[3320] | 1 | /* Based on ipsvd utilities written by Gerrit Pape <pape@smarden.org>
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| 2 | * which are released into public domain by the author.
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| 3 | * Homepage: http://smarden.sunsite.dk/ipsvd/
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| 4 | *
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| 5 | * Copyright (C) 2007 Denys Vlasenko.
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| 6 | *
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| 7 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 8 | */
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| 9 |
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| 10 | /* Based on ipsvd-0.12.1. This tcpsvd accepts all options
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| 11 | * which are supported by one from ipsvd-0.12.1, but not all are
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| 12 | * functional. See help text at the end of this file for details.
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| 13 | *
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| 14 | * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused.
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| 15 | *
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| 16 | * Busybox version exports TCPLOCALADDR instead of
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| 17 | * TCPLOCALIP + TCPLOCALPORT pair. ADDR more closely matches reality
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| 18 | * (which is "struct sockaddr_XXX". Port is not a separate entity,
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| 19 | * it's just a part of (AF_INET[6]) sockaddr!).
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| 20 | *
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| 21 | * TCPORIGDSTADDR is Busybox-specific addition.
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| 22 | *
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| 23 | * udp server is hacked up by reusing TCP code. It has the following
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| 24 | * limitation inherent in Unix DGRAM sockets implementation:
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| 25 | * - local IP address is retrieved (using recvmsg voodoo) but
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| 26 | * child's socket is not bound to it (bind cannot be called on
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| 27 | * already bound socket). Thus it still can emit outgoing packets
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| 28 | * with wrong source IP...
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| 29 | * - don't know how to retrieve ORIGDST for udp.
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| 30 | */
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| 31 |
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| 32 | #include "libbb.h"
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| 33 |
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| 34 | /* Wants <limits.h> etc, thus included after libbb.h: */
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| 35 | #ifdef __linux__
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| 36 | #include <linux/types.h> /* for __be32 etc */
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| 37 | #include <linux/netfilter_ipv4.h>
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| 38 | #endif
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| 39 |
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| 40 | // TODO: move into this file:
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| 41 | #include "tcpudp_perhost.h"
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| 42 |
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| 43 | #ifdef SSLSVD
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| 44 | #include "matrixSsl.h"
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| 45 | #include "ssl_io.h"
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| 46 | #endif
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| 47 |
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| 48 | struct globals {
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| 49 | unsigned verbose;
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| 50 | unsigned max_per_host;
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| 51 | unsigned cur_per_host;
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| 52 | unsigned cnum;
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| 53 | unsigned cmax;
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| 54 | char **env_cur;
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| 55 | char *env_var[1]; /* actually bigger */
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| 56 | } FIX_ALIASING;
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| 57 | #define G (*(struct globals*)&bb_common_bufsiz1)
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| 58 | #define verbose (G.verbose )
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| 59 | #define max_per_host (G.max_per_host)
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| 60 | #define cur_per_host (G.cur_per_host)
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| 61 | #define cnum (G.cnum )
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| 62 | #define cmax (G.cmax )
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| 63 | #define env_cur (G.env_cur )
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| 64 | #define env_var (G.env_var )
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| 65 | #define INIT_G() do { \
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| 66 | cmax = 30; \
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| 67 | env_cur = &env_var[0]; \
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| 68 | } while (0)
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| 69 |
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| 70 |
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| 71 | /* We have to be careful about leaking memory in repeated setenv's */
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| 72 | static void xsetenv_plain(const char *n, const char *v)
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| 73 | {
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| 74 | char *var = xasprintf("%s=%s", n, v);
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| 75 | *env_cur++ = var;
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| 76 | putenv(var);
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| 77 | }
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| 78 |
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| 79 | static void xsetenv_proto(const char *proto, const char *n, const char *v)
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| 80 | {
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| 81 | char *var = xasprintf("%s%s=%s", proto, n, v);
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| 82 | *env_cur++ = var;
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| 83 | putenv(var);
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| 84 | }
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| 85 |
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| 86 | static void undo_xsetenv(void)
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| 87 | {
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| 88 | char **pp = env_cur = &env_var[0];
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| 89 | while (*pp) {
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| 90 | char *var = *pp;
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| 91 | bb_unsetenv_and_free(var);
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| 92 | *pp++ = NULL;
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| 93 | }
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| 94 | }
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| 95 |
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| 96 | static void sig_term_handler(int sig)
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| 97 | {
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| 98 | if (verbose)
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| 99 | bb_error_msg("got signal %u, exit", sig);
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| 100 | kill_myself_with_sig(sig);
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| 101 | }
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| 102 |
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| 103 | /* Little bloated, but tries to give accurate info how child exited.
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| 104 | * Makes easier to spot segfaulting children etc... */
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| 105 | static void print_waitstat(unsigned pid, int wstat)
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| 106 | {
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| 107 | unsigned e = 0;
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| 108 | const char *cause = "?exit";
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| 109 |
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| 110 | if (WIFEXITED(wstat)) {
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| 111 | cause++;
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| 112 | e = WEXITSTATUS(wstat);
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| 113 | } else if (WIFSIGNALED(wstat)) {
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| 114 | cause = "signal";
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| 115 | e = WTERMSIG(wstat);
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| 116 | }
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| 117 | bb_error_msg("end %d %s %d", pid, cause, e);
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| 118 | }
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| 119 |
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| 120 | /* Must match getopt32 in main! */
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| 121 | enum {
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| 122 | OPT_c = (1 << 0),
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| 123 | OPT_C = (1 << 1),
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| 124 | OPT_i = (1 << 2),
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| 125 | OPT_x = (1 << 3),
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| 126 | OPT_u = (1 << 4),
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| 127 | OPT_l = (1 << 5),
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| 128 | OPT_E = (1 << 6),
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| 129 | OPT_b = (1 << 7),
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| 130 | OPT_h = (1 << 8),
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| 131 | OPT_p = (1 << 9),
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| 132 | OPT_t = (1 << 10),
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| 133 | OPT_v = (1 << 11),
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| 134 | OPT_V = (1 << 12),
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| 135 | OPT_U = (1 << 13), /* from here: sslsvd only */
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| 136 | OPT_slash = (1 << 14),
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| 137 | OPT_Z = (1 << 15),
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| 138 | OPT_K = (1 << 16),
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| 139 | };
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| 140 |
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| 141 | static void connection_status(void)
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| 142 | {
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| 143 | /* "only 1 client max" desn't need this */
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| 144 | if (cmax > 1)
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| 145 | bb_error_msg("status %u/%u", cnum, cmax);
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| 146 | }
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| 147 |
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| 148 | static void sig_child_handler(int sig UNUSED_PARAM)
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| 149 | {
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| 150 | int wstat;
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| 151 | pid_t pid;
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| 152 |
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| 153 | while ((pid = wait_any_nohang(&wstat)) > 0) {
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| 154 | if (max_per_host)
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| 155 | ipsvd_perhost_remove(pid);
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| 156 | if (cnum)
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| 157 | cnum--;
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| 158 | if (verbose)
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| 159 | print_waitstat(pid, wstat);
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| 160 | }
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| 161 | if (verbose)
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| 162 | connection_status();
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| 163 | }
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| 164 |
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| 165 | int tcpudpsvd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 166 | int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
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| 167 | {
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| 168 | char *str_C, *str_t;
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| 169 | char *user;
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| 170 | struct hcc *hccp;
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| 171 | const char *instructs;
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| 172 | char *msg_per_host = NULL;
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| 173 | unsigned len_per_host = len_per_host; /* gcc */
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| 174 | #ifndef SSLSVD
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| 175 | struct bb_uidgid_t ugid;
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| 176 | #endif
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| 177 | bool tcp;
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| 178 | uint16_t local_port;
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| 179 | char *preset_local_hostname = NULL;
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| 180 | char *remote_hostname = remote_hostname; /* for compiler */
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| 181 | char *remote_addr = remote_addr; /* for compiler */
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| 182 | len_and_sockaddr *lsa;
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| 183 | len_and_sockaddr local, remote;
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| 184 | socklen_t sa_len;
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| 185 | int pid;
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| 186 | int sock;
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| 187 | int conn;
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| 188 | unsigned backlog = 20;
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| 189 | unsigned opts;
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| 190 |
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| 191 | INIT_G();
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| 192 |
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| 193 | tcp = (applet_name[0] == 't');
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| 194 |
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| 195 | /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */
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| 196 | opt_complementary = "-3:i--i:ph:vv:b+:c+";
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| 197 | #ifdef SSLSVD
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| 198 | opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
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| 199 | &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
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| 200 | &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
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| 201 | );
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| 202 | #else
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| 203 | /* "+": stop on first non-option */
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| 204 | opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
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| 205 | &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
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| 206 | &backlog, &str_t, &verbose
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| 207 | );
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| 208 | #endif
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| 209 | if (opts & OPT_C) { /* -C n[:message] */
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| 210 | max_per_host = bb_strtou(str_C, &str_C, 10);
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| 211 | if (str_C[0]) {
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| 212 | if (str_C[0] != ':')
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| 213 | bb_show_usage();
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| 214 | msg_per_host = str_C + 1;
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| 215 | len_per_host = strlen(msg_per_host);
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| 216 | }
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| 217 | }
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| 218 | if (max_per_host > cmax)
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| 219 | max_per_host = cmax;
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| 220 | if (opts & OPT_u) {
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| 221 | xget_uidgid(&ugid, user);
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| 222 | }
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| 223 | #ifdef SSLSVD
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| 224 | if (opts & OPT_U) ssluser = optarg;
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| 225 | if (opts & OPT_slash) root = optarg;
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| 226 | if (opts & OPT_Z) cert = optarg;
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| 227 | if (opts & OPT_K) key = optarg;
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| 228 | #endif
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| 229 | argv += optind;
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| 230 | if (!argv[0][0] || LONE_CHAR(argv[0], '0'))
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| 231 | argv[0] = (char*)"0.0.0.0";
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| 232 |
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| 233 | /* Per-IP flood protection is not thought-out for UDP */
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| 234 | if (!tcp)
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| 235 | max_per_host = 0;
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| 236 |
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| 237 | bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
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| 238 |
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| 239 | #ifdef SSLSVD
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| 240 | sslser = user;
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| 241 | client = 0;
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| 242 | if ((getuid() == 0) && !(opts & OPT_u)) {
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| 243 | xfunc_exitcode = 100;
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| 244 | bb_error_msg_and_die(bb_msg_you_must_be_root);
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| 245 | }
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| 246 | if (opts & OPT_u)
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| 247 | if (!uidgid_get(&sslugid, ssluser, 1)) {
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| 248 | if (errno) {
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| 249 | bb_perror_msg_and_die("can't get user/group: %s", ssluser);
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| 250 | }
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| 251 | bb_error_msg_and_die("unknown user/group %s", ssluser);
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| 252 | }
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| 253 | if (!cert) cert = "./cert.pem";
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| 254 | if (!key) key = cert;
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| 255 | if (matrixSslOpen() < 0)
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| 256 | fatal("can't initialize ssl");
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| 257 | if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) {
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| 258 | if (client)
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| 259 | fatal("can't read cert, key, or ca file");
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| 260 | fatal("can't read cert or key file");
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| 261 | }
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| 262 | if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0)
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| 263 | fatal("can't create ssl session");
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| 264 | #endif
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| 265 |
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| 266 | sig_block(SIGCHLD);
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| 267 | signal(SIGCHLD, sig_child_handler);
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| 268 | bb_signals(BB_FATAL_SIGS, sig_term_handler);
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| 269 | signal(SIGPIPE, SIG_IGN);
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| 270 |
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| 271 | if (max_per_host)
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| 272 | ipsvd_perhost_init(cmax);
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| 273 |
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| 274 | local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0);
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| 275 | lsa = xhost2sockaddr(argv[0], local_port);
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| 276 | argv += 2;
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| 277 |
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| 278 | sock = xsocket(lsa->u.sa.sa_family, tcp ? SOCK_STREAM : SOCK_DGRAM, 0);
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| 279 | setsockopt_reuseaddr(sock);
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| 280 | sa_len = lsa->len; /* I presume sockaddr len stays the same */
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| 281 | xbind(sock, &lsa->u.sa, sa_len);
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| 282 | if (tcp) {
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| 283 | xlisten(sock, backlog);
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| 284 | close_on_exec_on(sock);
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| 285 | } else { /* udp: needed for recv_from_to to work: */
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| 286 | socket_want_pktinfo(sock);
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| 287 | }
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| 288 | /* ndelay_off(sock); - it is the default I think? */
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| 289 |
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| 290 | #ifndef SSLSVD
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| 291 | if (opts & OPT_u) {
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| 292 | /* drop permissions */
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| 293 | xsetgid(ugid.gid);
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| 294 | xsetuid(ugid.uid);
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| 295 | }
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| 296 | #endif
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| 297 |
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| 298 | if (verbose) {
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| 299 | char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa);
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| 300 | if (opts & OPT_u)
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| 301 | bb_error_msg("listening on %s, starting, uid %u, gid %u", addr,
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| 302 | (unsigned)ugid.uid, (unsigned)ugid.gid);
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| 303 | else
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| 304 | bb_error_msg("listening on %s, starting", addr);
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| 305 | free(addr);
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| 306 | }
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| 307 |
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| 308 | /* Main accept() loop */
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| 309 |
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| 310 | again:
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| 311 | hccp = NULL;
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| 312 |
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| 313 | while (cnum >= cmax)
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| 314 | wait_for_any_sig(); /* expecting SIGCHLD */
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| 315 |
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| 316 | /* Accept a connection to fd #0 */
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| 317 | again1:
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| 318 | close(0);
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| 319 | again2:
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| 320 | sig_unblock(SIGCHLD);
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| 321 | local.len = remote.len = sa_len;
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| 322 | if (tcp) {
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| 323 | conn = accept(sock, &remote.u.sa, &remote.len);
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| 324 | } else {
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| 325 | /* In case recv_from_to won't be able to recover local addr.
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| 326 | * Also sets port - recv_from_to is unable to do it. */
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| 327 | local = *lsa;
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| 328 | conn = recv_from_to(sock, NULL, 0, MSG_PEEK,
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| 329 | &remote.u.sa, &local.u.sa, sa_len);
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| 330 | }
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| 331 | sig_block(SIGCHLD);
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| 332 | if (conn < 0) {
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| 333 | if (errno != EINTR)
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| 334 | bb_perror_msg(tcp ? "accept" : "recv");
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| 335 | goto again2;
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| 336 | }
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| 337 | xmove_fd(tcp ? conn : sock, 0);
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| 338 |
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| 339 | if (max_per_host) {
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| 340 | /* Drop connection immediately if cur_per_host > max_per_host
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| 341 | * (minimizing load under SYN flood) */
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| 342 | remote_addr = xmalloc_sockaddr2dotted_noport(&remote.u.sa);
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| 343 | cur_per_host = ipsvd_perhost_add(remote_addr, max_per_host, &hccp);
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| 344 | if (cur_per_host > max_per_host) {
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| 345 | /* ipsvd_perhost_add detected that max is exceeded
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| 346 | * (and did not store ip in connection table) */
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| 347 | free(remote_addr);
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| 348 | if (msg_per_host) {
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| 349 | /* don't block or test for errors */
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| 350 | send(0, msg_per_host, len_per_host, MSG_DONTWAIT);
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| 351 | }
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| 352 | goto again1;
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| 353 | }
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| 354 | /* NB: remote_addr is not leaked, it is stored in conn table */
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| 355 | }
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| 356 |
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| 357 | if (!tcp) {
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| 358 | /* Voodoo magic: making udp sockets each receive its own
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| 359 | * packets is not trivial, and I still not sure
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| 360 | * I do it 100% right.
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| 361 | * 1) we have to do it before fork()
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| 362 | * 2) order is important - is it right now? */
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| 363 |
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| 364 | /* Open new non-connected UDP socket for further clients... */
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| 365 | sock = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
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| 366 | setsockopt_reuseaddr(sock);
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| 367 | /* Make plain write/send work for old socket by supplying default
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| 368 | * destination address. This also restricts incoming packets
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| 369 | * to ones coming from this remote IP. */
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| 370 | xconnect(0, &remote.u.sa, sa_len);
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| 371 | /* hole? at this point we have no wildcard udp socket...
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| 372 | * can this cause clients to get "port unreachable" icmp?
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| 373 | * Yup, time window is very small, but it exists (is it?) */
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| 374 | /* ..."open new socket", continued */
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| 375 | xbind(sock, &lsa->u.sa, sa_len);
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| 376 | socket_want_pktinfo(sock);
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| 377 |
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| 378 | /* Doesn't work:
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| 379 | * we cannot replace fd #0 - we will lose pending packet
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| 380 | * which is already buffered for us! And we cannot use fd #1
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| 381 | * instead - it will "intercept" all following packets, but child
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| 382 | * does not expect data coming *from fd #1*! */
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| 383 | #if 0
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| 384 | /* Make it so that local addr is fixed to localp->u.sa
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| 385 | * and we don't accidentally accept packets to other local IPs. */
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| 386 | /* NB: we possibly bind to the _very_ same_ address & port as the one
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| 387 | * already bound in parent! This seems to work in Linux.
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| 388 | * (otherwise we can move socket to fd #0 only if bind succeeds) */
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| 389 | close(0);
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| 390 | set_nport(localp, htons(local_port));
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| 391 | xmove_fd(xsocket(localp->u.sa.sa_family, SOCK_DGRAM, 0), 0);
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| 392 | setsockopt_reuseaddr(0); /* crucial */
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| 393 | xbind(0, &localp->u.sa, localp->len);
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| 394 | #endif
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| 395 | }
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| 396 |
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| 397 | pid = vfork();
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| 398 | if (pid == -1) {
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| 399 | bb_perror_msg("vfork");
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| 400 | goto again;
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| 401 | }
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| 402 |
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| 403 | if (pid != 0) {
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| 404 | /* Parent */
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| 405 | cnum++;
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| 406 | if (verbose)
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| 407 | connection_status();
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| 408 | if (hccp)
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| 409 | hccp->pid = pid;
|
---|
| 410 | /* clean up changes done by vforked child */
|
---|
| 411 | undo_xsetenv();
|
---|
| 412 | goto again;
|
---|
| 413 | }
|
---|
| 414 |
|
---|
| 415 | /* Child: prepare env, log, and exec prog */
|
---|
| 416 |
|
---|
| 417 | { /* vfork alert! every xmalloc in this block should be freed! */
|
---|
| 418 | char *local_hostname = local_hostname; /* for compiler */
|
---|
| 419 | char *local_addr = NULL;
|
---|
| 420 | char *free_me0 = NULL;
|
---|
| 421 | char *free_me1 = NULL;
|
---|
| 422 | char *free_me2 = NULL;
|
---|
| 423 |
|
---|
| 424 | if (verbose || !(opts & OPT_E)) {
|
---|
| 425 | if (!max_per_host) /* remote_addr is not yet known */
|
---|
| 426 | free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
|
---|
| 427 | if (opts & OPT_h) {
|
---|
| 428 | free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
|
---|
| 429 | if (!remote_hostname) {
|
---|
| 430 | bb_error_msg("can't look up hostname for %s", remote_addr);
|
---|
| 431 | remote_hostname = remote_addr;
|
---|
| 432 | }
|
---|
| 433 | }
|
---|
| 434 | /* Find out local IP peer connected to.
|
---|
| 435 | * Errors ignored (I'm not paranoid enough to imagine kernel
|
---|
| 436 | * which doesn't know local IP). */
|
---|
| 437 | if (tcp)
|
---|
| 438 | getsockname(0, &local.u.sa, &local.len);
|
---|
| 439 | /* else: for UDP it is done earlier by parent */
|
---|
| 440 | local_addr = xmalloc_sockaddr2dotted(&local.u.sa);
|
---|
| 441 | if (opts & OPT_h) {
|
---|
| 442 | local_hostname = preset_local_hostname;
|
---|
| 443 | if (!local_hostname) {
|
---|
| 444 | free_me2 = local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa);
|
---|
| 445 | if (!local_hostname)
|
---|
| 446 | bb_error_msg_and_die("can't look up hostname for %s", local_addr);
|
---|
| 447 | }
|
---|
| 448 | /* else: local_hostname is not NULL, but is NOT malloced! */
|
---|
| 449 | }
|
---|
| 450 | }
|
---|
| 451 | if (verbose) {
|
---|
| 452 | pid = getpid();
|
---|
| 453 | if (max_per_host) {
|
---|
| 454 | bb_error_msg("concurrency %s %u/%u",
|
---|
| 455 | remote_addr,
|
---|
| 456 | cur_per_host, max_per_host);
|
---|
| 457 | }
|
---|
| 458 | bb_error_msg((opts & OPT_h)
|
---|
| 459 | ? "start %u %s-%s (%s-%s)"
|
---|
| 460 | : "start %u %s-%s",
|
---|
| 461 | pid,
|
---|
| 462 | local_addr, remote_addr,
|
---|
| 463 | local_hostname, remote_hostname);
|
---|
| 464 | }
|
---|
| 465 |
|
---|
| 466 | if (!(opts & OPT_E)) {
|
---|
| 467 | /* setup ucspi env */
|
---|
| 468 | const char *proto = tcp ? "TCP" : "UDP";
|
---|
| 469 |
|
---|
| 470 | #ifdef SO_ORIGINAL_DST
|
---|
| 471 | /* Extract "original" destination addr:port
|
---|
| 472 | * from Linux firewall. Useful when you redirect
|
---|
| 473 | * an outbond connection to local handler, and it needs
|
---|
| 474 | * to know where it originally tried to connect */
|
---|
| 475 | if (tcp && getsockopt(0, SOL_IP, SO_ORIGINAL_DST, &local.u.sa, &local.len) == 0) {
|
---|
| 476 | char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
|
---|
| 477 | xsetenv_plain("TCPORIGDSTADDR", addr);
|
---|
| 478 | free(addr);
|
---|
| 479 | }
|
---|
| 480 | #endif
|
---|
| 481 | xsetenv_plain("PROTO", proto);
|
---|
| 482 | xsetenv_proto(proto, "LOCALADDR", local_addr);
|
---|
| 483 | xsetenv_proto(proto, "REMOTEADDR", remote_addr);
|
---|
| 484 | if (opts & OPT_h) {
|
---|
| 485 | xsetenv_proto(proto, "LOCALHOST", local_hostname);
|
---|
| 486 | xsetenv_proto(proto, "REMOTEHOST", remote_hostname);
|
---|
| 487 | }
|
---|
| 488 | //compat? xsetenv_proto(proto, "REMOTEINFO", "");
|
---|
| 489 | /* additional */
|
---|
| 490 | if (cur_per_host > 0) /* can not be true for udp */
|
---|
| 491 | xsetenv_plain("TCPCONCURRENCY", utoa(cur_per_host));
|
---|
| 492 | }
|
---|
| 493 | free(local_addr);
|
---|
| 494 | free(free_me0);
|
---|
| 495 | free(free_me1);
|
---|
| 496 | free(free_me2);
|
---|
| 497 | }
|
---|
| 498 |
|
---|
| 499 | xdup2(0, 1);
|
---|
| 500 |
|
---|
| 501 | signal(SIGPIPE, SIG_DFL); /* this one was SIG_IGNed */
|
---|
| 502 | /* Non-ignored signals revert to SIG_DFL on exec anyway */
|
---|
| 503 | /*signal(SIGCHLD, SIG_DFL);*/
|
---|
| 504 | sig_unblock(SIGCHLD);
|
---|
| 505 |
|
---|
| 506 | #ifdef SSLSVD
|
---|
| 507 | strcpy(id, utoa(pid));
|
---|
| 508 | ssl_io(0, argv);
|
---|
| 509 | bb_perror_msg_and_die("can't execute '%s'", argv[0]);
|
---|
| 510 | #else
|
---|
| 511 | BB_EXECVP_or_die(argv);
|
---|
| 512 | #endif
|
---|
| 513 | }
|
---|
| 514 |
|
---|
| 515 | /*
|
---|
| 516 | tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name]
|
---|
| 517 | [-i dir|-x cdb] [ -t sec] host port prog
|
---|
| 518 |
|
---|
| 519 | tcpsvd creates a TCP/IP socket, binds it to the address host:port,
|
---|
| 520 | and listens on the socket for incoming connections.
|
---|
| 521 |
|
---|
| 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.
|
---|
| 527 |
|
---|
| 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).
|
---|
| 531 |
|
---|
| 532 | host
|
---|
| 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
|
---|
| 535 | IP address.
|
---|
| 536 | * busybox accepts IPv6 addresses and host:port pairs too
|
---|
| 537 | In this case second parameter is ignored
|
---|
| 538 | port
|
---|
| 539 | tcpsvd accepts connections to host:port. port may be a name
|
---|
| 540 | from /etc/services or a number.
|
---|
| 541 | prog
|
---|
| 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,
|
---|
| 546 | see tcp-environ(5)
|
---|
| 547 | -i dir
|
---|
| 548 | read instructions for handling new connections from the instructions
|
---|
| 549 | directory dir. See ipsvd-instruct(5) for details.
|
---|
| 550 | * ignored by busyboxed version
|
---|
| 551 | -x cdb
|
---|
| 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
|
---|
| 556 | -t sec
|
---|
| 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
|
---|
| 565 | -l name
|
---|
| 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
|
---|
| 568 | to avoid loops.
|
---|
| 569 | -u user[:group]
|
---|
| 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.
|
---|
| 574 | -c n
|
---|
| 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.
|
---|
| 578 | -C n[:msg]
|
---|
| 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.
|
---|
| 585 |
|
---|
| 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.
|
---|
| 590 | -h
|
---|
| 591 | Look up the client's hostname in DNS.
|
---|
| 592 | -p
|
---|
| 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
|
---|
| 599 | -b n
|
---|
| 600 | backlog. Allow a backlog of approximately n TCP SYNs. On some systems n
|
---|
| 601 | is silently limited. Default is 20.
|
---|
| 602 | -E
|
---|
| 603 | no special environment. Do not set up TCP-related environment variables.
|
---|
| 604 | -v
|
---|
| 605 | verbose. Print verbose messsages to standard output.
|
---|
| 606 | -vv
|
---|
| 607 | more verbose. Print more verbose messages to standard output.
|
---|
| 608 | * no difference between -v and -vv in busyboxed version
|
---|
| 609 | */
|
---|