid symlink attacks */
 257                                 if (unlink(outfile) == 0 || errno == ENOENT)
 258                                         break;
 259                                 warn("%s: unlink %s", infile, outfile);
 260                                 return (1);
 261                         case S_IFDIR:
 262                                 warnc(EISDIR, "%s: %s", infile, outfile);
 263                                 return (1);
 264                         default:
 265                                 if (oflag) {
 266                                         /* trust command-line names */
 267                                         flags &= ~O_EXCL;
 268                                         break;
 269                                 }
 270                                 warnc(EEXIST, "%s: %s", infile, outfile);
 271                                 return (1);
 272                         }
 273                 } else if (errno != ENOENT) {
 274                         warn("%s: %s", infile, outfile);
 275                         return (1);
 276                 }
 277                 if ((fd = open(outfile, flags, mode)) < 0 ||
 278                     (outfp = fdopen(fd, "w")) == NULL) {
 279                         warn("%s: %s", infile, outfile);
 280                         return (1);
 281                 }
 282         }
 283
 284         if (base64)
 285                 return (base64_decode());
 286         else
 287                 return (uu_decode());
 288 }
 289
 290 static int
 291 get_line(char *buf, size_t size)
 292 {
 293
 294         if (fgets(buf, size, infp) != NULL)
 295                 return (2);
 296         if (rflag)
 297                 return (0);
 298         warnx("%s: %s: short file", infile, outfile);
 299         return (1);
 300 }
 301
 302 static int
 303 checkend(const char *ptr, const char *end, const char *msg)
 304 {
 305         size_t n;
 306
 307         n = strlen(end);
 308         if (strncmp(ptr, end, n) != 0 ||
 309             strspn(ptr + n, " \t\r\n") != strlen(ptr + n)) {
 310                 warnx("%s: %s: %s", infile, outfile, msg);
 311                 return (1);
 312         }
 313         if (fclose(outfp) != 0) {
 314                 warn("%s: %s", infile, outfile);
 315                 return (1);
 316         }
 317         return (0);
 318 }
 319
 320 static int
 321 uu_decode(void)
 322 {
 323         int i, ch;
 324         char *p;
 325         char buf[MAXPATHLEN+1];
 326
 327         /* for each input line */
 328         for (;;) {
 329                 switch (get_line(buf, sizeof(buf))) {
 330                 case 0:
 331                         return (0);
 332                 case 1:
 333                         return (1);
 334                 }
 335
 336 #define DEC(c)          (((c) - ' ') & 077)     /* single character decode */
 337 #define IS_DEC(c)        ( (((c) - ' ') >= 0) && (((c) - ' ') <= 077 + 1) )
 338
 339 #define OUT_OF_RANGE do {                                               \
 340         warnx("%s: %s: character out of range: [%d-%d]",                \
 341             infile, outfile, 1 + ' ', 077 + ' ' + 1);                   \
 342         return (1);                                                     \
 343 } while (0)
 344
 345                 /*
 346                  * `i' is used to avoid writing out all the characters
 347                  * at the end of the file.
 348                  */
 349                 p = buf;
 350                 if ((i = DEC(*p)) <= 0)
 351                         break;
 352                 for (++p; i > 0; p += 4, i -= 3)
 353                         if (i >= 3) {
 354                                 if (!(IS_DEC(*p) && IS_DEC(*(p + 1)) &&
 355                                     IS_DEC(*(p + 2)) && IS_DEC(*(p + 3))))
 356                                         OUT_OF_RANGE;
 357
 358                                 ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 359                                 putc(ch, outfp);
 360                                 ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 361                                 putc(ch, outfp);
 362                                 ch = DEC(p[2]) << 6 | DEC(p[3]);
 363                                 putc(ch, outfp);
 364                         } else {
 365                                 if (i >= 1) {
 366                                         if (!(IS_DEC(*p) && IS_DEC(*(p + 1))))
 367                                                 OUT_OF_RANGE;
 368                                         ch = DEC(p[0]) << 2 | DEC(p[1]) >> 4;
 369                                         putc(ch, outfp);
 370                                 }
 371                                 if (i >= 2) {
 372                                         if (!(IS_DEC(*(p + 1)) &&
 373                                             IS_DEC(*(p + 2))))
 374                                                 OUT_OF_RANGE;
 375
 376                                         ch = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
 377                                         putc(ch, outfp);
 378                                 }
 379                                 if (i >= 3) {
 380                                         if (!(IS_DEC(*(p + 2)) &&
 381                                             IS_DEC(*(p + 3))))
 382                                                 OUT_OF_RANGE;
 383                                         ch = DEC(p[2]) << 6 | DEC(p[3]);
 384                                         putc(ch, outfp);
 385                                 }
 386                         }
 387         }
 388         switch (get_line(buf, sizeof(buf))) {
 389         case 0:
 390                 return (0);
 391         case 1:
 392                 return (1);
 393         default:
 394                 return (checkend(buf, "end", "no \"end\" line"));
 395         }
 396 }
 397
 398 static int
 399 base64_decode(void)
 400 {
 401         int n, count, count4;
 402         char inbuf[MAXPATHLEN + 1], *p;
 403         unsigned char outbuf[MAXPATHLEN * 4];
 404         char leftover[MAXPATHLEN + 1];
 405
 406         leftover[0] = '\0';
 407         for (;;) {
 408                 strcpy(inbuf, leftover);
 409                 switch (get_line(inbuf + strlen(inbuf),
 410                     sizeof(inbuf) - strlen(inbuf))) {
 411                 case 0:
 412                         return (0);
 413                 case 1:
 414                         return (1);
 415                 }
 416
 417                 count = 0;
 418                 count4 = -1;
 419                 p = inbuf;
 420                 while (*p != '\0') {
 421                         /*
 422                          * Base64 encoded strings have the following
 423                          * characters in them: A-Z, a-z, 0-9 and +, / and =
 424                          */
 425                         if (isalnum(*p) || *p == '+' || *p == '/' || *p == '=')
 426                                 count++;
 427                         if (count % 4 == 0)
 428                                 count4 = p - inbuf;
 429                         p++;
 430                 }
 431
 432                 strcpy(leftover, inbuf + count4 + 1);
 433                 inbuf[count4 + 1] = 0;
 434
 435                 n = b64_pton(inbuf, outbuf, sizeof(outbuf));
 436
 437                 if (n < 0)
 438                         break;
 439                 fwrite(outbuf, 1, n, outfp);
 440         }
 441         return (checkend(inbuf, "====", "error decoding base64 input stream"));
 442 }
 443
 444 static void
 445 usage(void)
 446 {
 447
 448         (void)fprintf(stderr,
 449             "usage: uudecode [-cimprs] [file ...]\n"
 450             "       uudecode [-i] -o output_file [file]\n"
 451             "       b64decode [-cimprs] [file ...]\n"
 452             "       b64decode [-i] -o output_file [file]\n");
 453         exit(1);
 454 }