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 #include <linux/netfilter_ipv4.h> /* wants <limits.h> */
36 // TODO: move into this file:
37 #include "tcpudp_perhost.h"
40 #include "matrixSsl.h"
46 unsigned max_per_host;
47 unsigned cur_per_host;
51 char *env_var[1]; /* actually bigger */
53 #define G (*(struct globals*)&bb_common_bufsiz1)
54 #define verbose (G.verbose )
55 #define max_per_host (G.max_per_host)
56 #define cur_per_host (G.cur_per_host)
57 #define cnum (G.cnum )
58 #define cmax (G.cmax )
59 #define env_cur (G.env_cur )
60 #define env_var (G.env_var )
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 ATTRIBUTE_UNUSED)
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 ATTRIBUTE_UNUSED, 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 if (!get_uidgid(&ugid, user, 1))
220 bb_error_msg_and_die("unknown user/group: %s", user);
223 if (option_mask32 & OPT_U) ssluser = optarg;
224 if (option_mask32 & OPT_slash) root = optarg;
225 if (option_mask32 & OPT_Z) cert = optarg;
226 if (option_mask32 & OPT_K) key = optarg;
229 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
230 argv[0] = (char*)"0.0.0.0";
232 /* Per-IP flood protection is not thought-out for UDP */
236 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
241 if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
242 xfunc_exitcode = 100;
243 bb_error_msg_and_die("-U ssluser must be set when running as root");
245 if (option_mask32 & OPT_u)
246 if (!uidgid_get(&sslugid, ssluser, 1)) {
248 bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser);
250 bb_error_msg_and_die("unknown user/group '%s'", ssluser);
252 if (!cert) cert = "./cert.pem";
253 if (!key) key = cert;
254 if (matrixSslOpen() < 0)
255 fatal("cannot initialize ssl");
256 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
258 fatal("cannot read cert, key, or ca file");
259 fatal("cannot read cert or key file");
261 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
262 fatal("cannot create ssl session");
266 signal(SIGCHLD, sig_child_handler);
267 bb_signals(BB_FATAL_SIGS, sig_term_handler);
268 signal(SIGPIPE, SIG_IGN);
271 ipsvd_perhost_init(cmax);
273 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
274 lsa = xhost2sockaddr(argv[0], local_port);
277 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
278 setsockopt_reuseaddr(sock);
279 sa_len = lsa->len; /* I presume sockaddr len stays the same */
280 xbind(sock, &lsa->u.sa, sa_len);
282 xlisten(sock, backlog);
283 else /* udp: needed for recv_from_to to work: */
284 socket_want_pktinfo(sock);
285 /* ndelay_off(sock); - it is the default I think? */
288 if (option_mask32 & OPT_u) {
289 /* drop permissions */
296 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
297 bb_error_msg("listening on %s, starting", addr);
300 if (option_mask32 & OPT_u)
301 printf(", uid %u, gid %u",
302 (unsigned)ugid.uid, (unsigned)ugid.gid);
306 /* Main accept() loop */
312 wait_for_any_sig(); /* expecting SIGCHLD */
314 /* Accept a connection to fd #0 */
318 sig_unblock(SIGCHLD);
319 local.len = remote.len = sa_len;
321 conn = accept(sock, &remote.u.sa, &remote.len);
323 /* In case recv_from_to won't be able to recover local addr.
324 * Also sets port - recv_from_to is unable to do it. */
326 conn = recv_from_to(sock, NULL, 0, MSG_PEEK,
327 &remote.u.sa, &local.u.sa, sa_len);
332 bb_perror_msg(tcp ? "accept" : "recv");
335 xmove_fd(tcp ? conn : sock, 0);
338 /* Drop connection immediately if cur_per_host > max_per_host
339 * (minimizing load under SYN flood) */
340 remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
341 cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
342 if (cur_per_host > max_per_host) {
343 /* ipsvd_perhost_add detected that max is exceeded
344 * (and did not store ip in connection table) */
347 /* don't block or test for errors */
348 send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
352 /* NB: remote_addr is not leaked, it is stored in conn table */
356 /* Voodoo magic: making udp sockets each receive its own
357 * packets is not trivial, and I still not sure
358 * I do it 100% right.
359 * 1) we have to do it before fork()
360 * 2) order is important - is it right now? */
362 /* Open new non-connected UDP socket for further clients... */
363 sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
364 setsockopt_reuseaddr(sock);
365 /* Make plain write/send work for old socket by supplying default
366 * destination address. This also restricts incoming packets
367 * to ones coming from this remote IP. */
368 xconnect(0, &remote.u.sa, sa_len);
369 /* hole? at this point we have no wildcard udp socket...
370 * can this cause clients to get "port unreachable" icmp?
371 * Yup, time window is very small, but it exists (is it?) */
372 /* ..."open new socket", continued */
373 xbind(sock, &lsa->u.sa, sa_len);
374 socket_want_pktinfo(sock);
377 * we cannot replace fd #0 - we will lose pending packet
378 * which is already buffered for us! And we cannot use fd #1
379 * instead - it will "intercept" all following packets, but child
380 * does not expect data coming *from fd #1*! */
382 /* Make it so that local addr is fixed to localp->u.sa
383 * and we don't accidentally accept packets to other local IPs. */
384 /* NB: we possibly bind to the _very_ same_ address & port as the one
385 * already bound in parent! This seems to work in Linux.
386 * (otherwise we can move socket to fd #0 only if bind succeeds) */
388 set_nport(localp, htons(local_port));
389 xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
390 setsockopt_reuseaddr(0); /* crucial */
391 xbind(0, &localp->u.sa, localp->len);
397 bb_perror_msg("vfork");
408 /* clean up changes done by vforked child */
413 /* Child: prepare env, log, and exec prog */
415 /* Closing tcp listening socket */
419 { /* vfork alert! every xmalloc in this block should be freed! */
420 char *local_hostname = local_hostname; /* for compiler */
421 char *local_addr = NULL;
422 char *free_me0 = NULL;
423 char *free_me1 = NULL;
424 char *free_me2 = NULL;
426 if (verbose || !(option_mask32 & OPT_E)) {
427 if (!max_per_host) /* remote_addr is not yet known */
428 free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
429 if (option_mask32 & OPT_h) {
430 free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
431 if (!remote_hostname) {
432 bb_error_msg("cannot look up hostname for %s", remote_addr);
433 remote_hostname = remote_addr;
436 /* Find out local IP peer connected to.
437 * Errors ignored (I'm not paranoid enough to imagine kernel
438 * which doesn't know local IP). */
440 getsockname(0, &local.u.sa, &local.len);
441 /* else: for UDP it is done earlier by parent */
442 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
443 if (option_mask32 & OPT_h) {
444 local_hostname = preset_local_hostname;
445 if (!local_hostname) {
446 free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
448 bb_error_msg_and_die("cannot look up hostname for %s", local_addr);
450 /* else: local_hostname is not NULL, but is NOT malloced! */
456 bb_error_msg("concurrency %s %u/%u",
458 cur_per_host, max_per_host);
460 bb_error_msg((option_mask32 & OPT_h)
461 ? "start %u %s-%s (%s-%s)"
464 local_addr, remote_addr,
465 local_hostname, remote_hostname);
468 if (!(option_mask32 & OPT_E)) {
469 /* setup ucspi env */
470 const char *proto = tcp ? "TCP" : "UDP";
472 /* Extract "original" destination addr:port
473 * from Linux firewall. Useful when you redirect
474 * an outbond connection to local handler, and it needs
475 * to know where it originally tried to connect */
476 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
477 char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
478 xsetenv_plain("TCPORIGDSTADDR", addr);
481 xsetenv_plain("PROTO", proto);
482 xsetenv_proto(proto, "LOCALADDR", local_addr);
483 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
484 if (option_mask32 & OPT_h) {
485 xsetenv_proto(proto, "LOCALHOST", local_hostname);
486 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
488 //compat? xsetenv_proto(proto, "REMOTEINFO", "");
490 if (cur_per_host > 0) /* can not be true for udp */
491 xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
501 signal(SIGTERM, SIG_DFL);
502 signal(SIGPIPE, SIG_DFL);
503 signal(SIGCHLD, SIG_DFL);
504 sig_unblock(SIGCHLD);
507 strcpy(id, utoa(pid));
510 BB_EXECVP(argv[0], argv);
512 bb_perror_msg_and_die("exec '%s'", argv[0]);
516 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
517 [-i dir|-x cdb] [ -t sec] host port prog
519 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
520 and listens on the socket for incoming connections.
522 On each incoming connection, tcpsvd conditionally runs a program,
523 with standard input reading from the socket, and standard output
524 writing to the socket, to handle this connection. tcpsvd keeps
525 listening on the socket for new connections, and can handle
526 multiple connections simultaneously.
528 tcpsvd optionally checks for special instructions depending
529 on the IP address or hostname of the client that initiated
530 the connection, see ipsvd-instruct(5).
533 host either is a hostname, or a dotted-decimal IP address,
534 or 0. If host is 0, tcpsvd accepts connections to any local
536 * busybox accepts IPv6 addresses and host:port pairs too
537 In this case second parameter is ignored
539 tcpsvd accepts connections to host:port. port may be a name
540 from /etc/services or a number.
542 prog consists of one or more arguments. For each connection,
543 tcpsvd normally runs prog, with file descriptor 0 reading from
544 the network, and file descriptor 1 writing to the network.
545 By default it also sets up TCP-related environment variables,
548 read instructions for handling new connections from the instructions
549 directory dir. See ipsvd-instruct(5) for details.
550 * ignored by busyboxed version
552 read instructions for handling new connections from the constant database
553 cdb. The constant database normally is created from an instructions
554 directory by running ipsvd-cdb(8).
555 * ignored by busyboxed version
557 timeout. This option only takes effect if the -i option is given.
558 While checking the instructions directory, check the time of last access
559 of the file that matches the clients address or hostname if any, discard
560 and remove the file if it wasn't accessed within the last sec seconds;
561 tcpsvd does not discard or remove a file if the user's write permission
562 is not set, for those files the timeout is disabled. Default is 0,
563 which means that the timeout is disabled.
564 * ignored by busyboxed version
566 local hostname. Do not look up the local hostname in DNS, but use name
567 as hostname. This option must be set if tcpsvd listens on port 53
570 drop permissions. Switch user ID to user's UID, and group ID to user's
571 primary GID after creating and binding to the socket. If user is followed
572 by a colon and a group name, the group ID is switched to the GID of group
573 instead. All supplementary groups are removed.
575 concurrency. Handle up to n connections simultaneously. Default is 30.
576 If there are n connections active, tcpsvd defers acceptance of a new
577 connection until an active connection is closed.
579 per host concurrency. Allow only up to n connections from the same IP
580 address simultaneously. If there are n active connections from one IP
581 address, new incoming connections from this IP address are closed
582 immediately. If n is followed by :msg, the message msg is written
583 to the client if possible, before closing the connection. By default
584 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
586 For each accepted connection, the current per host concurrency is
587 available through the environment variable TCPCONCURRENCY. n and msg
588 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
589 By default tcpsvd doesn't keep track of connections.
591 Look up the client's hostname in DNS.
593 paranoid. After looking up the client's hostname in DNS, look up the IP
594 addresses in DNS for that hostname, and forget about the hostname
595 if none of the addresses match the client's IP address. You should
596 set this option if you use hostname based instructions. The -p option
597 implies the -h option.
598 * ignored by busyboxed version
600 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
601 is silently limited. Default is 20.
603 no special environment. Do not set up TCP-related environment variables.
605 verbose. Print verbose messsages to standard output.
607 more verbose. Print more verbose messages to standard output.
608 * no difference between -v and -vv in busyboxed version