Exemplo n.º 1
0
/* Handle --exec if appropriate, otherwise start the initial read events and set
   the idle timeout. */
static void post_connect(nsock_pool nsp, nsock_iod iod)
{
    /* Command to execute. */
    if (o.cmdexec) {
        struct fdinfo info;

        info.fd = nsi_getsd(iod);
#ifdef HAVE_OPENSSL
        info.ssl = (SSL *) nsi_getssl(iod);
#endif
        /* Convert Nsock's non-blocking socket to an ordinary blocking one. It's
           possible for a program to write fast enough that it will get an
           EAGAIN on write on a non-blocking socket. */
        block_socket(info.fd);
        netexec(&info, o.cmdexec);
    }

    /* Start the initial reads. */

    if (!o.sendonly)
        nsock_read(nsp, cs.sock_nsi, read_socket_handler, -1, NULL);

    if (!o.recvonly)
        nsock_readbytes(nsp, cs.stdin_nsi, read_stdin_handler, -1, NULL, 0);

    /* The --idle-timeout option says to exit after a certain period of
       inactivity. We start a timer here and reset it on every read event; see
       refresh_idle_timer. */
    if (o.idletimeout > 0) {
        cs.idle_timer_event_id =
            nsock_timer_create(nsp, idle_timer_handler, o.idletimeout, NULL);
    }
}
Exemplo n.º 2
0
/* This function handles the post connection specific actions that are needed
 * after a socket has been initialized(normal socket or ssl socket). */
static void post_handle_connection(struct fdinfo sinfo)
{
    /*
     * Are we executing a command? If so then don't add this guy
     * to our descriptor list or set.
     */
    if (o.cmdexec) {
        if (o.keepopen)
            netrun(&sinfo, o.cmdexec);
        else
            netexec(&sinfo, o.cmdexec);
    } else {
        /* Now that a client is connected, pay attention to stdin. */
        if (!stdin_eof)
            FD_SET(STDIN_FILENO, &master_readfds);
        if (!o.sendonly) {
            /* add to our lists */
            FD_SET(sinfo.fd, &master_readfds);
            /* add it to our list of fds for maintaining maxfd */
#ifdef HAVE_OPENSSL
            /* Don't add it twice (see handle_connection above) */
            if (!o.ssl)
#endif
            if (add_fdinfo(&client_fdlist, &sinfo) < 0)
                bye("add_fdinfo() failed.");
        }
        FD_SET(sinfo.fd, &master_broadcastfds);
        if (add_fdinfo(&broadcast_fdlist, &sinfo) < 0)
            bye("add_fdinfo() failed.");

        if (o.chat)
            chat_announce_connect(sinfo.fd, &sinfo.remoteaddr);
    }
}
Exemplo n.º 3
0
/* fork and exec a child process with netexec. Close the given file descriptor
   in the parent process. Return the child's PID or -1 on error. */
int netrun(struct fdinfo *info, char *cmdexec)
{
    int pid;

    errno = 0;
    pid = fork();
    if (pid == 0) {
        /* In the child process. */
        netexec(info, cmdexec);
    }

    Close(info->fd);

    if (pid == -1 && o.verbose)
        logdebug("Error in fork: %s\n", strerror(errno));

    return pid;
}
Exemplo n.º 4
0
/* This is sufficiently different from the TCP code (wrt SSL, etc) that it
 * resides in its own simpler function
 */
static int ncat_listen_dgram(int proto)
{
    struct {
        int fd;
        union sockaddr_u addr;
    } sockfd[NUM_LISTEN_ADDRS];
    int i, fdn = -1;
    int fdmax, nbytes, n, fds_ready;
    char buf[DEFAULT_UDP_BUF_LEN] = { 0 };
    char *tempbuf = NULL;
    fd_set read_fds;
    union sockaddr_u remotess;
    socklen_t sslen = sizeof(remotess.storage);
    struct timeval tv;
    struct timeval *tvp = NULL;
    unsigned int num_sockets;

    for (i = 0; i < NUM_LISTEN_ADDRS; i++) {
        sockfd[i].fd = -1;
        sockfd[i].addr.storage.ss_family = AF_UNSPEC;
    }

    FD_ZERO(&read_fds);

    /* Initialize remotess struct so recvfrom() doesn't hit the fan.. */
    zmem(&remotess.storage, sizeof(remotess.storage));
    remotess.storage.ss_family = o.af;

#ifdef WIN32
    set_pseudo_sigchld_handler(decrease_conn_count);
#else
    /* Reap on SIGCHLD */
    Signal(SIGCHLD, sigchld_handler);
    /* Ignore the SIGPIPE that occurs when a client disconnects suddenly and we
       send data to it before noticing. */
    Signal(SIGPIPE, SIG_IGN);
#endif

/* Not sure if this problem exists on Windows, but fcntl and /dev/null don't */
#ifndef WIN32
    /* Check whether stdin is closed. Because we treat this fd specially, we
     * can't risk it being reopened for an incoming connection, so we'll hold
     * it open instead. */
    if (fcntl(STDIN_FILENO, F_GETFD) == -1 && errno == EBADF) {
      logdebug("stdin is closed, attempting to reserve STDIN_FILENO\n");
      i = open("/dev/null", O_RDONLY);
      if (i >= 0 && i != STDIN_FILENO) {
        /* Oh well, we tried */
        logdebug("Couldn't reserve STDIN_FILENO\n");
        close(i);
      }
    }
#endif

    /* set for selecting udp listening sockets */
    fd_set listen_fds;
    fd_list_t listen_fdlist;
    FD_ZERO(&listen_fds);
    init_fdlist(&listen_fdlist, num_listenaddrs);

    num_sockets = 0;
    for (i = 0; i < num_listenaddrs; i++) {
        /* create the UDP listen sockets */
        sockfd[num_sockets].fd = do_listen(SOCK_DGRAM, proto, &listenaddrs[i]);
        if (sockfd[num_sockets].fd == -1) {
            if (o.debug > 0)
                logdebug("do_listen(\"%s\"): %s\n", inet_ntop_ez(&listenaddrs[i].storage, sizeof(listenaddrs[i].storage)), socket_strerror(socket_errno()));
            continue;
        }
        FD_SET(sockfd[num_sockets].fd, &listen_fds);
        add_fd(&listen_fdlist, sockfd[num_sockets].fd);
        sockfd[num_sockets].addr = listenaddrs[i];
        num_sockets++;
    }
    if (num_sockets == 0) {
        if (num_listenaddrs == 1)
            bye("Unable to open listening socket on %s: %s", inet_ntop_ez(&listenaddrs[0].storage, sizeof(listenaddrs[0].storage)), socket_strerror(socket_errno()));
        else
            bye("Unable to open any listening sockets.");
    }

    if (o.idletimeout > 0)
        tvp = &tv;

    while (1) {
        int i, j, conn_count, socket_n;

        if (fdn != -1) {
            /*remove socket descriptor which is burnt */
            FD_CLR(sockfd[fdn].fd, &listen_fds);
            rm_fd(&listen_fdlist, sockfd[fdn].fd);

            /* Rebuild the udp socket which got burnt */
            sockfd[fdn].fd = do_listen(SOCK_DGRAM, proto, &sockfd[fdn].addr);
            if (sockfd[fdn].fd == -1)
                bye("do_listen: %s", socket_strerror(socket_errno()));
            FD_SET(sockfd[fdn].fd, &listen_fds);
            add_fd(&listen_fdlist, sockfd[fdn].fd);

        }
        fdn = -1;
        socket_n = -1;
        fd_set fds;
        FD_ZERO(&fds);
        while (1) {
            /*
             * We just select to get a list of sockets which we can talk to
             */
            if (o.debug > 1)
                logdebug("selecting, fdmax %d\n", listen_fdlist.fdmax);
            fds = listen_fds;

            if (o.idletimeout > 0)
                ms_to_timeval(tvp, o.idletimeout);

            fds_ready = fselect(listen_fdlist.fdmax + 1, &fds, NULL, NULL, tvp);

            if (o.debug > 1)
                logdebug("select returned %d fds ready\n", fds_ready);

            if (fds_ready == 0)
                bye("Idle timeout expired (%d ms).", o.idletimeout);

            /*
             * Figure out which listening socket got a connection. This loop should
             * really call a function for each ready socket instead of breaking on
             * the first one.
             */
            for (i = 0; i <= listen_fdlist.fdmax && fds_ready > 0; i++) {
                /* Loop through descriptors until there is something ready */
                if (!FD_ISSET(i, &fds))
                    continue;

                /* Check each listening socket */
                for (j = 0; j < num_sockets; j++) {
                    if (i == sockfd[j].fd) {
                        if (o.debug > 1)
                            logdebug("Valid descriptor %d \n", i);
                        fdn = j;
                        socket_n = i;
                        break;
                    }
                }

                /* if we found a valid socket break */
                if (fdn != -1) {
                    fds_ready--;
                    break;
                }
            }

            /* Make sure someone connected */
            if (fdn == -1)
                continue;

            /*
             * We just peek so we can get the client connection details without
             * removing anything from the queue. Sigh.
             */
            nbytes = recvfrom(socket_n, buf, sizeof(buf), MSG_PEEK,
                              &remotess.sockaddr, &sslen);
            if (nbytes < 0) {
                loguser("%s.\n", socket_strerror(socket_errno()));
                close(socket_n);
                return 1;
            }

            /* Check conditions that might cause us to deny the connection. */
            conn_count = get_conn_count();
            if (conn_count >= o.conn_limit) {
                if (o.verbose)
                    loguser("New connection denied: connection limit reached (%d)\n", conn_count);
            } else if (!allow_access(&remotess)) {
                if (o.verbose)
                    loguser("New connection denied: not allowed\n");
            } else {
                /* Good to go. */
                break;
            }

            /* Dump the current datagram */
            nbytes = recv(socket_n, buf, sizeof(buf), 0);
            if (nbytes < 0) {
                loguser("%s.\n", socket_strerror(socket_errno()));
                close(socket_n);
                return 1;
            }
            ncat_log_recv(buf, nbytes);
        }

        if (o.debug > 1)
            logdebug("Valid Connection from %d\n", socket_n);

        conn_inc++;

        /*
         * We're using connected udp. This has the down side of only
         * being able to handle one udp client at a time
         */
        Connect(socket_n, &remotess.sockaddr, sslen);

        /* clean slate for buf */
        zmem(buf, sizeof(buf));

        /* are we executing a command? then do it */
        if (o.cmdexec) {
            struct fdinfo info = { 0 };

            info.fd = socket_n;
            if (o.keepopen)
                netrun(&info, o.cmdexec);
            else
                netexec(&info, o.cmdexec);
            continue;
        }

        FD_SET(socket_n, &read_fds);
        FD_SET(STDIN_FILENO, &read_fds);
        fdmax = socket_n;

        /* stdin -> socket and socket -> stdout */
        while (1) {
            fd_set fds;

            fds = read_fds;

            if (o.debug > 1)
                logdebug("udp select'ing\n");

            if (o.idletimeout > 0)
                ms_to_timeval(tvp, o.idletimeout);

            fds_ready = fselect(fdmax + 1, &fds, NULL, NULL, tvp);

            if (fds_ready == 0)
                bye("Idle timeout expired (%d ms).", o.idletimeout);

            if (FD_ISSET(STDIN_FILENO, &fds)) {
                nbytes = Read(STDIN_FILENO, buf, sizeof(buf));
                if (nbytes <= 0) {
                    if (nbytes < 0 && o.verbose) {
                        logdebug("Error reading from stdin: %s\n", strerror(errno));
                    } else if (nbytes == 0 && o.debug) {
                        logdebug("EOF on stdin\n");
                    }
                    FD_CLR(STDIN_FILENO, &read_fds);
                    if (nbytes < 0)
                        return 1;
                    continue;
                }
                if (o.crlf)
                    fix_line_endings((char *) buf, &nbytes, &tempbuf, &crlf_state);
                if (!o.recvonly) {
                    if (tempbuf != NULL)
                        n = send(socket_n, tempbuf, nbytes, 0);
                    else
                        n = send(socket_n, buf, nbytes, 0);
                    if (n < nbytes) {
                        loguser("%s.\n", socket_strerror(socket_errno()));
                        close(socket_n);
                        return 1;
                    }
                    ncat_log_send(buf, nbytes);
                }
                if (tempbuf != NULL) {
                    free(tempbuf);
                    tempbuf = NULL;
                }
            }
            if (FD_ISSET(socket_n, &fds)) {
                nbytes = recv(socket_n, buf, sizeof(buf), 0);
                if (nbytes < 0) {
                    loguser("%s.\n", socket_strerror(socket_errno()));
                    close(socket_n);
                    return 1;
                }
                ncat_log_recv(buf, nbytes);
                if (!o.sendonly)
                    Write(STDOUT_FILENO, buf, nbytes);
            }

            zmem(buf, sizeof(buf));
        }
    }

    return 0;
}
Exemplo n.º 5
0
/* This is sufficiently different from the TCP code (wrt SSL, etc) that it
 * resides in its own simpler function
 */
static int ncat_listen_dgram(int proto)
{
    int sockfd[NUM_LISTEN_ADDRS];
    int i, fdn = -1;
    int fdmax, nbytes, fds_ready;
    char buf[DEFAULT_UDP_BUF_LEN] = {0};
    char *tempbuf = NULL;
    fd_set read_fds;
    union sockaddr_u remotess;
    socklen_t sslen = sizeof(remotess.storage);

    for (i = 0; i < NUM_LISTEN_ADDRS; i++) {
        sockfd[i] = -1;
    }

    FD_ZERO(&read_fds);

    /* Initialize remotess struct so recvfrom() doesn't hit the fan.. */
    zmem(&remotess.storage, sizeof(remotess.storage));
    remotess.storage.ss_family = o.af;

#ifdef WIN32
    set_pseudo_sigchld_handler(decrease_conn_count);
#else
    /* Reap on SIGCHLD */
    Signal(SIGCHLD, sigchld_handler);
    /* Ignore the SIGPIPE that occurs when a client disconnects suddenly and we
       send data to it before noticing. */
    Signal(SIGPIPE, SIG_IGN);
#endif

    /* set for selecting udp listening sockets */
    fd_set listen_fds;
    fd_list_t listen_fdlist;
    FD_ZERO(&listen_fds);
    init_fdlist(&listen_fdlist, num_listenaddrs);

    for (i = 0; i < num_listenaddrs; i++) {
        /* create the UDP listen sockets */
        sockfd[i] = do_listen(SOCK_DGRAM, proto, &listenaddrs[i]);
        FD_SET(sockfd[i],&listen_fds);
        add_fd(&listen_fdlist, sockfd[i]);
    }

    while (1) {
        int i, j, conn_count, socket_n;

        if (fdn != -1) {
            /*remove socket descriptor which is burnt */
            FD_CLR(sockfd[fdn], &listen_fds);
            rm_fd(&listen_fdlist, sockfd[fdn]);

            /* Rebuild the udp socket which got burnt */
            sockfd[fdn] = do_listen(SOCK_DGRAM, proto, &listenaddrs[fdn]);
            FD_SET(sockfd[fdn],&listen_fds);
            add_fd(&listen_fdlist, sockfd[fdn]);

        }
        fdn = -1;
        socket_n = -1;
            fd_set fds;
            FD_ZERO(&fds);
        while (1) {
            /*
             * We just select to get a list of sockets which we can talk to
             */
            if (o.debug > 1)
                logdebug("selecting, fdmax %d\n", listen_fdlist.fdmax);
            fds = listen_fds;
            fds_ready = fselect(listen_fdlist.fdmax + 1, &fds, NULL, NULL, NULL);

            if (o.debug > 1)
                logdebug("select returned %d fds ready\n", fds_ready);


            /*
             * Figure out which listening socket got a connection. This loop should
             * really call a function for each ready socket instead of breaking on
             * the first one.
             */
            for (i = 0; i <= listen_fdlist.fdmax && fds_ready >0; i++) {
                /* Loop through descriptors until there is something ready */
                if (!FD_ISSET(i, &fds))
                    continue;

                /* Check each listening socket */
                for (j = 0; j < num_listenaddrs; j++) {
                    if (i == sockfd[j]) {
                        if (o.debug >1)
                            logdebug("Valid descriptor %d \n", i);
                        fdn = j;
                        socket_n = i;
                        break;
                    }
                }

                /* if we found a valid socket break */
                if (fdn != -1) {
                    fds_ready--;
                    break;
                }
            }

            /* Make sure someone connected */
            if (fdn == -1)
                continue;

            /*
             * We just peek so we can get the client connection details without
             * removing anything from the queue. Sigh.
             */
            nbytes = Recvfrom(socket_n, buf, sizeof(buf), MSG_PEEK,
                              &remotess.sockaddr, &sslen);

            /* Check conditions that might cause us to deny the connection. */
            conn_count = get_conn_count();
            if (conn_count >= o.conn_limit) {
                if (o.verbose)
                    loguser("New connection denied: connection limit reached (%d)\n", conn_count);
            } else if (!allow_access(&remotess)) {
                if (o.verbose)
                    loguser("New connection denied: not allowed\n");
            } else {
                /* Good to go. */
                break;
            }

            /* Dump the current datagram */
            Recv(socket_n, buf, sizeof(buf), 0);
        }

        if (o.debug > 1)
            logdebug("Valid Connection from %d\n", socket_n);

        conn_inc++;

        /*
         * We're using connected udp. This has the down side of only
         * being able to handle one udp client at a time
         */
        Connect(socket_n, &remotess.sockaddr, sslen);

        /* clean slate for buf */
        zmem(buf, sizeof(buf));

        /* are we executing a command? then do it */
        if (o.cmdexec) {
            struct fdinfo info = { 0 };

            info.fd = socket_n;
            if (o.keepopen)
                netrun(&info, o.cmdexec);
            else
                netexec(&info, o.cmdexec);
            continue;
        }

        FD_SET(socket_n, &read_fds);
        FD_SET(STDIN_FILENO, &read_fds);
        fdmax = socket_n;

        /* stdin -> socket and socket -> stdout */
        while (1) {
            fd_set fds;

            fds = read_fds;

            if (o.debug > 1)
                logdebug("udp select'ing\n");

            fds_ready = fselect(fdmax + 1, &fds, NULL, NULL, NULL);

            if (FD_ISSET(STDIN_FILENO, &fds)) {
                nbytes = Read(STDIN_FILENO, buf, sizeof(buf));
                if (nbytes < 0) {
                    loguser("%s.\n", strerror(errno));
                    return 1;
                } else if (nbytes == 0) {
                    return 0;
                }
                if (o.crlf)
                    fix_line_endings((char *) buf, &nbytes, &tempbuf, &crlf_state);
                if (!o.recvonly) {
                    if (tempbuf != NULL)
                        send(socket_n, tempbuf, nbytes, 0);
                    else
                        send(socket_n, buf, nbytes, 0);
                }
                if (tempbuf != NULL) {
                    free(tempbuf);
                    tempbuf = NULL;
                }
            }
            if (FD_ISSET(socket_n, &fds)) {
                nbytes = recv(socket_n, buf, sizeof(buf), 0);
                if (nbytes < 0) {
                    loguser("%s.\n", socket_strerror(socket_errno()));
                    close(socket_n);
                    return 1;
                }
                if (!o.sendonly)
                    Write(STDOUT_FILENO, buf, nbytes);
            }

            zmem(buf, sizeof(buf));
        }
    }

    return 0;
}