login-utils/utmpdump.c

   1 /*
   2  * utmpdump
   3  *
   4  * Simple program to dump UTMP and WTMP files in raw format, so they can be
   5  * examined.
   6  *
   7  * Based on utmpdump dump from sysvinit suite.
   8  *
   9  * Copyright (C) 1991-2000 Miquel van Smoorenburg <miquels@cistron.nl>
  10  *
  11  * Copyright (C) 1998 Danek Duvall <duvall@alumni.princeton.edu>
  12  * Copyright (C) 2012 Karel Zak <kzak@redhat.com>
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  27  */
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <utmpx.h>
  32 #include <time.h>
  33 #include <ctype.h>
  34 #include <getopt.h>
  35 #include <unistd.h>
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38 #include <sys/stat.h>
  39 #ifdef HAVE_INOTIFY_INIT
  40 #include <sys/inotify.h>
  41 #endif
  42
  43 #include "c.h"
  44 #include "nls.h"
  45 #include "xalloc.h"
  46 #include "closestream.h"
  47 #include "timeutils.h"
  48
  49 static time_t strtotime(const char *s_time)
  50 {
  51         struct tm tm;
  52
  53         memset(&tm, '\0', sizeof(struct tm));
  54
  55         if (s_time[0] == ' ' || s_time[0] == '\0')
  56                 return (time_t)0;
  57
  58         if (isdigit(s_time[0])) {
  59                 /* [1998-09-01T01:00:00,000000+00:00]
  60                  * Subseconds are parsed with strtousec().  Timezone is
  61                  * always UTC-0 */
  62                 strptime(s_time, "%Y-%m-%dT%H:%M:%S", &tm);
  63         } else {
  64                 /* [Tue Sep 01 00:00:00 1998 GMT] */
  65                 strptime(s_time, "%a %b %d %T %Y", &tm);
  66                 /* Cheesy way of checking for DST.  This could be needed
  67                  * with legacy dumps that used localtime(3).  */
  68                 if (s_time[26] == 'D')
  69                         tm.tm_isdst = 1;
  70         }
  71         return timegm(&tm);
  72 }
  73
  74 static suseconds_t strtousec(const char *s_time)
  75 {
  76         const char *s = strchr(s_time, ',');
  77         if (s)
  78                 return (suseconds_t) atoi(s + 1);
  79         return 0;
  80 }
  81
  82 #define cleanse(x) xcleanse(x, sizeof(x))
  83 static void xcleanse(char *s, int len)
  84 {
  85         for ( ; *s && len-- > 0; s++)
  86                 if (!isprint(*s) || *s == '[' || *s == ']')
  87                         *s = '?';
  88 }
  89
  90 static void print_utline(struct utmpx *ut, FILE *out)
  91 {
  92         const char *addr_string;
  93         char buffer[INET6_ADDRSTRLEN];
  94         char time_string[40];
  95         struct timeval tv;
  96
  97         if (ut->ut_addr_v6[1] || ut->ut_addr_v6[2] || ut->ut_addr_v6[3])
  98                 addr_string = inet_ntop(AF_INET6, &(ut->ut_addr_v6), buffer, sizeof(buffer));
  99         else
 100                 addr_string = inet_ntop(AF_INET, &(ut->ut_addr_v6), buffer, sizeof(buffer));
 101
 102         tv.tv_sec = ut->ut_tv.tv_sec;
 103         tv.tv_usec = ut->ut_tv.tv_usec;
 104
 105         if (strtimeval_iso(&tv, ISO_TIMESTAMP_COMMA_GT, time_string,
 106                            sizeof(time_string)) != 0)
 107                 return;
 108         cleanse(ut->ut_id);
 109         cleanse(ut->ut_user);
 110         cleanse(ut->ut_line);
 111         cleanse(ut->ut_host);
 112
 113         /*            type pid    id       user     line     host     addr    time */
 114         fprintf(out, "[%d] [%05d] [%-4.4s] [%-*.*s] [%-*.*s] [%-*.*s] [%-15s] [%s]\n",
 115                ut->ut_type, ut->ut_pid, ut->ut_id,
 116                8, (int)sizeof(ut->ut_user), ut->ut_user,
 117                12, (int)sizeof(ut->ut_line), ut->ut_line,
 118                20, (int)sizeof(ut->ut_host), ut->ut_host,
 119                addr_string, time_string);
 120 }
 121
 122 #ifdef HAVE_INOTIFY_INIT
 123 #define EVENTS          (IN_MODIFY|IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT)
 124 #define NEVENTS         4
 125
 126 static void roll_file(const char *filename, off_t *size, FILE *out)
 127 {
 128         FILE *in;
 129         struct stat st;
 130         struct utmpx ut;
 131         off_t pos;
 132
 133         if (!(in = fopen(filename, "r")))
 134                 err(EXIT_FAILURE, _("cannot open %s"), filename);
 135
 136         if (fstat(fileno(in), &st) == -1)
 137                 err(EXIT_FAILURE, _("stat of %s failed"), filename);
 138
 139         if (st.st_size == *size)
 140                 goto done;
 141
 142         if (fseek(in, *size, SEEK_SET) != (off_t) -1) {
 143                 while (fread(&ut, sizeof(ut), 1, in) == 1)
 144                         print_utline(&ut, out);
 145         }
 146
 147         pos = ftello(in);
 148         /* If we've successfully read something, use the file position, this
 149          * avoids data duplication.  If we read nothing or hit an error,
 150          * reset to the reported size, this handles truncated files.
 151          */
 152         *size = (pos != -1 && pos != *size) ? pos : st.st_size;
 153
 154 done:
 155         fclose(in);
 156 }
 157
 158 static int follow_by_inotify(FILE *in, const char *filename, FILE *out)
 159 {
 160         char buf[NEVENTS * sizeof(struct inotify_event)];
 161         int fd, wd, event;
 162         ssize_t length;
 163         off_t size;
 164
 165         fd = inotify_init();
 166         if (fd == -1)
 167                 return -1;      /* probably reached any limit ... */
 168
 169         size = ftello(in);
 170         fclose(in);
 171
 172         wd = inotify_add_watch(fd, filename, EVENTS);
 173         if (wd == -1)
 174                 err(EXIT_FAILURE, _("%s: cannot add inotify watch."), filename);
 175
 176         while (wd >= 0) {
 177                 errno = 0;
 178                 length = read(fd, buf, sizeof(buf));
 179
 180                 if (length < 0 && (errno == EINTR || errno == EAGAIN))
 181                         continue;
 182                 if (length < 0)
 183                         err(EXIT_FAILURE, _("%s: cannot read inotify events"),
 184                                     filename);
 185
 186                 for (event = 0; event < length;) {
 187                         struct inotify_event *ev =
 188                                     (struct inotify_event *) &buf[event];
 189
 190                         if (ev->mask & IN_MODIFY)
 191                                 roll_file(filename, &size, out);
 192                         else {
 193                                 close(wd);
 194                                 wd = -1;
 195                                 break;
 196                         }
 197                         event += sizeof(struct inotify_event) + ev->len;
 198                 }
 199         }
 200
 201         close(fd);
 202         return 0;
 203 }
 204 #endif /* HAVE_INOTIFY_INIT */
 205
 206 static FILE *dump(FILE *in, const char *filename, int follow, FILE *out)
 207 {
 208         struct utmpx ut;
 209
 210         if (follow)
 211                 ignore_result( fseek(in, -10 * sizeof(ut), SEEK_END) );
 212
 213         while (fread(&ut, sizeof(ut), 1, in) == 1)
 214                 print_utline(&ut, out);
 215
 216         if (!follow)
 217                 return in;
 218
 219 #ifdef HAVE_INOTIFY_INIT
 220         if (follow_by_inotify(in, filename, out) == 0)
 221                 return NULL;                            /* file already closed */
 222         else
 223 #endif
 224                 /* fallback for systems without inotify or with non-free
 225                  * inotify instances */
 226                 for (;;) {
 227                         while (fread(&ut, sizeof(ut), 1, in) == 1)
 228                                 print_utline(&ut, out);
 229                         sleep(1);
 230                 }
 231
 232         return in;
 233 }
 234
 235
 236 /* This function won't work properly if there's a ']' or a ' ' in the real
 237  * token.  Thankfully, this should never happen.  */
 238 static int gettok(char *line, char *dest, int size, int eatspace)
 239 {
 240         int bpos, epos, eaten;
 241
 242         bpos = strchr(line, '[') - line;
 243         if (bpos < 0)
 244                 errx(EXIT_FAILURE, _("Extraneous newline in file. Exiting."));
 245
 246         line += 1 + bpos;
 247         epos = strchr(line, ']') - line;
 248         if (epos < 0)
 249                 errx(EXIT_FAILURE, _("Extraneous newline in file. Exiting."));
 250
 251         line[epos] = '\0';
 252         eaten = bpos + epos + 1;
 253
 254         if (eatspace) {
 255                 char *t;
 256                 if ((t = strchr(line, ' ')))
 257                         *t = 0;
 258         }
 259         strncpy(dest, line, size);
 260
 261         return eaten + 1;
 262 }
 263
 264 static void undump(FILE *in, FILE *out)
 265 {
 266         struct utmpx ut;
 267         char s_addr[INET6_ADDRSTRLEN + 1], s_time[29], *linestart, *line;
 268
 269         linestart = xmalloc(1024 * sizeof(*linestart));
 270         s_time[28] = 0;
 271
 272         while (fgets(linestart, 1023, in)) {
 273                 line = linestart;
 274                 memset(&ut, '\0', sizeof(ut));
 275                 sscanf(line, "[%hd] [%d] [%4c] ", &ut.ut_type, &ut.ut_pid, ut.ut_id);
 276
 277                 line += 19;
 278                 line += gettok(line, ut.ut_user, sizeof(ut.ut_user), 1);
 279                 line += gettok(line, ut.ut_line, sizeof(ut.ut_line), 1);
 280                 line += gettok(line, ut.ut_host, sizeof(ut.ut_host), 1);
 281                 line += gettok(line, s_addr, sizeof(s_addr) - 1, 1);
 282                 gettok(line, s_time, sizeof(s_time) - 1, 0);
 283                 if (strchr(s_addr, '.'))
 284                         inet_pton(AF_INET, s_addr, &(ut.ut_addr_v6));
 285                 else
 286                         inet_pton(AF_INET6, s_addr, &(ut.ut_addr_v6));
 287
 288                 ut.ut_tv.tv_sec = strtotime(s_time);
 289                 ut.ut_tv.tv_usec = strtousec(s_time);
 290
 291                 ignore_result( fwrite(&ut, sizeof(ut), 1, out) );
 292         }
 293
 294         free(linestart);
 295 }
 296
 297 static void __attribute__((__noreturn__)) usage(void)
 298 {
 299         FILE *out = stdout;
 300         fputs(USAGE_HEADER, out);
 301
 302         fprintf(out,
 303                 _(" %s [options] [filename]\n"), program_invocation_short_name);
 304
 305         fputs(USAGE_SEPARATOR, out);
 306         fputs(_("Dump UTMP and WTMP files in raw format.\n"), out);
 307
 308         fputs(USAGE_OPTIONS, out);
 309         fputs(_(" -f, --follow         output appended data as the file grows\n"), out);
 310         fputs(_(" -r, --reverse        write back dumped data into utmp file\n"), out);
 311         fputs(_(" -o, --output <file>  write to file instead of standard output\n"), out);
 312         printf(USAGE_HELP_OPTIONS(22));
 313
 314         printf(USAGE_MAN_TAIL("utmpdump(1)"));
 315         exit(EXIT_SUCCESS);
 316 }
 317
 318 int main(int argc, char **argv)
 319 {
 320         int c;
 321         FILE *in = NULL, *out = NULL;
 322         int reverse = 0, follow = 0;
 323         const char *filename = NULL;
 324
 325         static const struct option longopts[] = {
 326                 { "follow",  no_argument,       NULL, 'f' },
 327                 { "reverse", no_argument,       NULL, 'r' },
 328                 { "output",  required_argument, NULL, 'o' },
 329                 { "help",    no_argument,       NULL, 'h' },
 330                 { "version", no_argument,       NULL, 'V' },
 331                 { NULL, 0, NULL, 0 }
 332         };
 333
 334         setlocale(LC_ALL, "");
 335         bindtextdomain(PACKAGE, LOCALEDIR);
 336         textdomain(PACKAGE);
 337         close_stdout_atexit();
 338
 339         while ((c = getopt_long(argc, argv, "fro:hV", longopts, NULL)) != -1) {
 340                 switch (c) {
 341                 case 'r':
 342                         reverse = 1;
 343                         break;
 344
 345                 case 'f':
 346                         follow = 1;
 347                         break;
 348
 349                 case 'o':
 350                         out = fopen(optarg, "w");
 351                         if (!out)
 352                                 err(EXIT_FAILURE, _("cannot open %s"),
 353                                     optarg);
 354                         break;
 355
 356                 case 'h':
 357                         usage();
 358                 case 'V':
 359                         print_version(EXIT_SUCCESS);
 360                 default:
 361                         errtryhelp(EXIT_FAILURE);
 362                 }
 363         }
 364
 365         if (!out)
 366                 out = stdout;
 367
 368         if (optind < argc) {
 369                 filename = argv[optind];
 370                 in = fopen(filename, "r");
 371                 if (!in)
 372                         err(EXIT_FAILURE, _("cannot open %s"), filename);
 373         } else {
 374                 if (follow)
 375                         errx(EXIT_FAILURE, _("following standard input is unsupported"));
 376                 filename = "/dev/stdin";
 377                 in = stdin;
 378         }
 379
 380         if (reverse) {
 381                 fprintf(stderr, _("Utmp undump of %s\n"), filename);
 382                 undump(in, out);
 383         } else {
 384                 fprintf(stderr, _("Utmp dump of %s\n"), filename);
 385                 in = dump(in, filename, follow, out);
 386         }
 387
 388         if (out != stdout && close_stream(out))
 389                 err(EXIT_FAILURE, _("write failed"));
 390
 391         if (in && in != stdin)
 392                 fclose(in);
 393
 394         return EXIT_SUCCESS;
 395 }