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 tarball for details.
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.
33 /* Wants <limits.h> etc, thus included after libbb.h: */
34 #include <linux/types.h> /* for __be32 etc */
35 #include <linux/netfilter_ipv4.h>
37 // TODO: move into this file:
38 #include "tcpudp_perhost.h"
41 #include "matrixSsl.h"
47 unsigned max_per_host;
48 unsigned cur_per_host;
52 char *env_var[1]; /* actually bigger */
54 #define G (*(struct globals*)&bb_common_bufsiz1)
55 #define verbose (G.verbose )
56 #define max_per_host (G.max_per_host)
57 #define cur_per_host (G.cur_per_host)
58 #define cnum (G.cnum )
59 #define cmax (G.cmax )
60 #define env_cur (G.env_cur )
61 #define env_var (G.env_var )
62 #define INIT_G() do { \
64 env_cur = &env_var[0]; \
68 /* We have to be careful about leaking memory in repeated setenv's */
69 static void xsetenv_plain(const char *n, const char *v)
71 char *var = xasprintf("%s=%s", n, v);
76 static void xsetenv_proto(const char *proto, const char *n, const char *v)
78 char *var = xasprintf("%s%s=%s", proto, n, v);
83 static void undo_xsetenv(void)
85 char **pp = env_cur = &env_var[0];
88 *strchrnul(var, '=') = '\0';
95 static void sig_term_handler(int sig)
98 bb_error_msg("got signal %u, exit", sig);
99 kill_myself_with_sig(sig);
102 /* Little bloated, but tries to give accurate info how child exited.
103 * Makes easier to spot segfaulting children etc... */
104 static void print_waitstat(unsigned pid, int wstat)
107 const char *cause = "?exit";
109 if (WIFEXITED(wstat)) {
111 e = WEXITSTATUS(wstat);
112 } else if (WIFSIGNALED(wstat)) {
116 bb_error_msg("end %d %s %d", pid, cause, e);
119 /* Must match getopt32 in main! */
134 OPT_U = (1 << 13), /* from here: sslsvd only */
135 OPT_slash = (1 << 14),
140 static void connection_status(void)
142 /* "only 1 client max" desn't need this */
144 bb_error_msg("status %u/%u", cnum, cmax);
147 static void sig_child_handler(int sig UNUSED_PARAM)
152 while ((pid = wait_any_nohang(&wstat)) > 0) {
154 ipsvd_perhost_remove(pid);
158 print_waitstat(pid, wstat);
164 int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
165 int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
170 const char *instructs;
171 char *msg_per_host = NULL;
172 unsigned len_per_host = len_per_host; /* gcc */
174 struct bb_uidgid_t ugid;
178 char *preset_local_hostname = NULL;
179 char *remote_hostname = remote_hostname; /* for compiler */
180 char *remote_addr = remote_addr; /* for compiler */
181 len_and_sockaddr *lsa;
182 len_and_sockaddr local, remote;
187 unsigned backlog = 20;
191 tcp = (applet_name[0] == 't');
193 /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */
194 opt_complementary = "-3:i--i:ph:vv:b+:c+";
196 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
197 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
198 &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
201 /* "+": stop on first non-option */
202 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
203 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
204 &backlog, &str_t, &verbose
207 if (option_mask32 & OPT_C) { /* -C n[:message] */
208 max_per_host = bb_strtou(str_C, &str_C, 10);
212 msg_per_host = str_C + 1;
213 len_per_host = strlen(msg_per_host);
216 if (max_per_host > cmax)
218 if (option_mask32 & OPT_u) {
219 xget_uidgid(&ugid, user);
222 if (option_mask32 & OPT_U) ssluser = optarg;
223 if (option_mask32 & OPT_slash) root = optarg;
224 if (option_mask32 & OPT_Z) cert = optarg;
225 if (option_mask32 & OPT_K) key = optarg;
228 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
229 argv[0] = (char*)"0.0.0.0";
231 /* Per-IP flood protection is not thought-out for UDP */
235 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
240 if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
241 xfunc_exitcode = 100;
242 bb_error_msg_and_die("-U ssluser must be set when running as root");
244 if (option_mask32 & OPT_u)
245 if (!uidgid_get(&sslugid, ssluser, 1)) {
247 bb_perror_msg_and_die("can't get user/group: %s", ssluser);
249 bb_error_msg_and_die("unknown user/group %s", ssluser);
251 if (!cert) cert = "./cert.pem";
252 if (!key) key = cert;
253 if (matrixSslOpen() < 0)
254 fatal("cannot initialize ssl");
255 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
257 fatal("cannot read cert, key, or ca file");
258 fatal("cannot read cert or key file");
260 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
261 fatal("cannot create ssl session");
265 signal(SIGCHLD, sig_child_handler);
266 bb_signals(BB_FATAL_SIGS, sig_term_handler);
267 signal(SIGPIPE, SIG_IGN);
270 ipsvd_perhost_init(cmax);
272 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
273 lsa = xhost2sockaddr(argv[0], local_port);
276 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
277 setsockopt_reuseaddr(sock);
278 sa_len = lsa->len; /* I presume sockaddr len stays the same */
279 xbind(sock, &lsa->u.sa, sa_len);
281 xlisten(sock, backlog);
282 else /* udp: needed for recv_from_to to work: */
283 socket_want_pktinfo(sock);
284 /* ndelay_off(sock); - it is the default I think? */
287 if (option_mask32 & OPT_u) {
288 /* drop permissions */
295 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
296 bb_error_msg("listening on %s, starting", addr);
299 if (option_mask32 & OPT_u)
300 printf(", uid %u, gid %u",
301 (unsigned)ugid.uid, (unsigned)ugid.gid);
305 /* Main accept() loop */
311 wait_for_any_sig(); /* expecting SIGCHLD */
313 /* Accept a connection to fd #0 */
317 sig_unblock(SIGCHLD);
318 local.len = remote.len = sa_len;
320 conn = accept(sock, &remote.u.sa, &remote.len);
322 /* In case recv_from_to won't be able to recover local addr.
323 * Also sets port - recv_from_to is unable to do it. */
325 conn = recv_from_to(sock, NULL, 0, MSG_PEEK,
326 &remote.u.sa, &local.u.sa, sa_len);
331 bb_perror_msg(tcp ? "accept" : "recv");
334 xmove_fd(tcp ? conn : sock, 0);
337 /* Drop connection immediately if cur_per_host > max_per_host
338 * (minimizing load under SYN flood) */
339 remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
340 cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
341 if (cur_per_host > max_per_host) {
342 /* ipsvd_perhost_add detected that max is exceeded
343 * (and did not store ip in connection table) */
346 /* don't block or test for errors */
347 send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
351 /* NB: remote_addr is not leaked, it is stored in conn table */
355 /* Voodoo magic: making udp sockets each receive its own
356 * packets is not trivial, and I still not sure
357 * I do it 100% right.
358 * 1) we have to do it before fork()
359 * 2) order is important - is it right now? */
361 /* Open new non-connected UDP socket for further clients... */
362 sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
363 setsockopt_reuseaddr(sock);
364 /* Make plain write/send work for old socket by supplying default
365 * destination address. This also restricts incoming packets
366 * to ones coming from this remote IP. */
367 xconnect(0, &remote.u.sa, sa_len);
368 /* hole? at this point we have no wildcard udp socket...
369 * can this cause clients to get "port unreachable" icmp?
370 * Yup, time window is very small, but it exists (is it?) */
371 /* ..."open new socket", continued */
372 xbind(sock, &lsa->u.sa, sa_len);
373 socket_want_pktinfo(sock);
376 * we cannot replace fd #0 - we will lose pending packet
377 * which is already buffered for us! And we cannot use fd #1
378 * instead - it will "intercept" all following packets, but child
379 * does not expect data coming *from fd #1*! */
381 /* Make it so that local addr is fixed to localp->u.sa
382 * and we don't accidentally accept packets to other local IPs. */
383 /* NB: we possibly bind to the _very_ same_ address & port as the one
384 * already bound in parent! This seems to work in Linux.
385 * (otherwise we can move socket to fd #0 only if bind succeeds) */
387 set_nport(localp, htons(local_port));
388 xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
389 setsockopt_reuseaddr(0); /* crucial */
390 xbind(0, &localp->u.sa, localp->len);
396 bb_perror_msg("vfork");
407 /* clean up changes done by vforked child */
412 /* Child: prepare env, log, and exec prog */
414 /* Closing tcp listening socket */
418 { /* vfork alert! every xmalloc in this block should be freed! */
419 char *local_hostname = local_hostname; /* for compiler */
420 char *local_addr = NULL;
421 char *free_me0 = NULL;
422 char *free_me1 = NULL;
423 char *free_me2 = NULL;
425 if (verbose || !(option_mask32 & OPT_E)) {
426 if (!max_per_host) /* remote_addr is not yet known */
427 free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
428 if (option_mask32 & OPT_h) {
429 free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
430 if (!remote_hostname) {
431 bb_error_msg("cannot look up hostname for %s", remote_addr);
432 remote_hostname = remote_addr;
435 /* Find out local IP peer connected to.
436 * Errors ignored (I'm not paranoid enough to imagine kernel
437 * which doesn't know local IP). */
439 getsockname(0, &local.u.sa, &local.len);
440 /* else: for UDP it is done earlier by parent */
441 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
442 if (option_mask32 & OPT_h) {
443 local_hostname = preset_local_hostname;
444 if (!local_hostname) {
445 free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
447 bb_error_msg_and_die("cannot look up hostname for %s", local_addr);
449 /* else: local_hostname is not NULL, but is NOT malloced! */
455 bb_error_msg("concurrency %s %u/%u",
457 cur_per_host, max_per_host);
459 bb_error_msg((option_mask32 & OPT_h)
460 ? "start %u %s-%s (%s-%s)"
463 local_addr, remote_addr,
464 local_hostname, remote_hostname);
467 if (!(option_mask32 & OPT_E)) {
468 /* setup ucspi env */
469 const char *proto = tcp ? "TCP" : "UDP";
471 /* Extract "original" destination addr:port
472 * from Linux firewall. Useful when you redirect
473 * an outbond connection to local handler, and it needs
474 * to know where it originally tried to connect */
475 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
476 char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
477 xsetenv_plain("TCPORIGDSTADDR", addr);
480 xsetenv_plain("PROTO", proto);
481 xsetenv_proto(proto, "LOCALADDR", local_addr);
482 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
483 if (option_mask32 & OPT_h) {
484 xsetenv_proto(proto, "LOCALHOST", local_hostname);
485 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
487 //compat? xsetenv_proto(proto, "REMOTEINFO", "");
489 if (cur_per_host > 0) /* can not be true for udp */
490 xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
500 signal(SIGTERM, SIG_DFL);
501 signal(SIGPIPE, SIG_DFL);
502 signal(SIGCHLD, SIG_DFL);
503 sig_unblock(SIGCHLD);
506 strcpy(id, utoa(pid));
509 BB_EXECVP(argv[0], argv);
511 bb_perror_msg_and_die("exec '%s'", argv[0]);
515 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
516 [-i dir|-x cdb] [ -t sec] host port prog
518 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
519 and listens on the socket for incoming connections.
521 On each incoming connection, tcpsvd conditionally runs a program,
522 with standard input reading from the socket, and standard output
523 writing to the socket, to handle this connection. tcpsvd keeps
524 listening on the socket for new connections, and can handle
525 multiple connections simultaneously.
527 tcpsvd optionally checks for special instructions depending
528 on the IP address or hostname of the client that initiated
529 the connection, see ipsvd-instruct(5).
532 host either is a hostname, or a dotted-decimal IP address,
533 or 0. If host is 0, tcpsvd accepts connections to any local
535 * busybox accepts IPv6 addresses and host:port pairs too
536 In this case second parameter is ignored
538 tcpsvd accepts connections to host:port. port may be a name
539 from /etc/services or a number.
541 prog consists of one or more arguments. For each connection,
542 tcpsvd normally runs prog, with file descriptor 0 reading from
543 the network, and file descriptor 1 writing to the network.
544 By default it also sets up TCP-related environment variables,
547 read instructions for handling new connections from the instructions
548 directory dir. See ipsvd-instruct(5) for details.
549 * ignored by busyboxed version
551 read instructions for handling new connections from the constant database
552 cdb. The constant database normally is created from an instructions
553 directory by running ipsvd-cdb(8).
554 * ignored by busyboxed version
556 timeout. This option only takes effect if the -i option is given.
557 While checking the instructions directory, check the time of last access
558 of the file that matches the clients address or hostname if any, discard
559 and remove the file if it wasn't accessed within the last sec seconds;
560 tcpsvd does not discard or remove a file if the user's write permission
561 is not set, for those files the timeout is disabled. Default is 0,
562 which means that the timeout is disabled.
563 * ignored by busyboxed version
565 local hostname. Do not look up the local hostname in DNS, but use name
566 as hostname. This option must be set if tcpsvd listens on port 53
569 drop permissions. Switch user ID to user's UID, and group ID to user's
570 primary GID after creating and binding to the socket. If user is followed
571 by a colon and a group name, the group ID is switched to the GID of group
572 instead. All supplementary groups are removed.
574 concurrency. Handle up to n connections simultaneously. Default is 30.
575 If there are n connections active, tcpsvd defers acceptance of a new
576 connection until an active connection is closed.
578 per host concurrency. Allow only up to n connections from the same IP
579 address simultaneously. If there are n active connections from one IP
580 address, new incoming connections from this IP address are closed
581 immediately. If n is followed by :msg, the message msg is written
582 to the client if possible, before closing the connection. By default
583 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
585 For each accepted connection, the current per host concurrency is
586 available through the environment variable TCPCONCURRENCY. n and msg
587 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
588 By default tcpsvd doesn't keep track of connections.
590 Look up the client's hostname in DNS.
592 paranoid. After looking up the client's hostname in DNS, look up the IP
593 addresses in DNS for that hostname, and forget about the hostname
594 if none of the addresses match the client's IP address. You should
595 set this option if you use hostname based instructions. The -p option
596 implies the -h option.
597 * ignored by busyboxed version
599 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
600 is silently limited. Default is 20.
602 no special environment. Do not set up TCP-related environment variables.
604 verbose. Print verbose messsages to standard output.
606 more verbose. Print more verbose messages to standard output.
607 * no difference between -v and -vv in busyboxed version