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

   1 /* -*-c-*-
   2  *
   3  * $Id: fw.c,v 1.3 1999/07/26 23:30:42 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 1.3  1999/07/26 23:30:42  mdw
  33  * Major reconstruction work for new design.
  34  *
  35  * Revision 1.2  1999/07/03 13:55:17  mdw
  36  * Various changes.  Add configuration grammar to help text.  Change to
  37  * root directory and open syslog when forking into background.
  38  *
  39  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  40  * Initial revision.
  41  *
  42  */
  43
  44 /*----- Header files ------------------------------------------------------*/
  45
  46 #include "config.h"
  47
  48 #include <ctype.h>
  49 #include <errno.h>
  50 #include <signal.h>
  51 #include <stdarg.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55 #include <time.h>
  56
  57 #include <unistd.h>
  58 #include <syslog.h>
  59
  60 #include <mLib/dstr.h>
  61 #include <mLib/mdwopt.h>
  62 #include <mLib/quis.h>
  63 #include <mLib/report.h>
  64 #include <mLib/sel.h>
  65 #include <mLib/sig.h>
  66 #include <mLib/sub.h>
  67
  68 #include "bres.h"
  69 #include "conf.h"
  70 #include "endpt.h"
  71 #include "exec.h"
  72 #include "fattr.h"
  73 #include "fw.h"
  74 #include "scan.h"
  75 #include "source.h"
  76
  77 /*----- Global variables --------------------------------------------------*/
  78
  79 sel_state *sel;                         /* Multiplexor for nonblocking I/O */
  80
  81 /*----- Static variables --------------------------------------------------*/
  82
  83 static unsigned flags = 0;              /* Global state flags */
  84 static unsigned active = 0;             /* Number of active things */
  85
  86 #define FW_SYSLOG 1u
  87 #define FW_QUIET 2u
  88 #define FW_SET 4u
  89
  90 /*----- Main code ---------------------------------------------------------*/
  91
  92 /* --- @fw_log@ --- *
  93  *
  94  * Arguments:   @time_t t@ = when the connection occurred or (@-1@)
  95  *              @const char *fmt@ = format string to fill in
  96  *              @...@ = other arguments
  97  *
  98  * Returns:     ---
  99  *
 100  * Use:         Logs a connection.
 101  */
 102
 103 void fw_log(time_t t, const char *fmt, ...)
 104 {
 105   struct tm *tm;
 106   dstr d = DSTR_INIT;
 107   va_list ap;
 108
 109   if (flags & FW_QUIET)
 110     return;
 111
 112   if (t == -1)
 113     t = time(0);
 114   tm = localtime(&t);
 115   DENSURE(&d, 64);
 116   d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S", tm);
 117   DPUTC(&d, ' ');
 118   va_start(ap, fmt);
 119   dstr_vputf(&d, fmt, ap);
 120   va_end(ap);
 121   if (flags & FW_SYSLOG)
 122     syslog(LOG_NOTICE, "%s", d.buf);
 123   else {
 124     DPUTC(&d, '\n');
 125     dstr_write(&d, stderr);
 126   }
 127   DDESTROY(&d);
 128 }
 129
 130 /* --- @fw_inc@, @fw_dec@ --- *
 131  *
 132  * Arguments:   ---
 133  *
 134  * Returns:     ---
 135  *
 136  * Use:         Increments or decrements the active thing count.  `fw' won't
 137  *              quit while there are active things.
 138  */
 139
 140 void fw_inc(void) { flags |= FW_SET; active++; }
 141 void fw_dec(void) { if (active) active--; }
 142
 143 /* --- @fw_exit@ --- *
 144  *
 145  * Arguments:   ---
 146  *
 147  * Returns:     ---
 148  *
 149  * Use:         Exits when appropriate.
 150  */
 151
 152 static void fw_exit(void)
 153 {
 154   endpt_killall();
 155   source_killall();
 156 }
 157
 158 /* --- @fw_tidy@ --- *
 159  *
 160  * Arguments:   @int n@ = signal number
 161  *              @void *p@ = an uninteresting argument
 162  *
 163  * Returns:     ---
 164  *
 165  * Use:         Handles various signals and causes a clean tidy-up.
 166  */
 167
 168 static void fw_tidy(int n, void *p)
 169 {
 170   const char *sn = "unexpected signal (bug!)";
 171   if (n == SIGTERM)
 172     sn = "SIGTERM";
 173   else if (n == SIGINT)
 174     sn = "SIGINT";
 175
 176   fw_log(-1, "closing down on %s", sn);
 177   fw_exit();
 178 }
 179
 180 /* --- Standard GNU help options --- */
 181
 182 static void version(FILE *fp)
 183 {
 184   fprintf(fp, "%s version " VERSION "\n", QUIS);
 185 }
 186
 187 static void usage(FILE *fp)
 188 {
 189   fprintf(stderr, "Usage: %s [-db] [-f file] [config statements...]\n",
 190           QUIS);
 191 }
 192
 193 static void help(FILE *fp)
 194 {
 195   version(fp);
 196   fputc('\n', fp);
 197   usage(fp);
 198   fputs("\n\
 199 An excessively full-featured port-forwarder, which subsumes large chunks\n\
 200 of the functionality of inetd, netcat, and normal cat.  Options available\n\
 201 are:\n\
 202 \n\
 203 -h, --help              Display this help message.\n\
 204 -v, --version           Display the program's version number.\n\
 205 -u, --usage             Display a terse usage summary.\n\
 206 \n\
 207 -f, --file=FILE         Read configuration from a file.\n\
 208 -d, --daemon            Fork into background after initializing.\n\
 209 \n\
 210 Configuration may be supplied in one or more configuration files, or on\n\
 211 the command line (or both).  If no `-f' option is present, and no\n\
 212 configuration is given on the command line, the standard input stream is\n\
 213 read.\n\
 214 \n\
 215 Configuration is free-form.  Comments begin with a `#' character and\n\
 216 continue to the end of the line.  Each command line argument is considered\n\
 217 to be a separate line.\n\
 218 \n\
 219 The syntax is too complicated to describe here.  Read the manual.\n\
 220 ", fp);
 221 }
 222
 223 /* --- @main@ --- *
 224  *
 225  * Arguments:   @int argc@ = number of command line arguments
 226  *              @char *argv[]@ = vector of argument strings
 227  *
 228  * Returns:     ---
 229  *
 230  * Use:         Simple port-forwarding server.
 231  */
 232
 233 int main(int argc, char *argv[])
 234 {
 235   unsigned f = 0;
 236   sel_state sst;
 237   sig s_term, s_int;
 238   scanner sc;
 239
 240   enum {
 241     f_bogus = 1,
 242     f_file = 2,
 243     f_fork = 8
 244   };
 245
 246   /* --- Initialize things --- */
 247
 248   ego(argv[0]);
 249   sel = &sst;
 250   sel_init(sel);
 251   sub_init();
 252   sig_init(sel);
 253   bres_init(sel);
 254   exec_init();
 255   fattr_init(&fattr_global);
 256   scan_create(&sc);
 257
 258   /* --- Set up some signal handlers --- */
 259
 260   sig_add(&s_term, SIGTERM, fw_tidy, 0);
 261   sig_add(&s_int, SIGINT, fw_tidy, 0);
 262   atexit(fw_exit);
 263
 264   /* --- Parse command line options --- */
 265
 266   for (;;) {
 267     static struct option opts[] = {
 268
 269       /* --- Standard GNU help options --- */
 270
 271       { "help",         0,              0,      'h' },
 272       { "version",      0,              0,      'v' },
 273       { "usage",        0,              0,      'u' },
 274
 275       /* --- Other useful arguments --- */
 276
 277       { "file",         OPTF_ARGREQ,    0,      'f' },
 278       { "fork",         0,              0,      'd' },
 279       { "daemon",       0,              0,      'd' },
 280       { "quiet",        0,              0,      'q' },
 281
 282       /* --- Magic terminator --- */
 283
 284       { 0,              0,              0,      0 }
 285     };
 286     int i = mdwopt(argc, argv, "+hvu f:d", opts, 0, 0, 0);
 287
 288     if (i < 0)
 289       break;
 290     switch (i) {
 291       case 'h':
 292         help(stdout);
 293         exit(0);
 294         break;
 295       case 'v':
 296         version(stdout);
 297         exit(0);
 298         break;
 299       case 'u':
 300         usage(stdout);
 301         exit(0);
 302         break;
 303       case 'f':
 304         if (strcmp(optarg, "-") == 0)
 305           scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
 306         else {
 307           FILE *fp;
 308           if ((fp = fopen(optarg, "r")) == 0)
 309             die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
 310           scan_add(&sc, scan_file(fp, optarg, 0));
 311         }
 312         f |= f_file;
 313         break;
 314       case 'd':
 315         f |= f_fork;
 316         break;
 317       case 'q':
 318         flags |= FW_QUIET;
 319         break;
 320       default:
 321         f |= f_bogus;
 322         break;
 323     }
 324   }
 325
 326   if (f & f_bogus) {
 327     usage(stderr);
 328     exit(1);
 329   }
 330
 331   /* --- Deal with the remaining arguments --- */
 332
 333   if (optind < argc)
 334     scan_add(&sc, scan_argv(argv + optind));
 335   else if (f & f_file)
 336     /* Cool */;
 337   else if (!isatty(STDIN_FILENO))
 338     scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
 339   else {
 340     moan("no configuration given and stdin is a terminal.");
 341     moan("type `%s --help' for usage information.", QUIS);
 342     exit(1);
 343   }
 344
 345   /* --- Parse the configuration now gathered --- */
 346
 347   conf_parse(&sc);
 348
 349   /* --- Fork into the background --- */
 350
 351   if (f & f_fork) {
 352     pid_t kid;
 353
 354     kid = fork();
 355     if (kid == -1)
 356       die(1, "couldn't fork: %s", strerror(errno));
 357     if (kid != 0)
 358       _exit(0);
 359
 360     close(0); close(1); close(2);
 361     chdir("/");
 362     setsid();
 363
 364     kid = fork();
 365     if (kid != 0)
 366       _exit(0);
 367
 368     flags |= FW_SYSLOG;
 369     openlog(QUIS, 0, LOG_DAEMON);
 370   }
 371
 372   /* --- Let rip --- */
 373
 374   if (!(flags & FW_SET))
 375     moan("nothing to do!");
 376   signal(SIGPIPE, SIG_IGN);
 377   while (active)
 378     sel_select(sel);
 379   return (0);
 380 }
 381
 382 /*----- That's all, folks -------------------------------------------------*/