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 Denis 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 * Output of verbose mode matches original (modulo bugs and
17 * unimplemented stuff). Unnatural splitting of IP and PORT
18 * is retained (personally I prefer one-value "IP:PORT" notation -
19 * it is a natural string representation of struct sockaddr_XX).
21 * TCPORIGDST{IP,PORT} 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 #define G (*(struct globals*)&bb_common_bufsiz1)
51 #define verbose (G.verbose )
52 #define max_per_host (G.max_per_host)
53 #define cur_per_host (G.cur_per_host)
54 #define cnum (G.cnum )
55 #define cmax (G.cmax )
62 static void xsetenv_proto(const char *proto, const char *n, const char *v)
64 putenv(xasprintf("%s%s=%s", proto, n, v));
67 static void sig_term_handler(int sig)
70 printf("%s: info: sigterm received, exit\n", applet_name);
74 /* Little bloated, but tries to give accurate info how child exited.
75 * Makes easier to spot segfaulting children etc... */
76 static void print_waitstat(unsigned pid, int wstat)
79 const char *cause = "?exit";
81 if (WIFEXITED(wstat)) {
83 e = WEXITSTATUS(wstat);
84 } else if (WIFSIGNALED(wstat)) {
88 printf("%s: info: end %d %s %d\n", applet_name, pid, cause, e);
91 /* Must match getopt32 in main! */
106 OPT_U = (1 << 13), /* from here: sslsvd only */
107 OPT_slash = (1 << 14),
112 static void connection_status(void)
114 /* "only 1 client max" desn't need this */
116 printf("%s: info: status %u/%u\n", applet_name, cnum, cmax);
119 static void sig_child_handler(int sig)
124 while ((pid = wait_any_nohang(&wstat)) > 0) {
126 ipsvd_perhost_remove(pid);
130 print_waitstat(pid, wstat);
136 int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
137 int tcpudpsvd_main(int argc, char **argv)
139 char *str_c, *str_C, *str_b, *str_t;
142 const char *instructs;
143 char *msg_per_host = NULL;
144 unsigned len_per_host = len_per_host; /* gcc */
146 struct bb_uidgid_t ugid;
148 bool need_hostnames, need_remote_ip, tcp;
150 char *local_hostname = NULL;
151 char *remote_hostname = (char*)""; /* "" used if no -h */
152 char *local_addr = local_addr; /* gcc */
153 char *remote_addr = remote_addr; /* gcc */
154 char *remote_ip = remote_addr; /* gcc */
155 len_and_sockaddr *lsa;
156 len_and_sockaddr local, remote;
161 unsigned backlog = 20;
165 tcp = (applet_name[0] == 't');
167 /* 3+ args, -i at most once, -p implies -h, -v is counter */
168 opt_complementary = "-3:i--i:ph:vv";
170 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
171 &str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
172 &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose
175 getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
176 &str_c, &str_C, &instructs, &instructs, &user, &local_hostname,
177 &str_b, &str_t, &verbose
180 if (option_mask32 & OPT_c)
181 cmax = xatou_range(str_c, 1, INT_MAX);
182 if (option_mask32 & OPT_C) { /* -C n[:message] */
183 max_per_host = bb_strtou(str_C, &str_C, 10);
187 msg_per_host = str_C + 1;
188 len_per_host = strlen(msg_per_host);
191 if (max_per_host > cmax)
193 if (option_mask32 & OPT_u) {
194 if (!get_uidgid(&ugid, user, 1))
195 bb_error_msg_and_die("unknown user/group: %s", user);
197 if (option_mask32 & OPT_b)
198 backlog = xatou(str_b);
200 if (option_mask32 & OPT_U) ssluser = optarg;
201 if (option_mask32 & OPT_slash) root = optarg;
202 if (option_mask32 & OPT_Z) cert = optarg;
203 if (option_mask32 & OPT_K) key = optarg;
206 if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
207 argv[0] = (char*)"0.0.0.0";
209 /* Per-IP flood protection is not thought-out for UDP */
213 /* stdout is used for logging, don't buffer */
215 bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
217 need_hostnames = verbose || !(option_mask32 & OPT_E);
218 need_remote_ip = max_per_host || need_hostnames;
223 if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
224 xfunc_exitcode = 100;
225 bb_error_msg_and_die("fatal: -U ssluser must be set when running as root");
227 if (option_mask32 & OPT_u)
228 if (!uidgid_get(&sslugid, ssluser, 1)) {
230 bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser);
232 bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser);
234 if (!cert) cert = "./cert.pem";
235 if (!key) key = cert;
236 if (matrixSslOpen() < 0)
237 fatal("cannot initialize ssl");
238 if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
240 fatal("cannot read cert, key, or ca file");
241 fatal("cannot read cert or key file");
243 if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
244 fatal("cannot create ssl session");
248 signal(SIGCHLD, sig_child_handler);
249 signal(SIGTERM, sig_term_handler);
250 signal(SIGPIPE, SIG_IGN);
253 ipsvd_perhost_init(cmax);
255 local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
256 lsa = xhost2sockaddr(argv[0], local_port);
257 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
258 setsockopt_reuseaddr(sock);
259 sa_len = lsa->len; /* I presume sockaddr len stays the same */
260 xbind(sock, &lsa->u.sa, sa_len);
262 xlisten(sock, backlog);
263 else /* udp: needed for recv_from_to to work: */
264 socket_want_pktinfo(sock);
265 /* ndelay_off(sock); - it is the default I think? */
268 if (option_mask32 & OPT_u) {
269 /* drop permissions */
276 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
277 printf("%s: info: listening on %s", applet_name, addr);
280 if (option_mask32 & OPT_u)
281 printf(", uid %u, gid %u",
282 (unsigned)ugid.uid, (unsigned)ugid.gid);
287 /* Main accept() loop */
293 sig_pause(); /* wait for any signal (expecting SIGCHLD) */
295 /* Accept a connection to fd #0 */
299 sig_unblock(SIGCHLD);
302 conn = accept(sock, &remote.u.sa, &remote.len);
304 /* In case recv_from_to won't be able to recover local addr.
305 * Also sets port - recv_from_to is unable to do it. */
307 conn = recv_from_to(sock, NULL, 0, MSG_PEEK, &remote.u.sa, &local.u.sa, sa_len);
312 bb_perror_msg(tcp ? "accept" : "recv");
315 xmove_fd(tcp ? conn : sock, 0);
318 /* Drop connection immediately if cur_per_host > max_per_host
319 * (minimizing load under SYN flood) */
320 remote_ip = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
321 cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp);
322 if (cur_per_host > max_per_host) {
323 /* ipsvd_perhost_add detected that max is exceeded
324 * (and did not store ip in connection table) */
327 /* don't block or test for errors */
329 write(0, msg_per_host, len_per_host);
336 /* Voodoo magic: making udp sockets each receive its own
337 * packets is not trivial, and I still not sure
338 * I do it 100% right.
339 * 1) we have to do it before fork()
340 * 2) order is important - is it right now? */
342 /* Make plain write/send work for this socket by supplying default
343 * destination address. This also restricts incoming packets
344 * to ones coming from this remote IP. */
345 xconnect(0, &remote.u.sa, sa_len);
346 /* hole? at this point we have no wildcard udp socket...
347 * can this cause clients to get "port unreachable" icmp?
348 * Yup, time window is very small, but it exists (is it?) */
349 /* Open new non-connected UDP socket for further clients */
350 sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
351 setsockopt_reuseaddr(sock);
352 xbind(sock, &lsa->u.sa, sa_len);
353 socket_want_pktinfo(sock);
356 * we cannot replace fd #0 - we will lose pending packet
357 * which is already buffered for us! And we cannot use fd #1
358 * instead - it will "intercept" all following packets, but child
359 * does not expect data coming *from fd #1*! */
361 /* Make it so that local addr is fixed to localp->u.sa
362 * and we don't accidentally accept packets to other local IPs. */
363 /* NB: we possibly bind to the _very_ same_ address & port as the one
364 * already bound in parent! This seems to work in Linux.
365 * (otherwise we can move socket to fd #0 only if bind succeeds) */
367 set_nport(localp, htons(local_port));
368 xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
369 setsockopt_reuseaddr(0); /* crucial */
370 xbind(0, &localp->u.sa, localp->len);
376 bb_perror_msg("fork");
391 /* Child: prepare env, log, and exec prog */
393 /* Closing tcp listening socket */
398 remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
400 if (need_hostnames) {
401 if (option_mask32 & OPT_h) {
402 remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
403 if (!remote_hostname) {
404 bb_error_msg("warning: cannot look up hostname for %s", remote_addr);
405 remote_hostname = (char*)"";
408 /* Find out local IP peer connected to.
409 * Errors ignored (I'm not paranoid enough to imagine kernel
410 * which doesn't know local IP). */
413 getsockname(0, &local.u.sa, &local.len);
415 local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
416 if (!local_hostname) {
417 local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
419 bb_error_msg_and_die("warning: cannot look up hostname for %s"+9, local_addr);
425 printf("%s: info: pid %u from %s\n", applet_name, pid, remote_addr);
427 printf("%s: info: concurrency %u %s %u/%u\n",
428 applet_name, pid, remote_ip, cur_per_host, max_per_host);
429 printf("%s: info: start %u %s:%s :%s:%s\n",
431 local_hostname, local_addr,
432 remote_hostname, remote_addr);
435 if (!(option_mask32 & OPT_E)) {
436 /* setup ucspi env */
437 const char *proto = tcp ? "TCP" : "UDP";
439 /* Extract "original" destination addr:port
440 * from Linux firewall. Useful when you redirect
441 * an outbond connection to local handler, and it needs
442 * to know where it originally tried to connect */
443 if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &lsa->u.sa, &lsa->len) == 0) {
444 char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
445 xsetenv("TCPORIGDSTADDR", addr);
448 xsetenv("PROTO", proto);
449 xsetenv_proto(proto, "LOCALADDR", local_addr);
450 xsetenv_proto(proto, "LOCALHOST", local_hostname);
451 xsetenv_proto(proto, "REMOTEADDR", remote_addr);
452 if (option_mask32 & OPT_h) {
453 xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
455 xsetenv_proto(proto, "REMOTEINFO", "");
457 if (cur_per_host > 0) /* can not be true for udp */
458 xsetenv("TCPCONCURRENCY", utoa(cur_per_host));
463 signal(SIGTERM, SIG_DFL);
464 signal(SIGPIPE, SIG_DFL);
465 signal(SIGCHLD, SIG_DFL);
466 sig_unblock(SIGCHLD);
470 strcpy(id, utoa(pid);
473 BB_EXECVP(argv[0], argv);
475 bb_perror_msg_and_die("exec '%s'", argv[0]);
479 tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
480 [-i dir|-x cdb] [ -t sec] host port prog
482 tcpsvd creates a TCP/IP socket, binds it to the address host:port,
483 and listens on the socket for incoming connections.
485 On each incoming connection, tcpsvd conditionally runs a program,
486 with standard input reading from the socket, and standard output
487 writing to the socket, to handle this connection. tcpsvd keeps
488 listening on the socket for new connections, and can handle
489 multiple connections simultaneously.
491 tcpsvd optionally checks for special instructions depending
492 on the IP address or hostname of the client that initiated
493 the connection, see ipsvd-instruct(5).
496 host either is a hostname, or a dotted-decimal IP address,
497 or 0. If host is 0, tcpsvd accepts connections to any local
499 * busybox accepts IPv6 addresses and host:port pairs too
500 In this case second parameter is ignored
502 tcpsvd accepts connections to host:port. port may be a name
503 from /etc/services or a number.
505 prog consists of one or more arguments. For each connection,
506 tcpsvd normally runs prog, with file descriptor 0 reading from
507 the network, and file descriptor 1 writing to the network.
508 By default it also sets up TCP-related environment variables,
511 read instructions for handling new connections from the instructions
512 directory dir. See ipsvd-instruct(5) for details.
513 * ignored by busyboxed version
515 read instructions for handling new connections from the constant database
516 cdb. The constant database normally is created from an instructions
517 directory by running ipsvd-cdb(8).
518 * ignored by busyboxed version
520 timeout. This option only takes effect if the -i option is given.
521 While checking the instructions directory, check the time of last access
522 of the file that matches the clients address or hostname if any, discard
523 and remove the file if it wasn't accessed within the last sec seconds;
524 tcpsvd does not discard or remove a file if the user's write permission
525 is not set, for those files the timeout is disabled. Default is 0,
526 which means that the timeout is disabled.
527 * ignored by busyboxed version
529 local hostname. Do not look up the local hostname in DNS, but use name
530 as hostname. This option must be set if tcpsvd listens on port 53
533 drop permissions. Switch user ID to user's UID, and group ID to user's
534 primary GID after creating and binding to the socket. If user is followed
535 by a colon and a group name, the group ID is switched to the GID of group
536 instead. All supplementary groups are removed.
538 concurrency. Handle up to n connections simultaneously. Default is 30.
539 If there are n connections active, tcpsvd defers acceptance of a new
540 connection until an active connection is closed.
542 per host concurrency. Allow only up to n connections from the same IP
543 address simultaneously. If there are n active connections from one IP
544 address, new incoming connections from this IP address are closed
545 immediately. If n is followed by :msg, the message msg is written
546 to the client if possible, before closing the connection. By default
547 msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
549 For each accepted connection, the current per host concurrency is
550 available through the environment variable TCPCONCURRENCY. n and msg
551 can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
552 By default tcpsvd doesn't keep track of connections.
554 Look up the client's hostname in DNS.
556 paranoid. After looking up the client's hostname in DNS, look up the IP
557 addresses in DNS for that hostname, and forget about the hostname
558 if none of the addresses match the client's IP address. You should
559 set this option if you use hostname based instructions. The -p option
560 implies the -h option.
561 * ignored by busyboxed version
563 backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
564 is silently limited. Default is 20.
566 no special environment. Do not set up TCP-related environment variables.
568 verbose. Print verbose messsages to standard output.
570 more verbose. Print more verbose messages to standard output.
571 * no difference between -v and -vv in busyboxed version