--- /dev/null
+/* -*-c-*-
+ *
+ * Port forwarding thingy
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the `fwd' port forwarder.
+ *
+ * `fwd' is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * `fwd' is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with `fwd'; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include "fwd.h"
+
+/*----- Global variables --------------------------------------------------*/
+
+sel_state *sel; /* Multiplexor for nonblocking I/O */
+
+/*----- Static variables --------------------------------------------------*/
+
+typedef struct conffile {
+ struct conffile *next;
+ char *name;
+} conffile;
+
+static unsigned flags = 0; /* Global state flags */
+static unsigned active = 0; /* Number of active things */
+static conffile *conffiles = 0; /* List of configuration files */
+
+#define FW_SYSLOG 1u
+#define FW_QUIET 2u
+#define FW_SET 4u
+
+/*----- Configuration parsing ---------------------------------------------*/
+
+/* --- @parse@ --- *
+ *
+ * Arguments: @scanner *sc@ = pointer to scanner definition
+ *
+ * Returns: ---
+ *
+ * Use: Parses a configuration file from the scanner.
+ */
+
+static source_ops *sources[] =
+ { &xsource_ops, &fsource_ops, &ssource_ops, 0 };
+static target_ops *targets[] =
+ { &xtarget_ops, &ftarget_ops, &starget_ops, 0 };
+
+void parse(scanner *sc)
+{
+ token(sc);
+
+ for (;;) {
+ if (sc->t == CTOK_EOF)
+ break;
+ if (sc->t != CTOK_WORD)
+ error(sc, "parse error, keyword expected");
+
+ /* --- Handle a forwarding request --- */
+
+ if (strcmp(sc->d.buf, "forward") == 0 ||
+ strcmp(sc->d.buf, "fwd") == 0 ||
+ strcmp(sc->d.buf, "from") == 0) {
+ source *s;
+ target *t;
+
+ token(sc);
+
+ /* --- Read a source description --- */
+
+ {
+ source_ops **sops;
+
+ /* --- Try to find a source type which understands --- */
+
+ s = 0;
+ for (sops = sources; *sops; sops++) {
+ if ((s = (*sops)->read(sc)) != 0)
+ goto found_source;
+ }
+ error(sc, "unknown source name `%s'", sc->d.buf);
+
+ /* --- Read any source-specific options --- */
+
+ found_source:
+ if (sc->t == '{') {
+ token(sc);
+ while (sc->t == CTOK_WORD) {
+ if (!s->ops->option || !s->ops->option(s, sc)) {
+ error(sc, "unknown %s source option `%s'",
+ s->ops->name, sc->d.buf);
+ }
+ if (sc->t == ';')
+ token(sc);
+ }
+ if (sc->t != '}')
+ error(sc, "parse error, missing `}'");
+ token(sc);
+ }
+ }
+
+ /* --- Read a destination description --- */
+
+ if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "to") == 0 ||
+ strcmp(sc->d.buf, "->") == 0))
+ token(sc);
+
+ {
+ target_ops **tops;
+
+ /* --- Try to find a target which understands --- */
+
+ t = 0;
+ for (tops = targets; *tops; tops++) {
+ if ((t = (*tops)->read(sc)) != 0)
+ goto found_target;
+ }
+ error(sc, "unknown target name `%s'", sc->d.buf);
+
+ /* --- Read any target-specific options --- */
+
+ found_target:
+ if (sc->t == '{') {
+ token(sc);
+ while (sc->t == CTOK_WORD) {
+ if (!t->ops->option || !t->ops->option(t, sc)) {
+ error(sc, "unknown %s target option `%s'",
+ t->ops->name, sc->d.buf);
+ }
+ if (sc->t == ';')
+ token(sc);
+ }
+ if (sc->t != '}')
+ error(sc, "parse error, `}' expected");
+ token(sc);
+ }
+ }
+
+ /* --- Combine the source and target --- */
+
+ s->ops->attach(s, sc, t);
+ if (t->ops->confirm)
+ t->ops->confirm(t);
+ }
+
+ /* --- Include configuration from a file --- *
+ *
+ * Slightly tricky. Scan the optional semicolon from the including
+ * stream, not the included one.
+ */
+
+ else if (strcmp(sc->d.buf, "include") == 0) {
+ FILE *fp;
+ dstr d = DSTR_INIT;
+
+ token(sc);
+ conf_name(sc, '/', &d);
+ if ((fp = fopen(d.buf, "r")) == 0)
+ error(sc, "can't include `%s': %s", d.buf, strerror(errno));
+ if (sc->t == ';')
+ token(sc);
+ pushback(sc);
+ scan_push(sc, scan_file(fp, d.buf, 0));
+ token(sc);
+ dstr_destroy(&d);
+ continue; /* Don't parse a trailing `;' */
+ }
+
+ /* --- Other configuration is handled elsewhere --- */
+
+ else {
+
+ /* --- First try among the sources --- */
+
+ {
+ source_ops **sops;
+
+ for (sops = sources; *sops; sops++) {
+ if ((*sops)->option && (*sops)->option(0, sc))
+ goto found_option;
+ }
+ }
+
+ /* --- Then try among the targets --- */
+
+ {
+ target_ops **tops;
+
+ for (tops = targets; *tops; tops++) {
+ if ((*tops)->option && (*tops)->option(0, sc))
+ goto found_option;
+ }
+ }
+
+ /* --- Nobody wants the option --- */
+
+ error(sc, "unknown global option or prefix `%s'", sc->d.buf);
+
+ found_option:;
+ }
+
+ if (sc->t == ';')
+ token(sc);
+ }
+}
+
+/*----- General utility functions -----------------------------------------*/
+
+/* --- @fw_log@ --- *
+ *
+ * Arguments: @time_t t@ = when the connection occurred or (@-1@)
+ * @const char *fmt@ = format string to fill in
+ * @...@ = other arguments
+ *
+ * Returns: ---
+ *
+ * Use: Logs a connection.
+ */
+
+void fw_log(time_t t, const char *fmt, ...)
+{
+ struct tm *tm;
+ dstr d = DSTR_INIT;
+ va_list ap;
+
+ if (flags & FW_QUIET)
+ return;
+
+ if (t == -1)
+ t = time(0);
+ tm = localtime(&t);
+ DENSURE(&d, 64);
+ d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S ", tm);
+ va_start(ap, fmt);
+ dstr_vputf(&d, fmt, &ap);
+ va_end(ap);
+ if (flags & FW_SYSLOG)
+ syslog(LOG_NOTICE, "%s", d.buf);
+ else {
+ DPUTC(&d, '\n');
+ dstr_write(&d, stderr);
+ }
+ DDESTROY(&d);
+}
+
+/* --- @fw_inc@, @fw_dec@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Increments or decrements the active thing count. `fwd' won't
+ * quit while there are active things.
+ */
+
+void fw_inc(void) { flags |= FW_SET; active++; }
+void fw_dec(void) { if (active) active--; }
+
+/* --- @fw_exit@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Exits when appropriate.
+ */
+
+static void fw_exit(void)
+{
+ endpt_killall();
+ source_killall();
+}
+
+/* --- @fw_tidy@ --- *
+ *
+ * Arguments: @int n@ = signal number
+ * @void *p@ = an uninteresting argument
+ *
+ * Returns: ---
+ *
+ * Use: Handles various signals and causes a clean tidy-up.
+ */
+
+static void fw_tidy(int n, void *p)
+{
+ const char *sn = 0;
+ switch (n) {
+ case SIGTERM: sn = "SIGTERM"; break;
+ case SIGINT: sn = "SIGINT"; break;
+ default: abort();
+ }
+
+ fw_log(-1, "closing down gracefully on %s", sn);
+ source_killall();
+}
+
+/* --- @fw_die@ --- *
+ *
+ * Arguments: @int n@ = signal number
+ * @void *p@ = an uninteresting argument
+ *
+ * Returns: ---
+ *
+ * Use: Handles various signals and causes an abrupt shutdown.
+ */
+
+static void fw_die(int n, void *p)
+{
+ const char *sn = 0;
+ switch (n) {
+ case SIGQUIT: sn = "SIGQUIT"; break;
+ default: abort();
+ }
+
+ fw_log(-1, "closing down abruptly on %s", sn);
+ source_killall();
+ endpt_killall();
+}
+
+/* --- @fw_reload@ --- *
+ *
+ * Arguments: @int n@ = a signal number
+ * @void *p@ = an uninteresting argument
+ *
+ * Returns: ---
+ *
+ * Use: Handles a hangup signal by re-reading configuration files.
+ */
+
+static void fw_reload(int n, void *p)
+{
+ FILE *fp;
+ scanner sc;
+ conffile *cf;
+
+ assert(n == SIGHUP);
+ if (!conffiles) {
+ fw_log(-1, "no configuration files to reload: ignoring SIGHUP");
+ return;
+ }
+ fw_log(-1, "reloading configuration files...");
+ source_killall();
+ scan_create(&sc);
+ for (cf = conffiles; cf; cf = cf->next) {
+ if ((fp = fopen(cf->name, "r")) == 0)
+ fw_log(-1, "error loading `%s': %s", cf->name, strerror(errno));
+ else
+ scan_add(&sc, scan_file(fp, cf->name, 0));
+ }
+ parse(&sc);
+ fw_log(-1, "... reload completed OK");
+}
+
+/*----- Startup and options parsing ---------------------------------------*/
+
+/* --- Standard GNU help options --- */
+
+static void version(FILE *fp)
+{
+ pquis(fp, "$ version " VERSION "\n");
+}
+
+static void usage(FILE *fp)
+{
+ pquis(fp, "Usage: $ [-dql] [-p PIDFILE] [-f FILE] [CONFIG-STMTS...]\n");
+}
+
+static void help(FILE *fp)
+{
+ version(fp);
+ fputc('\n', fp);
+ usage(fp);
+ pquis(fp, "\n\
+An excessively full-featured port-forwarder, which subsumes large chunks\n\
+of the functionality of inetd, netcat, and normal cat.\n\
+\n\
+Configuration may be supplied in one or more configuration files, or on\n\
+the command line (or both). If no `-f' option is present, and no\n\
+configuration is given on the command line, the standard input stream is\n\
+read.\n\
+\n\
+Configuration is free-form. Comments begin with a `#' character and\n\
+continue to the end of the line. Each command line argument is considered\n\
+to be a separate line.\n\
+\n\
+The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\
+For a summary of the various options, run `$ --options'.\n\
+\n\
+Options available are:\n\
+\n\
+Help options:\n\
+ -h, --help Display this help message.\n\
+ -v, --version Display the program's version number.\n\
+ -u, --usage Display a terse usage summary.\n\
+\n\
+Configuration summary:\n\
+ -G, --grammar Show a summary of the configuration language.\n\
+ -O, --options Show a summary of the source and target options.\n\
+\n\
+Other options:\n\
+ -f, --file=FILE Read configuration from a file.\n\
+ -q, --quiet Don't emit any logging information.\n\
+ -d, --daemon Fork into background after initializing.\n\
+ -p, --pidfile=FILE Write process-id to the named FILE.\n\
+ -l, --syslog Send log output to the system logger.\n\
+ -s, --setuid=USER Change uid to USER after initializing sources.\n\
+ -g, --setgid=GRP Change gid to GRP after initializing sources.\n\
+");
+}
+
+/* --- Other helpful options --- */
+
+static void grammar(FILE *fp)
+{
+ version(fp);
+ fputs("\nGrammar summary\n\n", fp);
+ fputs(grammar_text, fp);
+}
+
+static void options(FILE *fp)
+{
+ version(fp);
+ fputs("\nOption summary\n\n", fp);
+ fputs(option_text, fp);
+}
+
+/* --- @main@ --- *
+ *
+ * Arguments: @int argc@ = number of command line arguments
+ * @char *argv[]@ = vector of argument strings
+ *
+ * Returns: ---
+ *
+ * Use: Simple port-forwarding server.
+ */
+
+int main(int argc, char *argv[])
+{
+ unsigned f = 0;
+ sel_state sst;
+ sig s_term, s_quit, s_int, s_hup;
+ scanner sc;
+ uid_t drop = -1;
+ gid_t dropg = -1;
+ const char *pidfile = 0;
+ conffile *cf, **cff = &conffiles;
+
+#define f_bogus 1u
+#define f_file 2u
+#define f_syslog 4u
+#define f_fork 8u
+
+ /* --- Initialize things --- */
+
+ ego(argv[0]);
+ sel = &sst;
+ sel_init(sel);
+ sub_init();
+ sig_init(sel);
+ bres_init(sel);
+ bres_exec(0);
+ exec_init();
+ fattr_init(&fattr_global);
+ scan_create(&sc);
+
+ atexit(fw_exit);
+
+ /* --- Parse command line options --- */
+
+ for (;;) {
+ static struct option opts[] = {
+
+ /* --- Standard GNU help options --- */
+
+ { "help", 0, 0, 'h' },
+ { "version", 0, 0, 'v' },
+ { "usage", 0, 0, 'u' },
+
+ /* --- Other help options --- */
+
+ { "grammar", 0, 0, 'G' },
+ { "options", 0, 0, 'O' },
+
+ /* --- Other useful arguments --- */
+
+ { "file", OPTF_ARGREQ, 0, 'f' },
+ { "fork", 0, 0, 'd' },
+ { "daemon", 0, 0, 'd' },
+ { "pidfile", OPTF_ARGREQ, 0, 'p' },
+ { "syslog", 0, 0, 'l' },
+ { "log", 0, 0, 'l' },
+ { "quiet", 0, 0, 'q' },
+ { "setuid", OPTF_ARGREQ, 0, 's' },
+ { "uid", OPTF_ARGREQ, 0, 's' },
+ { "setgid", OPTF_ARGREQ, 0, 'g' },
+ { "gid", OPTF_ARGREQ, 0, 'g' },
+
+ /* --- Magic terminator --- */
+
+ { 0, 0, 0, 0 }
+ };
+ int i = mdwopt(argc, argv, "+hvu" "GO" "f:dp:ls:g:", opts, 0, 0, 0);
+
+ if (i < 0)
+ break;
+ switch (i) {
+ case 'h':
+ help(stdout);
+ exit(0);
+ break;
+ case 'v':
+ version(stdout);
+ exit(0);
+ break;
+ case 'u':
+ usage(stdout);
+ exit(0);
+ break;
+ case 'G':
+ grammar(stdout);
+ exit(0);
+ break;
+ case 'O':
+ options(stdout);
+ exit(0);
+ break;
+ case 'f':
+ if (strcmp(optarg, "-") == 0)
+ scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
+ else {
+ FILE *fp;
+ if ((fp = fopen(optarg, "r")) == 0)
+ die(1, "couldn't open file `%s': %s", optarg, strerror(errno));
+ cf = CREATE(conffile);
+ cf->name = optarg;
+ *cff = cf;
+ cff = &cf->next;
+ scan_add(&sc, scan_file(fp, optarg, 0));
+ }
+ f |= f_file;
+ break;
+ case 'd':
+ f |= f_fork;
+ break;
+ case 'p':
+ pidfile = optarg;
+ break;
+ case 'l':
+ f |= f_syslog;
+ break;
+ case 'q':
+ flags |= FW_QUIET;
+ break;
+ case 's':
+ if (isdigit((unsigned char )optarg[0])) {
+ char *q;
+ drop = strtol(optarg, &q, 0);
+ if (*q)
+ die(1, "bad uid `%s'", optarg);
+ } else {
+ struct passwd *pw = getpwnam(optarg);
+ if (!pw)
+ die(1, "unknown user `%s'", optarg);
+ drop = pw->pw_uid;
+ }
+ break;
+ case 'g':
+ if (isdigit((unsigned char )optarg[0])) {
+ char *q;
+ dropg = strtol(optarg, &q, 0);
+ if (*q)
+ die(1, "bad gid `%s'", optarg);
+ } else {
+ struct group *gr = getgrnam(optarg);
+ if (!gr)
+ die(1, "unknown group `%s'", optarg);
+ dropg = gr->gr_gid;
+ }
+ break;
+ default:
+ f |= f_bogus;
+ break;
+ }
+ }
+
+ if (f & f_bogus) {
+ usage(stderr);
+ exit(1);
+ }
+ *cff = 0;
+
+ /* --- Deal with the remaining arguments --- */
+
+ if (optind < argc)
+ scan_add(&sc, scan_argv(argv + optind));
+ else if (f & f_file)
+ /* Cool */;
+ else if (!isatty(STDIN_FILENO))
+ scan_add(&sc, scan_file(stdin, "<stdin>", SCF_NOCLOSE));
+ else {
+ moan("no configuration given and stdin is a terminal.");
+ moan("type `%s --help' for usage information.", QUIS);
+ exit(1);
+ }
+
+ /* --- Parse the configuration now gathered --- */
+
+ parse(&sc);
+
+ /* --- Set up some signal handlers --- *
+ *
+ * Don't enable @SIGINT@ if the caller already disabled it.
+ */
+
+ {
+ struct sigaction sa;
+
+ sig_add(&s_term, SIGTERM, fw_tidy, 0);
+ sig_add(&s_quit, SIGQUIT, fw_die, 0);
+ sigaction(SIGINT, 0, &sa);
+ if (sa.sa_handler != SIG_IGN)
+ sig_add(&s_int, SIGINT, fw_tidy, 0);
+ sig_add(&s_hup, SIGHUP, fw_reload, 0);
+ }
+
+ /* --- Fork into the background --- */
+
+ if (f & f_fork) {
+ pid_t kid;
+
+ kid = fork();
+ if (kid == -1)
+ die(1, "couldn't fork: %s", strerror(errno));
+ if (kid != 0)
+ _exit(0);
+
+ close(0); close(1); close(2);
+ chdir("/");
+ setsid();
+
+ kid = fork();
+ if (kid != 0)
+ _exit(0);
+ }
+ if (pidfile) {
+ FILE *fp = fopen(pidfile, "w");
+ if (!fp) {
+ die(EXIT_FAILURE, "couldn't create pidfile `%s': %s",
+ pidfile, strerror(errno));
+ }
+ fprintf(fp, "%lu\n", (unsigned long)getpid());
+ if (fflush(fp) || ferror(fp) || fclose(fp)) {
+ die(EXIT_FAILURE, "couldn't write pidfile `%s': %s",
+ pidfile, strerror(errno));
+ }
+ }
+
+ if (f & f_syslog) {
+ flags |= FW_SYSLOG;
+ openlog(QUIS, 0, LOG_DAEMON);
+ }
+
+ /* --- Drop privileges --- */
+
+ if (drop != (uid_t)-1)
+ privconn_split(sel);
+#ifdef HAVE_SETGROUPS
+ if ((dropg != (gid_t)-1 && (setgid(dropg) || setgroups(1, &dropg))) ||
+ (drop != (uid_t)-1 && setuid(drop)))
+ die(1, "couldn't drop privileges: %s", strerror(errno));
+#else
+ if ((dropg != (gid_t)-1 && setgid(dropg)) ||
+ (drop != (uid_t)-1 && setuid(drop)))
+ die(1, "couldn't drop privileges: %s", strerror(errno));
+#endif
+
+ /* --- Let rip --- */
+
+ if (!(flags & FW_SET))
+ moan("nothing to do!");
+ signal(SIGPIPE, SIG_IGN);
+
+ {
+ int selerr = 0;
+ while (active) {
+ if (!sel_select(sel))
+ selerr = 0;
+ else if (errno != EINTR && errno != EAGAIN) {
+ fw_log(-1, "error from select: %s", strerror(errno));
+ selerr++;
+ if (selerr > 8) {
+ fw_log(-1, "too many consecutive select errors: bailing out");
+ exit(EXIT_FAILURE);
+ }
+ }
+ }
+ }
+
+ return (0);
+}
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / fwd / blobdiff