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/
5 * Copyright (C) 2007 Denys Vlasenko.
7 * Licensed under GPLv2, see file LICENSE in this source tree.
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.
14 * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused.
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!).
21 * TCPORIGDSTADDR is Busybox-specific addition.
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.
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 for incoming connections.\n"
38 //usage: "Run PROG for each connection.\n"
39 //usage: "\n IP PORT IP:PORT to listen on"
40 //usage: "\n PROG ARGS Program to run"
41 //usage: "\n -u USER[:GRP] Change to user/group after bind"
42 //usage: "\n -c N Up to N connections simultaneously (default 30)"
43 //usage: "\n -b N Allow backlog of approximately N TCP SYNs (default 20)"
44 //usage: "\n -C N[:MSG] Allow only up to N connections from the same IP:"
45 //usage: "\n new connections from this IP address are closed"
46 //usage: "\n immediately, MSG is written to the peer before close"
47 //usage: "\n -E Don't set up environment"
48 //usage: "\n -h Look up peer's hostname"
49 //usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
50 //usage: "\n -v Verbose"
52 //usage: "\nEnvironment if no -E:"
53 //usage: "\nPROTO='TCP'"
54 //usage: "\nTCPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
55 //usage: "\nTCPLOCALADDR='ip:port'"
56 //usage: "\nTCPORIGDSTADDR='ip:port' of destination before firewall"
57 //usage: "\n Useful for REDIRECTed-to-local connections:"
58 //usage: "\n iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 8080"
59 //usage: "\nTCPCONCURRENCY=num_of_connects_from_this_ip"
61 //usage: "\nTCPLOCALHOST='hostname' (-l NAME is used if specified)"
62 //usage: "\nTCPREMOTEHOST='hostname'"
65 //usage:#define udpsvd_trivial_usage
66 //usage: "[-hEv] [-c N] [-u USER] [-l NAME] IP PORT PROG"
67 //usage:#define udpsvd_full_usage "\n\n"
68 //usage: "Create UDP socket, bind to IP:PORT and wait for incoming packets.\n"
69 //usage: "Run PROG for each packet, redirecting all further packets with same\n"
70 //usage: "peer ip:port to it.\n"
71 //usage: "\n IP PORT IP:PORT to listen on"
72 //usage: "\n PROG ARGS Program to run"
73 //usage: "\n -u USER[:GRP] Change to user/group after bind"
74 //usage: "\n -c N Up to N connections simultaneously (default 30)"
75 //usage: "\n -E Don't set up environment"
76 //usage: "\n -h Look up peer's hostname"
77 //usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
78 //usage: "\n -v Verbose"
80 //usage: "\nEnvironment if no -E:"
81 //usage: "\nPROTO='UDP'"
82 //usage: "\nUDPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
83 //usage: "\nUDPLOCALADDR='ip:port'"
85 //usage: "\nUDPLOCALHOST='hostname' (-l NAME is used if specified)"
86 //usage: "\nUDPREMOTEHOST='hostname'"
89 #include "common_bufsiz.h"
91 /* Wants <limits.h> etc, thus included after libbb.h: */
93 #include <linux/types.h> /* for __be32 etc */
94 #include <linux/netfilter_ipv4.h>
97 // TODO: move into this file:
98 #include "tcpudp_perhost.h"
101 #include "matrixSsl.h"
107 unsigned max_per_host;
108 unsigned cur_per_host;
112 char *env_var[1]; /* actually bigger */
114 #define G (*(struct globals*)bb_common_bufsiz1)
115 #define verbose (G.verbose )
116 #define max_per_host (G.max_per_host)
117 #define cur_per_host (G.cur_per_host)
118 #define cnum (G.cnum )
119 #define cmax (G.cmax )
120 #define env_cur (G.env_cur )
121 #define env_var (G.env_var )
122 #define INIT_G() do { \
123 setup_common_bufsiz(); \
125 env_cur = &env_var[0]; \
129 /* We have to be careful about leaking memory in repeated setenv's */
130 static void xsetenv_plain(const char *n, const char *v)
132 char *var = xasprintf("%s=%s", n, v);
137 static void xsetenv_proto(const char *proto, const char *n, const char *v)
139 char *var = xasprintf("%s%s=%s", proto, n, v);
144 static void undo_xsetenv(void)
146 char **pp = env_cur = &env_var[0];
149 bb_unsetenv_and_free(var);
154 static void sig_term_handler(int sig)
157 bb_error_msg("got signal %u, exit", sig);
158 kill_myself_with_sig(sig);
161 /* Little bloated, but tries to give accurate info how child exited.
162 * Makes easier to spot segfaulting children etc... */
163 static void print_waitstat(unsigned pid, int wstat)
166 const char *cause = "?exit";
168 if (WIFEXITED(wstat)) {
170 e = WEXITSTATUS(wstat);
171 } else if (WIFSIGNALED(wstat)) {
175 bb_error_msg("end %d %s %d", pid, cause, e);
178 /* Must match getopt32 in main! */
193 OPT_U = (1 << 13), /* from here: sslsvd only */
194 OPT_slash = (1 << 14),
199 static void connection_status(void)
201 /* "only 1 client max" desn't need this */
203 bb_error_msg("status %u/%u", cnum, cmax);
206 static void sig_child_handler(int sig UNUSED_PARAM)
211 while ((pid = wait_any_nohang(&wstat)) > 0) {
213 ipsvd_perhost_remove(pid);
217 print_waitstat(pid, wstat);
223 int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
224 int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
229 const char *instructs;
230 char *msg_per_host = NULL;
231 unsigned len_per_host = len_per_host; /* gcc */
233 struct bb_uidgid_t ugid;
237 char *preset_local_hostname = NULL;
238 char *remote_hostname = remote_hostname; /* for compiler */
239 char *remote_addr = remote_addr; /* for compiler */
240 len_and_sockaddr *lsa;
241 len_and_sockaddr local, remote;
246 unsigned backlog = 20;
251 tcp = (applet_name[0] == 't');
253 /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */
254 opt_complementary = "-3:i--i:ph:vv";
256 opts = getopt32(argv, "+c:+C:i:x:u:l:Eb:+hpt:vU:/:Z:K:",
257 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
258 &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
261 /* "+": stop on first non-option */
262 opts = getopt32(argv, "+c:+C:i:x:u:l:Eb:hpt:v",
263 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
264 &backlog, &str_t, &verbose
267 if (opts & OPT_C) { /* -C n[:message] */
268 max_per_host = bb_strtou(str_C, &str_C, 10);
272 msg_per_host = str_C + 1;
273 len_per_host = strlen(msg_per_host);
276 if (max_per_host > cmax)
279 xget_uidgid(&ugid, user);
282 if (opts & OPT_U) ssluser = optarg;
283 if (opts & OPT_slash) root = optarg;
284 if (opts & OPT_Z) cert = optarg;
285 if (opts & OPT_K) key = optarg;
288 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
289 argv[0] = (char*)"0.0.0.0";
291 /* Per-IP flood protection is not thought-out for UDP */
295 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
300 if ((getuid() == 0) && !(opts & OPT_u)) {
301 xfunc_exitcode = 100;
302 bb_error_msg_and_die(bb_msg_you_must_be_root);
305 if (!uidgid_get(&sslugid, ssluser, 1)) {
307 bb_perror_msg_and_die("can't get user/group: %s", ssluser);
309 bb_error_msg_and_die("unknown user/group %s", ssluser);
311 if (!cert) cert = "./cert.pem";
312 if (!key) key = cert;
313 if (matrixSslOpen() < 0)
314 fatal("can't initialize ssl");
315 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
317 fatal("can't read cert, key, or ca file");
318 fatal("can't read cert or key file");
320 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
321 fatal("can't create ssl session");
325 signal(SIGCHLD, sig_child_handler);
326 bb_signals(BB_FATAL_SIGS, sig_term_handler);
327 signal(SIGPIPE, SIG_IGN);
330 ipsvd_perhost_init(cmax);
332 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
333 lsa = xhost2sockaddr(argv[0], local_port);
336 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
337 setsockopt_reuseaddr(sock);
338 sa_len = lsa->len; /* I presume sockaddr len stays the same */
339 xbind(sock, &lsa->u.sa, sa_len);
341 xlisten(sock, backlog);
342 close_on_exec_on(sock);
343 } else { /* udp: needed for recv_from_to to work: */
344 socket_want_pktinfo(sock);
346 /* ndelay_off(sock); - it is the default I think? */
350 /* drop permissions */
357 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
359 bb_error_msg("listening on %s, starting, uid %u, gid %u", addr,
360 (unsigned)ugid.uid, (unsigned)ugid.gid);
362 bb_error_msg("listening on %s, starting", addr);
366 /* Main accept() loop */
373 /* It's important to close(0) _before_ wait loop:
374 * fd#0 can be a shared connection fd.
375 * If kept open by us, peer can't detect PROG closing it.
378 wait_for_any_sig(); /* expecting SIGCHLD */
381 sig_unblock(SIGCHLD);
382 local.len = remote.len = sa_len;
384 /* Accept a connection to fd #0 */
385 conn = accept(sock, &remote.u.sa, &remote.len);
387 /* In case recv_from_to won't be able to recover local addr.
388 * Also sets port - recv_from_to is unable to do it. */
390 conn = recv_from_to(sock, NULL, 0, MSG_PEEK,
391 &remote.u.sa, &local.u.sa, sa_len);
396 bb_perror_msg(tcp ? "accept" : "recv");
399 xmove_fd(tcp ? conn : sock, 0);
402 /* Drop connection immediately if cur_per_host > max_per_host
403 * (minimizing load under SYN flood) */
404 remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
405 cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
406 if (cur_per_host > max_per_host) {
407 /* ipsvd_perhost_add detected that max is exceeded
408 * (and did not store ip in connection table) */
411 /* don't block or test for errors */
412 send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
416 /* NB: remote_addr is not leaked, it is stored in conn table */
420 /* Voodoo magic: making udp sockets each receive its own
421 * packets is not trivial, and I still not sure
422 * I do it 100% right.
423 * 1) we have to do it before fork()
424 * 2) order is important - is it right now? */
426 /* Open new non-connected UDP socket for further clients... */
427 sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
428 setsockopt_reuseaddr(sock);
429 /* Make plain write/send work for old socket by supplying default
430 * destination address. This also restricts incoming packets
431 * to ones coming from this remote IP. */
432 xconnect(0, &remote.u.sa, sa_len);
433 /* hole? at this point we have no wildcard udp socket...
434 * can this cause clients to get "port unreachable" icmp?
435 * Yup, time window is very small, but it exists (is it?) */
436 /* ..."open new socket", continued */
437 xbind(sock, &lsa->u.sa, sa_len);
438 socket_want_pktinfo(sock);
441 * we cannot replace fd #0 - we will lose pending packet
442 * which is already buffered for us! And we cannot use fd #1
443 * instead - it will "intercept" all following packets, but child
444 * does not expect data coming *from fd #1*! */
446 /* Make it so that local addr is fixed to localp->u.sa
447 * and we don't accidentally accept packets to other local IPs. */
448 /* NB: we possibly bind to the _very_ same_ address & port as the one
449 * already bound in parent! This seems to work in Linux.
450 * (otherwise we can move socket to fd #0 only if bind succeeds) */
452 set_nport(&localp->u.sa, htons(local_port));
453 xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
454 setsockopt_reuseaddr(0); /* crucial */
455 xbind(0, &localp->u.sa, localp->len);
461 bb_perror_msg("vfork");
472 /* clean up changes done by vforked child */
477 /* Child: prepare env, log, and exec prog */
479 { /* vfork alert! every xmalloc in this block should be freed! */
480 char *local_hostname = local_hostname; /* for compiler */
481 char *local_addr = NULL;
482 char *free_me0 = NULL;
483 char *free_me1 = NULL;
484 char *free_me2 = NULL;
486 if (verbose || !(opts & OPT_E)) {
487 if (!max_per_host) /* remote_addr is not yet known */
488 free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
490 free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
491 if (!remote_hostname) {
492 bb_error_msg("can't look up hostname for %s", remote_addr);
493 remote_hostname = remote_addr;
496 /* Find out local IP peer connected to.
497 * Errors ignored (I'm not paranoid enough to imagine kernel
498 * which doesn't know local IP). */
500 getsockname(0, &local.u.sa, &local.len);
501 /* else: for UDP it is done earlier by parent */
502 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
504 local_hostname = preset_local_hostname;
505 if (!local_hostname) {
506 free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
508 bb_error_msg_and_die("can't look up hostname for %s", local_addr);
510 /* else: local_hostname is not NULL, but is NOT malloced! */
516 bb_error_msg("concurrency %s %u/%u",
518 cur_per_host, max_per_host);
520 bb_error_msg((opts & OPT_h)
521 ? "start %u %s-%s (%s-%s)"
524 local_addr, remote_addr,
525 local_hostname, remote_hostname);
528 if (!(opts & OPT_E)) {
529 /* setup ucspi env */
530 const char *proto = tcp ? "TCP" : "UDP";
532 #ifdef SO_ORIGINAL_DST
533 /* Extract "original" destination addr:port
534 * from Linux firewall. Useful when you redirect
535 * an outbond connection to local handler, and it needs
536 * to know where it originally tried to connect */
537 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
538 char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
539 xsetenv_plain("TCPORIGDSTADDR", addr);
543 xsetenv_plain("PROTO", proto);
544 xsetenv_proto(proto, "LOCALADDR", local_addr);
545 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
547 xsetenv_proto(proto, "LOCALHOST", local_hostname);
548 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
550 //compat? xsetenv_proto(proto, "REMOTEINFO", "");
552 if (cur_per_host > 0) /* can not be true for udp */
553 xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
563 signal(SIGPIPE, SIG_DFL); /* this one was SIG_IGNed */
564 /* Non-ignored signals revert to SIG_DFL on exec anyway */
565 /*signal(SIGCHLD, SIG_DFL);*/
566 sig_unblock(SIGCHLD);
569 strcpy(id, utoa(pid));
571 bb_perror_msg_and_die("can't execute '%s'", argv[0]);
573 BB_EXECVP_or_die(argv);
578 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
579 [-i dir|-x cdb] [ -t sec] host port prog
581 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
582 and listens on the socket for incoming connections.
584 On each incoming connection, tcpsvd conditionally runs a program,
585 with standard input reading from the socket, and standard output
586 writing to the socket, to handle this connection. tcpsvd keeps
587 listening on the socket for new connections, and can handle
588 multiple connections simultaneously.
590 tcpsvd optionally checks for special instructions depending
591 on the IP address or hostname of the client that initiated
592 the connection, see ipsvd-instruct(5).
595 host either is a hostname, or a dotted-decimal IP address,
596 or 0. If host is 0, tcpsvd accepts connections to any local
598 * busybox accepts IPv6 addresses and host:port pairs too
599 In this case second parameter is ignored
601 tcpsvd accepts connections to host:port. port may be a name
602 from /etc/services or a number.
604 prog consists of one or more arguments. For each connection,
605 tcpsvd normally runs prog, with file descriptor 0 reading from
606 the network, and file descriptor 1 writing to the network.
607 By default it also sets up TCP-related environment variables,
610 read instructions for handling new connections from the instructions
611 directory dir. See ipsvd-instruct(5) for details.
612 * ignored by busyboxed version
614 read instructions for handling new connections from the constant database
615 cdb. The constant database normally is created from an instructions
616 directory by running ipsvd-cdb(8).
617 * ignored by busyboxed version
619 timeout. This option only takes effect if the -i option is given.
620 While checking the instructions directory, check the time of last access
621 of the file that matches the clients address or hostname if any, discard
622 and remove the file if it wasn't accessed within the last sec seconds;
623 tcpsvd does not discard or remove a file if the user's write permission
624 is not set, for those files the timeout is disabled. Default is 0,
625 which means that the timeout is disabled.
626 * ignored by busyboxed version
628 local hostname. Do not look up the local hostname in DNS, but use name
629 as hostname. This option must be set if tcpsvd listens on port 53
632 drop permissions. Switch user ID to user's UID, and group ID to user's
633 primary GID after creating and binding to the socket. If user is followed
634 by a colon and a group name, the group ID is switched to the GID of group
635 instead. All supplementary groups are removed.
637 concurrency. Handle up to n connections simultaneously. Default is 30.
638 If there are n connections active, tcpsvd defers acceptance of a new
639 connection until an active connection is closed.
641 per host concurrency. Allow only up to n connections from the same IP
642 address simultaneously. If there are n active connections from one IP
643 address, new incoming connections from this IP address are closed
644 immediately. If n is followed by :msg, the message msg is written
645 to the client if possible, before closing the connection. By default
646 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
648 For each accepted connection, the current per host concurrency is
649 available through the environment variable TCPCONCURRENCY. n and msg
650 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
651 By default tcpsvd doesn't keep track of connections.
653 Look up the client's hostname in DNS.
655 paranoid. After looking up the client's hostname in DNS, look up the IP
656 addresses in DNS for that hostname, and forget about the hostname
657 if none of the addresses match the client's IP address. You should
658 set this option if you use hostname based instructions. The -p option
659 implies the -h option.
660 * ignored by busyboxed version
662 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
663 is silently limited. Default is 20.
665 no special environment. Do not set up TCP-related environment variables.
667 verbose. Print verbose messsages to standard output.
669 more verbose. Print more verbose messages to standard output.
670 * no difference between -v and -vv in busyboxed version