mdw@git.distorted.org.uk Git - fwd/blob - fw.c

   1 /* -*-c-*-
   2  *
   3  * $Id: fw.c,v 1.5 1999/10/22 22:47:50 mdw Exp $
   4  *
   5  * Port forwarding thingy
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' 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  * `fw' 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 `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: fw.c,v $
  32  * Revision 1.5  1999/10/22 22:47:50  mdw
  33  * Grammar changes.  Also, don't enable SIGINT if it's currently ignored.
  34  *
  35  * Revision 1.4  1999/10/10 16:46:12  mdw
  36  * New resolver to initialize.  Also, include options for grammar and
  37  * options references.
  38  *
  39  * Revision 1.3  1999/07/26 23:30:42  mdw
  40  * Major reconstruction work for new design.
  41  *
  42  * Revision 1.2  1999/07/03 13:55:17  mdw
  43  * Various changes.  Add configuration grammar to help text.  Change to
  44  * root directory and open syslog when forking into background.
  45  *
  46  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  47  * Initial revision.
  48  *
  49  */
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include "config.h"
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <signal.h>
  58 #include <stdarg.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <time.h>
  63
  64 #include <unistd.h>
  65 #include <syslog.h>
  66
  67 #include <mLib/bres.h>
  68 #include <mLib/dstr.h>
  69 #include <mLib/mdwopt.h>
  70 #include <mLib/quis.h>
  71 #include <mLib/report.h>
  72 #include <mLib/sel.h>
  73 #include <mLib/sig.h>
  74 #include <mLib/sub.h>
  75
  76 #include "conf.h"
  77 #include "endpt.h"
  78 #include "exec.h"
  79 #include "fattr.h"
  80 #include "fw.h"
  81 #include "scan.h"
  82 #include "source.h"
  83
  84 /*----- Global variables --------------------------------------------------*/
  85
  86 sel_state *sel;                         /* Multiplexor for nonblocking I/O */
  87
  88 /*----- Static variables --------------------------------------------------*/
  89
  90 static unsigned flags = 0;              /* Global state flags */
  91 static unsigned active = 0;             /* Number of active things */
  92
  93 #define FW_SYSLOG 1u
  94 #define FW_QUIET 2u
  95 #define FW_SET 4u
  96
  97 /*----- Main code ---------------------------------------------------------*/
  98
  99 /* --- @fw_log@ --- *
 100  *
 101  * Arguments:   @time_t t@ = when the connection occurred or (@-1@)
 102  *              @const char *fmt@ = format string to fill in
 103  *              @...@ = other arguments
 104  *
 105  * Returns:     ---
 106  *
 107  * Use:         Logs a connection.
 108  */
 109
 110 void fw_log(time_t t, const char *fmt, ...)
 111 {
 112   struct tm *tm;
 113   dstr d = DSTR_INIT;
 114   va_list ap;
 115
 116   if (flags & FW_QUIET)
 117     return;
 118
 119   if (t == -1)
 120     t = time(0);
 121   tm = localtime(&t);
 122   DENSURE(&d, 64);
 123   d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S", tm);
 124   DPUTC(&d, ' ');
 125   va_start(ap, fmt);
 126   dstr_vputf(&d, fmt, ap);
 127   va_end(ap);
 128   if (flags & FW_SYSLOG)
 129     syslog(LOG_NOTICE, "%s", d.buf);
 130   else {
 131     DPUTC(&d, '\n');
 132     dstr_write(&d, stderr);
 133   }
 134   DDESTROY(&d);
 135 }
 136
 137 /* --- @fw_inc@, @fw_dec@ --- *
 138  *
 139  * Arguments:   ---
 140  *
 141  * Returns:     ---
 142  *
 143  * Use:         Increments or decrements the active thing count.  `fw' won't
 144  *              quit while there are active things.
 145  */
 146
 147 void fw_inc(void) { flags |= FW_SET; active++; }
 148 void fw_dec(void) { if (active) active--; }
 149
 150 /* --- @fw_exit@ --- *
 151  *
 152  * Arguments:   ---
 153  *
 154  * Returns:     ---
 155  *
 156  * Use:         Exits when appropriate.
 157  */
 158
 159 static void fw_exit(void)
 160 {
 161   endpt_killall();
 162   source_killall();
 163 }
 164
 165 /* --- @fw_tidy@ --- *
 166  *
 167  * Arguments:   @int n@ = signal number
 168  *              @void *p@ = an uninteresting argument
 169  *
 170  * Returns:     ---
 171  *
 172  * Use:         Handles various signals and causes a clean tidy-up.
 173  */
 174
 175 static void fw_tidy(int n, void *p)
 176 {
 177   const char *sn = "unexpected signal (bug!)";
 178   if (n == SIGTERM)
 179     sn = "SIGTERM";
 180   else if (n == SIGINT)
 181     sn = "SIGINT";
 182
 183   fw_log(-1, "closing down on %s", sn);
 184   fw_exit();
 185 }
 186
 187 /* --- Standard GNU help options --- */
 188
 189 static void version(FILE *fp)
 190 {
 191   pquis(fp, "$ version " VERSION "\n");
 192 }
 193
 194 static void usage(FILE *fp)
 195 {
 196   pquis(fp, "Usage: $ [-db] [-f file] [config statements...]\n");
 197 }
 198
 199 static void help(FILE *fp)
 200 {
 201   version(fp);
 202   fputc('\n', fp);
 203   usage(fp);
 204   pquis(fp, "\n\
 205 An excessively full-featured port-forwarder, which subsumes large chunks\n\
 206 of the functionality of inetd, netcat, and normal cat.  Options available\n\
 207 are:\n\
 208 \n\
 209 -h, --help              Display this help message.\n\
 210 -v, --version           Display the program's version number.\n\
 211 -u, --usage             Display a terse usage summary.\n\
 212 \n\
 213 -g, --grammar           Show a summary of the configuration language.\n\
 214 -o, --options           Show a summary of the source and target options.\n\
 215 \n\
 216 -f, --file=FILE         Read configuration from a file.\n\
 217 -d, --daemon            Fork into background after initializing.\n\
 218 \n\
 219 Configuration may be supplied in one or more configuration files, or on\n\
 220 the command line (or both).  If no `-f' option is present, and no\n\
 221 configuration is given on the command line, the standard input stream is\n\
 222 read.\n\
 223 \n\
 224 Configuration is free-form.  Comments begin with a `#' character and\n\
 225 continue to the end of the line.  Each command line argument is considered\n\
 226 to be a separate line.\n\
 227 \n\
 228 The grammar is fairly complicated.  For a summary, run `$ --grammar'.\n\
 229 For a summary of the various options, run `$ --options'.\n\
 230 ");
 231 }
 232
 233 /* --- Other helpful options --- */
 234
 235 static void grammar(FILE *fp)
 236 {
 237   version(fp);
 238   pquis(fp, "\n\
 239 Grammar summary\n\
 240 \n\
 241 Basic syntax\n\
 242         file ::= empty | file stmt [`;']\n\
 243         stmt ::= option-stmt | fw-stmt\n\
 244         fw-stmt ::= `fw' source options [`to'|`->'] target options\n\
 245         options ::= `{' option-seq `}'\n\
 246         option-seq ::= empty | option-stmt [`;'] option-seq\n\
 247 \n\
 248 Option syntax\n\
 249         option-stmt ::= q-option\n\
 250         q-option ::= option\n\
 251              | prefix `.' q-option\n\
 252              | prefix `{' option-seq `}'\n\
 253         prefix ::= word\n\
 254 \n\
 255 File source and target\n\
 256         source ::= file\n\
 257         target ::= file\n\
 258         file ::= `file' [`.'] fspec [`,' fspec]\n\
 259         fspec ::= fd-spec | name-spec | null-spec\n\
 260         fd-spec ::= [[`:']`fd'[`:']] number|`stdin'|`stdout'\n\
 261         name-spec ::= [[`:']`file'[`:']] file-name\n\
 262         file-name ::= path-seq | [ path-seq ]\n\
 263         path-seq ::= path-elt | path-seq path-elt\n\
 264         path-elt ::= `/' | word\n\
 265         null-spec ::= [`:']`null'[`:']\n\
 266 \n\
 267 Exec source and target\n\
 268         source ::= exec\n\
 269         target ::= exec\n\
 270         exec ::= `exec' [`.'] cmd-spec\n\
 271         cmd-spec ::= shell-cmd | [prog-name] `[' argv0 arg-seq `]'\n\
 272         arg-seq ::= word | arg-seq word\n\
 273         shell-cmd ::= word\n\
 274         argv0 ::= word\n\
 275 \n\
 276 Socket source and target\n\
 277         source ::= socket-source\n\
 278         target ::= socket-target\n\
 279         socket-source ::= [`socket'[`.']] [[`:']addr-type[`:']] source-addr\n\
 280         socket-target ::= [`socket'[`.']] [[`:']addr-type[`:']] target-addr\n\
 281 \n\
 282         inet-source-addr ::= [port] port\n\
 283         inet-target-addr ::= address [`:'] port\n\
 284         address ::= addr-elt | address addr-elt\n\
 285         addr-elt ::= `.' | word\n\
 286 \n\
 287         unix-source-addr ::= file-name\n\
 288         unix-target-addr ::= file-name\n\
 289 ");
 290 }
 291
 292 static void options(FILE *fp)
 293 {
 294   version(fp);
 295   pquis(fp, "\n\
 296 Options summary\n\
 297 \n\
 298 File attributes (`fattr')\n\
 299         prefix.fattr.mode [=] mode\n\
 300         prefix.fattr.owner [=] user\n\
 301         prefix.fattr.group [=] group\n\
 302 \n\
 303 File options\n\
 304         file.create [=] yes|no\n\
 305         file.open [=] no|truncate|append\n\
 306         file.fattr.*\n\
 307 \n\
 308 Exec options\n\
 309         exec.logging [=] yes|no\n\
 310         exec.dir [=] file-name\n\
 311         exec.root [=] file-name\n\
 312         exec.user [=] user\n\
 313         exec.group [=] group\n\
 314         exec.rlimit.limit[.hard|.soft] [=] value\n\
 315         exec.env.clear\n\
 316         exec.env.unset var\n\
 317         exec.env.[set] var [=] value\n\
 318 \n\
 319 Socket options\n\
 320         socket.conn [=] number|unlimited|one-shot\n\
 321         socket.logging [=] yes|no\n\
 322         socket.inet.[allow|deny] [from] address [/ address]\n\
 323         socket.unix.fattr.*\n\
 324 ");
 325 }
 326
 327 /* --- @main@ --- *
 328  *
 329  * Arguments:   @int argc@ = number of command line arguments
 330  *              @char *argv[]@ = vector of argument strings
 331  *
 332  * Returns:     ---
 333  *
 334  * Use:         Simple port-forwarding server.
 335  */
 336
 337 int main(int argc, char *argv[])
 338 {
 339   unsigned f = 0;
 340   sel_state sst;
 341   sig s_term, s_int;
 342   scanner sc;
 343
 344   enum {
 345     f_bogus = 1,
 346     f_file = 2,
 347     f_fork = 8
 348   };
 349
 350   /* --- Initialize things --- */
 351
 352   ego(argv[0]);
 353   sel = &sst;
 354   sel_init(sel);
 355   sub_init();
 356   sig_init(sel);
 357   bres_init(sel);
 358   bres_exec(0);
 359   exec_init();
 360   fattr_init(&fattr_global);
 361   scan_create(&sc);
 362
 363   /* --- Set up some signal handlers --- *
 364    *
 365    * Don't enable @SIGINT@ if the caller already disabled it.
 366    */
 367
 368   {
 369     struct sigaction sa;
 370
 371     sig_add(&s_term, SIGTERM, fw_tidy, 0);
 372     sigaction(SIGINT, 0, &sa);
 373     if (sa.sa_handler != SIG_IGN)
 374       sig_add(&s_int, SIGINT, fw_tidy, 0);
 375   }
 376
 377   atexit(fw_exit);
 378
 379   /* --- Parse command line options --- */
 380
 381   for (;;) {
 382     static struct option opts[] = {
 383
 384       /* --- Standard GNU help options --- */
 385
 386       { "help",         0,              0,      'h' },
 387       { "version",      0,              0,      'v' },
 388       { "usage",        0,              0,      'u' },
 389
 390       /* --- Other help options --- */
 391
 392       { "grammar",      0,              0,      'g' },
 393       { "options",      0,              0,      'o' },
 394
 395       /* --- Other useful arguments --- */
 396
 397       { "file",         OPTF_ARGREQ,    0,      'f' },
 398       { "fork",         0,              0,      'd' },
 399       { "daemon",       0,              0,      'd' },
 400       { "quiet",        0,              0,      'q' },
 401
 402       /* --- Magic terminator --- */
 403
 404       { 0,              0,              0,      0 }
 405     };
 406     int i = mdwopt(argc, argv, "+hvu go f:d", opts, 0, 0, 0);
 407
 408     if (i < 0)
 409       break;
 410     switch (i) {
 411       case 'h':
 412         help(stdout);
 413         exit(0);
 414         break;
 415       case 'v':
 416         version(stdout);
 417         exit(0);
 418         break;
 419       case 'u':
 420         usage(stdout);
 421         exit(0);
 422         break;
 423       case 'g':
 424         grammar(stdout);
 425         exit(0);
 426         break;
 427       case 'o':
 428         options(stdout);
 429         exit(0);
 430         break;
 431       case 'f':
 432         if (strcmp(optarg, "-") == 0)
 433           scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
 434         else {
 435           FILE *fp;
 436           if ((fp = fopen(optarg, "r")) == 0)
 437             die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
 438           scan_add(&sc, scan_file(fp, optarg, 0));
 439         }
 440         f |= f_file;
 441         break;
 442       case 'd':
 443         f |= f_fork;
 444         break;
 445       case 'q':
 446         flags |= FW_QUIET;
 447         break;
 448       default:
 449         f |= f_bogus;
 450         break;
 451     }
 452   }
 453
 454   if (f & f_bogus) {
 455     usage(stderr);
 456     exit(1);
 457   }
 458
 459   /* --- Deal with the remaining arguments --- */
 460
 461   if (optind < argc)
 462     scan_add(&sc, scan_argv(argv + optind));
 463   else if (f & f_file)
 464     /* Cool */;
 465   else if (!isatty(STDIN_FILENO))
 466     scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
 467   else {
 468     moan("no configuration given and stdin is a terminal.");
 469     moan("type `%s --help' for usage information.", QUIS);
 470     exit(1);
 471   }
 472
 473   /* --- Parse the configuration now gathered --- */
 474
 475   conf_parse(&sc);
 476
 477   /* --- Fork into the background --- */
 478
 479   if (f & f_fork) {
 480     pid_t kid;
 481
 482     kid = fork();
 483     if (kid == -1)
 484       die(1, "couldn't fork: %s", strerror(errno));
 485     if (kid != 0)
 486       _exit(0);
 487
 488     close(0); close(1); close(2);
 489     chdir("/");
 490     setsid();
 491
 492     kid = fork();
 493     if (kid != 0)
 494       _exit(0);
 495
 496     flags |= FW_SYSLOG;
 497     openlog(QUIS, 0, LOG_DAEMON);
 498   }
 499
 500   /* --- Let rip --- */
 501
 502   if (!(flags & FW_SET))
 503     moan("nothing to do!");
 504   signal(SIGPIPE, SIG_IGN);
 505   while (active)
 506     sel_select(sel);
 507   return (0);
 508 }
 509
 510 /*----- That's all, folks -------------------------------------------------*/