busybox/networking/tcpudp.c

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/* Based on ipsvd utilities written by Gerrit Pape <pape@smarden.org>
* which are released into public domain by the author.
* Homepage: http://smarden.sunsite.dk/ipsvd/
*
* Copyright (C) 2007 Denys Vlasenko.
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
/* Based on ipsvd-0.12.1. This tcpsvd accepts all options
* which are supported by one from ipsvd-0.12.1, but not all are
* functional. See help text at the end of this file for details.
*
* Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused.
*
* Busybox version exports TCPLOCALADDR instead of
* TCPLOCALIP + TCPLOCALPORT pair. ADDR more closely matches reality
* (which is "struct sockaddr_XXX". Port is not a separate entity,
* it's just a part of (AF_INET[6]) sockaddr!).
*
* TCPORIGDSTADDR is Busybox-specific addition.
*
* udp server is hacked up by reusing TCP code. It has the following
* limitation inherent in Unix DGRAM sockets implementation:
* - local IP address is retrieved (using recvmsg voodoo) but
* child's socket is not bound to it (bind cannot be called on
* already bound socket). Thus it still can emit outgoing packets
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* with wrong source IP...
* - don't know how to retrieve ORIGDST for udp.
*/
//config:config TCPSVD
//config: bool "tcpsvd (13 kb)"
//config: default y
//config: help
//config: tcpsvd listens on a TCP port and runs a program for each new
//config: connection.
//config:
//config:config UDPSVD
//config: bool "udpsvd (13 kb)"
//config: default y
//config: help
//config: udpsvd listens on an UDP port and runs a program for each new
//config: connection.
//applet:IF_TCPSVD(APPLET_ODDNAME(tcpsvd, tcpudpsvd, BB_DIR_USR_BIN, BB_SUID_DROP, tcpsvd))
//applet:IF_UDPSVD(APPLET_ODDNAME(udpsvd, tcpudpsvd, BB_DIR_USR_BIN, BB_SUID_DROP, udpsvd))
//kbuild:lib-$(CONFIG_TCPSVD) += tcpudp.o tcpudp_perhost.o
//kbuild:lib-$(CONFIG_UDPSVD) += tcpudp.o tcpudp_perhost.o
//usage:#define tcpsvd_trivial_usage
//usage: "[-hEv] [-c N] [-C N[:MSG]] [-b N] [-u USER] [-l NAME] IP PORT PROG"
/* with not-implemented options: */
/* //usage: "[-hpEvv] [-c N] [-C N[:MSG]] [-b N] [-u USER] [-l NAME] [-i DIR|-x CDB] [-t SEC] IP PORT PROG" */
//usage:#define tcpsvd_full_usage "\n\n"
//usage: "Create TCP socket, bind to IP:PORT and listen for incoming connections.\n"
//usage: "Run PROG for each connection.\n"
//usage: "\n IP PORT IP:PORT to listen on"
//usage: "\n PROG ARGS Program to run"
//usage: "\n -u USER[:GRP] Change to user/group after bind"
//usage: "\n -c N Up to N connections simultaneously (default 30)"
//usage: "\n -b N Allow backlog of approximately N TCP SYNs (default 20)"
//usage: "\n -C N[:MSG] Allow only up to N connections from the same IP:"
//usage: "\n new connections from this IP address are closed"
//usage: "\n immediately, MSG is written to the peer before close"
//usage: "\n -E Don't set up environment"
//usage: "\n -h Look up peer's hostname"
//usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
//usage: "\n -v Verbose"
//usage: "\n"
//usage: "\nEnvironment if no -E:"
//usage: "\nPROTO='TCP'"
//usage: "\nTCPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
//usage: "\nTCPLOCALADDR='ip:port'"
//usage: "\nTCPORIGDSTADDR='ip:port' of destination before firewall"
//usage: "\n Useful for REDIRECTed-to-local connections:"
//usage: "\n iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 8080"
//usage: "\nTCPCONCURRENCY=num_of_connects_from_this_ip"
//usage: "\nIf -h:"
//usage: "\nTCPLOCALHOST='hostname' (-l NAME is used if specified)"
//usage: "\nTCPREMOTEHOST='hostname'"
//usage:
//usage:#define udpsvd_trivial_usage
//usage: "[-hEv] [-c N] [-u USER] [-l NAME] IP PORT PROG"
//usage:#define udpsvd_full_usage "\n\n"
//usage: "Create UDP socket, bind to IP:PORT and wait for incoming packets.\n"
//usage: "Run PROG for each packet, redirecting all further packets with same\n"
//usage: "peer ip:port to it.\n"
//usage: "\n IP PORT IP:PORT to listen on"
//usage: "\n PROG ARGS Program to run"
//usage: "\n -u USER[:GRP] Change to user/group after bind"
//usage: "\n -c N Up to N connections simultaneously (default 30)"
//usage: "\n -E Don't set up environment"
//usage: "\n -h Look up peer's hostname"
//usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
//usage: "\n -v Verbose"
//usage: "\n"
//usage: "\nEnvironment if no -E:"
//usage: "\nPROTO='UDP'"
//usage: "\nUDPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
//usage: "\nUDPLOCALADDR='ip:port'"
//usage: "\nIf -h:"
//usage: "\nUDPLOCALHOST='hostname' (-l NAME is used if specified)"
//usage: "\nUDPREMOTEHOST='hostname'"
#include "libbb.h"
#include "common_bufsiz.h"
#ifdef __linux__
/* from linux/netfilter_ipv4.h: */
# undef SO_ORIGINAL_DST
# define SO_ORIGINAL_DST 80
#endif
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// TODO: move into this file:
#include "tcpudp_perhost.h"
#ifdef SSLSVD
#include "matrixSsl.h"
#include "ssl_io.h"
#endif
struct globals {
unsigned verbose;
unsigned max_per_host;
unsigned cur_per_host;
unsigned cnum;
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unsigned cmax;
char **env_cur;
char *env_var[1]; /* actually bigger */
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define verbose (G.verbose )
#define max_per_host (G.max_per_host)
#define cur_per_host (G.cur_per_host)
#define cnum (G.cnum )
#define cmax (G.cmax )
#define env_cur (G.env_cur )
#define env_var (G.env_var )
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#define INIT_G() do { \
setup_common_bufsiz(); \
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cmax = 30; \
env_cur = &env_var[0]; \
} while (0)
/* We have to be careful about leaking memory in repeated setenv's */
static void xsetenv_plain(const char *n, const char *v)
{
char *var = xasprintf("%s=%s", n, v);
*env_cur++ = var;
putenv(var);
}
static void xsetenv_proto(const char *proto, const char *n, const char *v)
{
char *var = xasprintf("%s%s=%s", proto, n, v);
*env_cur++ = var;
putenv(var);
}
static void undo_xsetenv(void)
{
char **pp = env_cur = &env_var[0];
while (*pp) {
char *var = *pp;
bb_unsetenv_and_free(var);
*pp++ = NULL;
}
}
static void sig_term_handler(int sig)
{
if (verbose)
bb_error_msg("got signal %u, exit", sig);
kill_myself_with_sig(sig);
}
/* Little bloated, but tries to give accurate info how child exited.
* Makes easier to spot segfaulting children etc... */
static void print_waitstat(unsigned pid, int wstat)
{
unsigned e = 0;
const char *cause = "?exit";
if (WIFEXITED(wstat)) {
cause++;
e = WEXITSTATUS(wstat);
} else if (WIFSIGNALED(wstat)) {
cause = "signal";
e = WTERMSIG(wstat);
}
bb_error_msg("end %d %s %d", pid, cause, e);
}
/* Must match getopt32 in main! */
enum {
OPT_c = (1 << 0),
OPT_C = (1 << 1),
OPT_i = (1 << 2),
OPT_x = (1 << 3),
OPT_u = (1 << 4),
OPT_l = (1 << 5),
OPT_E = (1 << 6),
OPT_b = (1 << 7),
OPT_h = (1 << 8),
OPT_p = (1 << 9),
OPT_t = (1 << 10),
OPT_v = (1 << 11),
OPT_V = (1 << 12),
OPT_U = (1 << 13), /* from here: sslsvd only */
OPT_slash = (1 << 14),
OPT_Z = (1 << 15),
OPT_K = (1 << 16),
};
static void connection_status(void)
{
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/* "only 1 client max" desn't need this */
if (cmax > 1)
bb_error_msg("status %u/%u", cnum, cmax);
}
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static void sig_child_handler(int sig UNUSED_PARAM)
{
int wstat;
pid_t pid;
while ((pid = wait_any_nohang(&wstat)) > 0) {
if (max_per_host)
ipsvd_perhost_remove(pid);
if (cnum)
cnum--;
if (verbose)
print_waitstat(pid, wstat);
}
if (verbose)
connection_status();
}
int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
{
char *str_C, *str_t;
char *user;
struct hcc *hccp;
const char *instructs;
char *msg_per_host = NULL;
unsigned len_per_host = len_per_host; /* gcc */
#ifndef SSLSVD
struct bb_uidgid_t ugid;
#endif
bool tcp;
uint16_t local_port;
char *preset_local_hostname = NULL;
char *remote_hostname = remote_hostname; /* for compiler */
char *remote_addr = remote_addr; /* for compiler */
len_and_sockaddr *lsa;
len_and_sockaddr local, remote;
socklen_t sa_len;
int pid;
int sock;
int conn;
unsigned backlog = 20;
unsigned opts;
INIT_G();
tcp = (applet_name[0] == 't');
#ifdef SSLSVD
getopt32: remove opt_complementary function old new delta vgetopt32 1318 1392 +74 runsvdir_main 703 713 +10 bb_make_directory 423 425 +2 collect_cpu 546 545 -1 opt_chars 3 - -3 opt_complementary 4 - -4 tftpd_main 567 562 -5 ntp_init 476 471 -5 zcip_main 1266 1256 -10 xxd_main 428 418 -10 whois_main 140 130 -10 who_main 463 453 -10 which_main 212 202 -10 wget_main 2535 2525 -10 watchdog_main 291 281 -10 watch_main 222 212 -10 vlock_main 399 389 -10 uuencode_main 332 322 -10 uudecode_main 316 306 -10 unlink_main 45 35 -10 udhcpd_main 1482 1472 -10 udhcpc_main 2762 2752 -10 tune2fs_main 290 280 -10 tunctl_main 366 356 -10 truncate_main 218 208 -10 tr_main 518 508 -10 time_main 1134 1124 -10 tftp_main 286 276 -10 telnetd_main 1873 1863 -10 tcpudpsvd_main 1785 1775 -10 taskset_main 521 511 -10 tar_main 1009 999 -10 tail_main 1644 1634 -10 syslogd_main 1967 1957 -10 switch_root_main 368 358 -10 svlogd_main 1454 1444 -10 sv 1296 1286 -10 stat_main 104 94 -10 start_stop_daemon_main 1028 1018 -10 split_main 542 532 -10 sort_main 796 786 -10 slattach_main 624 614 -10 shuf_main 504 494 -10 setsid_main 96 86 -10 setserial_main 1132 1122 -10 setfont_main 388 378 -10 setconsole_main 78 68 -10 sendmail_main 1209 1199 -10 sed_main 677 667 -10 script_main 1077 1067 -10 run_parts_main 325 315 -10 rtcwake_main 454 444 -10 rm_main 175 165 -10 reformime_main 119 109 -10 readlink_main 123 113 -10 rdate_main 246 236 -10 pwdx_main 189 179 -10 pstree_main 317 307 -10 pscan_main 663 653 -10 popmaildir_main 818 808 -10 pmap_main 80 70 -10 nc_main 1042 1032 -10 mv_main 558 548 -10 mountpoint_main 477 467 -10 mount_main 1264 1254 -10 modprobe_main 768 758 -10 modinfo_main 333 323 -10 mktemp_main 200 190 -10 mkswap_main 324 314 -10 mkfs_vfat_main 1489 1479 -10 microcom_main 715 705 -10 md5_sha1_sum_main 521 511 -10 man_main 867 857 -10 makedevs_main 1052 1042 -10 ls_main 563 553 -10 losetup_main 432 422 -10 loadfont_main 89 79 -10 ln_main 524 514 -10 link_main 75 65 -10 ipcalc_main 544 534 -10 iostat_main 2397 2387 -10 install_main 768 758 -10 id_main 480 470 -10 i2cset_main 1239 1229 -10 i2cget_main 380 370 -10 i2cdump_main 1482 1472 -10 i2cdetect_main 682 672 -10 hwclock_main 406 396 -10 httpd_main 741 731 -10 grep_main 837 827 -10 getty_main 1559 1549 -10 fuser_main 297 287 -10 ftpgetput_main 345 335 -10 ftpd_main 2232 2222 -10 fstrim_main 251 241 -10 fsfreeze_main 77 67 -10 fsck_minix_main 2921 2911 -10 flock_main 314 304 -10 flashcp_main 740 730 -10 flash_eraseall_main 833 823 -10 fdformat_main 532 522 -10 expand_main 680 670 -10 eject_main 335 325 -10 dumpleases_main 630 620 -10 du_main 314 304 -10 dos2unix_main 441 431 -10 diff_main 1350 1340 -10 df_main 1064 1054 -10 date_main 1095 1085 -10 cut_main 961 951 -10 cryptpw_main 228 218 -10 crontab_main 575 565 -10 crond_main 1149 1139 -10 cp_main 370 360 -10 common_traceroute_main 3834 3824 -10 common_ping_main 1767 1757 -10 comm_main 239 229 -10 cmp_main 655 645 -10 chrt_main 379 369 -10 chpst_main 704 694 -10 chpasswd_main 308 298 -10 chown_main 171 161 -10 chmod_main 158 148 -10 cat_main 428 418 -10 bzip2_main 120 110 -10 blkdiscard_main 264 254 -10 base64_main 221 211 -10 arping_main 1665 1655 -10 ar_main 556 546 -10 adjtimex_main 406 396 -10 adduser_main 882 872 -10 addgroup_main 411 401 -10 acpid_main 1198 1188 -10 optstring 11 - -11 opt_string 18 - -18 OPT_STR 25 - -25 ubi_tools_main 1288 1258 -30 ls_options 31 - -31 ------------------------------------------------------------------------------ (add/remove: 0/6 grow/shrink: 3/129 up/down: 86/-1383) Total: -1297 bytes text data bss dec hex filename 915428 485 6876 922789 e14a5 busybox_old 914629 485 6872 921986 e1182 busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2017-08-09 01:25:02 +05:30
opts = getopt32(argv, "^+"
"c:+C:i:x:u:l:Eb:+hpt:vU:/:Z:K:" /* -c NUM, -b NUM */
/* 3+ args, -i at most once, -p implies -h, -v is a counter */
"\0" "-3:i--i:ph:vv",
&cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
&backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
);
#else
/* "+": stop on first non-option */
opts = getopt32(argv, "+c:+C:i:x:u:l:Eb:hpt:v",
&cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
&backlog, &str_t, &verbose
);
#endif
if (opts & OPT_C) { /* -C n[:message] */
max_per_host = bb_strtou(str_C, &str_C, 10);
if (str_C[0]) {
if (str_C[0] != ':')
bb_show_usage();
msg_per_host = str_C + 1;
len_per_host = strlen(msg_per_host);
}
}
if (max_per_host > cmax)
max_per_host = cmax;
if (opts & OPT_u) {
xget_uidgid(&ugid, user);
}
#ifdef SSLSVD
if (opts & OPT_U) ssluser = optarg;
if (opts & OPT_slash) root = optarg;
if (opts & OPT_Z) cert = optarg;
if (opts & OPT_K) key = optarg;
#endif
argv += optind;
if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
argv[0] = (char*)"0.0.0.0";
/* Per-IP flood protection is not thought-out for UDP */
if (!tcp)
max_per_host = 0;
bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
#ifdef SSLSVD
sslser = user;
client = 0;
if ((getuid() == 0) && !(opts & OPT_u)) {
xfunc_exitcode = 100;
bb_error_msg_and_die(bb_msg_you_must_be_root);
}
if (opts & OPT_u)
if (!uidgid_get(&sslugid, ssluser, 1)) {
if (errno) {
bb_perror_msg_and_die("can't get user/group: %s", ssluser);
}
bb_error_msg_and_die("unknown user/group %s", ssluser);
}
if (!cert) cert = "./cert.pem";
if (!key) key = cert;
if (matrixSslOpen() < 0)
fatal("can't initialize ssl");
if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
if (client)
fatal("can't read cert, key, or ca file");
fatal("can't read cert or key file");
}
if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
fatal("can't create ssl session");
#endif
sig_block(SIGCHLD);
signal(SIGCHLD, sig_child_handler);
bb_signals(BB_FATAL_SIGS, sig_term_handler);
signal(SIGPIPE, SIG_IGN);
if (max_per_host)
ipsvd_perhost_init(cmax);
local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
lsa = xhost2sockaddr(argv[0], local_port);
argv += 2;
sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
setsockopt_reuseaddr(sock);
sa_len = lsa->len; /* I presume sockaddr len stays the same */
xbind(sock, &lsa->u.sa, sa_len);
if (tcp) {
xlisten(sock, backlog);
close_on_exec_on(sock);
} else { /* udp: needed for recv_from_to to work: */
socket_want_pktinfo(sock);
}
/* ndelay_off(sock); - it is the default I think? */
#ifndef SSLSVD
if (opts & OPT_u) {
/* drop permissions */
xsetgid(ugid.gid);
xsetuid(ugid.uid);
}
#endif
if (verbose) {
char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
if (opts & OPT_u)
bb_error_msg("listening on %s, starting, uid %u, gid %u", addr,
(unsigned)ugid.uid, (unsigned)ugid.gid);
else
bb_error_msg("listening on %s, starting", addr);
free(addr);
}
/* Main accept() loop */
again:
hccp = NULL;
again1:
close(0);
/* It's important to close(0) _before_ wait loop:
* fd#0 can be a shared connection fd.
* If kept open by us, peer can't detect PROG closing it.
*/
while (cnum >= cmax)
wait_for_any_sig(); /* expecting SIGCHLD */
again2:
sig_unblock(SIGCHLD);
local.len = remote.len = sa_len;
if (tcp) {
/* Accept a connection to fd #0 */
conn = accept(sock, &remote.u.sa, &remote.len);
} else {
2007-04-04 23:19:47 +05:30
/* In case recv_from_to won't be able to recover local addr.
* Also sets port - recv_from_to is unable to do it. */
local = *lsa;
conn = recv_from_to(sock, NULL, 0, MSG_PEEK,
&remote.u.sa, &local.u.sa, sa_len);
}
sig_block(SIGCHLD);
if (conn < 0) {
if (errno != EINTR)
bb_perror_msg(tcp ? "accept" : "recv");
goto again2;
}
xmove_fd(tcp ? conn : sock, 0);
if (max_per_host) {
/* Drop connection immediately if cur_per_host > max_per_host
* (minimizing load under SYN flood) */
remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
if (cur_per_host > max_per_host) {
/* ipsvd_perhost_add detected that max is exceeded
* (and did not store ip in connection table) */
free(remote_addr);
if (msg_per_host) {
/* don't block or test for errors */
send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
}
goto again1;
}
/* NB: remote_addr is not leaked, it is stored in conn table */
}
if (!tcp) {
/* Voodoo magic: making udp sockets each receive its own
* packets is not trivial, and I still not sure
* I do it 100% right.
* 1) we have to do it before fork()
* 2) order is important - is it right now? */
/* Open new non-connected UDP socket for further clients... */
sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
setsockopt_reuseaddr(sock);
/* Make plain write/send work for old socket by supplying default
* destination address. This also restricts incoming packets
* to ones coming from this remote IP. */
xconnect(0, &remote.u.sa, sa_len);
/* hole? at this point we have no wildcard udp socket...
* can this cause clients to get "port unreachable" icmp?
* Yup, time window is very small, but it exists (is it?) */
/* ..."open new socket", continued */
xbind(sock, &lsa->u.sa, sa_len);
socket_want_pktinfo(sock);
/* Doesn't work:
* we cannot replace fd #0 - we will lose pending packet
* which is already buffered for us! And we cannot use fd #1
* instead - it will "intercept" all following packets, but child
2007-08-24 15:57:41 +05:30
* does not expect data coming *from fd #1*! */
#if 0
/* Make it so that local addr is fixed to localp->u.sa
* and we don't accidentally accept packets to other local IPs. */
/* NB: we possibly bind to the _very_ same_ address & port as the one
* already bound in parent! This seems to work in Linux.
* (otherwise we can move socket to fd #0 only if bind succeeds) */
close(0);
set_nport(&localp->u.sa, htons(local_port));
xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
setsockopt_reuseaddr(0); /* crucial */
xbind(0, &localp->u.sa, localp->len);
#endif
}
pid = vfork();
if (pid == -1) {
bb_perror_msg("vfork");
goto again;
}
if (pid != 0) {
/* Parent */
cnum++;
if (verbose)
connection_status();
if (hccp)
hccp->pid = pid;
/* clean up changes done by vforked child */
undo_xsetenv();
goto again;
}
/* Child: prepare env, log, and exec prog */
{ /* vfork alert! every xmalloc in this block should be freed! */
char *local_hostname = local_hostname; /* for compiler */
char *local_addr = NULL;
char *free_me0 = NULL;
char *free_me1 = NULL;
char *free_me2 = NULL;
if (verbose || !(opts & OPT_E)) {
if (!max_per_host) /* remote_addr is not yet known */
free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
if (opts & OPT_h) {
free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
if (!remote_hostname) {
bb_error_msg("can't look up hostname for %s", remote_addr);
remote_hostname = remote_addr;
}
}
/* Find out local IP peer connected to.
* Errors ignored (I'm not paranoid enough to imagine kernel
* which doesn't know local IP). */
if (tcp)
getsockname(0, &local.u.sa, &local.len);
/* else: for UDP it is done earlier by parent */
local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
if (opts & OPT_h) {
local_hostname = preset_local_hostname;
if (!local_hostname) {
free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
if (!local_hostname)
bb_error_msg_and_die("can't look up hostname for %s", local_addr);
}
/* else: local_hostname is not NULL, but is NOT malloced! */
}
}
if (verbose) {
pid = getpid();
if (max_per_host) {
bb_error_msg("concurrency %s %u/%u",
remote_addr,
cur_per_host, max_per_host);
}
bb_error_msg((opts & OPT_h)
? "start %u %s-%s (%s-%s)"
: "start %u %s-%s",
pid,
local_addr, remote_addr,
local_hostname, remote_hostname);
}
if (!(opts & OPT_E)) {
/* setup ucspi env */
const char *proto = tcp ? "TCP" : "UDP";
#ifdef SO_ORIGINAL_DST
/* Extract "original" destination addr:port
* from Linux firewall. Useful when you redirect
* an outbond connection to local handler, and it needs
* to know where it originally tried to connect */
if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
xsetenv_plain("TCPORIGDSTADDR", addr);
free(addr);
}
#endif
xsetenv_plain("PROTO", proto);
xsetenv_proto(proto, "LOCALADDR", local_addr);
xsetenv_proto(proto, "REMOTEADDR", remote_addr);
if (opts & OPT_h) {
xsetenv_proto(proto, "LOCALHOST", local_hostname);
xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
}
//compat? xsetenv_proto(proto, "REMOTEINFO", "");
/* additional */
if (cur_per_host > 0) /* can not be true for udp */
xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
}
free(local_addr);
free(free_me0);
free(free_me1);
free(free_me2);
}
xdup2(0, 1);
signal(SIGPIPE, SIG_DFL); /* this one was SIG_IGNed */
/* Non-ignored signals revert to SIG_DFL on exec anyway */
/*signal(SIGCHLD, SIG_DFL);*/
sig_unblock(SIGCHLD);
#ifdef SSLSVD
strcpy(id, utoa(pid));
ssl_io(0, argv);
bb_perror_msg_and_die("can't execute '%s'", argv[0]);
#else
BB_EXECVP_or_die(argv);
#endif
}
/*
tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
[-i dir|-x cdb] [ -t sec] host port prog
tcpsvd creates a TCP/IP socket, binds it to the address host:port,
and listens on the socket for incoming connections.
On each incoming connection, tcpsvd conditionally runs a program,
with standard input reading from the socket, and standard output
writing to the socket, to handle this connection. tcpsvd keeps
listening on the socket for new connections, and can handle
multiple connections simultaneously.
tcpsvd optionally checks for special instructions depending
on the IP address or hostname of the client that initiated
the connection, see ipsvd-instruct(5).
host
host either is a hostname, or a dotted-decimal IP address,
or 0. If host is 0, tcpsvd accepts connections to any local
IP address.
* busybox accepts IPv6 addresses and host:port pairs too
In this case second parameter is ignored
port
tcpsvd accepts connections to host:port. port may be a name
from /etc/services or a number.
prog
prog consists of one or more arguments. For each connection,
tcpsvd normally runs prog, with file descriptor 0 reading from
the network, and file descriptor 1 writing to the network.
By default it also sets up TCP-related environment variables,
see tcp-environ(5)
-i dir
read instructions for handling new connections from the instructions
directory dir. See ipsvd-instruct(5) for details.
* ignored by busyboxed version
-x cdb
read instructions for handling new connections from the constant database
cdb. The constant database normally is created from an instructions
directory by running ipsvd-cdb(8).
* ignored by busyboxed version
-t sec
timeout. This option only takes effect if the -i option is given.
While checking the instructions directory, check the time of last access
of the file that matches the clients address or hostname if any, discard
and remove the file if it wasn't accessed within the last sec seconds;
tcpsvd does not discard or remove a file if the user's write permission
is not set, for those files the timeout is disabled. Default is 0,
which means that the timeout is disabled.
* ignored by busyboxed version
-l name
local hostname. Do not look up the local hostname in DNS, but use name
as hostname. This option must be set if tcpsvd listens on port 53
to avoid loops.
-u user[:group]
drop permissions. Switch user ID to user's UID, and group ID to user's
primary GID after creating and binding to the socket. If user is followed
by a colon and a group name, the group ID is switched to the GID of group
instead. All supplementary groups are removed.
-c n
concurrency. Handle up to n connections simultaneously. Default is 30.
If there are n connections active, tcpsvd defers acceptance of a new
connection until an active connection is closed.
-C n[:msg]
per host concurrency. Allow only up to n connections from the same IP
address simultaneously. If there are n active connections from one IP
address, new incoming connections from this IP address are closed
immediately. If n is followed by :msg, the message msg is written
to the client if possible, before closing the connection. By default
msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg.
For each accepted connection, the current per host concurrency is
available through the environment variable TCPCONCURRENCY. n and msg
can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5).
By default tcpsvd doesn't keep track of connections.
-h
Look up the client's hostname in DNS.
-p
paranoid. After looking up the client's hostname in DNS, look up the IP
addresses in DNS for that hostname, and forget about the hostname
if none of the addresses match the client's IP address. You should
set this option if you use hostname based instructions. The -p option
implies the -h option.
* ignored by busyboxed version
-b n
backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
is silently limited. Default is 20.
-E
no special environment. Do not set up TCP-related environment variables.
-v
verbose. Print verbose messages to standard output.
-vv
more verbose. Print more verbose messages to standard output.
* no difference between -v and -vv in busyboxed version
*/