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

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