diff options
Diffstat (limited to 'ipsvd/tcpsvd.c')
| -rw-r--r-- | ipsvd/tcpsvd.c | 514 |
1 files changed, 514 insertions, 0 deletions
diff --git a/ipsvd/tcpsvd.c b/ipsvd/tcpsvd.c new file mode 100644 index 0000000..9a0a348 --- /dev/null +++ b/ipsvd/tcpsvd.c @@ -0,0 +1,514 @@ +/* +# /usr/bin/tcpsvd -v 0 1234 true +tcpsvd: info: pid 24916 from 127.0.0.1 +tcpsvd: info: start 24916 localhost:127.0.0.1 ::127.0.0.1:47905 +tcpsvd: info: pid 24918 from 127.0.0.1 +tcpsvd: info: start 24918 localhost:127.0.0.1 ::127.0.0.1:47906 +# ./busybox tcpsvd -v 0 1234 true +tcpsvd: info: pid 24924 from 127.0.0.1 +tcpsvd: info: start 24924 localhost:1234:127.0.0.1:1234 ::127.0.0.1:47908 +tcpsvd: info: pid 24926 from 127.0.0.1 +tcpsvd: info: start 24926 localhost:1234:127.0.0.1:1234 ::127.0.0.1:47909 +*/ + +#include "busybox.h" +#include "ipsvd_perhost.h" + +#ifdef SSLSVD +#include "matrixSsl.h" +#include "ssl_io.h" +#endif + + +static unsigned max_per_host; /* originally in ipsvd_check.c */ +static unsigned cur_per_host; +static unsigned verbose; +static unsigned cnum; +static unsigned cmax = 30; + +/* 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), + OPT_slash = (1 << 14), + OPT_Z = (1 << 15), + OPT_K = (1 << 16), +}; + +static void connection_status(void) +{ + printf("%s: info: status %u/%u\n", applet_name, cnum, cmax); +} + +static void sig_term_handler(int sig) +{ + if (verbose) + printf("%s: info: sigterm received, exit\n", applet_name); + exit(0); +} + +static void sig_child_handler(int sig) +{ + int wstat; + int pid; + + while ((pid = wait_nohang(&wstat)) > 0) { + if (max_per_host) + ipsvd_perhost_remove(pid); + if (cnum) + cnum--; + if (verbose) { + /* Little bloated, but tries to give accurate info + * how child exited. Makes easier to spot segfaulting + * children etc... */ + unsigned e = 0; + const char *cause = "?exit"; + if (WIFEXITED(wstat)) { + cause++; + e = WEXITSTATUS(wstat); + } else if (WIFSIGNALED(wstat)) { + cause = "signal"; + e = WTERMSIG(wstat); + } + printf("%s: info: end %d %s %d\n", + applet_name, pid, cause, e); + } + } + if (verbose) + connection_status(); +} + +int tcpsvd_main(int argc, char **argv); +int tcpsvd_main(int argc, char **argv) +{ + char *str_c, *str_C, *str_b, *str_t; + char *user; + struct hcc *hccp; + const char *instructs; + char *msg_per_host = NULL; + unsigned len_per_host = len_per_host; /* gcc */ + int need_addresses; + int pid; + int sock; + int conn; + unsigned backlog = 20; + union { + struct sockaddr sa; + struct sockaddr_in sin; + USE_FEATURE_IPV6(struct sockaddr_in6 sin6;) + } sock_adr; + socklen_t sockadr_size; + uint16_t local_port = local_port; + uint16_t remote_port; + unsigned port; + char *local_hostname = NULL; + char *remote_hostname = (char*)""; /* "" used if no -h */ + char *local_ip = local_ip; + char *remote_ip = NULL; + //unsigned iscdb = 0; /* = option_mask32 & OPT_x (TODO) */ + //unsigned long timeout = 0; +#ifndef SSLSVD + struct bb_uidgid_t ugid; +#endif + + /* 3+ args, -i at most once, -p implies -h, -v is counter */ + opt_complementary = "-3:?:i--i:ph:vv"; +#ifdef SSLSVD + getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:", + &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, + &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose + ); +#else + getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:v", + &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, + &str_b, &str_t, &verbose + ); +#endif + if (option_mask32 & OPT_c) + cmax = xatou_range(str_c, 1, INT_MAX); + if (option_mask32 & 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 (option_mask32 & OPT_u) { + if (!get_uidgid(&ugid, user, 1)) + bb_error_msg_and_die("unknown user/group: %s", user); + } + if (option_mask32 & OPT_b) + backlog = xatou(str_b); +// if (option_mask32 & OPT_t) timeout = xatou(str_t); +#ifdef SSLSVD + if (option_mask32 & OPT_U) ssluser = (char*)optarg; break; + if (option_mask32 & OPT_slash) root = (char*)optarg; break; + if (option_mask32 & OPT_Z) cert = (char*)optarg; break; + if (option_mask32 & OPT_K) key = (char*)optarg; break; +#endif + argv += optind; + if (!argv[0][0] || LONE_CHAR(argv[0], '0')) + argv[0] = (char*)"0.0.0.0"; + + need_addresses = verbose || !(option_mask32 & OPT_E); + +#ifdef SSLSVD + sslser = user; + client = 0; + if ((getuid() == 0) && !(option_mask32 & OPT_u)) { + xfunc_exitcode = 100; + bb_error_msg_and_die("fatal: -U ssluser must be set when running as root"); + } + if (option_mask32 & OPT_u) + if (!uidgid_get(&sslugid, ssluser, 1)) { + if (errno) { + xfunc_exitcode = 100; + bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser); + } + xfunc_exitcode = 111; + bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser); + } + if (!cert) cert = "./cert.pem"; + if (!key) key = cert; + if (matrixSslOpen() < 0) + fatal("cannot initialize ssl"); + if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) { + if (client) + fatal("cannot read cert, key, or ca file"); + fatal("cannot read cert or key file"); + } + if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0) + fatal("cannot create ssl session"); +#endif + + sig_block(SIGCHLD); + signal(SIGCHLD, sig_child_handler); + signal(SIGTERM, sig_term_handler); + signal(SIGPIPE, SIG_IGN); + + if (max_per_host) + ipsvd_perhost_init(cmax); + + port = bb_lookup_port(argv[1], "tcp", 0); + sock = create_and_bind_stream_or_die(argv[0], port); + xlisten(sock, backlog); + /* ndelay_off(sock); - it is the default I think? */ + +#ifndef SSLSVD + if (option_mask32 & OPT_u) { + /* drop permissions */ + xsetgid(ugid.gid); + xsetuid(ugid.uid); + } +#endif + bb_sanitize_stdio(); /* fd# 1,2 must be opened */ + close(0); + + if (verbose) { + /* we do it only for ":port" cosmetics... oh well */ + len_and_sockaddr *lsa = xhost2sockaddr(argv[0], port); + char *addr = xmalloc_sockaddr2dotted(&lsa->sa, lsa->len); + + printf("%s: info: listening on %s", applet_name, addr); + free(addr); +#ifndef SSLSVD + if (option_mask32 & OPT_u) + printf(", uid %u, gid %u", + (unsigned)ugid.uid, (unsigned)ugid.uid); +#endif + puts(", starting"); + } + + /* The rest is a main accept() loop */ + + again: + hccp = NULL; + + while (cnum >= cmax) + sig_pause(); /* wait for any signal (expecting SIGCHLD) */ + + sockadr_size = sizeof(sock_adr); + sig_unblock(SIGCHLD); + conn = accept(sock, &sock_adr.sa, &sockadr_size); + sig_block(SIGCHLD); + if (conn == -1) { + if (errno != EINTR) + bb_perror_msg("accept"); + goto again; + } + + if (max_per_host) { + /* we drop connection immediately if cur_per_host > max_per_host + * (minimizing load under SYN flood) */ + free(remote_ip); + remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size); + cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp); + if (cur_per_host > max_per_host) { + /* ipsvd_perhost_add detected that max is exceeded + * (and did not store us in connection table) */ + if (msg_per_host) { + ndelay_on(conn); + /* don't test for errors */ + write(conn, msg_per_host, len_per_host); + } + close(conn); + goto again; + } + } + + cnum++; + if (verbose) + connection_status(); + + pid = fork(); + if (pid == -1) { + bb_perror_msg("fork"); + close(conn); + goto again; + } + if (pid != 0) { + /* parent */ + close(conn); + if (hccp) + hccp->pid = pid; + goto again; + } + + /* Child: prepare env, log, and exec prog */ + + close(sock); + + if (!max_per_host) + remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sizeof(sock_adr)); + /* else it is already done */ + + remote_port = get_nport(&sock_adr.sa); + remote_port = ntohs(remote_port); + + if (verbose) { + pid = getpid(); + printf("%s: info: pid %d from %s\n", applet_name, pid, remote_ip); + } + + if (need_addresses && (option_mask32 & OPT_h)) { + remote_hostname = xmalloc_sockaddr2host(&sock_adr.sa, sizeof(sock_adr)); + if (!remote_hostname) { + bb_error_msg("warning: cannot look up hostname for %s", remote_ip); + remote_hostname = (char*)""; + } + } + + sockadr_size = sizeof(sock_adr); + /* Errors ignored (I'm not paranoid enough to imagine kernel + * which doesn't know local ip) */ + getsockname(conn, &sock_adr.sa, &sockadr_size); + + if (need_addresses) { + local_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size); + local_port = get_nport(&sock_adr.sa); + local_port = ntohs(local_port); + if (!local_hostname) { + local_hostname = xmalloc_sockaddr2host_noport(&sock_adr.sa, sockadr_size); + if (!local_hostname) + bb_error_msg_and_die("cannot look up local hostname for %s", local_ip); + } + } + + if (!(option_mask32 & OPT_E)) { + /* setup ucspi env */ + xsetenv("PROTO", "TCP"); + xsetenv("TCPLOCALIP", local_ip); + xsetenv("TCPLOCALPORT", utoa(local_port)); + xsetenv("TCPLOCALHOST", local_hostname); + xsetenv("TCPREMOTEIP", remote_ip); + xsetenv("TCPREMOTEPORT", utoa(remote_port)); + if (option_mask32 & OPT_h) { + xsetenv("TCPREMOTEHOST", remote_hostname); + } + xsetenv("TCPREMOTEINFO", ""); + /* additional */ + if (cur_per_host > 0) + xsetenv("TCPCONCURRENCY", utoa(cur_per_host)); + } + +#if 0 + if (instructs) { + ac = ipsvd_check(iscdb, &inst, &match, (char*)instructs, + remote_ip, remote_hostname, timeout); + if (ac == -1) drop2("cannot check inst", remote_ip); + if (ac == IPSVD_ERR) drop2("cannot read", (char*)instructs); + } else + ac = IPSVD_DEFAULT; +#endif + + if (max_per_host && verbose) + printf("%s: info: concurrency %u %s %u/%u\n", + applet_name, pid, remote_ip, cur_per_host, max_per_host); + + if (verbose) { + printf("%s: info: start %u %s:%s :%s:%s:%u\n", + applet_name, pid, + local_hostname, local_ip, + remote_hostname, remote_ip, (unsigned)remote_port); +#if 0 + switch(ac) { + case IPSVD_DENY: + printf("deny "); break; + case IPSVD_DEFAULT: + case IPSVD_INSTRUCT: + printf("start "); break; + case IPSVD_EXEC: + printf("exec "); break; + } + ... + if (instructs) { + printf(" "); + if (iscdb) { + printf((char*)instructs); + printf("/"); + } + outfix(match.s); + if(inst.s && inst.len && (verbose > 1)) { + printf(": "); + printf(&inst); + } + } + printf("\n"); +#endif + } + +#if 0 + if (ac == IPSVD_DENY) { + close(conn); + _exit(100); + } + if (ac == IPSVD_EXEC) { + args[0] = "/bin/sh"; + args[1] = "-c"; + args[2] = inst.s; + args[3] = 0; + run = args; + } else + run = argv + 2; /* below: we use argv+2 (was using run) */ +#endif + + xmove_fd(conn, 0); + dup2(0, 1); + signal(SIGTERM, SIG_DFL); + signal(SIGPIPE, SIG_DFL); + signal(SIGCHLD, SIG_DFL); + sig_unblock(SIGCHLD); + + argv += 2; +#ifdef SSLSVD + strcpy(id, utoa(pid); + ssl_io(0, argv); +#else + BB_EXECVP(argv[0], argv); +#endif + bb_perror_msg_and_die("exec '%s'", argv[0]); +} + +/* +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. +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. +-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). +-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. +-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. +-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 messsages to standard output. +-vv + more verbose. Print more verbose messages to standard output. +*/ |