| /* 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 tarball for details. |
| */ |
| |
| /* Based on ipsvd 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. |
| * |
| * Output of verbose mode matches original (modulo bugs and |
| * unimplemented stuff). Unnatural splitting of IP and PORT |
| * is retained (personally I prefer one-value "IP:PORT" notation - |
| * it is a natural string representation of struct sockaddr_XX). |
| * |
| * TCPORIGDST{IP,PORT} 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 |
| * with wrong source IP... |
| * - don't know how to retrieve ORIGDST for udp. |
| */ |
| |
| #include <limits.h> |
| #include <linux/netfilter_ipv4.h> /* wants <limits.h> */ |
| |
| #include "libbb.h" |
| #include "ipsvd_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; |
| unsigned cmax; |
| }; |
| #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 INIT_G() \ |
| do { \ |
| cmax = 30; \ |
| } while (0) |
| |
| |
| static void xsetenv_proto(const char *proto, const char *n, const char *v) |
| { |
| putenv(xasprintf("%s%s=%s", proto, n, v)); |
| } |
| |
| static void sig_term_handler(int sig) |
| { |
| if (verbose) |
| printf("%s: info: sigterm received, exit\n", applet_name); |
| 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); |
| } |
| printf("%s: info: end %d %s %d\n", applet_name, 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) |
| { |
| /* "only 1 client max" desn't need this */ |
| if (cmax > 1) |
| printf("%s: info: status %u/%u\n", applet_name, cnum, cmax); |
| } |
| |
| static void sig_child_handler(int sig) |
| { |
| int wstat; |
| int 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; |
| int tcpudpsvd_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 */ |
| #ifndef SSLSVD |
| struct bb_uidgid_t ugid; |
| #endif |
| bool need_hostnames, need_remote_ip, tcp; |
| uint16_t local_port; |
| char *local_hostname = NULL; |
| char *remote_hostname = (char*)""; /* "" used if no -h */ |
| char *local_addr = local_addr; /* gcc */ |
| char *remote_addr = remote_addr; /* gcc */ |
| char *remote_ip = remote_addr; /* gcc */ |
| len_and_sockaddr *lsa; |
| len_and_sockaddr local, remote; |
| socklen_t sa_len; |
| int pid; |
| int sock; |
| int conn; |
| unsigned backlog = 20; |
| |
| INIT_G(); |
| |
| tcp = (applet_name[0] == 't'); |
| |
| /* 3+ args, -i at most once, -p implies -h, -v is counter */ |
| opt_complementary = "-3:i--i:ph:vv"; |
| #ifdef SSLSVD |
| getopt32(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(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); |
| #ifdef SSLSVD |
| if (option_mask32 & OPT_U) ssluser = optarg; |
| if (option_mask32 & OPT_slash) root = optarg; |
| if (option_mask32 & OPT_Z) cert = optarg; |
| if (option_mask32 & 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; |
| |
| /* stdout is used for logging, don't buffer */ |
| setlinebuf(stdout); |
| bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */ |
| |
| need_hostnames = verbose || !(option_mask32 & OPT_E); |
| need_remote_ip = max_per_host || need_hostnames; |
| |
| #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) { |
| bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser); |
| } |
| 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); |
| |
| local_port = bb_lookup_port(argv[1], tcp ? "tcp" : "udp", 0); |
| lsa = xhost2sockaddr(argv[0], local_port); |
| 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); |
| 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 (option_mask32 & OPT_u) { |
| /* drop permissions */ |
| xsetgid(ugid.gid); |
| xsetuid(ugid.uid); |
| } |
| #endif |
| |
| if (verbose) { |
| char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa); |
| 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.gid); |
| #endif |
| puts(", starting"); |
| } |
| |
| /* Main accept() loop */ |
| |
| again: |
| hccp = NULL; |
| |
| while (cnum >= cmax) |
| wait_for_any_sig(); /* expecting SIGCHLD */ |
| |
| /* Accept a connection to fd #0 */ |
| again1: |
| close(0); |
| again2: |
| sig_unblock(SIGCHLD); |
| if (tcp) { |
| remote.len = sa_len; |
| conn = accept(sock, &remote.u.sa, &remote.len); |
| } else { |
| /* 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_ip = xmalloc_sockaddr2dotted_noport(&remote.u.sa); |
| 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 ip in connection table) */ |
| free(remote_ip); |
| if (msg_per_host) { |
| /* don't block or test for errors */ |
| ndelay_on(0); |
| write(0, msg_per_host, len_per_host); |
| } |
| goto again1; |
| } |
| } |
| |
| 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 |
| * 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, 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 = fork(); |
| if (pid == -1) { |
| bb_perror_msg("fork"); |
| goto again; |
| } |
| |
| if (pid != 0) { |
| /* parent */ |
| cnum++; |
| if (verbose) |
| connection_status(); |
| if (hccp) |
| hccp->pid = pid; |
| goto again; |
| } |
| |
| /* Child: prepare env, log, and exec prog */ |
| |
| /* Closing tcp listening socket */ |
| if (tcp) |
| close(sock); |
| |
| if (need_remote_ip) |
| remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa); |
| |
| if (need_hostnames) { |
| if (option_mask32 & OPT_h) { |
| remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa); |
| if (!remote_hostname) { |
| bb_error_msg("warning: cannot look up hostname for %s", remote_addr); |
| remote_hostname = (char*)""; |
| } |
| } |
| /* 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) { |
| local.len = sa_len; |
| getsockname(0, &local.u.sa, &local.len); |
| } |
| local_addr = xmalloc_sockaddr2dotted(&local.u.sa); |
| if (!local_hostname) { |
| local_hostname = xmalloc_sockaddr2host_noport(&local.u.sa); |
| if (!local_hostname) |
| bb_error_msg_and_die("warning: cannot look up hostname for %s"+9, local_addr); |
| } |
| } |
| |
| if (verbose) { |
| pid = getpid(); |
| printf("%s: info: pid %u from %s\n", applet_name, pid, remote_addr); |
| if (max_per_host) |
| printf("%s: info: concurrency %u %s %u/%u\n", |
| applet_name, pid, remote_ip, cur_per_host, max_per_host); |
| printf("%s: info: start %u %s:%s :%s:%s\n", |
| applet_name, pid, |
| local_hostname, local_addr, |
| remote_hostname, remote_addr); |
| } |
| |
| if (!(option_mask32 & OPT_E)) { |
| /* setup ucspi env */ |
| const char *proto = tcp ? "TCP" : "UDP"; |
| |
| /* 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, &lsa->u.sa, &lsa->len) == 0) { |
| char *addr = xmalloc_sockaddr2dotted(&lsa->u.sa); |
| xsetenv("TCPORIGDSTADDR", addr); |
| free(addr); |
| } |
| xsetenv("PROTO", proto); |
| xsetenv_proto(proto, "LOCALADDR", local_addr); |
| xsetenv_proto(proto, "LOCALHOST", local_hostname); |
| xsetenv_proto(proto, "REMOTEADDR", remote_addr); |
| if (option_mask32 & OPT_h) { |
| xsetenv_proto(proto, "REMOTEHOST", remote_hostname); |
| } |
| xsetenv_proto(proto, "REMOTEINFO", ""); |
| /* additional */ |
| if (cur_per_host > 0) /* can not be true for udp */ |
| xsetenv("TCPCONCURRENCY", utoa(cur_per_host)); |
| } |
| |
| 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. |
| * 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 messsages to standard output. |
| -vv |
| more verbose. Print more verbose messages to standard output. |
| * no difference between -v and -vv in busyboxed version |
| */ |