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 bb_unsetenv_and_free(var);
93 static void sig_term_handler(int sig)
96 bb_error_msg("got signal %u, exit", sig);
97 kill_myself_with_sig(sig);
100 /* Little bloated, but tries to give accurate info how child exited.
101 * Makes easier to spot segfaulting children etc... */
102 static void print_waitstat(unsigned pid, int wstat)
105 const char *cause = "?exit";
107 if (WIFEXITED(wstat)) {
109 e = WEXITSTATUS(wstat);
110 } else if (WIFSIGNALED(wstat)) {
114 bb_error_msg("end %d %s %d", pid, cause, e);
117 /* Must match getopt32 in main! */
132 OPT_U = (1 << 13), /* from here: sslsvd only */
133 OPT_slash = (1 << 14),
138 static void connection_status(void)
140 /* "only 1 client max" desn't need this */
142 bb_error_msg("status %u/%u", cnum, cmax);
145 static void sig_child_handler(int sig UNUSED_PARAM)
150 while ((pid = wait_any_nohang(&wstat)) > 0) {
152 ipsvd_perhost_remove(pid);
156 print_waitstat(pid, wstat);
162 int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
163 int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
168 const char *instructs;
169 char *msg_per_host = NULL;
170 unsigned len_per_host = len_per_host; /* gcc */
172 struct bb_uidgid_t ugid;
176 char *preset_local_hostname = NULL;
177 char *remote_hostname = remote_hostname; /* for compiler */
178 char *remote_addr = remote_addr; /* for compiler */
179 len_and_sockaddr *lsa;
180 len_and_sockaddr local, remote;
185 unsigned backlog = 20;
190 tcp = (applet_name[0] == 't');
192 /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */
193 opt_complementary = "-3:i--i:ph:vv:b+:c+";
195 opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
196 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
197 &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
200 /* "+": stop on first non-option */
201 opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
202 &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
203 &backlog, &str_t, &verbose
206 if (opts & OPT_C) { /* -C n[:message] */
207 max_per_host = bb_strtou(str_C, &str_C, 10);
211 msg_per_host = str_C + 1;
212 len_per_host = strlen(msg_per_host);
215 if (max_per_host > cmax)
218 xget_uidgid(&ugid, user);
221 if (opts & OPT_U) ssluser = optarg;
222 if (opts & OPT_slash) root = optarg;
223 if (opts & OPT_Z) cert = optarg;
224 if (opts & OPT_K) key = optarg;
227 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
228 argv[0] = (char*)"0.0.0.0";
230 /* Per-IP flood protection is not thought-out for UDP */
234 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
239 if ((getuid() == 0) && !(opts & OPT_u)) {
240 xfunc_exitcode = 100;
241 bb_error_msg_and_die(bb_msg_you_must_be_root);
244 if (!uidgid_get(&sslugid, ssluser, 1)) {
246 bb_perror_msg_and_die("can't get user/group: %s", ssluser);
248 bb_error_msg_and_die("unknown user/group %s", ssluser);
250 if (!cert) cert = "./cert.pem";
251 if (!key) key = cert;
252 if (matrixSslOpen() < 0)
253 fatal("can't initialize ssl");
254 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
256 fatal("can't read cert, key, or ca file");
257 fatal("can't read cert or key file");
259 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
260 fatal("can't create ssl session");
264 signal(SIGCHLD, sig_child_handler);
265 bb_signals(BB_FATAL_SIGS, sig_term_handler);
266 signal(SIGPIPE, SIG_IGN);
269 ipsvd_perhost_init(cmax);
271 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
272 lsa = xhost2sockaddr(argv[0], local_port);
275 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
276 setsockopt_reuseaddr(sock);
277 sa_len = lsa->len; /* I presume sockaddr len stays the same */
278 xbind(sock, &lsa->u.sa, sa_len);
280 xlisten(sock, backlog);
281 close_on_exec_on(sock);
282 } else { /* udp: needed for recv_from_to to work: */
283 socket_want_pktinfo(sock);
285 /* ndelay_off(sock); - it is the default I think? */
289 /* drop permissions */
296 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
298 bb_error_msg("listening on %s, starting, uid %u, gid %u", addr,
299 (unsigned)ugid.uid, (unsigned)ugid.gid);
301 bb_error_msg("listening on %s, starting", addr);
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 { /* vfork alert! every xmalloc in this block should be freed! */
415 char *local_hostname = local_hostname; /* for compiler */
416 char *local_addr = NULL;
417 char *free_me0 = NULL;
418 char *free_me1 = NULL;
419 char *free_me2 = NULL;
421 if (verbose || !(opts & OPT_E)) {
422 if (!max_per_host) /* remote_addr is not yet known */
423 free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
425 free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
426 if (!remote_hostname) {
427 bb_error_msg("can't look up hostname for %s", remote_addr);
428 remote_hostname = remote_addr;
431 /* Find out local IP peer connected to.
432 * Errors ignored (I'm not paranoid enough to imagine kernel
433 * which doesn't know local IP). */
435 getsockname(0, &local.u.sa, &local.len);
436 /* else: for UDP it is done earlier by parent */
437 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
439 local_hostname = preset_local_hostname;
440 if (!local_hostname) {
441 free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
443 bb_error_msg_and_die("can't look up hostname for %s", local_addr);
445 /* else: local_hostname is not NULL, but is NOT malloced! */
451 bb_error_msg("concurrency %s %u/%u",
453 cur_per_host, max_per_host);
455 bb_error_msg((opts & OPT_h)
456 ? "start %u %s-%s (%s-%s)"
459 local_addr, remote_addr,
460 local_hostname, remote_hostname);
463 if (!(opts & OPT_E)) {
464 /* setup ucspi env */
465 const char *proto = tcp ? "TCP" : "UDP";
467 /* Extract "original" destination addr:port
468 * from Linux firewall. Useful when you redirect
469 * an outbond connection to local handler, and it needs
470 * to know where it originally tried to connect */
471 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
472 char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
473 xsetenv_plain("TCPORIGDSTADDR", addr);
476 xsetenv_plain("PROTO", proto);
477 xsetenv_proto(proto, "LOCALADDR", local_addr);
478 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
480 xsetenv_proto(proto, "LOCALHOST", local_hostname);
481 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
483 //compat? xsetenv_proto(proto, "REMOTEINFO", "");
485 if (cur_per_host > 0) /* can not be true for udp */
486 xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
496 signal(SIGPIPE, SIG_DFL); /* this one was SIG_IGNed */
497 /* Non-ignored signals revert to SIG_DFL on exec anyway */
498 /*signal(SIGCHLD, SIG_DFL);*/
499 sig_unblock(SIGCHLD);
502 strcpy(id, utoa(pid));
504 bb_perror_msg_and_die("can't execute '%s'", argv[0]);
506 BB_EXECVP_or_die(argv);
511 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
512 [-i dir|-x cdb] [ -t sec] host port prog
514 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
515 and listens on the socket for incoming connections.
517 On each incoming connection, tcpsvd conditionally runs a program,
518 with standard input reading from the socket, and standard output
519 writing to the socket, to handle this connection. tcpsvd keeps
520 listening on the socket for new connections, and can handle
521 multiple connections simultaneously.
523 tcpsvd optionally checks for special instructions depending
524 on the IP address or hostname of the client that initiated
525 the connection, see ipsvd-instruct(5).
528 host either is a hostname, or a dotted-decimal IP address,
529 or 0. If host is 0, tcpsvd accepts connections to any local
531 * busybox accepts IPv6 addresses and host:port pairs too
532 In this case second parameter is ignored
534 tcpsvd accepts connections to host:port. port may be a name
535 from /etc/services or a number.
537 prog consists of one or more arguments. For each connection,
538 tcpsvd normally runs prog, with file descriptor 0 reading from
539 the network, and file descriptor 1 writing to the network.
540 By default it also sets up TCP-related environment variables,
543 read instructions for handling new connections from the instructions
544 directory dir. See ipsvd-instruct(5) for details.
545 * ignored by busyboxed version
547 read instructions for handling new connections from the constant database
548 cdb. The constant database normally is created from an instructions
549 directory by running ipsvd-cdb(8).
550 * ignored by busyboxed version
552 timeout. This option only takes effect if the -i option is given.
553 While checking the instructions directory, check the time of last access
554 of the file that matches the clients address or hostname if any, discard
555 and remove the file if it wasn't accessed within the last sec seconds;
556 tcpsvd does not discard or remove a file if the user's write permission
557 is not set, for those files the timeout is disabled. Default is 0,
558 which means that the timeout is disabled.
559 * ignored by busyboxed version
561 local hostname. Do not look up the local hostname in DNS, but use name
562 as hostname. This option must be set if tcpsvd listens on port 53
565 drop permissions. Switch user ID to user's UID, and group ID to user's
566 primary GID after creating and binding to the socket. If user is followed
567 by a colon and a group name, the group ID is switched to the GID of group
568 instead. All supplementary groups are removed.
570 concurrency. Handle up to n connections simultaneously. Default is 30.
571 If there are n connections active, tcpsvd defers acceptance of a new
572 connection until an active connection is closed.
574 per host concurrency. Allow only up to n connections from the same IP
575 address simultaneously. If there are n active connections from one IP
576 address, new incoming connections from this IP address are closed
577 immediately. If n is followed by :msg, the message msg is written
578 to the client if possible, before closing the connection. By default
579 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
581 For each accepted connection, the current per host concurrency is
582 available through the environment variable TCPCONCURRENCY. n and msg
583 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
584 By default tcpsvd doesn't keep track of connections.
586 Look up the client's hostname in DNS.
588 paranoid. After looking up the client's hostname in DNS, look up the IP
589 addresses in DNS for that hostname, and forget about the hostname
590 if none of the addresses match the client's IP address. You should
591 set this option if you use hostname based instructions. The -p option
592 implies the -h option.
593 * ignored by busyboxed version
595 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
596 is silently limited. Default is 20.
598 no special environment. Do not set up TCP-related environment variables.
600 verbose. Print verbose messsages to standard output.
602 more verbose. Print more verbose messages to standard output.
603 * no difference between -v and -vv in busyboxed version