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 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 #include "ipsvd_perhost.h"
39 #include "matrixSsl.h"
45 unsigned max_per_host;
46 unsigned cur_per_host;
50 char *env_var[1]; /* actually bigger */
52 #define G (*(struct globals*)&bb_common_bufsiz1)
53 #define verbose (G.verbose )
54 #define max_per_host (G.max_per_host)
55 #define cur_per_host (G.cur_per_host)
56 #define cnum (G.cnum )
57 #define cmax (G.cmax )
58 #define env_cur (G.env_cur )
59 #define env_var (G.env_var )
63 env_cur = &env_var[0]; \
67 /* We have to be careful about leaking memory in repeated setenv's */
68 static void xsetenv_plain(const char *n, const char *v)
70 char *var = xasprintf("%s=%s", n, v);
75 static void xsetenv_proto(const char *proto, const char *n, const char *v)
77 char *var = xasprintf("%s%s=%s", proto, n, v);
82 static void undo_xsetenv(void)
84 char **pp = env_cur = &env_var[0];
87 *strchrnul(var, '=') = '\0';
94 static void sig_term_handler(int sig)
97 bb_error_msg("got signal %u, exit", sig);
98 kill_myself_with_sig(sig);
101 /* Little bloated, but tries to give accurate info how child exited.
102 * Makes easier to spot segfaulting children etc... */
103 static void print_waitstat(unsigned pid, int wstat)
106 const char *cause = "?exit";
108 if (WIFEXITED(wstat)) {
110 e = WEXITSTATUS(wstat);
111 } else if (WIFSIGNALED(wstat)) {
115 bb_error_msg("end %d %s %d", pid, cause, e);
118 /* Must match getopt32 in main! */
133 OPT_U = (1 << 13), /* from here: sslsvd only */
134 OPT_slash = (1 << 14),
139 static void connection_status(void)
141 /* "only 1 client max" desn't need this */
143 bb_error_msg("status %u/%u", cnum, cmax);
146 static void sig_child_handler(int sig)
151 while ((pid = wait_any_nohang(&wstat)) > 0) {
153 ipsvd_perhost_remove(pid);
157 print_waitstat(pid, wstat);
163 int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
164 int tcpudpsvd_main(int argc, char **argv)
166 char *str_c, *str_C, *str_b, *str_t;
169 const char *instructs;
170 char *msg_per_host = NULL;
171 unsigned len_per_host = len_per_host; /* gcc */
173 struct bb_uidgid_t ugid;
177 char *preset_local_hostname = NULL;
178 char *remote_hostname = remote_hostname; /* for compiler */
179 char *remote_addr = remote_addr; /* for compiler */
180 len_and_sockaddr *lsa;
181 len_and_sockaddr local, remote;
186 unsigned backlog = 20;
190 tcp = (applet_name[0] == 't');
192 /* 3+ args, -i at most once, -p implies -h, -v is counter */
193 opt_complementary = "-3:i--i:ph:vv";
195 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
196 &str_c, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
197 &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose
200 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
201 &str_c, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
202 &str_b, &str_t, &verbose
205 if (option_mask32 & OPT_c)
206 cmax = xatou_range(str_c, 1, INT_MAX);
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);
222 if (option_mask32 & OPT_b)
223 backlog = xatou(str_b);
225 if (option_mask32 & OPT_U) ssluser = optarg;
226 if (option_mask32 & OPT_slash) root = optarg;
227 if (option_mask32 & OPT_Z) cert = optarg;
228 if (option_mask32 & OPT_K) key = optarg;
231 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
232 argv[0] = (char*)"0.0.0.0";
234 /* Per-IP flood protection is not thought-out for UDP */
238 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
243 if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
244 xfunc_exitcode = 100;
245 bb_error_msg_and_die("-U ssluser must be set when running as root");
247 if (option_mask32 & OPT_u)
248 if (!uidgid_get(&sslugid, ssluser, 1)) {
250 bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser);
252 bb_error_msg_and_die("unknown user/group '%s'", ssluser);
254 if (!cert) cert = "./cert.pem";
255 if (!key) key = cert;
256 if (matrixSslOpen() < 0)
257 fatal("cannot initialize ssl");
258 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
260 fatal("cannot read cert, key, or ca file");
261 fatal("cannot read cert or key file");
263 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
264 fatal("cannot create ssl session");
268 signal(SIGCHLD, sig_child_handler);
269 bb_signals(BB_SIGS_FATAL, sig_term_handler);
270 signal(SIGPIPE, SIG_IGN);
273 ipsvd_perhost_init(cmax);
275 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
276 lsa = xhost2sockaddr(argv[0], local_port);
279 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
280 setsockopt_reuseaddr(sock);
281 sa_len = lsa->len; /* I presume sockaddr len stays the same */
282 xbind(sock, &lsa->u.sa, sa_len);
284 xlisten(sock, backlog);
285 else /* udp: needed for recv_from_to to work: */
286 socket_want_pktinfo(sock);
287 /* ndelay_off(sock); - it is the default I think? */
290 if (option_mask32 & OPT_u) {
291 /* drop permissions */
298 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
299 bb_error_msg("listening on %s, starting", addr);
302 if (option_mask32 & OPT_u)
303 printf(", uid %u, gid %u",
304 (unsigned)ugid.uid, (unsigned)ugid.gid);
308 /* Main accept() loop */
314 wait_for_any_sig(); /* expecting SIGCHLD */
316 /* Accept a connection to fd #0 */
320 sig_unblock(SIGCHLD);
321 local.len = remote.len = sa_len;
323 conn = accept(sock, &remote.u.sa, &remote.len);
325 /* In case recv_from_to won't be able to recover local addr.
326 * Also sets port - recv_from_to is unable to do it. */
328 conn = recv_from_to(sock, NULL, 0, MSG_DONTWAIT | MSG_PEEK,
329 &remote.u.sa, &local.u.sa, sa_len);
334 bb_perror_msg(tcp ? "accept" : "recv");
337 xmove_fd(tcp ? conn : sock, 0);
340 /* Drop connection immediately if cur_per_host > max_per_host
341 * (minimizing load under SYN flood) */
342 remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
343 cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
344 if (cur_per_host > max_per_host) {
345 /* ipsvd_perhost_add detected that max is exceeded
346 * (and did not store ip in connection table) */
349 /* don't block or test for errors */
350 send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
354 /* NB: remote_addr is not leaked, it is stored in conn table */
358 /* Voodoo magic: making udp sockets each receive its own
359 * packets is not trivial, and I still not sure
360 * I do it 100% right.
361 * 1) we have to do it before fork()
362 * 2) order is important - is it right now? */
364 /* Open new non-connected UDP socket for further clients... */
365 sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
366 setsockopt_reuseaddr(sock);
367 /* Make plain write/send work for old socket by supplying default
368 * destination address. This also restricts incoming packets
369 * to ones coming from this remote IP. */
370 xconnect(0, &remote.u.sa, sa_len);
371 /* hole? at this point we have no wildcard udp socket...
372 * can this cause clients to get "port unreachable" icmp?
373 * Yup, time window is very small, but it exists (is it?) */
374 /* ..."open new socket", continued */
375 xbind(sock, &lsa->u.sa, sa_len);
376 socket_want_pktinfo(sock);
379 * we cannot replace fd #0 - we will lose pending packet
380 * which is already buffered for us! And we cannot use fd #1
381 * instead - it will "intercept" all following packets, but child
382 * does not expect data coming *from fd #1*! */
384 /* Make it so that local addr is fixed to localp->u.sa
385 * and we don't accidentally accept packets to other local IPs. */
386 /* NB: we possibly bind to the _very_ same_ address & port as the one
387 * already bound in parent! This seems to work in Linux.
388 * (otherwise we can move socket to fd #0 only if bind succeeds) */
390 set_nport(localp, htons(local_port));
391 xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
392 setsockopt_reuseaddr(0); /* crucial */
393 xbind(0, &localp->u.sa, localp->len);
399 bb_perror_msg("vfork");
410 /* clean up changes done by vforked child */
415 /* Child: prepare env, log, and exec prog */
417 /* Closing tcp listening socket */
421 { /* vfork alert! every xmalloc in this block should be freed! */
422 char *local_hostname = local_hostname; /* for compiler */
423 char *local_addr = NULL;
424 char *free_me0 = NULL;
425 char *free_me1 = NULL;
426 char *free_me2 = NULL;
428 if (verbose || !(option_mask32 & OPT_E)) {
429 if (!max_per_host) /* remote_addr is not yet known */
430 free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
431 if (option_mask32 & OPT_h) {
432 free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
433 if (!remote_hostname) {
434 bb_error_msg("cannot look up hostname for %s", remote_addr);
435 remote_hostname = remote_addr;
438 /* Find out local IP peer connected to.
439 * Errors ignored (I'm not paranoid enough to imagine kernel
440 * which doesn't know local IP). */
442 getsockname(0, &local.u.sa, &local.len);
443 /* else: for UDP it is done earlier by parent */
444 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
445 if (option_mask32 & OPT_h) {
446 local_hostname = preset_local_hostname;
447 if (!local_hostname) {
448 free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
450 bb_error_msg_and_die("cannot look up hostname for %s", local_addr);
452 /* else: local_hostname is not NULL, but is NOT malloced! */
458 bb_error_msg("concurrency %s %u/%u",
460 cur_per_host, max_per_host);
462 bb_error_msg((option_mask32 & OPT_h)
463 ? "start %u %s-%s (%s-%s)"
466 local_addr, remote_addr,
467 local_hostname, remote_hostname);
470 if (!(option_mask32 & OPT_E)) {
471 /* setup ucspi env */
472 const char *proto = tcp ? "TCP" : "UDP";
474 /* Extract "original" destination addr:port
475 * from Linux firewall. Useful when you redirect
476 * an outbond connection to local handler, and it needs
477 * to know where it originally tried to connect */
478 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
479 char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
480 xsetenv_plain("TCPORIGDSTADDR", addr);
483 xsetenv_plain("PROTO", proto);
484 xsetenv_proto(proto, "LOCALADDR", local_addr);
485 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
486 if (option_mask32 & OPT_h) {
487 xsetenv_proto(proto, "LOCALHOST", local_hostname);
488 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
490 //compat? xsetenv_proto(proto, "REMOTEINFO", "");
492 if (cur_per_host > 0) /* can not be true for udp */
493 xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
503 signal(SIGTERM, SIG_DFL);
504 signal(SIGPIPE, SIG_DFL);
505 signal(SIGCHLD, SIG_DFL);
506 sig_unblock(SIGCHLD);
509 strcpy(id, utoa(pid));
512 BB_EXECVP(argv[0], argv);
514 bb_perror_msg_and_die("exec '%s'", argv[0]);
518 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
519 [-i dir|-x cdb] [ -t sec] host port prog
521 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
522 and listens on the socket for incoming connections.
524 On each incoming connection, tcpsvd conditionally runs a program,
525 with standard input reading from the socket, and standard output
526 writing to the socket, to handle this connection. tcpsvd keeps
527 listening on the socket for new connections, and can handle
528 multiple connections simultaneously.
530 tcpsvd optionally checks for special instructions depending
531 on the IP address or hostname of the client that initiated
532 the connection, see ipsvd-instruct(5).
535 host either is a hostname, or a dotted-decimal IP address,
536 or 0. If host is 0, tcpsvd accepts connections to any local
538 * busybox accepts IPv6 addresses and host:port pairs too
539 In this case second parameter is ignored
541 tcpsvd accepts connections to host:port. port may be a name
542 from /etc/services or a number.
544 prog consists of one or more arguments. For each connection,
545 tcpsvd normally runs prog, with file descriptor 0 reading from
546 the network, and file descriptor 1 writing to the network.
547 By default it also sets up TCP-related environment variables,
550 read instructions for handling new connections from the instructions
551 directory dir. See ipsvd-instruct(5) for details.
552 * ignored by busyboxed version
554 read instructions for handling new connections from the constant database
555 cdb. The constant database normally is created from an instructions
556 directory by running ipsvd-cdb(8).
557 * ignored by busyboxed version
559 timeout. This option only takes effect if the -i option is given.
560 While checking the instructions directory, check the time of last access
561 of the file that matches the clients address or hostname if any, discard
562 and remove the file if it wasn't accessed within the last sec seconds;
563 tcpsvd does not discard or remove a file if the user's write permission
564 is not set, for those files the timeout is disabled. Default is 0,
565 which means that the timeout is disabled.
566 * ignored by busyboxed version
568 local hostname. Do not look up the local hostname in DNS, but use name
569 as hostname. This option must be set if tcpsvd listens on port 53
572 drop permissions. Switch user ID to user's UID, and group ID to user's
573 primary GID after creating and binding to the socket. If user is followed
574 by a colon and a group name, the group ID is switched to the GID of group
575 instead. All supplementary groups are removed.
577 concurrency. Handle up to n connections simultaneously. Default is 30.
578 If there are n connections active, tcpsvd defers acceptance of a new
579 connection until an active connection is closed.
581 per host concurrency. Allow only up to n connections from the same IP
582 address simultaneously. If there are n active connections from one IP
583 address, new incoming connections from this IP address are closed
584 immediately. If n is followed by :msg, the message msg is written
585 to the client if possible, before closing the connection. By default
586 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
588 For each accepted connection, the current per host concurrency is
589 available through the environment variable TCPCONCURRENCY. n and msg
590 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
591 By default tcpsvd doesn't keep track of connections.
593 Look up the client's hostname in DNS.
595 paranoid. After looking up the client's hostname in DNS, look up the IP
596 addresses in DNS for that hostname, and forget about the hostname
597 if none of the addresses match the client's IP address. You should
598 set this option if you use hostname based instructions. The -p option
599 implies the -h option.
600 * ignored by busyboxed version
602 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
603 is silently limited. Default is 20.
605 no special environment. Do not set up TCP-related environment variables.
607 verbose. Print verbose messsages to standard output.
609 more verbose. Print more verbose messages to standard output.
610 * no difference between -v and -vv in busyboxed version