[libpcap] / rpcapd / rpcapd.c

/*
 * Copyright (c) 2002 - 2003
 * NetGroup, Politecnico di Torino (Italy)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "ftmacros.h"

#include <errno.h>              // for the errno variable
#include <string.h>             // for strtok, etc
#include <stdlib.h>             // for malloc(), free(), ...
#include <pcap.h>               // for PCAP_ERRBUF_SIZE
#include <signal.h>             // for signal()

#include "fmtutils.h"
#include "sockutils.h"          // for socket calls
#include "portability.h"
#include "rpcapd.h"
#include "fileconf.h"           // for the configuration file management
#include "rpcap-protocol.h"
#include "daemon.h"             // the true main() method of this daemon
#include "log.h"

#ifdef _WIN32
  #include <process.h>          // for thread stuff
  #include "win32-svc.h"        // for Win32 service stuff
  #include "getopt.h"           // for getopt()-for-Windows
#else
  #include <unistd.h>           // for exit()
  #include <sys/wait.h>         // waitpid()
#endif

//
// Element in list of sockets on which we're listening for connections.
//
struct listen_sock {
        struct listen_sock *next;
        SOCKET sock;
};

// Global variables
char hostlist[MAX_HOST_LIST + 1];               //!< Keeps the list of the hosts that are allowed to connect to this server
struct active_pars activelist[MAX_ACTIVE_LIST];         //!< Keeps the list of the hosts (host, port) on which I want to connect to (active mode)
int nullAuthAllowed;                            //!< '1' if we permit NULL authentication, '0' otherwise
static struct listen_sock *listen_socks;        //!< sockets on which we listen
char loadfile[MAX_LINE + 1];                    //!< Name of the file from which we have to load the configuration
int passivemode = 1;                            //!< '1' if we want to run in passive mode as well
struct addrinfo mainhints;                      //!< temporary struct to keep settings needed to open the new socket
char address[MAX_LINE + 1];                     //!< keeps the network address (either numeric or literal) to bind to
char port[MAX_LINE + 1];                        //!< keeps the network port to bind to
#ifdef _WIN32
static HANDLE shutdown_event;                   //!< event to signal to shut down the main loop
#else
static volatile sig_atomic_t shutdown_server;   //!< '1' if the server is to shut down
static volatile sig_atomic_t reread_config;     //!< '1' if the server is to re-read its configuration
#endif

extern char *optarg;    // for getopt()

// Function definition
#ifdef _WIN32
static unsigned __stdcall main_active(void *ptr);
static BOOL WINAPI main_ctrl_event(DWORD);
#else
static void *main_active(void *ptr);
static void main_terminate(int sign);
static void main_reread_config(int sign);
#endif
static void accept_connections(void);
static void accept_connection(SOCKET listen_sock);
#ifdef _WIN32
static void main_abort(int sign);
#else
static void main_reap_children(int sign);
#endif

#define RPCAP_ACTIVE_WAIT 30            /* Waiting time between two attempts to open a connection, in active mode (default: 30 sec) */

/*!
        \brief Prints the usage screen if it is launched in console mode.
*/
static void printusage(void)
{
        char *usagetext =
        "USAGE:"
        " "  PROGRAM_NAME " [-b <address>] [-p <port>] [-4] [-l <host_list>] [-a <host,port>]\n"
        "              [-n] [-v] [-d] [-s <file>] [-f <file>]\n\n"
        "  -b <address>    the address to bind to (either numeric or literal).\n"
        "                  Default: binds to all local IPv4 and IPv6 addresses\n\n"
        "  -p <port>       the port to bind to.\n"
        "                  Default: binds to port " RPCAP_DEFAULT_NETPORT "\n\n"
        "  -4              use only IPv4.\n"
        "                  Default: use both IPv4 and IPv6 waiting sockets\n\n"
        "  -l <host_list>  a file that contains a list of hosts that are allowed\n"
        "                  to connect to this server (if more than one, list them one per line).\n"
        "                  We suggest to use literal names (instead of numeric ones) in\n"
        "                  order to avoid problems with different address families.\n\n"
        "  -n              permit NULL authentication (usually used with '-l')\n\n"
        "  -a <host,port>  run in active mode when connecting to 'host' on port 'port'\n"
        "                  In case 'port' is omitted, the default port (" RPCAP_DEFAULT_NETPORT_ACTIVE ") is used\n\n"
        "  -v              run in active mode only (default: if '-a' is specified, it accepts\n"
        "                  passive connections as well\n\n"
        "  -d              run in daemon mode (UNIX only) or as a service (Win32 only)\n"
        "                  Warning (Win32): this switch is provided automatically when the service\n"
        "                  is started from the control panel\n\n"
        "  -s <file>       save the current configuration to file\n\n"
        "  -f <file>       load the current configuration from file; all switches\n"
        "                  specified from the command line are ignored\n\n"
        "  -h              print this help screen\n\n";

        (void)fprintf(stderr, "RPCAPD, a remote packet capture daemon.\n"
        "Compiled with %s\n\n", pcap_lib_version());
        printf("%s", usagetext);
}



//! Program main
int main(int argc, char *argv[])
{
        char savefile[MAX_LINE + 1];            // name of the file on which we have to save the configuration
        int isdaemon = 0;                       // Not null if the user wants to run this program as a daemon
        int retval;                             // keeps the returning value from several functions
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed
#ifndef _WIN32
        struct sigaction action;
#endif

        savefile[0] = 0;
        loadfile[0] = 0;
        hostlist[0] = 0;

        // Initialize errbuf
        memset(errbuf, 0, sizeof(errbuf));

        if (sock_init(errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                SOCK_ASSERT(errbuf, 1);
                exit(-1);
        }

        strncpy(address, RPCAP_DEFAULT_NETADDR, MAX_LINE);
        strncpy(port, RPCAP_DEFAULT_NETPORT, MAX_LINE);

        // Prepare to open a new server socket
        memset(&mainhints, 0, sizeof(struct addrinfo));

        mainhints.ai_family = PF_UNSPEC;
        mainhints.ai_flags = AI_PASSIVE;        // Ready to a bind() socket
        mainhints.ai_socktype = SOCK_STREAM;

        // Getting the proper command line options
        while ((retval = getopt(argc, argv, "b:dhp:4l:na:s:f:v")) != -1)
        {
                switch (retval)
                {
                        case 'b':
                                strncpy(address, optarg, MAX_LINE);
                                break;
                        case 'p':
                                strncpy(port, optarg, MAX_LINE);
                                break;
                        case '4':
                                mainhints.ai_family = PF_INET;          // IPv4 server only
                                break;
                        case 'd':
                                isdaemon = 1;
                                break;
                        case 'n':
                                nullAuthAllowed = 1;
                                break;
                        case 'v':
                                passivemode = 0;
                                break;
                        case 'l':
                        {
                                strncpy(hostlist, optarg, sizeof(hostlist));
                                break;
                        }
                        case 'a':
                        {
                                char *tmpaddress, *tmpport;
                                char *lasts;
                                int i = 0;

                                tmpaddress = pcap_strtok_r(optarg, RPCAP_HOSTLIST_SEP, &lasts);

                                while ((tmpaddress != NULL) && (i < MAX_ACTIVE_LIST))
                                {
                                        tmpport = pcap_strtok_r(NULL, RPCAP_HOSTLIST_SEP, &lasts);

                                        strlcpy(activelist[i].address, tmpaddress, MAX_LINE);

                                        if ((tmpport == NULL) || (strcmp(tmpport, "DEFAULT") == 0)) // the user choose a custom port
                                                strlcpy(activelist[i].port, RPCAP_DEFAULT_NETPORT_ACTIVE, MAX_LINE);
                                        else
                                                strlcpy(activelist[i].port, tmpport, MAX_LINE);

                                        tmpaddress = pcap_strtok_r(NULL, RPCAP_HOSTLIST_SEP, &lasts);

                                        i++;
                                }

                                if (i > MAX_ACTIVE_LIST)
                                        SOCK_ASSERT("Only MAX_ACTIVE_LIST active connections are currently supported.", 1);

                                // I don't initialize the remaining part of the structure, since
                                // it is already zeroed (it is a global var)
                                break;
                        }
                        case 'f':
                                strlcpy(loadfile, optarg, MAX_LINE);
                                break;
                        case 's':
                                strlcpy(savefile, optarg, MAX_LINE);
                                break;
                        case 'h':
                                printusage();
                                exit(0);
                        default:
                                break;
                }
        }

        if (savefile[0])
        {
                if (fileconf_save(savefile))
                        SOCK_ASSERT("Error when saving the configuration to file", 1);
        }

        // If the file does not exist, it keeps the settings provided by the command line
        if (loadfile[0])
                fileconf_read();

#ifdef WIN32
        //
        // Create a handle to signal when the main loop is to shut down.
        //
        // Events are a bit annoying if you're waiting for multiple
        // events; unlike UN*X select() and poll(), which indicate
        // which FDs are available, WaitForMultipleObjects() and
        // WSAWaitForMultipleEvents() don't give you an indication
        // of *all* of the events that are signaled, they just tell
        // you the first one that's signaled.
        //
        // Therefore, we must use WaitForSingleObject() to test
        // this event; that means it must not be auto-reset,
        // as that means that once WSAWaitForMultipleEvents() is
        // woken up, it's no longer signaled.
        //
        shutdown_event = CreateEvent(NULL, TRUE, FALSE, NULL);
        if (shutdown_event == NULL)
        {
                sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                rpcapd_log(LOGPRIO_ERROR, "Can't create shutdown event: %s",
                    errbuf);
                exit(2);
        }

        //
        // Catch control signals.
        //
        if (!SetConsoleCtrlHandler(main_ctrl_event, TRUE))
        {
                sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                rpcapd_log(LOGPRIO_ERROR, "Can't set control handler: %s",
                    errbuf);
                exit(2);
        }
#else
        memset(&action, 0, sizeof (action));
        action.sa_handler = main_terminate;
        action.sa_flags = 0;
        sigemptyset(&action.sa_mask);
        sigaction(SIGTERM, &action, NULL);
        memset(&action, 0, sizeof (action));
        action.sa_handler = main_reap_children;
        action.sa_flags = 0;
        sigemptyset(&action.sa_mask);
        sigaction(SIGCHLD, &action, NULL);
        // Ignore SIGPIPE - we'll get EPIPE when trying to write to a closed
        // connection, we don't want to get killed by a signal in that case
        signal(SIGPIPE, SIG_IGN);
#endif

        // forking a daemon, if it is needed
        if (isdaemon)
        {
#ifndef _WIN32
                int pid;

                // Unix Network Programming, pg 336
                if ((pid = fork()) != 0)
                        exit(0);                // Parent terminates

                // First child continues
                // Set daemon mode
                setsid();

                // generated under unix with 'kill -HUP', needed to reload the configuration
                memset(&action, 0, sizeof (action));
                action.sa_handler = main_reread_config;
                action.sa_flags = 0;
                sigemptyset(&action.sa_mask);
                sigaction(SIGHUP, &action, NULL);

                if ((pid = fork()) != 0)
                        exit(0);                // First child terminates

                // LINUX WARNING: the current linux implementation of pthreads requires a management thread
                // to handle some hidden stuff. So, as soon as you create the first thread, two threads are
                // created. Fom this point on, the number of threads active are always one more compared
                // to the number you're expecting

                // Second child continues
//              umask(0);
//              chdir("/");
#else
                // We use the SIGABRT signal to kill the Win32 service
                signal(SIGABRT, main_abort);

                // If this call succeeds, it is blocking on Win32
                if (svc_start() != 1)
                        SOCK_ASSERT("Unable to start the service", 1);

                // When the previous call returns, the entire application has to be stopped.
                exit(0);
#endif
        }
        else    // Console mode
        {
#ifndef _WIN32
                // Enable the catching of Ctrl+C
                memset(&action, 0, sizeof (action));
                action.sa_handler = main_terminate;
                action.sa_flags = 0;
                sigemptyset(&action.sa_mask);
                sigaction(SIGINT, &action, NULL);

                // generated under unix with 'kill -HUP', needed to reload the configuration
                // We do not have this kind of signal in Win32
                memset(&action, 0, sizeof (action));
                action.sa_handler = main_reread_config;
                action.sa_flags = 0;
                sigemptyset(&action.sa_mask);
                sigaction(SIGHUP, &action, NULL);
#endif

                printf("Press CTRL + C to stop the server...\n");
        }

        // If we're a Win32 service, we have already called this function in the service_main
        main_startup();

        // The code should never arrive here (since the main_startup is blocking)
        //  however this avoids a compiler warning
        exit(0);
}

void main_startup(void)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed
        struct addrinfo *addrinfo;              // keeps the addrinfo chain; required to open a new socket
        int i;
#ifdef _WIN32
        HANDLE threadId;                        // handle for the subthread
#else
        pid_t pid;
#endif

        i = 0;
        addrinfo = NULL;
        memset(errbuf, 0, sizeof(errbuf));

        // Starts all the active threads
        while ((i < MAX_ACTIVE_LIST) && (activelist[i].address[0] != 0))
        {
                activelist[i].ai_family = mainhints.ai_family;

#ifdef _WIN32
                threadId = (HANDLE)_beginthreadex(NULL, 0, main_active,
                    (void *)&activelist[i], 0, NULL);
                if (threadId == 0)
                {
                        SOCK_ASSERT("Error creating the active child threads", 1);
                        continue;
                }
                CloseHandle(threadId);
#else
                if ((pid = fork()) == 0)        // I am the child
                {
                        main_active((void *) &activelist[i]);
                        exit(0);
                }
#endif
                i++;
        }

        /*
         * The code that manages the active connections is not blocking;
         * the code that manages the passive connection is blocking.
         * So, if the user does not want to run in passive mode, we have
         * to block the main thread here, otherwise the program ends and
         * all threads are stopped.
         *
         * WARNING: this means that in case we have only active mode,
         * the program does not terminate even if all the child thread
         * terminates. The user has always to press Ctrl+C (or send a
         * SIGTERM) to terminate the program.
         */
        if (passivemode)
        {
                struct addrinfo *tempaddrinfo;

                //
                // Get a list of sockets on which to listen.
                //
                if (sock_initaddress((address[0]) ? address : NULL, port, &mainhints, &addrinfo, errbuf, PCAP_ERRBUF_SIZE) == -1)
                {
                        SOCK_ASSERT(errbuf, 1);
                        return;
                }

                for (tempaddrinfo = addrinfo; tempaddrinfo;
                     tempaddrinfo = tempaddrinfo->ai_next)
                {
                        SOCKET sock;
                        struct listen_sock *sock_info;

                        if ((sock = sock_open(tempaddrinfo, SOCKOPEN_SERVER, SOCKET_MAXCONN, errbuf, PCAP_ERRBUF_SIZE)) == INVALID_SOCKET)
                        {
                                SOCK_ASSERT(errbuf, 1);
                                continue;
                        }

                        sock_info = (struct listen_sock *) malloc(sizeof (struct listen_sock));
                        if (sock_info == NULL)
                        {
                                rpcapd_log(LOGPRIO_ERROR, "Can't allocate structure for listen socket");
                                exit(2);
                        }
                        sock_info->sock = sock;
                        sock_info->next = listen_socks;
                        listen_socks = sock_info;
                }

                freeaddrinfo(addrinfo);

                //
                // Now listen on all of them, waiting for connections.
                //
                accept_connections();
        }

        //
        // We're done; exit.
        //
        SOCK_ASSERT(PROGRAM_NAME " is closing.\n", 1);

#ifndef _WIN32
        //
        // Sends a KILL signal to all the processes in this process's
        // process group; i.e., it kills all the child processes
        // we've created.
        //
        // XXX - that also includes us, so we will be killed as well;
        // that may cause a message to be printed or logged.
        //
        kill(0, SIGKILL);
#endif

        //
        // Just leave.  We shouldn't need to clean up sockets or
        // anything else, and if we try to do so, we'll could end
        // up closing sockets, or shutting Winsock down, out from
        // under service loops, causing all sorts of noisy error
        // messages.
        //
        // We shouldn't need to worry about cleaning up any resources
        // such as handles, sockets, threads, etc. - exit() should
        // terminate the process, causing all those resources to be
        // cleaned up.
        //
        exit(0);
}

#ifdef _WIN32
static BOOL WINAPI main_ctrl_event(DWORD ctrltype)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed

        //
        // ctrltype is one of:
        //
        // CTRL_C_EVENT - we got a ^C; this is like SIGINT
        // CTRL_BREAK_EVENT - we got Ctrl+Break
        // CTRL_CLOSE_EVENT - the console was closed; this is like SIGHUP
        // CTRL_LOGOFF_EVENT - a user is logging off; this is received
        //   only by services
        // CTRL_SHUTDOWN_EVENT - the systemis shutting down; this is
        //   received only by services
        //
        // For now, we treat all but CTRL_LOGOFF_EVENT as indications
        // that we should shut down.
        //
        switch (ctrltype)
        {
                case CTRL_C_EVENT:
                case CTRL_BREAK_EVENT:
                case CTRL_CLOSE_EVENT:
                case CTRL_SHUTDOWN_EVENT:
                        //
                        // Set the shutdown event.
                        // That will wake up WSAWaitForMultipleEvents().
                        //
                        if (!SetEvent(shutdown_event))
                        {
                                sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                                rpcapd_log(LOGPRIO_ERROR, "SetEvent on shutdown event failed: %s", errbuf);
                        }
                        break;

                default:
                        break;
        }

        //
        // We handled this.
        //
        return TRUE;
}
#else
static void main_terminate(int sign)
{
        //
        // Note that the server should shut down.
        // select() should get an EINTR error when we return,
        // so it will wake up and know it needs to check the flag.
        //
        shutdown_server = 1;
}

static void main_reread_config(int sign)
{
        //
        // Note that the server should re-read its configuration file.
        // select() should get an EINTR error when we return,
        // so it will wake up and know it needs to check the flag.
        //
        reread_config = 1;
}
#endif

#ifdef _WIN32
static void main_abort(int sign)
{
        struct listen_sock *sock_info;

        SOCK_ASSERT(PROGRAM_NAME " is closing due to a SIGABRT.\n", 1);

        //
        // XXX - there should be a way to poke the main thread to get
        // it to shut down the service.
        //

        //
        // Close all the listen sockets.
        //
        for (sock_info = listen_socks; sock_info; sock_info = sock_info->next)
        {
                closesocket(sock_info->sock);
        }
        sock_cleanup();

        /*
         * This is a Win32 service, so we're a child thread, and we want
         * just to terminate ourself. This is because the exit(0) will
         * be invoked by the main thread, which is blocked waiting that
         * all childs terminates. We are forced to call exit from the
         * main thread, otherwise the Win32 service control manager
         * (SCM) does not work well.
         */
}
#endif

#ifndef _WIN32
static void main_reap_children(int sign)
{
        pid_t pid;
        int exitstat;

        // Reap all child processes that have exited.
        // For reference, Stevens, pg 128

        while ((pid = waitpid(-1, &exitstat, WNOHANG)) > 0)
                SOCK_ASSERT("Child terminated", 1);

        return;
}
#endif

//
// Loop waiting for incoming connections and accepting them.
//
static void
accept_connections(void)
{
#ifdef _WIN32
        struct listen_sock *sock_info;
        DWORD num_events;
        WSAEVENT *events;
        int i;
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed

        //
        // How big does the set of events need to be?
        // One for the shutdown event, plus one for every socket on which
        // we'll be listening.
        //
        num_events = 1;         // shutdown event
        for (sock_info = listen_socks; sock_info;
            sock_info = sock_info->next)
        {
                if (num_events == WSA_MAXIMUM_WAIT_EVENTS)
                {
                        //
                        // WSAWaitForMultipleEvents() doesn't support
                        // more than WSA_MAXIMUM_WAIT_EVENTS events
                        // on which to wait.
                        //
                        rpcapd_log(LOGPRIO_ERROR, "Too many sockets on which to listen");
                        exit(2);
                }
                num_events++;
        }

        //
        // Allocate the array of events.
        //
        events = (WSAEVENT *) malloc(num_events * sizeof (WSAEVENT));
        if (events == NULL)
        {
                rpcapd_log(LOGPRIO_ERROR, "Can't allocate array of events which to listen");
                exit(2);
        }

        //
        // Fill it in.
        //
        events[0] = shutdown_event;     // shutdown event first
        for (sock_info = listen_socks, i = 1; sock_info;
            sock_info = sock_info->next, i++)
        {
                WSAEVENT event;

                //
                // Create an event that is signaled if there's a connection
                // to accept on the socket in question.
                //
                event = WSACreateEvent();
                if (event == WSA_INVALID_EVENT)
                {
                        sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                        rpcapd_log(LOGPRIO_ERROR, "Can't create socket event: %s", errbuf);
                        exit(2);
                }
                if (WSAEventSelect(sock_info->sock, event, FD_ACCEPT) == SOCKET_ERROR)
                {
                        sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                        rpcapd_log(LOGPRIO_ERROR, "Can't setup socket event: %s", errbuf);
                        exit(2);
                }
                events[i] = event;
        }

        for (;;)
        {
                //
                // Wait for incoming connections.
                //
                DWORD ret;

                ret = WSAWaitForMultipleEvents(num_events, events, FALSE,
                    WSA_INFINITE, FALSE);
                if (ret == WSA_WAIT_FAILED)
                {
                        sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                        rpcapd_log(LOGPRIO_ERROR, "WSAWaitForMultipleEvents failed: %s", errbuf);
                        exit(2);
                }

                //
                // Check the shutdown event.
                //
                if (WaitForSingleObject(shutdown_event, 0) == WAIT_OBJECT_0)
                {
                        //
                        // Time to quit.
                        // Clear the event, for cleanliness.
                        //
                        if (!ResetEvent(shutdown_event))
                        {
                                sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                                rpcapd_log(LOGPRIO_ERROR, "ResetEvent on shutdown event failed: %s", errbuf);
                        }

                        //
                        // Exit the loop, so we quit.
                        //
                        break;
                }

                //
                // Check each socket.
                //
                for (sock_info = listen_socks, i = 1; sock_info;
                    sock_info = sock_info->next, i++)
                {
                        WSANETWORKEVENTS network_events;

                        if (WSAEnumNetworkEvents(sock_info->sock,
                            events[i], &network_events) == SOCKET_ERROR)
                        {
                                sock_geterror(NULL, errbuf, PCAP_ERRBUF_SIZE);
                                rpcapd_log(LOGPRIO_ERROR, "WSAEnumNetworkEvents failed: %s", errbuf);
                                exit(2);
                        }
                        if (network_events.lNetworkEvents & FD_ACCEPT)
                        {
                                //
                                // Did an error occur?
                                //
                                if (network_events.iErrorCode[FD_ACCEPT_BIT] != 0)
                                {
                                        //
                                        // Yes - report it and keep going.
                                        //
                                        sock_fmterror(NULL,
                                            network_events.iErrorCode[FD_ACCEPT_BIT],
                                            errbuf,
                                            PCAP_ERRBUF_SIZE);
                                        rpcapd_log(LOGPRIO_ERROR, "Socket error: %s", errbuf);
                                        continue;
                                }

                                //
                                // Accept the connection.
                                //
                                accept_connection(sock_info->sock);
                        }
                }
        }
#else
        struct listen_sock *sock_info;
        int num_sock_fds;

        //
        // How big does the bitset of sockets on which to select() have
        // to be?
        //
        num_sock_fds = 0;
        for (sock_info = listen_socks; sock_info; sock_info = sock_info->next)
        {
                if (sock_info->sock + 1 > num_sock_fds)
                {
                        if (sock_info->sock + 1 > FD_SETSIZE)
                        {
                                rpcapd_log(LOGPRIO_ERROR, "Socket FD is too bit for an fd_set");
                                exit(2);
                        }
                        num_sock_fds = sock_info->sock + 1;
                }
        }

        for (;;)
        {
                fd_set sock_fds;
                int ret;

                //
                // Set up an fd_set for all the sockets on which we're
                // listening.
                //
                // This set is modified by select(), so we have to
                // construct it anew each time.
                //
                FD_ZERO(&sock_fds);
                for (sock_info = listen_socks; sock_info;
                    sock_info = sock_info->next)
                {
                        FD_SET(sock_info->sock, &sock_fds);
                }

                //
                // Wait for incoming connections.
                //
                ret = select(num_sock_fds, &sock_fds, NULL, NULL, NULL);
                if (ret == -1)
                {
                        if (errno == EINTR)
                        {
                                //
                                // If this is a "terminate the
                                // server" signal, exit the loop,
                                // otherwise just keep trying.
                                //
                                if (shutdown_server)
                                        break;
                                else {
                                        if (reread_config)
                                        {
                                                //
                                                // This is a "re-read the
                                                // configuration file"
                                                // signal.  Clear the
                                                // flag and re-read
                                                // the file.
                                                //
                                                reread_config = 0;
                                                fileconf_read();
                                        }
                                        continue;
                                }
                        }
                        else
                        {
                                rpcapd_log(LOGPRIO_ERROR, "select failed: %s",
                                    strerror(errno));
                                exit(2);
                        }
                }

                //
                // Check each socket.
                //
                for (sock_info = listen_socks; sock_info;
                    sock_info = sock_info->next)
                {
                        if (FD_ISSET(sock_info->sock, &sock_fds))
                        {
                                //
                                // Accept the connection.
                                //
                                accept_connection(sock_info->sock);
                        }
                }
        }
#endif
}

//
// Accept a connection and start a worker thread, on Windows, or a
// worker process, on UN*X, to handle the connection.
//
static void
accept_connection(SOCKET listen_sock)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed
        SOCKET sockctrl;                        // keeps the socket ID for this control connection
        struct sockaddr_storage from;           // generic sockaddr_storage variable
        socklen_t fromlen;                      // keeps the length of the sockaddr_storage variable

#ifdef _WIN32
        HANDLE threadId;                        // handle for the subthread
#else
        pid_t pid;
#endif
        struct daemon_slpars *pars;     // parameters needed by the daemon_serviceloop()

        // Initialize errbuf
        memset(errbuf, 0, sizeof(errbuf));

        for (;;)
        {
                // Accept the connection
                fromlen = sizeof(struct sockaddr_storage);

                sockctrl = accept(listen_sock, (struct sockaddr *) &from, &fromlen);

                if (sockctrl != INVALID_SOCKET)
                {
                        // Success.
                        break;
                }

                // The accept() call can return this error when a signal is catched
                // In this case, we have simply to ignore this error code
                // Stevens, pg 124
#ifdef _WIN32
                if (WSAGetLastError() == WSAEINTR)
#else
                if (errno == EINTR)
#endif
                        continue;

                // Don't check for errors here, since the error can be due to the fact that the thread
                // has been killed
                sock_geterror("accept(): ", errbuf, PCAP_ERRBUF_SIZE);
                rpcapd_log(LOGPRIO_ERROR, "Accept of control connection from client failed: %s",
                    errbuf);
                return;
        }

        //
        // We have a connection.
        // Check whether the connecting host is among the ones allowed.
        //
        if (sock_check_hostlist(hostlist, RPCAP_HOSTLIST_SEP, &from, errbuf, PCAP_ERRBUF_SIZE) < 0)
        {
                rpcap_senderror(sockctrl, 0, PCAP_ERR_HOSTNOAUTH, errbuf, NULL);
                sock_close(sockctrl, NULL, 0);
                return;
        }


#ifdef _WIN32
        // in case of passive mode, this variable is deallocated by the daemon_serviceloop()
        pars = (struct daemon_slpars *) malloc (sizeof(struct daemon_slpars));
        if (pars == NULL)
        {
                pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
                    errno, "malloc() failed");
                rpcap_senderror(sockctrl, 0, PCAP_ERR_OPEN, errbuf, NULL);
                sock_close(sockctrl, NULL, 0);
                return;
        }

        pars->sockctrl = sockctrl;
        pars->activeclose = 0;          // useless in passive mode
        pars->isactive = 0;
        pars->nullAuthAllowed = nullAuthAllowed;

        threadId = (HANDLE)_beginthreadex(NULL, 0, daemon_serviceloop,
            (void *) pars, 0, NULL);
        if (threadId == 0)
        {
                pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error creating the child thread");
                rpcap_senderror(sockctrl, 0, PCAP_ERR_OPEN, errbuf, NULL);
                sock_close(sockctrl, NULL, 0);
                return;
        }
        CloseHandle(threadId);
#else
        pid = fork();
        if (pid == -1)
        {
                pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error creating the child process");
                rpcap_senderror(sockctrl, 0, PCAP_ERR_OPEN, errbuf, NULL);
                sock_close(sockctrl, NULL, 0);
                return;
        }
        if (pid == 0)
        {
                //
                // Child process.
                // This is passive mode, so this variable is deallocated
                // by the daemon_serviceloop().
                //
                pars = (struct daemon_slpars *) malloc (sizeof(struct daemon_slpars));
                if (pars == NULL)
                {
                        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Can't allocate memory for the child process");
                        rpcap_senderror(sockctrl, 0, PCAP_ERR_OPEN, errbuf, NULL);
                        sock_close(sockctrl, NULL, 0);
                        return;
                }

                pars->sockctrl = sockctrl;
                pars->activeclose = 0;          // useless in passive mode
                pars->isactive = 0;
                pars->nullAuthAllowed = nullAuthAllowed;

                //
                // Close the socket on which we're listening (must
                // be open only in the parent).
                //
                closesocket(listen_sock);

                //
                // Run the service loop.
                //
                daemon_serviceloop((void *) pars);
                exit(0);
        }

        // I am the parent
        // Close the socket for this session (must be open only in the child)
        closesocket(sockctrl);
#endif
}

/*!
        \brief 'true' main of the program in case the active mode is turned on.

        This function loops forever trying to connect to the remote host, until the
        daemon is turned down.

        \param ptr: it keeps the 'activepars' parameters.  It is a 'void *'
        just because the thread APIs want this format.
*/
#ifdef _WIN32
static unsigned __stdcall
#else
static void *
#endif
main_active(void *ptr)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed
        SOCKET sockctrl;                        // keeps the socket ID for this control connection
        struct addrinfo hints;                  // temporary struct to keep settings needed to open the new socket
        struct addrinfo *addrinfo;              // keeps the addrinfo chain; required to open a new socket
        struct active_pars *activepars;
        struct daemon_slpars *pars;             // parameters needed by the daemon_serviceloop()

        activepars = (struct active_pars *) ptr;

        // Prepare to open a new server socket
        memset(&hints, 0, sizeof(struct addrinfo));
                                                // WARNING Currently it supports only ONE socket family among IPv4 and IPv6
        hints.ai_family = AF_INET;              // PF_UNSPEC to have both IPv4 and IPv6 server
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_family = activepars->ai_family;

        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Connecting to host %s, port %s, using protocol %s",
                        activepars->address, activepars->port, (hints.ai_family == AF_INET) ? "IPv4":
                        (hints.ai_family == AF_INET6) ? "IPv6" : "Unspecified");
        SOCK_ASSERT(errbuf, 1);

        // Initialize errbuf
        memset(errbuf, 0, sizeof(errbuf));

        // Do the work
        if (sock_initaddress(activepars->address, activepars->port, &hints, &addrinfo, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                SOCK_ASSERT(errbuf, 1);
                return 0;
        }

        for (;;)
        {
                int activeclose;

                if ((sockctrl = sock_open(addrinfo, SOCKOPEN_CLIENT, 0, errbuf, PCAP_ERRBUF_SIZE)) == INVALID_SOCKET)
                {
                        SOCK_ASSERT(errbuf, 1);

                        pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error connecting to host %s, port %s, using protocol %s",
                                        activepars->address, activepars->port, (hints.ai_family == AF_INET) ? "IPv4":
                                        (hints.ai_family == AF_INET6) ? "IPv6" : "Unspecified");

                        SOCK_ASSERT(errbuf, 1);

                        sleep_secs(RPCAP_ACTIVE_WAIT);

                        continue;
                }

                pars = (struct daemon_slpars *) malloc (sizeof(struct daemon_slpars));
                if (pars == NULL)
                {
                        pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
                            errno, "malloc() failed");
                        continue;
                }

                pars->sockctrl = sockctrl;
                pars->activeclose = 0;
                pars->isactive = 1;
                pars->nullAuthAllowed = nullAuthAllowed;

                daemon_serviceloop((void *) pars);

                activeclose = pars->activeclose;

                free(pars);

                // If the connection is closed by the user explicitely, don't try to connect to it again
                // just exit the program
                if (activeclose == 1)
                        break;
        }

        freeaddrinfo(addrinfo);
        return 0;
}