1 files changed, 609 insertions, 0 deletions

diff --git a/networking/tcpudp.c b/networking/tcpudp.c
new file mode 100644
index 000000000..f97787497
--- /dev/null
+++ b/networking/tcpudp.c
@@ -0,0 +1,609 @@
+/* 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-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
+ *   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"
+// 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;
+        unsigned cmax;
+        char **env_cur;
+        char *env_var[1]; /* actually bigger */
+};
+#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     )
+#define INIT_G() \
+        do { \
+                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;
+                *strchrnul(var, '=') = '\0';
+                unsetenv(var);
+                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)
+{
+        /* "only 1 client max" desn't need this */
+        if (cmax > 1)
+                bb_error_msg("status %u/%u", cnum, cmax);
+}
+
+static void sig_child_handler(int sig ATTRIBUTE_UNUSED)
+{
+        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 ATTRIBUTE_UNUSED, 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;
+
+        INIT_G();
+
+        tcp = (applet_name[0] == 't');
+
+        /* 3+ args, -i at most once, -p implies -h, -v is counter, -b N, -c N */
+        opt_complementary = "-3:i--i:ph:vv:b+:c+";
+#ifdef SSLSVD
+        getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:",
+                &cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
+                &backlog, &str_t, &ssluser, &root, &cert, &key, &verbose
+        );
+#else
+        /* "+": stop on first non-option */
+        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 (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);
+        }
+#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;
+
+        bb_sanitize_stdio(); /* fd# 0,1,2 must be opened */
+
+#ifdef SSLSVD
+        sslser = user;
+        client = 0;
+        if ((getuid() == 0) && !(option_mask32 & OPT_u)) {
+                xfunc_exitcode = 100;
+                bb_error_msg_and_die("-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("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);
+        bb_signals(BB_SIGS_FATAL, 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);
+        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);
+                bb_error_msg("listening on %s, starting", addr);
+                free(addr);
+#ifndef SSLSVD
+                if (option_mask32 & OPT_u)
+                        printf(", uid %u, gid %u",
+                                (unsigned)ugid.uid, (unsigned)ugid.gid);
+#endif
+        }
+
+        /* 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);
+        local.len = remote.len = sa_len;
+        if (tcp) {
+                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_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
+                 * 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 = 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 */
+
+        /* Closing tcp listening socket */
+        if (tcp)
+                close(sock);
+
+        { /* 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 || !(option_mask32 & OPT_E)) {
+                        if (!max_per_host) /* remote_addr is not yet known */
+                                free_me0 = remote_addr = xmalloc_sockaddr2dotted(&remote.u.sa);
+                        if (option_mask32 & OPT_h) {
+                                free_me1 = remote_hostname = xmalloc_sockaddr2host_noport(&remote.u.sa);
+                                if (!remote_hostname) {
+                                        bb_error_msg("cannot 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 (option_mask32 & 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("cannot 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((option_mask32 & OPT_h)
+                                ? "start %u %s-%s (%s-%s)"
+                                : "start %u %s-%s",
+                                pid,
+                                local_addr, remote_addr,
+                                local_hostname, remote_hostname);
+                }
+
+                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, &local.u.sa, &local.len) == 0) {
+                                char *addr = xmalloc_sockaddr2dotted(&local.u.sa);
+                                xsetenv_plain("TCPORIGDSTADDR", addr);
+                                free(addr);
+                        }
+                        xsetenv_plain("PROTO", proto);
+                        xsetenv_proto(proto, "LOCALADDR", local_addr);
+                        xsetenv_proto(proto, "REMOTEADDR", remote_addr);
+                        if (option_mask32 & 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(SIGTERM, SIG_DFL);
+        signal(SIGPIPE, SIG_DFL);
+        signal(SIGCHLD, SIG_DFL);
+        sig_unblock(SIGCHLD);
+
+#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
+*/