blob: 3df6a98d8cd377e23979a8be8f1d8cfc0850b59f
1 | /* Based on ipsvd utilities written by Gerrit Pape <pape@smarden.org> |
2 | * which are released into public domain by the author. |
3 | * Homepage: http://smarden.sunsite.dk/ipsvd/ |
4 | * |
5 | * Copyright (C) 2007 Denys Vlasenko. |
6 | * |
7 | * Licensed under GPLv2, see file LICENSE in this source tree. |
8 | */ |
9 | |
10 | /* Based on ipsvd-0.12.1. This tcpsvd accepts all options |
11 | * which are supported by one from ipsvd-0.12.1, but not all are |
12 | * functional. See help text at the end of this file for details. |
13 | * |
14 | * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused. |
15 | * |
16 | * Busybox version exports TCPLOCALADDR instead of |
17 | * TCPLOCALIP + TCPLOCALPORT pair. ADDR more closely matches reality |
18 | * (which is "struct sockaddr_XXX". Port is not a separate entity, |
19 | * it's just a part of (AF_INET[6]) sockaddr!). |
20 | * |
21 | * TCPORIGDSTADDR is Busybox-specific addition. |
22 | * |
23 | * udp server is hacked up by reusing TCP code. It has the following |
24 | * limitation inherent in Unix DGRAM sockets implementation: |
25 | * - local IP address is retrieved (using recvmsg voodoo) but |
26 | * child's socket is not bound to it (bind cannot be called on |
27 | * already bound socket). Thus it still can emit outgoing packets |
28 | * with wrong source IP... |
29 | * - don't know how to retrieve ORIGDST for udp. |
30 | */ |
31 | |
32 | //usage:#define tcpsvd_trivial_usage |
33 | //usage: "[-hEv] [-c N] [-C N[:MSG]] [-b N] [-u USER] [-l NAME] IP PORT PROG" |
34 | /* with not-implemented options: */ |
35 | /* //usage: "[-hpEvv] [-c N] [-C N[:MSG]] [-b N] [-u USER] [-l NAME] [-i DIR|-x CDB] [-t SEC] IP PORT PROG" */ |
36 | //usage:#define tcpsvd_full_usage "\n\n" |
37 | //usage: "Create TCP socket, bind to IP:PORT and listen\n" |
38 | //usage: "for incoming connection. Run PROG for each connection.\n" |
39 | //usage: "\n IP IP to listen on, 0 = all" |
40 | //usage: "\n PORT Port to listen on" |
41 | //usage: "\n PROG ARGS Program to run" |
42 | //usage: "\n -l NAME Local hostname (else looks up local hostname in DNS)" |
43 | //usage: "\n -u USER[:GRP] Change to user/group after bind" |
44 | //usage: "\n -c N Handle up to N connections simultaneously" |
45 | //usage: "\n -b N Allow a backlog of approximately N TCP SYNs" |
46 | //usage: "\n -C N[:MSG] Allow only up to N connections from the same IP" |
47 | //usage: "\n New connections from this IP address are closed" |
48 | //usage: "\n immediately. MSG is written to the peer before close" |
49 | //usage: "\n -h Look up peer's hostname" |
50 | //usage: "\n -E Don't set up environment variables" |
51 | //usage: "\n -v Verbose" |
52 | //usage: |
53 | //usage:#define udpsvd_trivial_usage |
54 | //usage: "[-hEv] [-c N] [-u USER] [-l NAME] IP PORT PROG" |
55 | //usage:#define udpsvd_full_usage "\n\n" |
56 | //usage: "Create UDP socket, bind to IP:PORT and wait\n" |
57 | //usage: "for incoming packets. Run PROG for each packet,\n" |
58 | //usage: "redirecting all further packets with same peer ip:port to it.\n" |
59 | //usage: "\n IP IP to listen on, 0 = all" |
60 | //usage: "\n PORT Port to listen on" |
61 | //usage: "\n PROG ARGS Program to run" |
62 | //usage: "\n -l NAME Local hostname (else looks up local hostname in DNS)" |
63 | //usage: "\n -u USER[:GRP] Change to user/group after bind" |
64 | //usage: "\n -c N Handle up to N connections simultaneously" |
65 | //usage: "\n -h Look up peer's hostname" |
66 | //usage: "\n -E Don't set up environment variables" |
67 | //usage: "\n -v Verbose" |
68 | |
69 | #include "libbb.h" |
70 | |
71 | /* Wants <limits.h> etc, thus included after libbb.h: */ |
72 | #ifdef __linux__ |
73 | #include <linux/types.h> /* for __be32 etc */ |
74 | #include <linux/netfilter_ipv4.h> |
75 | #endif |
76 | |
77 | // TODO: move into this file: |
78 | #include "tcpudp_perhost.h" |
79 | |
80 | #ifdef SSLSVD |
81 | #include "matrixSsl.h" |
82 | #include "ssl_io.h" |
83 | #endif |
84 | |
85 | struct globals { |
86 | unsigned verbose; |
87 | unsigned max_per_host; |
88 | unsigned cur_per_host; |
89 | unsigned cnum; |
90 | unsigned cmax; |
91 | char **env_cur; |
92 | char *env_var[1]; /* actually bigger */ |
93 | } FIX_ALIASING; |
94 | #define G (*(struct globals*)&bb_common_bufsiz1) |
95 | #define verbose (G.verbose ) |
96 | #define max_per_host (G.max_per_host) |
97 | #define cur_per_host (G.cur_per_host) |
98 | #define cnum (G.cnum ) |
99 | #define cmax (G.cmax ) |
100 | #define env_cur (G.env_cur ) |
101 | #define env_var (G.env_var ) |
102 | #define INIT_G() do { \ |
103 | cmax = 30; \ |
104 | env_cur = &env_var[0]; \ |
105 | } while (0) |
106 | |
107 | |
108 | /* We have to be careful about leaking memory in repeated setenv's */ |
109 | static void xsetenv_plain(const char *n, const char *v) |
110 | { |
111 | char *var = xasprintf("%s=%s", n, v); |
112 | *env_cur++ = var; |
113 | putenv(var); |
114 | } |
115 | |
116 | static void xsetenv_proto(const char *proto, const char *n, const char *v) |
117 | { |
118 | char *var = xasprintf("%s%s=%s", proto, n, v); |
119 | *env_cur++ = var; |
120 | putenv(var); |
121 | } |
122 | |
123 | static void undo_xsetenv(void) |
124 | { |
125 | char **pp = env_cur = &env_var[0]; |
126 | while (*pp) { |
127 | char *var = *pp; |
128 | bb_unsetenv_and_free(var); |
129 | *pp++ = NULL; |
130 | } |
131 | } |
132 | |
133 | static void sig_term_handler(int sig) |
134 | { |
135 | if (verbose) |
136 | bb_error_msg("got signal %u, exit", sig); |
137 | kill_myself_with_sig(sig); |
138 | } |
139 | |
140 | /* Little bloated, but tries to give accurate info how child exited. |
141 | * Makes easier to spot segfaulting children etc... */ |
142 | static void print_waitstat(unsigned pid, int wstat) |
143 | { |
144 | unsigned e = 0; |
145 | const char *cause = "?exit"; |
146 | |
147 | if (WIFEXITED(wstat)) { |
148 | cause++; |
149 | e = WEXITSTATUS(wstat); |
150 | } else if (WIFSIGNALED(wstat)) { |
151 | cause = "signal"; |
152 | e = WTERMSIG(wstat); |
153 | } |
154 | bb_error_msg("end %d %s %d", pid, cause, e); |
155 | } |
156 | |
157 | /* Must match getopt32 in main! */ |
158 | enum { |
159 | OPT_c = (1 << 0), |
160 | OPT_C = (1 << 1), |
161 | OPT_i = (1 << 2), |
162 | OPT_x = (1 << 3), |
163 | OPT_u = (1 << 4), |
164 | OPT_l = (1 << 5), |
165 | OPT_E = (1 << 6), |
166 | OPT_b = (1 << 7), |
167 | OPT_h = (1 << 8), |
168 | OPT_p = (1 << 9), |
169 | OPT_t = (1 << 10), |
170 | OPT_v = (1 << 11), |
171 | OPT_V = (1 << 12), |
172 | OPT_U = (1 << 13), /* from here: sslsvd only */ |
173 | OPT_slash = (1 << 14), |
174 | OPT_Z = (1 << 15), |
175 | OPT_K = (1 << 16), |
176 | }; |
177 | |
178 | static void connection_status(void) |
179 | { |
180 | /* "only 1 client max" desn't need this */ |
181 | if (cmax > 1) |
182 | bb_error_msg("status %u/%u", cnum, cmax); |
183 | } |
184 | |
185 | static void sig_child_handler(int sig UNUSED_PARAM) |
186 | { |
187 | int wstat; |
188 | pid_t pid; |
189 | |
190 | while ((pid = wait_any_nohang(&wstat)) > 0) { |
191 | if (max_per_host) |
192 | ipsvd_perhost_remove(pid); |
193 | if (cnum) |
194 | cnum--; |
195 | if (verbose) |
196 | print_waitstat(pid, wstat); |
197 | } |
198 | if (verbose) |
199 | connection_status(); |
200 | } |
201 | |
202 | int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
203 | int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv) |
204 | { |
205 | char *str_C, *str_t; |
206 | char *user; |
207 | struct hcc *hccp; |
208 | const char *instructs; |
209 | char *msg_per_host = NULL; |
210 | unsigned len_per_host = len_per_host; /* gcc */ |
211 | #ifndef SSLSVD |
212 | struct bb_uidgid_t ugid; |
213 | #endif |
214 | bool tcp; |
215 | uint16_t local_port; |
216 | char *preset_local_hostname = NULL; |
217 | char *remote_hostname = remote_hostname; /* for compiler */ |
218 | char *remote_addr = remote_addr; /* for compiler */ |
219 | len_and_sockaddr *lsa; |
220 | len_and_sockaddr local, remote; |
221 | socklen_t sa_len; |
222 | int pid; |
223 | int sock; |
224 | int conn; |
225 | unsigned backlog = 20; |
226 | unsigned opts; |
227 | |
228 | INIT_G(); |
229 | |
230 | tcp = (applet_name[0] == 't'); |
231 | |
232 | /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */ |
233 | opt_complementary = "-3:i--i:ph:vv:b+:c+"; |
234 | #ifdef SSLSVD |
235 | opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:", |
236 | &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname, |
237 | &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose |
238 | ); |
239 | #else |
240 | /* "+": stop on first non-option */ |
241 | opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v", |
242 | &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname, |
243 | &backlog, &str_t, &verbose |
244 | ); |
245 | #endif |
246 | if (opts & OPT_C) { /* -C n[:message] */ |
247 | max_per_host = bb_strtou(str_C, &str_C, 10); |
248 | if (str_C[0]) { |
249 | if (str_C[0] != ':') |
250 | bb_show_usage(); |
251 | msg_per_host = str_C + 1; |
252 | len_per_host = strlen(msg_per_host); |
253 | } |
254 | } |
255 | if (max_per_host > cmax) |
256 | max_per_host = cmax; |
257 | if (opts & OPT_u) { |
258 | xget_uidgid(&ugid, user); |
259 | } |
260 | #ifdef SSLSVD |
261 | if (opts & OPT_U) ssluser = optarg; |
262 | if (opts & OPT_slash) root = optarg; |
263 | if (opts & OPT_Z) cert = optarg; |
264 | if (opts & OPT_K) key = optarg; |
265 | #endif |
266 | argv += optind; |
267 | if (!argv[0][0] || LONE_CHAR(argv[0], '0')) |
268 | argv[0] = (char*)"0.0.0.0"; |
269 | |
270 | /* Per-IP flood protection is not thought-out for UDP */ |
271 | if (!tcp) |
272 | max_per_host = 0; |
273 | |
274 | bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */ |
275 | |
276 | #ifdef SSLSVD |
277 | sslser = user; |
278 | client = 0; |
279 | if ((getuid() == 0) && !(opts & OPT_u)) { |
280 | xfunc_exitcode = 100; |
281 | bb_error_msg_and_die(bb_msg_you_must_be_root); |
282 | } |
283 | if (opts & OPT_u) |
284 | if (!uidgid_get(&sslugid, ssluser, 1)) { |
285 | if (errno) { |
286 | bb_perror_msg_and_die("can't get user/group: %s", ssluser); |
287 | } |
288 | bb_error_msg_and_die("unknown user/group %s", ssluser); |
289 | } |
290 | if (!cert) cert = "./cert.pem"; |
291 | if (!key) key = cert; |
292 | if (matrixSslOpen() < 0) |
293 | fatal("can't initialize ssl"); |
294 | if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) { |
295 | if (client) |
296 | fatal("can't read cert, key, or ca file"); |
297 | fatal("can't read cert or key file"); |
298 | } |
299 | if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0) |
300 | fatal("can't create ssl session"); |
301 | #endif |
302 | |
303 | sig_block(SIGCHLD); |
304 | signal(SIGCHLD, sig_child_handler); |
305 | bb_signals(BB_FATAL_SIGS, sig_term_handler); |
306 | signal(SIGPIPE, SIG_IGN); |
307 | |
308 | if (max_per_host) |
309 | ipsvd_perhost_init(cmax); |
310 | |
311 | local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0); |
312 | lsa = xhost2sockaddr(argv[0], local_port); |
313 | argv += 2; |
314 | |
315 | sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0); |
316 | setsockopt_reuseaddr(sock); |
317 | sa_len = lsa->len; /* I presume sockaddr len stays the same */ |
318 | xbind(sock, &lsa->u.sa, sa_len); |
319 | if (tcp) { |
320 | xlisten(sock, backlog); |
321 | close_on_exec_on(sock); |
322 | } else { /* udp: needed for recv_from_to to work: */ |
323 | socket_want_pktinfo(sock); |
324 | } |
325 | /* ndelay_off(sock); - it is the default I think? */ |
326 | |
327 | #ifndef SSLSVD |
328 | if (opts & OPT_u) { |
329 | /* drop permissions */ |
330 | xsetgid(ugid.gid); |
331 | xsetuid(ugid.uid); |
332 | } |
333 | #endif |
334 | |
335 | if (verbose) { |
336 | char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa); |
337 | if (opts & OPT_u) |
338 | bb_error_msg("listening on %s, starting, uid %u, gid %u", addr, |
339 | (unsigned)ugid.uid, (unsigned)ugid.gid); |
340 | else |
341 | bb_error_msg("listening on %s, starting", addr); |
342 | free(addr); |
343 | } |
344 | |
345 | /* Main accept() loop */ |
346 | |
347 | again: |
348 | hccp = NULL; |
349 | |
350 | while (cnum >= cmax) |
351 | wait_for_any_sig(); /* expecting SIGCHLD */ |
352 | |
353 | /* Accept a connection to fd #0 */ |
354 | again1: |
355 | close(0); |
356 | again2: |
357 | sig_unblock(SIGCHLD); |
358 | local.len = remote.len = sa_len; |
359 | if (tcp) { |
360 | conn = accept(sock, &remote.u.sa, &remote.len); |
361 | } else { |
362 | /* In case recv_from_to won't be able to recover local addr. |
363 | * Also sets port - recv_from_to is unable to do it. */ |
364 | local = *lsa; |
365 | conn = recv_from_to(sock, NULL, 0, MSG_PEEK, |
366 | &remote.u.sa, &local.u.sa, sa_len); |
367 | } |
368 | sig_block(SIGCHLD); |
369 | if (conn < 0) { |
370 | if (errno != EINTR) |
371 | bb_perror_msg(tcp ? "accept" : "recv"); |
372 | goto again2; |
373 | } |
374 | xmove_fd(tcp ? conn : sock, 0); |
375 | |
376 | if (max_per_host) { |
377 | /* Drop connection immediately if cur_per_host > max_per_host |
378 | * (minimizing load under SYN flood) */ |
379 | remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa); |
380 | cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp); |
381 | if (cur_per_host > max_per_host) { |
382 | /* ipsvd_perhost_add detected that max is exceeded |
383 | * (and did not store ip in connection table) */ |
384 | free(remote_addr); |
385 | if (msg_per_host) { |
386 | /* don't block or test for errors */ |
387 | send(0, msg_per_host, len_per_host, MSG_DONTWAIT); |
388 | } |
389 | goto again1; |
390 | } |
391 | /* NB: remote_addr is not leaked, it is stored in conn table */ |
392 | } |
393 | |
394 | if (!tcp) { |
395 | /* Voodoo magic: making udp sockets each receive its own |
396 | * packets is not trivial, and I still not sure |
397 | * I do it 100% right. |
398 | * 1) we have to do it before fork() |
399 | * 2) order is important - is it right now? */ |
400 | |
401 | /* Open new non-connected UDP socket for further clients... */ |
402 | sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0); |
403 | setsockopt_reuseaddr(sock); |
404 | /* Make plain write/send work for old socket by supplying default |
405 | * destination address. This also restricts incoming packets |
406 | * to ones coming from this remote IP. */ |
407 | xconnect(0, &remote.u.sa, sa_len); |
408 | /* hole? at this point we have no wildcard udp socket... |
409 | * can this cause clients to get "port unreachable" icmp? |
410 | * Yup, time window is very small, but it exists (is it?) */ |
411 | /* ..."open new socket", continued */ |
412 | xbind(sock, &lsa->u.sa, sa_len); |
413 | socket_want_pktinfo(sock); |
414 | |
415 | /* Doesn't work: |
416 | * we cannot replace fd #0 - we will lose pending packet |
417 | * which is already buffered for us! And we cannot use fd #1 |
418 | * instead - it will "intercept" all following packets, but child |
419 | * does not expect data coming *from fd #1*! */ |
420 | #if 0 |
421 | /* Make it so that local addr is fixed to localp->u.sa |
422 | * and we don't accidentally accept packets to other local IPs. */ |
423 | /* NB: we possibly bind to the _very_ same_ address & port as the one |
424 | * already bound in parent! This seems to work in Linux. |
425 | * (otherwise we can move socket to fd #0 only if bind succeeds) */ |
426 | close(0); |
427 | set_nport(&localp->u.sa, htons(local_port)); |
428 | xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0); |
429 | setsockopt_reuseaddr(0); /* crucial */ |
430 | xbind(0, &localp->u.sa, localp->len); |
431 | #endif |
432 | } |
433 | |
434 | pid = vfork(); |
435 | if (pid == -1) { |
436 | bb_perror_msg("vfork"); |
437 | goto again; |
438 | } |
439 | |
440 | if (pid != 0) { |
441 | /* Parent */ |
442 | cnum++; |
443 | if (verbose) |
444 | connection_status(); |
445 | if (hccp) |
446 | hccp->pid = pid; |
447 | /* clean up changes done by vforked child */ |
448 | undo_xsetenv(); |
449 | goto again; |
450 | } |
451 | |
452 | /* Child: prepare env, log, and exec prog */ |
453 | |
454 | { /* vfork alert! every xmalloc in this block should be freed! */ |
455 | char *local_hostname = local_hostname; /* for compiler */ |
456 | char *local_addr = NULL; |
457 | char *free_me0 = NULL; |
458 | char *free_me1 = NULL; |
459 | char *free_me2 = NULL; |
460 | |
461 | if (verbose || !(opts & OPT_E)) { |
462 | if (!max_per_host) /* remote_addr is not yet known */ |
463 | free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa); |
464 | if (opts & OPT_h) { |
465 | free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa); |
466 | if (!remote_hostname) { |
467 | bb_error_msg("can't look up hostname for %s", remote_addr); |
468 | remote_hostname = remote_addr; |
469 | } |
470 | } |
471 | /* Find out local IP peer connected to. |
472 | * Errors ignored (I'm not paranoid enough to imagine kernel |
473 | * which doesn't know local IP). */ |
474 | if (tcp) |
475 | getsockname(0, &local.u.sa, &local.len); |
476 | /* else: for UDP it is done earlier by parent */ |
477 | local_addr = xmalloc_sockaddr2dotted(&local.u.sa); |
478 | if (opts & OPT_h) { |
479 | local_hostname = preset_local_hostname; |
480 | if (!local_hostname) { |
481 | free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa); |
482 | if (!local_hostname) |
483 | bb_error_msg_and_die("can't look up hostname for %s", local_addr); |
484 | } |
485 | /* else: local_hostname is not NULL, but is NOT malloced! */ |
486 | } |
487 | } |
488 | if (verbose) { |
489 | pid = getpid(); |
490 | if (max_per_host) { |
491 | bb_error_msg("concurrency %s %u/%u", |
492 | remote_addr, |
493 | cur_per_host, max_per_host); |
494 | } |
495 | bb_error_msg((opts & OPT_h) |
496 | ? "start %u %s-%s (%s-%s)" |
497 | : "start %u %s-%s", |
498 | pid, |
499 | local_addr, remote_addr, |
500 | local_hostname, remote_hostname); |
501 | } |
502 | |
503 | if (!(opts & OPT_E)) { |
504 | /* setup ucspi env */ |
505 | const char *proto = tcp ? "TCP" : "UDP"; |
506 | |
507 | #ifdef SO_ORIGINAL_DST |
508 | /* Extract "original" destination addr:port |
509 | * from Linux firewall. Useful when you redirect |
510 | * an outbond connection to local handler, and it needs |
511 | * to know where it originally tried to connect */ |
512 | if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) { |
513 | char *addr = xmalloc_sockaddr2dotted(&local.u.sa); |
514 | xsetenv_plain("TCPORIGDSTADDR", addr); |
515 | free(addr); |
516 | } |
517 | #endif |
518 | xsetenv_plain("PROTO", proto); |
519 | xsetenv_proto(proto, "LOCALADDR", local_addr); |
520 | xsetenv_proto(proto, "REMOTEADDR", remote_addr); |
521 | if (opts & OPT_h) { |
522 | xsetenv_proto(proto, "LOCALHOST", local_hostname); |
523 | xsetenv_proto(proto, "REMOTEHOST", remote_hostname); |
524 | } |
525 | //compat? xsetenv_proto(proto, "REMOTEINFO", ""); |
526 | /* additional */ |
527 | if (cur_per_host > 0) /* can not be true for udp */ |
528 | xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host)); |
529 | } |
530 | free(local_addr); |
531 | free(free_me0); |
532 | free(free_me1); |
533 | free(free_me2); |
534 | } |
535 | |
536 | xdup2(0, 1); |
537 | |
538 | signal(SIGPIPE, SIG_DFL); /* this one was SIG_IGNed */ |
539 | /* Non-ignored signals revert to SIG_DFL on exec anyway */ |
540 | /*signal(SIGCHLD, SIG_DFL);*/ |
541 | sig_unblock(SIGCHLD); |
542 | |
543 | #ifdef SSLSVD |
544 | strcpy(id, utoa(pid)); |
545 | ssl_io(0, argv); |
546 | bb_perror_msg_and_die("can't execute '%s'", argv[0]); |
547 | #else |
548 | BB_EXECVP_or_die(argv); |
549 | #endif |
550 | } |
551 | |
552 | /* |
553 | tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name] |
554 | [-i dir|-x cdb] [ -t sec] host port prog |
555 | |
556 | tcpsvd creates a TCP/IP socket, binds it to the address host:port, |
557 | and listens on the socket for incoming connections. |
558 | |
559 | On each incoming connection, tcpsvd conditionally runs a program, |
560 | with standard input reading from the socket, and standard output |
561 | writing to the socket, to handle this connection. tcpsvd keeps |
562 | listening on the socket for new connections, and can handle |
563 | multiple connections simultaneously. |
564 | |
565 | tcpsvd optionally checks for special instructions depending |
566 | on the IP address or hostname of the client that initiated |
567 | the connection, see ipsvd-instruct(5). |
568 | |
569 | host |
570 | host either is a hostname, or a dotted-decimal IP address, |
571 | or 0. If host is 0, tcpsvd accepts connections to any local |
572 | IP address. |
573 | * busybox accepts IPv6 addresses and host:port pairs too |
574 | In this case second parameter is ignored |
575 | port |
576 | tcpsvd accepts connections to host:port. port may be a name |
577 | from /etc/services or a number. |
578 | prog |
579 | prog consists of one or more arguments. For each connection, |
580 | tcpsvd normally runs prog, with file descriptor 0 reading from |
581 | the network, and file descriptor 1 writing to the network. |
582 | By default it also sets up TCP-related environment variables, |
583 | see tcp-environ(5) |
584 | -i dir |
585 | read instructions for handling new connections from the instructions |
586 | directory dir. See ipsvd-instruct(5) for details. |
587 | * ignored by busyboxed version |
588 | -x cdb |
589 | read instructions for handling new connections from the constant database |
590 | cdb. The constant database normally is created from an instructions |
591 | directory by running ipsvd-cdb(8). |
592 | * ignored by busyboxed version |
593 | -t sec |
594 | timeout. This option only takes effect if the -i option is given. |
595 | While checking the instructions directory, check the time of last access |
596 | of the file that matches the clients address or hostname if any, discard |
597 | and remove the file if it wasn't accessed within the last sec seconds; |
598 | tcpsvd does not discard or remove a file if the user's write permission |
599 | is not set, for those files the timeout is disabled. Default is 0, |
600 | which means that the timeout is disabled. |
601 | * ignored by busyboxed version |
602 | -l name |
603 | local hostname. Do not look up the local hostname in DNS, but use name |
604 | as hostname. This option must be set if tcpsvd listens on port 53 |
605 | to avoid loops. |
606 | -u user[:group] |
607 | drop permissions. Switch user ID to user's UID, and group ID to user's |
608 | primary GID after creating and binding to the socket. If user is followed |
609 | by a colon and a group name, the group ID is switched to the GID of group |
610 | instead. All supplementary groups are removed. |
611 | -c n |
612 | concurrency. Handle up to n connections simultaneously. Default is 30. |
613 | If there are n connections active, tcpsvd defers acceptance of a new |
614 | connection until an active connection is closed. |
615 | -C n[:msg] |
616 | per host concurrency. Allow only up to n connections from the same IP |
617 | address simultaneously. If there are n active connections from one IP |
618 | address, new incoming connections from this IP address are closed |
619 | immediately. If n is followed by :msg, the message msg is written |
620 | to the client if possible, before closing the connection. By default |
621 | msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg. |
622 | |
623 | For each accepted connection, the current per host concurrency is |
624 | available through the environment variable TCPCONCURRENCY. n and msg |
625 | can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5). |
626 | By default tcpsvd doesn't keep track of connections. |
627 | -h |
628 | Look up the client's hostname in DNS. |
629 | -p |
630 | paranoid. After looking up the client's hostname in DNS, look up the IP |
631 | addresses in DNS for that hostname, and forget about the hostname |
632 | if none of the addresses match the client's IP address. You should |
633 | set this option if you use hostname based instructions. The -p option |
634 | implies the -h option. |
635 | * ignored by busyboxed version |
636 | -b n |
637 | backlog. Allow a backlog of approximately n TCP SYNs. On some systems n |
638 | is silently limited. Default is 20. |
639 | -E |
640 | no special environment. Do not set up TCP-related environment variables. |
641 | -v |
642 | verbose. Print verbose messsages to standard output. |
643 | -vv |
644 | more verbose. Print more verbose messages to standard output. |
645 | * no difference between -v and -vv in busyboxed version |
646 | */ |
647 |