[libpcap] / rpcapd / daemon.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 "varattrs.h"

#include <errno.h>              // for the errno variable
#include <stdlib.h>             // for malloc(), free(), ...
#include <string.h>             // for strlen(), ...
#include <limits.h>             // for INT_MAX

#ifdef _WIN32
  #include <process.h>          // for threads
#else
  #include <unistd.h>
  #include <pthread.h>
  #include <signal.h>
  #include <sys/time.h>
  #include <sys/types.h>        // for select() and such
  #include <pwd.h>              // for password management
#endif

#ifdef HAVE_GETSPNAM
#include <shadow.h>             // for password management
#endif

#include <pcap.h>               // for libpcap/WinPcap calls

#include "fmtutils.h"
#include "sockutils.h"          // for socket calls
#include "portability.h"
#include "rpcap-protocol.h"
#include "daemon.h"
#include "log.h"

#ifdef HAVE_OPENSSL
#include <openssl/ssl.h>
#include "sslutils.h"
#endif

//
// Timeout, in seconds, when we're waiting for a client to send us an
// authentication request; if they don't send us a request within that
// interval, we drop the connection, so we don't stay stuck forever.
//
#define RPCAP_TIMEOUT_INIT 90

//
// Timeout, in seconds, when we're waiting for an authenticated client
// to send us a request, if a capture isn't in progress; if they don't
// send us a request within that interval, we drop the connection, so
// we don't stay stuck forever.
//
#define RPCAP_TIMEOUT_RUNTIME 180

//
// Time, in seconds, that we wait after a failed authentication attempt
// before processing the next request; this prevents a client from
// rapidly trying different accounts or passwords.
//
#define RPCAP_SUSPEND_WRONGAUTH 1

// Parameters for the service loop.
struct daemon_slpars
{
        SOCKET sockctrl;        //!< SOCKET ID of the control connection
        SSL *ssl;               //!< Optional SSL handler for the controlling sockets
        int isactive;           //!< Not null if the daemon has to run in active mode
        int nullAuthAllowed;    //!< '1' if we permit NULL authentication, '0' otherwise
};

//
// Data for a session managed by a thread.
// It includes both a Boolean indicating whether we *have* a thread,
// and a platform-dependent (UN*X vs. Windows) identifier for the
// thread; on Windows, we could use an invalid handle to indicate
// that we don't have a thread, but there *is* no portable "no thread"
// value for a pthread_t on UN*X.
//
struct session {
        SOCKET sockctrl;
        SOCKET sockdata;
        SSL *ctrl_ssl, *data_ssl; // optional SSL handlers for sockctrl and sockdata.
        uint8 protocol_version;
        pcap_t *fp;
        unsigned int TotCapt;
        int     have_thread;
#ifdef _WIN32
        HANDLE thread;
#else
        pthread_t thread;
#endif
};

// Locally defined functions
static int daemon_msg_err(SOCKET sockctrl, SSL *, uint32 plen);
static int daemon_msg_auth_req(struct daemon_slpars *pars, uint32 plen);
static int daemon_AuthUserPwd(char *username, char *password, char *errbuf);

static int daemon_msg_findallif_req(uint8 ver, struct daemon_slpars *pars,
    uint32 plen);

static int daemon_msg_open_req(uint8 ver, struct daemon_slpars *pars,
    uint32 plen, char *source, size_t sourcelen);
static int daemon_msg_startcap_req(uint8 ver, struct daemon_slpars *pars,
    uint32 plen, char *source, struct session **sessionp,
    struct rpcap_sampling *samp_param, int uses_ssl);
static int daemon_msg_endcap_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session);

static int daemon_msg_updatefilter_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session, uint32 plen);
static int daemon_unpackapplyfilter(SOCKET sockctrl, SSL *, struct session *session, uint32 *plenp, char *errbuf);

static int daemon_msg_stats_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session, uint32 plen, struct pcap_stat *stats,
    unsigned int svrcapt);

static int daemon_msg_setsampling_req(uint8 ver, struct daemon_slpars *pars,
    uint32 plen, struct rpcap_sampling *samp_param);

static void daemon_seraddr(struct sockaddr_storage *sockaddrin, struct rpcap_sockaddr *sockaddrout);
#ifdef _WIN32
static unsigned __stdcall daemon_thrdatamain(void *ptr);
#else
static void *daemon_thrdatamain(void *ptr);
static void noop_handler(int sign);
#endif

static int rpcapd_recv_msg_header(SOCKET sock, SSL *, struct rpcap_header *headerp);
static int rpcapd_recv(SOCKET sock, SSL *, char *buffer, size_t toread, uint32 *plen, char *errmsgbuf);
static int rpcapd_discard(SOCKET sock, SSL *, uint32 len);
static void session_close(struct session *);

//
// TLS record layer header; used when processing the first message from
// the client, in case we aren't doing TLS but they are.
//
struct tls_record_header {
        uint8 type;             // ContentType - will be 22, for Handshake
        uint8 version_major;    // TLS protocol major version
        uint8 version_injor;    // TLS protocol minor version
        // This is *not* aligned on a 2-byte boundary; we just
        // declare it as two bytes.  Don't assume any particular
        // compiler's mechanism for saying "packed"!
        uint8 length_hi;        // Upper 8 bits of payload length
        uint8 length_lo;        // Low 8 bits of payload length
};

#define TLS_RECORD_HEADER_LEN   5       // Don't use sizeof in case it's padded

#define TLS_RECORD_TYPE_ALERT           21
#define TLS_RECORD_TYPE_HANDSHAKE       22

//
// TLS alert message.
//
struct tls_alert {
        uint8 alert_level;
        uint8 alert_description;
};

#define TLS_ALERT_LEN                   2

#define TLS_ALERT_LEVEL_FATAL           2
#define TLS_ALERT_HANDSHAKE_FAILURE     40

static int is_url(const char *source);

int
daemon_serviceloop(SOCKET sockctrl, int isactive, char *passiveClients,
    int nullAuthAllowed, int uses_ssl)
{
        uint8 first_octet;
        struct tls_record_header tls_header;
        struct tls_alert tls_alert;
        struct daemon_slpars pars;              // service loop parameters
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed
        char errmsgbuf[PCAP_ERRBUF_SIZE + 1];   // buffer for errors to send to the client
        int host_port_check_status;
        SSL *ssl = NULL;
        int nrecv;
        struct rpcap_header header;             // RPCAP message general header
        uint32 plen;                            // payload length from header
        int authenticated = 0;                  // 1 if the client has successfully authenticated
        char source[PCAP_BUF_SIZE+1];           // keeps the string that contains the interface to open
        int got_source = 0;                     // 1 if we've gotten the source from an open request
#ifndef _WIN32
        struct sigaction action;
#endif
        struct session *session = NULL;         // struct session main variable
        const char *msg_type_string;            // string for message type
        int client_told_us_to_close = 0;        // 1 if the client told us to close the capture

        // needed to save the values of the statistics
        struct pcap_stat stats;
        unsigned int svrcapt;

        struct rpcap_sampling samp_param;       // in case sampling has been requested

        // Structures needed for the select() call
        fd_set rfds;                            // set of socket descriptors we have to check
        struct timeval tv;                      // maximum time the select() can block waiting for data
        int retval;                             // select() return value

        *errbuf = 0;    // Initialize errbuf

        //
        // Peek into the socket to determine whether the client sent us
        // a TLS handshake message or a non-TLS rpcapd message.
        //
        // The first byte of an rpcapd request is the version number;
        // the first byte of a TLS handshake message is 22.  The
        // first request to an rpcapd server must be an authentication
        // request or a close request, and must have a version number
        // of 0, so it will be possible to distinguish between an
        // initial plaintext request to a server and an initial TLS
        // handshake message.
        //
        nrecv = sock_recv(sockctrl, NULL, (char *)&first_octet, 1,
            SOCK_EOF_ISNT_ERROR|SOCK_MSG_PEEK, errbuf, PCAP_ERRBUF_SIZE);
        if (nrecv == -1)
        {
                // Fatal error.
                rpcapd_log(LOGPRIO_ERROR, "Peek from client failed: %s", errbuf);
                goto end;
        }
        if (nrecv == 0)
        {
                // Client closed the connection.
                goto end;
        }

#ifdef HAVE_OPENSSL
        //
        // We have to upgrade to TLS as soon as possible, so that the
        // whole protocol goes through the encrypted tunnel, including
        // early error messages.
        //
        // Even in active mode, the other end has to initiate the TLS
        // handshake as we still are the server as far as TLS is concerned,
        // so we don't check isactive.
        //
        if (uses_ssl)
        {
                //
                // We're expecting a TLS handshake message.  If this
                // isn't one, assume it's a non-TLS rpcapd message.
                //
                // The first octet of a TLS handshake is
                // TLS_RECORD_TYPE_HANDSHAKE.
                //
                if (first_octet != TLS_RECORD_TYPE_HANDSHAKE)
                {
                        //
                        // We assume this is a non-TLS rpcapd message.
                        //
                        // Read the message header from the client.
                        //
                        nrecv = rpcapd_recv_msg_header(sockctrl, NULL, &header);
                        if (nrecv == -1)
                        {
                                // Fatal error.
                                goto end;
                        }
                        if (nrecv == -2)
                        {
                                // Client closed the connection.
                                goto end;
                        }
                        plen = header.plen;

                        // Discard the rest of the message.
                        if (rpcapd_discard(sockctrl, NULL, plen) == -1)
                        {
                                // Network error.
                                goto end;
                        }

                        //
                        // Send an authentication error, indicating
                        // that we require TLS.
                        //
                        if (rpcap_senderror(sockctrl, NULL, header.ver,
                            PCAP_ERR_TLS_REQUIRED,
                            "TLS is required by this server", errbuf) == -1)
                        {
                                // That failed; log a message and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        // Shut the session down.
                        goto end;
                }
                ssl = ssl_promotion(1, sockctrl, errbuf, PCAP_ERRBUF_SIZE);
                if (! ssl)
                {
                        rpcapd_log(LOGPRIO_ERROR, "TLS handshake on control connection failed: %s",
                            errbuf);
                        goto end;
                }
        }
        else
#endif
        {
                //
                // We're expecting a non-TLS rpcapd message.  If this
                // looks, instead, like a TLS handshake message, send
                // a TLS handshake_failed alert.
                //
                // The first octet of a TLS handshake is
                // TLS_RECORD_TYPE_HANDSHAKE.
                //
                if (first_octet == TLS_RECORD_TYPE_HANDSHAKE)
                {
                        //
                        // TLS handshake.
                        // Read the record header.
                        //
                        nrecv = sock_recv(sockctrl, ssl, (char *) &tls_header,
                            sizeof tls_header, SOCK_RECEIVEALL_YES|SOCK_EOF_ISNT_ERROR,
                            errbuf, PCAP_ERRBUF_SIZE);
                        if (nrecv == -1)
                        {
                                // Network error.
                                rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                                goto end;
                        }
                        if (nrecv == 0)
                        {
                                // Immediate EOF
                                goto end;
                        }
                        plen = (tls_header.length_hi << 8) | tls_header.length_lo;

                        // Discard the rest of the message.
                        if (rpcapd_discard(sockctrl, NULL, plen) == -1)
                        {
                                // Network error.
                                goto end;
                        }

                        //
                        // Send a TLS handshake failure alert.
                        // Use the same version the client sent us.
                        //
                        tls_header.type = TLS_RECORD_TYPE_ALERT;
                        tls_header.length_hi = 0;
                        tls_header.length_lo = TLS_ALERT_LEN;

                        if (sock_send(sockctrl, NULL, (char *) &tls_header,
                            TLS_RECORD_HEADER_LEN, errbuf, PCAP_ERRBUF_SIZE) == -1)
                        {
                                // That failed; log a messsage and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        tls_alert.alert_level = TLS_ALERT_LEVEL_FATAL;
                        tls_alert.alert_description = TLS_ALERT_HANDSHAKE_FAILURE;
                        if (sock_send(sockctrl, NULL, (char *) &tls_alert,
                            TLS_ALERT_LEN, errbuf, PCAP_ERRBUF_SIZE) == -1)
                        {
                                // That failed; log a messsage and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }
                        //
                        // Give up anyway.
                        //
                        goto end;
                }
        }

        // Set parameters structure
        pars.sockctrl = sockctrl;
        pars.ssl = ssl;
        pars.isactive = isactive;               // active mode
        pars.nullAuthAllowed = nullAuthAllowed;

        //
        // We have a connection.
        //
        // If it's a passive mode connection, check whether the connecting
        // host is among the ones allowed.
        //
        // In either case, we were handed a copy of the host list; free it
        // as soon as we're done with it.
        //
        if (pars.isactive)
        {
                // Nothing to do.
                free(passiveClients);
                passiveClients = NULL;
        }
        else
        {
                struct sockaddr_storage from;
                socklen_t fromlen;

                //
                // Get the address of the other end of the connection.
                //
                fromlen = sizeof(struct sockaddr_storage);
                if (getpeername(pars.sockctrl, (struct sockaddr *)&from,
                    &fromlen) == -1)
                {
                        sock_geterror("getpeername()", errmsgbuf, PCAP_ERRBUF_SIZE);
                        if (rpcap_senderror(pars.sockctrl, pars.ssl, 0, PCAP_ERR_NETW, errmsgbuf, errbuf) == -1)
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                        goto end;
                }

                //
                // Are they in the list of host/port combinations we allow?
                //
                host_port_check_status = sock_check_hostlist(passiveClients, RPCAP_HOSTLIST_SEP, &from, errmsgbuf, PCAP_ERRBUF_SIZE);
                free(passiveClients);
                passiveClients = NULL;
                if (host_port_check_status < 0)
                {
                        if (host_port_check_status == -2) {
                                //
                                // We got an error; log it.
                                //
                                rpcapd_log(LOGPRIO_ERROR, "%s", errmsgbuf);
                        }

                        //
                        // Sorry, we can't let you in.
                        //
                        if (rpcap_senderror(pars.sockctrl, pars.ssl, 0, PCAP_ERR_HOSTNOAUTH, errmsgbuf, errbuf) == -1)
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                        goto end;
                }
        }

#ifndef _WIN32
        //
        // Catch SIGUSR1, but do nothing.  We use it to interrupt the
        // capture thread to break it out of a loop in which it's
        // blocked waiting for packets to arrive.
        //
        // We don't want interrupted system calls to restart, so that
        // the read routine for the pcap_t gets EINTR rather than
        // restarting if it's blocked in a system call.
        //
        memset(&action, 0, sizeof (action));
        action.sa_handler = noop_handler;
        action.sa_flags = 0;
        sigemptyset(&action.sa_mask);
        sigaction(SIGUSR1, &action, NULL);
#endif

        //
        // The client must first authenticate; loop until they send us a
        // message with a version we support and credentials we accept,
        // they send us a close message indicating that they're giving up,
        // or we get a network error or other fatal error.
        //
        while (!authenticated)
        {
                //
                // If we're not in active mode, we use select(), with a
                // timeout, to wait for an authentication request; if
                // the timeout expires, we drop the connection, so that
                // a client can't just connect to us and leave us
                // waiting forever.
                //
                if (!pars.isactive)
                {
                        FD_ZERO(&rfds);
                        // We do not have to block here
                        tv.tv_sec = RPCAP_TIMEOUT_INIT;
                        tv.tv_usec = 0;

                        FD_SET(pars.sockctrl, &rfds);

                        retval = select((int)pars.sockctrl + 1, &rfds, NULL, NULL, &tv);
                        if (retval == -1)
                        {
                                sock_geterror("select() failed", errmsgbuf, PCAP_ERRBUF_SIZE);
                                if (rpcap_senderror(pars.sockctrl, pars.ssl, 0, PCAP_ERR_NETW, errmsgbuf, errbuf) == -1)
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        // The timeout has expired
                        // So, this was a fake connection. Drop it down
                        if (retval == 0)
                        {
                                if (rpcap_senderror(pars.sockctrl, pars.ssl, 0, PCAP_ERR_INITTIMEOUT, "The RPCAP initial timeout has expired", errbuf) == -1)
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }
                }

                //
                // Read the message header from the client.
                //
                nrecv = rpcapd_recv_msg_header(pars.sockctrl, pars.ssl, &header);
                if (nrecv == -1)
                {
                        // Fatal error.
                        goto end;
                }
                if (nrecv == -2)
                {
                        // Client closed the connection.
                        goto end;
                }

                plen = header.plen;

                //
                // While we're in the authentication pharse, all requests
                // must use version 0.
                //
                if (header.ver != 0)
                {
                        //
                        // Send it back to them with their version.
                        //
                        if (rpcap_senderror(pars.sockctrl, pars.ssl, header.ver,
                            PCAP_ERR_WRONGVER,
                            "RPCAP version in requests in the authentication phase must be 0",
                            errbuf) == -1)
                        {
                                // That failed; log a message and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        // Discard the rest of the message and drop the
                        // connection.
                        (void)rpcapd_discard(pars.sockctrl, pars.ssl, plen);
                        goto end;
                }

                switch (header.type)
                {
                        case RPCAP_MSG_AUTH_REQ:
                                retval = daemon_msg_auth_req(&pars, plen);
                                if (retval == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                if (retval == -2)
                                {
                                        // Non-fatal error; we sent back
                                        // an error message, so let them
                                        // try again.
                                        continue;
                                }

                                // OK, we're authenticated; we sent back
                                // a reply, so start serving requests.
                                authenticated = 1;
                                break;

                        case RPCAP_MSG_CLOSE:
                                //
                                // The client is giving up.
                                // Discard the rest of the message, if
                                // there is anything more.
                                //
                                (void)rpcapd_discard(pars.sockctrl, pars.ssl, plen);
                                // We're done with this client.
                                goto end;

                        case RPCAP_MSG_ERROR:
                                // Log this and close the connection?
                                // XXX - is this what happens in active
                                // mode, where *we* initiate the
                                // connection, and the client gives us
                                // an error message rather than a "let
                                // me log in" message, indicating that
                                // we're not allowed to connect to them?
                                (void)daemon_msg_err(pars.sockctrl, pars.ssl, plen);
                                goto end;

                        case RPCAP_MSG_FINDALLIF_REQ:
                        case RPCAP_MSG_OPEN_REQ:
                        case RPCAP_MSG_STARTCAP_REQ:
                        case RPCAP_MSG_UPDATEFILTER_REQ:
                        case RPCAP_MSG_STATS_REQ:
                        case RPCAP_MSG_ENDCAP_REQ:
                        case RPCAP_MSG_SETSAMPLING_REQ:
                                //
                                // These requests can't be sent until
                                // the client is authenticated.
                                //
                                msg_type_string = rpcap_msg_type_string(header.type);
                                if (msg_type_string != NULL)
                                {
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "%s request sent before authentication was completed", msg_type_string);
                                }
                                else
                                {
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Message of type %u sent before authentication was completed", header.type);
                                }
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver, PCAP_ERR_WRONGMSG,
                                    errmsgbuf, errbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Network error.
                                        goto end;
                                }
                                break;

                        case RPCAP_MSG_PACKET:
                        case RPCAP_MSG_FINDALLIF_REPLY:
                        case RPCAP_MSG_OPEN_REPLY:
                        case RPCAP_MSG_STARTCAP_REPLY:
                        case RPCAP_MSG_UPDATEFILTER_REPLY:
                        case RPCAP_MSG_AUTH_REPLY:
                        case RPCAP_MSG_STATS_REPLY:
                        case RPCAP_MSG_ENDCAP_REPLY:
                        case RPCAP_MSG_SETSAMPLING_REPLY:
                                //
                                // These are server-to-client messages.
                                //
                                msg_type_string = rpcap_msg_type_string(header.type);
                                if (msg_type_string != NULL)
                                {
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Server-to-client message %s received from client", msg_type_string);
                                }
                                else
                                {
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Server-to-client message of type %u received from client", header.type);
                                }
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver, PCAP_ERR_WRONGMSG,
                                    errmsgbuf, errbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Fatal error.
                                        goto end;
                                }
                                break;

                        default:
                                //
                                // Unknown message type.
                                //
                                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Unknown message type %u", header.type);
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver, PCAP_ERR_WRONGMSG,
                                    errmsgbuf, errbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Fatal error.
                                        goto end;
                                }
                                break;
                }
        }

        //
        // OK, the client has authenticated itself, and we can start
        // processing regular requests from it.
        //

        //
        // We don't have any statistics yet.
        //
        stats.ps_ifdrop = 0;
        stats.ps_recv = 0;
        stats.ps_drop = 0;
        svrcapt = 0;

        //
        // Service requests.
        //
        for (;;)
        {
                errbuf[0] = 0;  // clear errbuf

                // Avoid zombies connections; check if the connection is opens but no commands are performed
                // from more than RPCAP_TIMEOUT_RUNTIME
                // Conditions:
                // - I have to be in normal mode (no active mode)
                // - if the device is open, I don't have to be in the middle of a capture (session->sockdata)
                // - if the device is closed, I have always to check if a new command arrives
                //
                // Be carefully: the capture can have been started, but an error occurred (so session != NULL, but
                //  sockdata is 0
                if ((!pars.isactive) &&  ((session == NULL) || ((session != NULL) && (session->sockdata == 0))))
                {
                        // Check for the initial timeout
                        FD_ZERO(&rfds);
                        // We do not have to block here
                        tv.tv_sec = RPCAP_TIMEOUT_RUNTIME;
                        tv.tv_usec = 0;

                        FD_SET(pars.sockctrl, &rfds);

                        retval = select((int)pars.sockctrl + 1, &rfds, NULL, NULL, &tv);
                        if (retval == -1)
                        {
                                sock_geterror("select() failed", errmsgbuf, PCAP_ERRBUF_SIZE);
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    0, PCAP_ERR_NETW,
                                    errmsgbuf, errbuf) == -1)
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        // The timeout has expired
                        // So, this was a fake connection. Drop it down
                        if (retval == 0)
                        {
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    0, PCAP_ERR_INITTIMEOUT,
                                    "The RPCAP initial timeout has expired",
                                    errbuf) == -1)
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }
                }

                //
                // Read the message header from the client.
                //
                nrecv = rpcapd_recv_msg_header(pars.sockctrl, pars.ssl, &header);
                if (nrecv == -1)
                {
                        // Fatal error.
                        goto end;
                }
                if (nrecv == -2)
                {
                        // Client closed the connection.
                        goto end;
                }

                plen = header.plen;

                //
                // Did the client specify a protocol version that we
                // support?
                //
                if (!RPCAP_VERSION_IS_SUPPORTED(header.ver))
                {
                        //
                        // Tell them it's not a supported version.
                        // Send the error message with their version,
                        // so they don't reject it as having the wrong
                        // version.
                        //
                        if (rpcap_senderror(pars.sockctrl, pars.ssl,
                            header.ver, PCAP_ERR_WRONGVER,
                            "RPCAP version in message isn't supported by the server",
                            errbuf) == -1)
                        {
                                // That failed; log a message and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                goto end;
                        }

                        // Discard the rest of the message.
                        (void)rpcapd_discard(pars.sockctrl, pars.ssl, plen);
                        // Give up on them.
                        goto end;
                }

                switch (header.type)
                {
                        case RPCAP_MSG_ERROR:           // The other endpoint reported an error
                        {
                                (void)daemon_msg_err(pars.sockctrl, pars.ssl, plen);
                                // Do nothing; just exit; the error code is already into the errbuf
                                // XXX - actually exit....
                                break;
                        }

                        case RPCAP_MSG_FINDALLIF_REQ:
                        {
                                if (daemon_msg_findallif_req(header.ver, &pars, plen) == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                break;
                        }

                        case RPCAP_MSG_OPEN_REQ:
                        {
                                //
                                // Process the open request, and keep
                                // the source from it, for use later
                                // when the capture is started.
                                //
                                // XXX - we don't care if the client sends
                                // us multiple open requests, the last
                                // one wins.
                                //
                                retval = daemon_msg_open_req(header.ver, &pars,
                                    plen, source, sizeof(source));
                                if (retval == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                got_source = 1;
                                break;
                        }

                        case RPCAP_MSG_STARTCAP_REQ:
                        {
                                if (!got_source)
                                {
                                        // They never told us what device
                                        // to capture on!
                                        if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                            header.ver,
                                            PCAP_ERR_STARTCAPTURE,
                                            "No capture device was specified",
                                            errbuf) == -1)
                                        {
                                                // Fatal error; log an
                                                // error and  give up.
                                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                                goto end;
                                        }
                                        if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                        {
                                                goto end;
                                        }
                                        break;
                                }

                                if (daemon_msg_startcap_req(header.ver, &pars,
                                    plen, source, &session, &samp_param,
                                    uses_ssl) == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                break;
                        }

                        case RPCAP_MSG_UPDATEFILTER_REQ:
                        {
                                if (session)
                                {
                                        if (daemon_msg_updatefilter_req(header.ver,
                                            &pars, session, plen) == -1)
                                        {
                                                // Fatal error; a message has
                                                // been logged, so just give up.
                                                goto end;
                                        }
                                }
                                else
                                {
                                        if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                            header.ver,
                                            PCAP_ERR_UPDATEFILTER,
                                            "Device not opened. Cannot update filter",
                                            errbuf) == -1)
                                        {
                                                // That failed; log a message and give up.
                                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                                goto end;
                                        }
                                }
                                break;
                        }

                        case RPCAP_MSG_CLOSE:           // The other endpoint close the pcap session
                        {
                                //
                                // Indicate to our caller that the client
                                // closed the control connection.
                                // This is used only in case of active mode.
                                //
                                client_told_us_to_close = 1;
                                rpcapd_log(LOGPRIO_DEBUG, "The other end system asked to close the connection.");
                                goto end;
                        }

                        case RPCAP_MSG_STATS_REQ:
                        {
                                if (daemon_msg_stats_req(header.ver, &pars,
                                    session, plen, &stats, svrcapt) == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                break;
                        }

                        case RPCAP_MSG_ENDCAP_REQ:              // The other endpoint close the current capture session
                        {
                                if (session)
                                {
                                        // Save statistics (we can need them in the future)
                                        if (pcap_stats(session->fp, &stats))
                                        {
                                                svrcapt = session->TotCapt;
                                        }
                                        else
                                        {
                                                stats.ps_ifdrop = 0;
                                                stats.ps_recv = 0;
                                                stats.ps_drop = 0;
                                                svrcapt = 0;
                                        }

                                        if (daemon_msg_endcap_req(header.ver,
                                            &pars, session) == -1)
                                        {
                                                free(session);
                                                session = NULL;
                                                // Fatal error; a message has
                                                // been logged, so just give up.
                                                goto end;
                                        }
                                        free(session);
                                        session = NULL;
                                }
                                else
                                {
                                        rpcap_senderror(pars.sockctrl, pars.ssl,
                                            header.ver,
                                            PCAP_ERR_ENDCAPTURE,
                                            "Device not opened. Cannot close the capture",
                                            errbuf);
                                }
                                break;
                        }

                        case RPCAP_MSG_SETSAMPLING_REQ:
                        {
                                if (daemon_msg_setsampling_req(header.ver,
                                    &pars, plen, &samp_param) == -1)
                                {
                                        // Fatal error; a message has
                                        // been logged, so just give up.
                                        goto end;
                                }
                                break;
                        }

                        case RPCAP_MSG_AUTH_REQ:
                        {
                                //
                                // We're already authenticated; you don't
                                // get to reauthenticate.
                                //
                                rpcapd_log(LOGPRIO_INFO, "The client sent an RPCAP_MSG_AUTH_REQ message after authentication was completed");
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver,
                                    PCAP_ERR_WRONGMSG,
                                    "RPCAP_MSG_AUTH_REQ request sent after authentication was completed",
                                    errbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Fatal error.
                                        goto end;
                                }
                                goto end;

                        case RPCAP_MSG_PACKET:
                        case RPCAP_MSG_FINDALLIF_REPLY:
                        case RPCAP_MSG_OPEN_REPLY:
                        case RPCAP_MSG_STARTCAP_REPLY:
                        case RPCAP_MSG_UPDATEFILTER_REPLY:
                        case RPCAP_MSG_AUTH_REPLY:
                        case RPCAP_MSG_STATS_REPLY:
                        case RPCAP_MSG_ENDCAP_REPLY:
                        case RPCAP_MSG_SETSAMPLING_REPLY:
                                //
                                // These are server-to-client messages.
                                //
                                msg_type_string = rpcap_msg_type_string(header.type);
                                if (msg_type_string != NULL)
                                {
                                        rpcapd_log(LOGPRIO_INFO, "The client sent a %s server-to-client message", msg_type_string);
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Server-to-client message %s received from client", msg_type_string);
                                }
                                else
                                {
                                        rpcapd_log(LOGPRIO_INFO, "The client sent a server-to-client message of type %u", header.type);
                                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Server-to-client message of type %u received from client", header.type);
                                }
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver, PCAP_ERR_WRONGMSG,
                                    errmsgbuf, errbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Fatal error.
                                        goto end;
                                }
                                goto end;

                        default:
                                //
                                // Unknown message type.
                                //
                                rpcapd_log(LOGPRIO_INFO, "The client sent a message of type %u", header.type);
                                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Unknown message type %u", header.type);
                                if (rpcap_senderror(pars.sockctrl, pars.ssl,
                                    header.ver, PCAP_ERR_WRONGMSG,
                                    errbuf, errmsgbuf) == -1)
                                {
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        goto end;
                                }
                                // Discard the rest of the message.
                                if (rpcapd_discard(pars.sockctrl, pars.ssl, plen) == -1)
                                {
                                        // Fatal error.
                                        goto end;
                                }
                                goto end;
                        }
                }
        }

end:
        // The service loop is finishing up.
        // If we have a capture session running, close it.
        if (session)
        {
                session_close(session);
                free(session);
                session = NULL;
        }

        //
        // Finish using the SSL handle for the control socket, if we
        // have an SSL connection, and close the control socket.
        //
#ifdef HAVE_OPENSSL
        if (ssl)
        {
                // Finish using the SSL handle for the socket.
                // This must be done *before* the socket is closed.
                ssl_finish(ssl);
        }
#endif
        sock_close(sockctrl, NULL, 0);

        // Print message and return
        rpcapd_log(LOGPRIO_DEBUG, "I'm exiting from the child loop");

        return client_told_us_to_close;
}

/*
 * This handles the RPCAP_MSG_ERR message.
 */
static int
daemon_msg_err(SOCKET sockctrl, SSL *ssl, uint32 plen)
{
        char errbuf[PCAP_ERRBUF_SIZE];
        char remote_errbuf[PCAP_ERRBUF_SIZE];

        if (plen >= PCAP_ERRBUF_SIZE)
        {
                /*
                 * Message is too long; just read as much of it as we
                 * can into the buffer provided, and discard the rest.
                 */
                if (sock_recv(sockctrl, ssl, remote_errbuf, PCAP_ERRBUF_SIZE - 1,
                    SOCK_RECEIVEALL_YES|SOCK_EOF_IS_ERROR, errbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                {
                        // Network error.
                        rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                        return -1;
                }
                if (rpcapd_discard(sockctrl, ssl, plen - (PCAP_ERRBUF_SIZE - 1)) == -1)
                {
                        // Network error.
                        return -1;
                }

                /*
                 * Null-terminate it.
                 */
                remote_errbuf[PCAP_ERRBUF_SIZE - 1] = '\0';
        }
        else if (plen == 0)
        {
                /* Empty error string. */
                remote_errbuf[0] = '\0';
        }
        else
        {
                if (sock_recv(sockctrl, ssl, remote_errbuf, plen,
                    SOCK_RECEIVEALL_YES|SOCK_EOF_IS_ERROR, errbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                {
                        // Network error.
                        rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                        return -1;
                }

                /*
                 * Null-terminate it.
                 */
                remote_errbuf[plen] = '\0';
        }
        // Log the message
        rpcapd_log(LOGPRIO_ERROR, "Error from client: %s", remote_errbuf);
        return 0;
}

/*
 * This handles the RPCAP_MSG_AUTH_REQ message.
 * It checks if the authentication credentials supplied by the user are valid.
 *
 * This function is called if the daemon receives a RPCAP_MSG_AUTH_REQ
 * message in its authentication loop.  It reads the body of the
 * authentication message from the network and checks whether the
 * credentials are valid.
 *
 * \param sockctrl: the socket for the control connection.
 *
 * \param nullAuthAllowed: '1' if the NULL authentication is allowed.
 *
 * \param errbuf: a user-allocated buffer in which the error message
 * (if one) has to be written.  It must be at least PCAP_ERRBUF_SIZE
 * bytes long.
 *
 * \return '0' if everything is fine, '-1' if an unrecoverable error occurred,
 * or '-2' if the authentication failed.  For errors, an error message is
 * returned in the 'errbuf' variable; this gives a message for the
 * unrecoverable error or for the authentication failure.
 */
static int
daemon_msg_auth_req(struct daemon_slpars *pars, uint32 plen)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        int status;
        struct rpcap_auth auth;                 // RPCAP authentication header
        char sendbuf[RPCAP_NETBUF_SIZE];        // temporary buffer in which data to be sent is buffered
        int sendbufidx = 0;                     // index which keeps the number of bytes currently buffered
        struct rpcap_authreply *authreply;      // authentication reply message

        status = rpcapd_recv(pars->sockctrl, pars->ssl, (char *) &auth, sizeof(struct rpcap_auth), &plen, errmsgbuf);
        if (status == -1)
        {
                return -1;
        }
        if (status == -2)
        {
                goto error;
        }

        switch (ntohs(auth.type))
        {
                case RPCAP_RMTAUTH_NULL:
                {
                        if (!pars->nullAuthAllowed)
                        {
                                // Send the client an error reply.
                                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE,
                                    "Authentication failed; NULL authentication not permitted.");
                                if (rpcap_senderror(pars->sockctrl, pars->ssl,
                                    0, PCAP_ERR_AUTH_FAILED, errmsgbuf, errbuf) == -1)
                                {
                                        // That failed; log a message and give up.
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        return -1;
                                }
                                goto error_noreply;
                        }
                        break;
                }

                case RPCAP_RMTAUTH_PWD:
                {
                        char *username, *passwd;
                        uint32 usernamelen, passwdlen;

                        usernamelen = ntohs(auth.slen1);
                        username = (char *) malloc (usernamelen + 1);
                        if (username == NULL)
                        {
                                pcap_fmt_errmsg_for_errno(errmsgbuf,
                                    PCAP_ERRBUF_SIZE, errno, "malloc() failed");
                                goto error;
                        }
                        status = rpcapd_recv(pars->sockctrl, pars->ssl, username, usernamelen, &plen, errmsgbuf);
                        if (status == -1)
                        {
                                free(username);
                                return -1;
                        }
                        if (status == -2)
                        {
                                free(username);
                                goto error;
                        }
                        username[usernamelen] = '\0';

                        passwdlen = ntohs(auth.slen2);
                        passwd = (char *) malloc (passwdlen + 1);
                        if (passwd == NULL)
                        {
                                pcap_fmt_errmsg_for_errno(errmsgbuf,
                                    PCAP_ERRBUF_SIZE, errno, "malloc() failed");
                                free(username);
                                goto error;
                        }
                        status = rpcapd_recv(pars->sockctrl, pars->ssl, passwd, passwdlen, &plen, errmsgbuf);
                        if (status == -1)
                        {
                                free(username);
                                free(passwd);
                                return -1;
                        }
                        if (status == -2)
                        {
                                free(username);
                                free(passwd);
                                goto error;
                        }
                        passwd[passwdlen] = '\0';

                        if (daemon_AuthUserPwd(username, passwd, errmsgbuf))
                        {
                                //
                                // Authentication failed.  Let the client
                                // know.
                                //
                                free(username);
                                free(passwd);
                                if (rpcap_senderror(pars->sockctrl, pars->ssl,
                                    0, PCAP_ERR_AUTH_FAILED, errmsgbuf, errbuf) == -1)
                                {
                                        // That failed; log a message and give up.
                                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                        return -1;
                                }

                                //
                                // Suspend for 1 second, so that they can't
                                // hammer us with repeated tries with an
                                // attack such as a dictionary attack.
                                //
                                // WARNING: this delay is inserted only
                                // at this point; if the client closes the
                                // connection and reconnects, the suspension
                                // time does not have any effect.
                                //
                                sleep_secs(RPCAP_SUSPEND_WRONGAUTH);
                                goto error_noreply;
                        }

                        free(username);
                        free(passwd);
                        break;
                        }

                default:
                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE,
                            "Authentication type not recognized.");
                        if (rpcap_senderror(pars->sockctrl, pars->ssl,
                            0, PCAP_ERR_AUTH_TYPE_NOTSUP, errmsgbuf, errbuf) == -1)
                        {
                                // That failed; log a message and give up.
                                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                                return -1;
                        }
                        goto error_noreply;
        }

        // The authentication succeeded; let the client know.
        if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL, &sendbufidx,
            RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        rpcap_createhdr((struct rpcap_header *) sendbuf, 0,
            RPCAP_MSG_AUTH_REPLY, 0, sizeof(struct rpcap_authreply));

        authreply = (struct rpcap_authreply *) &sendbuf[sendbufidx];

        if (sock_bufferize(NULL, sizeof(struct rpcap_authreply), NULL, &sendbufidx,
            RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        //
        // Indicate to our peer what versions we support.
        //
        memset(authreply, 0, sizeof(struct rpcap_authreply));
        authreply->minvers = RPCAP_MIN_VERSION;
        authreply->maxvers = RPCAP_MAX_VERSION;

        // Send the reply.
        if (sock_send(pars->sockctrl, pars->ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                // That failed; log a messsage and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }

        return 0;

error:
        if (rpcap_senderror(pars->sockctrl, pars->ssl, 0, PCAP_ERR_AUTH,
            errmsgbuf, errbuf) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

error_noreply:
        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }

        return -2;
}

static int
daemon_AuthUserPwd(char *username, char *password, char *errbuf)
{
#ifdef _WIN32
        /*
         * Warning: the user which launches the process must have the
         * SE_TCB_NAME right.
         * This corresponds to have the "Act as part of the Operating System"
         * turned on (administrative tools, local security settings, local
         * policies, user right assignment)
         * However, it seems to me that if you run it as a service, this
         * right should be provided by default.
         *
         * XXX - hopefully, this returns errors such as ERROR_LOGON_FAILURE,
         * which merely indicates that the user name or password is
         * incorrect, not whether it's the user name or the password
         * that's incorrect, so a client that's trying to brute-force
         * accounts doesn't know whether it's the user name or the
         * password that's incorrect, so it doesn't know whether to
         * stop trying to log in with a given user name and move on
         * to another user name.
         */
        DWORD error;
        HANDLE Token;
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to log

        if (LogonUser(username, ".", password, LOGON32_LOGON_NETWORK, LOGON32_PROVIDER_DEFAULT, &Token) == 0)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                error = GetLastError();
                if (error != ERROR_LOGON_FAILURE)
                {
                        // Some error other than an authentication error;
                        // log it.
                        pcap_fmt_errmsg_for_win32_err(errmsgbuf,
                            PCAP_ERRBUF_SIZE, error, "LogonUser() failed");
                        rpcapd_log(LOGPRIO_ERROR, "%s", errmsgbuf);
                }                   
                return -1;
        }

        // This call should change the current thread to the selected user.
        // I didn't test it.
        if (ImpersonateLoggedOnUser(Token) == 0)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                pcap_fmt_errmsg_for_win32_err(errmsgbuf, PCAP_ERRBUF_SIZE,
                    GetLastError(), "ImpersonateLoggedOnUser() failed");
                rpcapd_log(LOGPRIO_ERROR, "%s", errmsgbuf);
                CloseHandle(Token);
                return -1;
        }

        CloseHandle(Token);
        return 0;

#else
        /*
         * See
         *
         *      http://www.unixpapa.com/incnote/passwd.html
         *
         * We use the Solaris/Linux shadow password authentication if
         * we have getspnam(), otherwise we just do traditional
         * authentication, which, on some platforms, might work, even
         * with shadow passwords, if we're running as root.  Traditional
         * authenticaion won't work if we're not running as root, as
         * I think these days all UN*Xes either won't return the password
         * at all with getpwnam() or will only do so if you're root.
         *
         * XXX - perhaps what we *should* be using is PAM, if we have
         * it.  That might hide all the details of username/password
         * authentication, whether it's done with a visible-to-root-
         * only password database or some other authentication mechanism,
         * behind its API.
         */
        int error;
        struct passwd *user;
        char *user_password;
#ifdef HAVE_GETSPNAM
        struct spwd *usersp;
#endif
        char *crypt_password;

        // This call is needed to get the uid
        if ((user = getpwnam(username)) == NULL)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                return -1;
        }

#ifdef HAVE_GETSPNAM
        // This call is needed to get the password; otherwise 'x' is returned
        if ((usersp = getspnam(username)) == NULL)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                return -1;
        }
        user_password = usersp->sp_pwdp;
#else
        /*
         * XXX - what about other platforms?
         * The unixpapa.com page claims this Just Works on *BSD if you're
         * running as root - it's from 2000, so it doesn't indicate whether
         * macOS (which didn't come out until 2001, under the name Mac OS
         * X) behaves like the *BSDs or not, and might also work on AIX.
         * HP-UX does something else.
         *
         * Again, hopefully PAM hides all that.
         */
        user_password = user->pw_passwd;
#endif

        //
        // The Single UNIX Specification says that if crypt() fails it
        // sets errno, but some implementatons that haven't been run
        // through the SUS test suite might not do so.
        //
        errno = 0;
        crypt_password = crypt(password, user_password);
        if (crypt_password == NULL)
        {
                error = errno;
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                if (error == 0)
                {
                        // It didn't set errno.
                        rpcapd_log(LOGPRIO_ERROR, "crypt() failed");
                }
                else
                {
                        rpcapd_log(LOGPRIO_ERROR, "crypt() failed: %s",
                            strerror(error));
                }
                return -1;
        }
        if (strcmp(user_password, crypt_password) != 0)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Authentication failed");
                return -1;
        }

        if (setuid(user->pw_uid))
        {
                error = errno;
                pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
                    error, "setuid");
                rpcapd_log(LOGPRIO_ERROR, "setuid() failed: %s",
                    strerror(error));
                return -1;
        }

/*      if (setgid(user->pw_gid))
        {
                error = errno;
                pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
                    errno, "setgid");
                rpcapd_log(LOGPRIO_ERROR, "setgid() failed: %s",
                    strerror(error));
                return -1;
        }
*/
        return 0;

#endif

}

static int
daemon_msg_findallif_req(uint8 ver, struct daemon_slpars *pars, uint32 plen)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        char sendbuf[RPCAP_NETBUF_SIZE];        // temporary buffer in which data to be sent is buffered
        int sendbufidx = 0;                     // index which keeps the number of bytes currently buffered
        pcap_if_t *alldevs = NULL;              // pointer to the header of the interface chain
        pcap_if_t *d;                           // temp pointer needed to scan the interface chain
        struct pcap_addr *address;              // pcap structure that keeps a network address of an interface
        struct rpcap_findalldevs_if *findalldevs_if;// rpcap structure that packet all the data of an interface together
        uint32 replylen;                        // length of reply payload
        uint16 nif = 0;                         // counts the number of interface listed

        // Discard the rest of the message; there shouldn't be any payload.
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                // Network error.
                return -1;
        }

        // Retrieve the device list
        if (pcap_findalldevs(&alldevs, errmsgbuf) == -1)
                goto error;

        if (alldevs == NULL)
        {
                if (rpcap_senderror(pars->sockctrl, pars->ssl, ver,
                        PCAP_ERR_NOREMOTEIF,
                        "No interfaces found! Make sure libpcap/WinPcap is properly installed"
                        " and you have the right to access to the remote device.",
                        errbuf) == -1)
                {
                        rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                        return -1;
                }
                return 0;
        }

        // This checks the number of interfaces and computes the total
        // length of the payload.
        replylen = 0;
        for (d = alldevs; d != NULL; d = d->next)
        {
                nif++;

                if (d->description)
                        replylen += strlen(d->description);
                if (d->name)
                        replylen += strlen(d->name);

                replylen += sizeof(struct rpcap_findalldevs_if);

                for (address = d->addresses; address != NULL; address = address->next)
                {
                        /*
                         * Send only IPv4 and IPv6 addresses over the wire.
                         */
                        switch (address->addr->sa_family)
                        {
                        case AF_INET:
#ifdef AF_INET6
                        case AF_INET6:
#endif
                                replylen += (sizeof(struct rpcap_sockaddr) * 4);
                                break;

                        default:
                                break;
                        }
                }
        }

        // RPCAP findalldevs command
        if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL,
            &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf,
            PCAP_ERRBUF_SIZE) == -1)
                goto error;

        rpcap_createhdr((struct rpcap_header *) sendbuf, ver,
            RPCAP_MSG_FINDALLIF_REPLY, nif, replylen);

        // send the interface list
        for (d = alldevs; d != NULL; d = d->next)
        {
                uint16 lname, ldescr;

                findalldevs_if = (struct rpcap_findalldevs_if *) &sendbuf[sendbufidx];

                if (sock_bufferize(NULL, sizeof(struct rpcap_findalldevs_if), NULL,
                    &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                        goto error;

                memset(findalldevs_if, 0, sizeof(struct rpcap_findalldevs_if));

                if (d->description) ldescr = (short) strlen(d->description);
                else ldescr = 0;
                if (d->name) lname = (short) strlen(d->name);
                else lname = 0;

                findalldevs_if->desclen = htons(ldescr);
                findalldevs_if->namelen = htons(lname);
                findalldevs_if->flags = htonl(d->flags);

                for (address = d->addresses; address != NULL; address = address->next)
                {
                        /*
                         * Send only IPv4 and IPv6 addresses over the wire.
                         */
                        switch (address->addr->sa_family)
                        {
                        case AF_INET:
#ifdef AF_INET6
                        case AF_INET6:
#endif
                                findalldevs_if->naddr++;
                                break;

                        default:
                                break;
                        }
                }
                findalldevs_if->naddr = htons(findalldevs_if->naddr);

                if (sock_bufferize(d->name, lname, sendbuf, &sendbufidx,
                    RPCAP_NETBUF_SIZE, SOCKBUF_BUFFERIZE, errmsgbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                        goto error;

                if (sock_bufferize(d->description, ldescr, sendbuf, &sendbufidx,
                    RPCAP_NETBUF_SIZE, SOCKBUF_BUFFERIZE, errmsgbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                        goto error;

                // send all addresses
                for (address = d->addresses; address != NULL; address = address->next)
                {
                        struct rpcap_sockaddr *sockaddr;

                        /*
                         * Send only IPv4 and IPv6 addresses over the wire.
                         */
                        switch (address->addr->sa_family)
                        {
                        case AF_INET:
#ifdef AF_INET6
                        case AF_INET6:
#endif
                                sockaddr = (struct rpcap_sockaddr *) &sendbuf[sendbufidx];
                                if (sock_bufferize(NULL, sizeof(struct rpcap_sockaddr), NULL,
                                    &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                                        goto error;
                                daemon_seraddr((struct sockaddr_storage *) address->addr, sockaddr);

                                sockaddr = (struct rpcap_sockaddr *) &sendbuf[sendbufidx];
                                if (sock_bufferize(NULL, sizeof(struct rpcap_sockaddr), NULL,
                                    &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                                        goto error;
                                daemon_seraddr((struct sockaddr_storage *) address->netmask, sockaddr);

                                sockaddr = (struct rpcap_sockaddr *) &sendbuf[sendbufidx];
                                if (sock_bufferize(NULL, sizeof(struct rpcap_sockaddr), NULL,
                                    &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                                        goto error;
                                daemon_seraddr((struct sockaddr_storage *) address->broadaddr, sockaddr);

                                sockaddr = (struct rpcap_sockaddr *) &sendbuf[sendbufidx];
                                if (sock_bufferize(NULL, sizeof(struct rpcap_sockaddr), NULL,
                                    &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                                        goto error;
                                daemon_seraddr((struct sockaddr_storage *) address->dstaddr, sockaddr);
                                break;

                        default:
                                break;
                        }
                }
        }

        // We no longer need the device list. Free it.
        pcap_freealldevs(alldevs);

        // Send a final command that says "now send it!"
        if (sock_send(pars->sockctrl, pars->ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        return 0;

error:
        if (alldevs)
                pcap_freealldevs(alldevs);

        if (rpcap_senderror(pars->sockctrl, pars->ssl, ver,
            PCAP_ERR_FINDALLIF, errmsgbuf, errbuf) == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }
        return 0;
}

/*
        \param plen: the length of the current message (needed in order to be able
        to discard excess data in the message, if present)
*/
static int
daemon_msg_open_req(uint8 ver, struct daemon_slpars *pars, uint32 plen,
    char *source, size_t sourcelen)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        pcap_t *fp;                             // pcap_t main variable
        int nread;
        char sendbuf[RPCAP_NETBUF_SIZE];        // temporary buffer in which data to be sent is buffered
        int sendbufidx = 0;                     // index which keeps the number of bytes currently buffered
        struct rpcap_openreply *openreply;      // open reply message

        if (plen > sourcelen - 1)
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Source string too long");
                goto error;
        }

        nread = sock_recv(pars->sockctrl, pars->ssl, source, plen,
            SOCK_RECEIVEALL_YES|SOCK_EOF_IS_ERROR, errbuf, PCAP_ERRBUF_SIZE);
        if (nread == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                return -1;
        }
        source[nread] = '\0';
        plen -= nread;

        // Is this a URL rather than a device?
        // If so, reject it.
        if (is_url(source))
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Source string refers to a remote device");
                goto error;
        }

        // Open the selected device
        // This is a fake open, since we do that only to get the needed parameters, then we close the device again
        if ((fp = pcap_open_live(source,
                        1500 /* fake snaplen */,
                        0 /* no promis */,
                        1000 /* fake timeout */,
                        errmsgbuf)) == NULL)
                goto error;

        // Now, I can send a RPCAP open reply message
        if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL, &sendbufidx,
            RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        rpcap_createhdr((struct rpcap_header *) sendbuf, ver,
            RPCAP_MSG_OPEN_REPLY, 0, sizeof(struct rpcap_openreply));

        openreply = (struct rpcap_openreply *) &sendbuf[sendbufidx];

        if (sock_bufferize(NULL, sizeof(struct rpcap_openreply), NULL, &sendbufidx,
            RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        memset(openreply, 0, sizeof(struct rpcap_openreply));
        openreply->linktype = htonl(pcap_datalink(fp));
        /*
         * This is always 0 for live captures; we no longer support it
         * as something we read from capture files and supply to
         * clients, but we have to send it over the wire, as open
         * replies are expected to have 8 bytes of payload by
         * existing clients.
         */
        openreply->tzoff = 0;

        // We're done with the pcap_t.
        pcap_close(fp);

        // Send the reply.
        if (sock_send(pars->sockctrl, pars->ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }
        return 0;

error:
        if (rpcap_senderror(pars->sockctrl, pars->ssl, ver, PCAP_ERR_OPEN,
            errmsgbuf, errbuf) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }
        return 0;
}

/*
        \param plen: the length of the current message (needed in order to be able
        to discard excess data in the message, if present)
*/
static int
daemon_msg_startcap_req(uint8 ver, struct daemon_slpars *pars, uint32 plen,
    char *source, struct session **sessionp,
    struct rpcap_sampling *samp_param _U_, int uses_ssl)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        char portdata[PCAP_BUF_SIZE];           // temp variable needed to derive the data port
        char peerhost[PCAP_BUF_SIZE];           // temp variable needed to derive the host name of our peer
        struct session *session = NULL;         // saves state of session
        int status;
        char sendbuf[RPCAP_NETBUF_SIZE];        // temporary buffer in which data to be sent is buffered
        int sendbufidx = 0;                     // index which keeps the number of bytes currently buffered

        // socket-related variables
        struct addrinfo hints;                  // temp, needed to open a socket connection
        struct addrinfo *addrinfo;              // temp, needed to open a socket connection
        struct sockaddr_storage saddr;          // temp, needed to retrieve the network data port chosen on the local machine
        socklen_t saddrlen;                     // temp, needed to retrieve the network data port chosen on the local machine
        int ret;                                // return value from functions

        // RPCAP-related variables
        struct rpcap_startcapreq startcapreq;           // start capture request message
        struct rpcap_startcapreply *startcapreply;      // start capture reply message
        int serveropen_dp;                                                      // keeps who is going to open the data connection

        addrinfo = NULL;

        status = rpcapd_recv(pars->sockctrl, pars->ssl, (char *) &startcapreq,
            sizeof(struct rpcap_startcapreq), &plen, errmsgbuf);
        if (status == -1)
        {
                goto fatal_error;
        }
        if (status == -2)
        {
                goto error;
        }

        startcapreq.flags = ntohs(startcapreq.flags);

        // Check that the client does not ask for UDP is the server has been asked
        // to enforce encryption, as SSL is not supported yet with UDP:
        if (uses_ssl && (startcapreq.flags & RPCAP_STARTCAPREQ_FLAG_DGRAM))
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE,
                    "SSL not supported with UDP forward of remote packets");
                goto error;
        }

        // Create a session structure
        session = malloc(sizeof(struct session));
        if (session == NULL)
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Can't allocate session structure");
                goto error;
        }

        session->sockdata = INVALID_SOCKET;
        session->ctrl_ssl = session->data_ssl = NULL;
        // We don't have a thread yet.
        session->have_thread = 0;
        //
        // We *shouldn't* have to initialize the thread indicator
        // itself, because the compiler *should* realize that we
        // only use this if have_thread isn't 0, but we *do* have
        // to do it, because not all compilers *do* realize that.
        //
        // There is no "invalid thread handle" value for a UN*X
        // pthread_t, so we just zero it out.
        //
#ifdef _WIN32
        session->thread = INVALID_HANDLE_VALUE;
#else
        memset(&session->thread, 0, sizeof(session->thread));
#endif

        // Open the selected device
        if ((session->fp = pcap_open_live(source,
                        ntohl(startcapreq.snaplen),
                        (startcapreq.flags & RPCAP_STARTCAPREQ_FLAG_PROMISC) ? 1 : 0 /* local device, other flags not needed */,
                        ntohl(startcapreq.read_timeout),
                        errmsgbuf)) == NULL)
                goto error;

#if 0
        // Apply sampling parameters
        fp->rmt_samp.method = samp_param->method;
        fp->rmt_samp.value = samp_param->value;
#endif

        /*
        We're in active mode if:
        - we're using TCP, and the user wants us to be in active mode
        - we're using UDP
        */
        serveropen_dp = (startcapreq.flags & RPCAP_STARTCAPREQ_FLAG_SERVEROPEN) || (startcapreq.flags & RPCAP_STARTCAPREQ_FLAG_DGRAM) || pars->isactive;

        /*
        Gets the sockaddr structure referred to the other peer in the ctrl connection

        We need that because:
        - if we're in passive mode, we need to know the address family we want to use
        (the same used for the ctrl socket)
        - if we're in active mode, we need to know the network address of the other host
        we want to connect to
        */
        saddrlen = sizeof(struct sockaddr_storage);
        if (getpeername(pars->sockctrl, (struct sockaddr *) &saddr, &saddrlen) == -1)
        {
                sock_geterror("getpeername()", errmsgbuf, PCAP_ERRBUF_SIZE);
                goto error;
        }

        memset(&hints, 0, sizeof(struct addrinfo));
        hints.ai_socktype = (startcapreq.flags & RPCAP_STARTCAPREQ_FLAG_DGRAM) ? SOCK_DGRAM : SOCK_STREAM;
        hints.ai_family = saddr.ss_family;

        // Now we have to create a new socket to send packets
        if (serveropen_dp)              // Data connection is opened by the server toward the client
        {
                snprintf(portdata, sizeof portdata, "%d", ntohs(startcapreq.portdata));

                // Get the name of the other peer (needed to connect to that specific network address)
                if (getnameinfo((struct sockaddr *) &saddr, saddrlen, peerhost,
                                sizeof(peerhost), NULL, 0, NI_NUMERICHOST))
                {
                        sock_geterror("getnameinfo()", errmsgbuf, PCAP_ERRBUF_SIZE);
                        goto error;
                }

                if (sock_initaddress(peerhost, portdata, &hints, &addrinfo, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                        goto error;

                if ((session->sockdata = sock_open(addrinfo, SOCKOPEN_CLIENT, 0, errmsgbuf, PCAP_ERRBUF_SIZE)) == INVALID_SOCKET)
                        goto error;
        }
        else            // Data connection is opened by the client toward the server
        {
                hints.ai_flags = AI_PASSIVE;

                // Let's the server socket pick up a free network port for us
                if (sock_initaddress(NULL, "0", &hints, &addrinfo, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                        goto error;

                if ((session->sockdata = sock_open(addrinfo, SOCKOPEN_SERVER, 1 /* max 1 connection in queue */, errmsgbuf, PCAP_ERRBUF_SIZE)) == INVALID_SOCKET)
                        goto error;

                // get the complete sockaddr structure used in the data connection
                saddrlen = sizeof(struct sockaddr_storage);
                if (getsockname(session->sockdata, (struct sockaddr *) &saddr, &saddrlen) == -1)
                {
                        sock_geterror("getsockname()", errmsgbuf, PCAP_ERRBUF_SIZE);
                        goto error;
                }

                // Get the local port the system picked up
                if (getnameinfo((struct sockaddr *) &saddr, saddrlen, NULL,
                                0, portdata, sizeof(portdata), NI_NUMERICSERV))
                {
                        sock_geterror("getnameinfo()", errmsgbuf, PCAP_ERRBUF_SIZE);
                        goto error;
                }
        }

        // addrinfo is no longer used
        freeaddrinfo(addrinfo);
        addrinfo = NULL;

        // Needed to send an error on the ctrl connection
        session->sockctrl = pars->sockctrl;
        session->ctrl_ssl = pars->ssl;
        session->protocol_version = ver;

        // Now I can set the filter
        ret = daemon_unpackapplyfilter(pars->sockctrl, pars->ssl, session, &plen, errmsgbuf);
        if (ret == -1)
        {
                // Fatal error.  A message has been logged; just give up.
                goto fatal_error;
        }
        if (ret == -2)
        {
                // Non-fatal error.  Send an error message to the client.
                goto error;
        }

        // Now, I can send a RPCAP start capture reply message
        if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL, &sendbufidx,
            RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        rpcap_createhdr((struct rpcap_header *) sendbuf, ver,
            RPCAP_MSG_STARTCAP_REPLY, 0, sizeof(struct rpcap_startcapreply));

        startcapreply = (struct rpcap_startcapreply *) &sendbuf[sendbufidx];

        if (sock_bufferize(NULL, sizeof(struct rpcap_startcapreply), NULL,
            &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        memset(startcapreply, 0, sizeof(struct rpcap_startcapreply));
        startcapreply->bufsize = htonl(pcap_bufsize(session->fp));

        if (!serveropen_dp)
        {
                unsigned short port = (unsigned short)strtoul(portdata,NULL,10);
                startcapreply->portdata = htons(port);
        }

        if (sock_send(pars->sockctrl, pars->ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                goto fatal_error;
        }

        if (!serveropen_dp)
        {
                SOCKET socktemp;        // We need another socket, since we're going to accept() a connection

                // Connection creation
                saddrlen = sizeof(struct sockaddr_storage);

                socktemp = accept(session->sockdata, (struct sockaddr *) &saddr, &saddrlen);

                if (socktemp == INVALID_SOCKET)
                {
                        sock_geterror("accept()", errbuf, PCAP_ERRBUF_SIZE);
                        rpcapd_log(LOGPRIO_ERROR, "Accept of data connection failed: %s",
                            errbuf);
                        goto error;
                }

                // Now that I accepted the connection, the server socket is no longer needed
                sock_close(session->sockdata, NULL, 0);
                session->sockdata = socktemp;
        }

        SSL *ssl = NULL;
        if (uses_ssl)
        {
#ifdef HAVE_OPENSSL
                /* In both active or passive cases, wait for the client to initiate the
                 * TLS handshake. Yes during that time the control socket will not be
                 * served, but the same was true from the above call to accept(). */
                ssl = ssl_promotion(1, session->sockdata, errbuf, PCAP_ERRBUF_SIZE);
                if (! ssl)
                {
                        rpcapd_log(LOGPRIO_ERROR, "TLS handshake failed: %s", errbuf);
                        goto error;
                }
#endif
        }
        session->data_ssl = ssl;

        // Now we have to create a new thread to receive packets
#ifdef _WIN32
        session->thread = (HANDLE)_beginthreadex(NULL, 0, daemon_thrdatamain,
            (void *) session, 0, NULL);
        if (session->thread == 0)
        {
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error creating the data thread");
                goto error;
        }
#else
        ret = pthread_create(&session->thread, NULL, daemon_thrdatamain,
            (void *) session);
        if (ret != 0)
        {
                pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
                    ret, "Error creating the data thread");
                goto error;
        }
#endif
        session->have_thread = 1;

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
                goto fatal_error;

        *sessionp = session;
        return 0;

error:
        //
        // Not a fatal error, so send the client an error message and
        // keep serving client requests.
        //
        *sessionp = NULL;

        if (addrinfo)
                freeaddrinfo(addrinfo);

        if (session)
        {
                session_close(session);
                free(session);
        }

        if (rpcap_senderror(pars->sockctrl, pars->ssl, ver,
            PCAP_ERR_STARTCAPTURE, errmsgbuf, errbuf) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                // Network error.
                return -1;
        }

        return 0;

fatal_error:
        //
        // Fatal network error, so don't try to communicate with
        // the client, just give up.
        //
        *sessionp = NULL;

        if (session)
        {
                session_close(session);
                free(session);
        }

        return -1;
}

static int
daemon_msg_endcap_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        struct rpcap_header header;

        session_close(session);

        rpcap_createhdr(&header, ver, RPCAP_MSG_ENDCAP_REPLY, 0, 0);

        if (sock_send(pars->sockctrl, pars->ssl, (char *) &header, sizeof(struct rpcap_header), errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        return 0;
}

//
// We impose a limit on the filter program size, so that, on Windows,
// where there's only one server process with multiple threads, it's
// harder to eat all the server address space by sending larger filter
// programs.  (This isn't an issue on UN*X, where there are multiple
// server processes, one per client connection.)
//
// We pick a value that limits each filter to 64K; that value is twice
// the in-kernel limit for Linux and 16 times the in-kernel limit for
// *BSD and macOS.
//
// It also prevents an overflow on 32-bit platforms when calculating
// the total size of the filter program.  (It's not an issue on 64-bit
// platforms with a 64-bit size_t, as the filter size is 32 bits.)
//
#define RPCAP_BPF_MAXINSNS      8192

static int
daemon_unpackapplyfilter(SOCKET sockctrl, SSL *ctrl_ssl, struct session *session, uint32 *plenp, char *errmsgbuf)
{
        int status;
        struct rpcap_filter filter;
        struct rpcap_filterbpf_insn insn;
        struct bpf_insn *bf_insn;
        struct bpf_program bf_prog;
        unsigned int i;

        status = rpcapd_recv(sockctrl, ctrl_ssl, (char *) &filter,
            sizeof(struct rpcap_filter), plenp, errmsgbuf);
        if (status == -1)
        {
                return -1;
        }
        if (status == -2)
        {
                return -2;
        }

        bf_prog.bf_len = ntohl(filter.nitems);

        if (ntohs(filter.filtertype) != RPCAP_UPDATEFILTER_BPF)
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Only BPF/NPF filters are currently supported");
                return -2;
        }

        if (bf_prog.bf_len > RPCAP_BPF_MAXINSNS)
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE,
                    "Filter program is larger than the maximum size of %u instructions",
                    RPCAP_BPF_MAXINSNS);
                return -2;
        }
        bf_insn = (struct bpf_insn *) malloc (sizeof(struct bpf_insn) * bf_prog.bf_len);
        if (bf_insn == NULL)
        {
                pcap_fmt_errmsg_for_errno(errmsgbuf, PCAP_ERRBUF_SIZE,
                    errno, "malloc() failed");
                return -2;
        }

        bf_prog.bf_insns = bf_insn;

        for (i = 0; i < bf_prog.bf_len; i++)
        {
                status = rpcapd_recv(sockctrl, ctrl_ssl, (char *) &insn,
                    sizeof(struct rpcap_filterbpf_insn), plenp, errmsgbuf);
                if (status == -1)
                {
                        return -1;
                }
                if (status == -2)
                {
                        return -2;
                }

                bf_insn->code = ntohs(insn.code);
                bf_insn->jf = insn.jf;
                bf_insn->jt = insn.jt;
                bf_insn->k = ntohl(insn.k);

                bf_insn++;
        }

        //
        // XXX - pcap_setfilter() should do the validation for us.
        //
        if (bpf_validate(bf_prog.bf_insns, bf_prog.bf_len) == 0)
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "The filter contains bogus instructions");
                return -2;
        }

        if (pcap_setfilter(session->fp, &bf_prog))
        {
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "RPCAP error: %s", pcap_geterr(session->fp));
                return -2;
        }

        return 0;
}

static int
daemon_msg_updatefilter_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session, uint32 plen)
{
        char errbuf[PCAP_ERRBUF_SIZE];
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        int ret;                                // status of daemon_unpackapplyfilter()
        struct rpcap_header header;             // keeps the answer to the updatefilter command

        ret = daemon_unpackapplyfilter(pars->sockctrl, pars->ssl, session, &plen, errmsgbuf);
        if (ret == -1)
        {
                // Fatal error.  A message has been logged; just give up.
                return -1;
        }
        if (ret == -2)
        {
                // Non-fatal error.  Send an error reply to the client.
                goto error;
        }

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                // Network error.
                return -1;
        }

        // A response is needed, otherwise the other host does not know that everything went well
        rpcap_createhdr(&header, ver, RPCAP_MSG_UPDATEFILTER_REPLY, 0, 0);

        if (sock_send(pars->sockctrl, pars->ssl, (char *) &header, sizeof (struct rpcap_header), pcap_geterr(session->fp), PCAP_ERRBUF_SIZE))
        {
                // That failed; log a messsage and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        return 0;

error:
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }
        rpcap_senderror(pars->sockctrl, pars->ssl, ver, PCAP_ERR_UPDATEFILTER,
            errmsgbuf, NULL);

        return 0;
}

/*!
        \brief Received the sampling parameters from remote host and it stores in the pcap_t structure.
*/
static int
daemon_msg_setsampling_req(uint8 ver, struct daemon_slpars *pars, uint32 plen,
    struct rpcap_sampling *samp_param)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];
        struct rpcap_header header;
        struct rpcap_sampling rpcap_samp;
        int status;

        status = rpcapd_recv(pars->sockctrl, pars->ssl, (char *) &rpcap_samp, sizeof(struct rpcap_sampling), &plen, errmsgbuf);
        if (status == -1)
        {
                return -1;
        }
        if (status == -2)
        {
                goto error;
        }

        // Save these settings in the pcap_t
        samp_param->method = rpcap_samp.method;
        samp_param->value = ntohl(rpcap_samp.value);

        // A response is needed, otherwise the other host does not know that everything went well
        rpcap_createhdr(&header, ver, RPCAP_MSG_SETSAMPLING_REPLY, 0, 0);

        if (sock_send(pars->sockctrl, pars->ssl, (char *) &header, sizeof (struct rpcap_header), errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                // That failed; log a messsage and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }

        return 0;

error:
        if (rpcap_senderror(pars->sockctrl, pars->ssl, ver, PCAP_ERR_SETSAMPLING,
            errmsgbuf, errbuf) == -1)
        {
                // That failed; log a message and give up.
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        // Check if all the data has been read; if not, discard the data in excess
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                return -1;
        }

        return 0;
}

static int
daemon_msg_stats_req(uint8 ver, struct daemon_slpars *pars,
    struct session *session, uint32 plen, struct pcap_stat *stats,
    unsigned int svrcapt)
{
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors
        char errmsgbuf[PCAP_ERRBUF_SIZE];       // buffer for errors to send to the client
        char sendbuf[RPCAP_NETBUF_SIZE];        // temporary buffer in which data to be sent is buffered
        int sendbufidx = 0;                     // index which keeps the number of bytes currently buffered
        struct rpcap_stats *netstats;           // statistics sent on the network

        // Checks that the header does not contain other data; if so, discard it
        if (rpcapd_discard(pars->sockctrl, pars->ssl, plen) == -1)
        {
                // Network error.
                return -1;
        }

        if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL,
            &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        rpcap_createhdr((struct rpcap_header *) sendbuf, ver,
            RPCAP_MSG_STATS_REPLY, 0, (uint16) sizeof(struct rpcap_stats));

        netstats = (struct rpcap_stats *) &sendbuf[sendbufidx];

        if (sock_bufferize(NULL, sizeof(struct rpcap_stats), NULL,
            &sendbufidx, RPCAP_NETBUF_SIZE, SOCKBUF_CHECKONLY, errmsgbuf, PCAP_ERRBUF_SIZE) == -1)
                goto error;

        if (session && session->fp)
        {
                if (pcap_stats(session->fp, stats) == -1)
                {
                        snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "%s", pcap_geterr(session->fp));
                        goto error;
                }

                netstats->ifdrop = htonl(stats->ps_ifdrop);
                netstats->ifrecv = htonl(stats->ps_recv);
                netstats->krnldrop = htonl(stats->ps_drop);
                netstats->svrcapt = htonl(session->TotCapt);
        }
        else
        {
                // We have to keep compatibility with old applications,
                // which ask for statistics also when the capture has
                // already stopped.
                netstats->ifdrop = htonl(stats->ps_ifdrop);
                netstats->ifrecv = htonl(stats->ps_recv);
                netstats->krnldrop = htonl(stats->ps_drop);
                netstats->svrcapt = htonl(svrcapt);
        }

        // Send the packet
        if (sock_send(pars->sockctrl, pars->ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Send to client failed: %s", errbuf);
                return -1;
        }

        return 0;

error:
        rpcap_senderror(pars->sockctrl, pars->ssl, ver, PCAP_ERR_GETSTATS,
            errmsgbuf, NULL);
        return 0;
}

#ifdef _WIN32
static unsigned __stdcall
#else
static void *
#endif
daemon_thrdatamain(void *ptr)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // error buffer
        struct session *session;                // pointer to the struct session for this session
        int retval;                                                     // general variable used to keep the return value of other functions
        struct rpcap_pkthdr *net_pkt_header;// header of the packet
        struct pcap_pkthdr *pkt_header;         // pointer to the buffer that contains the header of the current packet
        u_char *pkt_data;                                       // pointer to the buffer that contains the current packet
        size_t sendbufsize;                     // size for the send buffer
        char *sendbuf;                                          // temporary buffer in which data to be sent is buffered
        int sendbufidx;                                         // index which keeps the number of bytes currently buffered
        int status;
#ifndef _WIN32
        sigset_t sigusr1;                       // signal set with just SIGUSR1
#endif

        session = (struct session *) ptr;

        session->TotCapt = 0;                   // counter which is incremented each time a packet is received

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

        //
        // We need a buffer large enough to hold a buffer large enough
        // for a maximum-size packet for this pcap_t.
        //
        if (pcap_snapshot(session->fp) < 0)
        {
                //
                // The snapshot length is negative.
                // This "should not happen".
                //
                rpcapd_log(LOGPRIO_ERROR,
                    "Unable to allocate the buffer for this child thread: snapshot length of %d is negative",
                        pcap_snapshot(session->fp));
                sendbuf = NULL; // we can't allocate a buffer, so nothing to free
                goto error;
        }
        //
        // size_t is unsigned, and the result of pcap_snapshot() is signed;
        // on no platform that we support is int larger than size_t.
        // This means that, unless the extra information we prepend to
        // a maximum-sized packet is impossibly large, the sum of the
        // snapshot length and the size of that extra information will
        // fit in a size_t.
        //
        // So we don't need to make sure that sendbufsize will overflow.
        //
        // However, we *do* need to make sure its value fits in an int,
        // because sock_send() can't send more than INT_MAX bytes (it could
        // do so on 64-bit UN*Xes, but can't do so on Windows, not even
        // 64-bit Windows, as the send() buffer size argument is an int
        // in Winsock).
        //
        sendbufsize = sizeof(struct rpcap_header) + sizeof(struct rpcap_pkthdr) + pcap_snapshot(session->fp);
        if (sendbufsize > INT_MAX)
        {
                rpcapd_log(LOGPRIO_ERROR,
                    "Buffer size for this child thread would be larger than %d",
                    INT_MAX);
                sendbuf = NULL; // we haven't allocated a buffer, so nothing to free
                goto error;
        }
        sendbuf = (char *) malloc (sendbufsize);
        if (sendbuf == NULL)
        {
                rpcapd_log(LOGPRIO_ERROR,
                    "Unable to allocate the buffer for this child thread");
                goto error;
        }

#ifndef _WIN32
        //
        // Set the signal set to include just SIGUSR1, and block that
        // signal; we only want it unblocked when we're reading
        // packets - we dn't want any other system calls, such as
        // ones being used to send to the client or to log messages,
        // to be interrupted.
        //
        sigemptyset(&sigusr1);
        sigaddset(&sigusr1, SIGUSR1);
        pthread_sigmask(SIG_BLOCK, &sigusr1, NULL);
#endif

        // Retrieve the packets
        for (;;)
        {
#ifndef _WIN32
                //
                // Unblock SIGUSR1 while we might be waiting for packets.
                //
                pthread_sigmask(SIG_UNBLOCK, &sigusr1, NULL);
#endif
                retval = pcap_next_ex(session->fp, &pkt_header, (const u_char **) &pkt_data);   // cast to avoid a compiler warning
#ifndef _WIN32
                //
                // Now block it again.
                //
                pthread_sigmask(SIG_BLOCK, &sigusr1, NULL);
#endif
                if (retval < 0)
                        break;          // error
                if (retval == 0)        // Read timeout elapsed
                        continue;

                sendbufidx = 0;

                // Bufferize the general header
                if (sock_bufferize(NULL, sizeof(struct rpcap_header), NULL,
                    &sendbufidx, (int)sendbufsize, SOCKBUF_CHECKONLY, errbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                {
                        rpcapd_log(LOGPRIO_ERROR,
                            "sock_bufferize() error sending packet message: %s",
                            errbuf);
                        goto error;
                }

                rpcap_createhdr((struct rpcap_header *) sendbuf,
                    session->protocol_version, RPCAP_MSG_PACKET, 0,
                    (uint16) (sizeof(struct rpcap_pkthdr) + pkt_header->caplen));

                net_pkt_header = (struct rpcap_pkthdr *) &sendbuf[sendbufidx];

                // Bufferize the pkt header
                if (sock_bufferize(NULL, sizeof(struct rpcap_pkthdr), NULL,
                    &sendbufidx, (int)sendbufsize, SOCKBUF_CHECKONLY, errbuf,
                    PCAP_ERRBUF_SIZE) == -1)
                {
                        rpcapd_log(LOGPRIO_ERROR,
                            "sock_bufferize() error sending packet message: %s",
                            errbuf);
                        goto error;
                }

                net_pkt_header->caplen = htonl(pkt_header->caplen);
                net_pkt_header->len = htonl(pkt_header->len);
                net_pkt_header->npkt = htonl(++(session->TotCapt));
                //
                // This protocol needs to be updated with a new version
                // before 2038-01-19 03:14:07 UTC.
                //
                net_pkt_header->timestamp_sec = htonl((uint32)pkt_header->ts.tv_sec);
                net_pkt_header->timestamp_usec = htonl((uint32)pkt_header->ts.tv_usec);

                // Bufferize the pkt data
                if (sock_bufferize((char *) pkt_data, pkt_header->caplen,
                    sendbuf, &sendbufidx, (int)sendbufsize, SOCKBUF_BUFFERIZE,
                    errbuf, PCAP_ERRBUF_SIZE) == -1)
                {
                        rpcapd_log(LOGPRIO_ERROR,
                            "sock_bufferize() error sending packet message: %s",
                            errbuf);
                        goto error;
                }

                // Send the packet
                // If the client dropped the connection, don't report an
                // error, just quit.
                status = sock_send(session->sockdata, session->data_ssl, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE);
                if (status < 0)
                {
                        if (status == -1)
                        {
                                //
                                // Error other than "client closed the
                                // connection out from under us"; report
                                // it.
                                //
                                rpcapd_log(LOGPRIO_ERROR,
                                    "Send of packet to client failed: %s",
                                    errbuf);
                        }

                        //
                        // Give up in either case.
                        //
                        goto error;
                }
        }

        if (retval < 0 && retval != PCAP_ERROR_BREAK)
        {
                //
                // Failed with an error other than "we were told to break
                // out of the loop".
                //
                // The latter just means that the client told us to stop
                // capturing, so there's no error to report.
                //
                snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error reading the packets: %s", pcap_geterr(session->fp));
                rpcap_senderror(session->sockctrl, session->ctrl_ssl, session->protocol_version,
                    PCAP_ERR_READEX, errbuf, NULL);
        }

error:
        //
        // The main thread will clean up the session structure.
        //
        free(sendbuf);

        return 0;
}

#ifndef _WIN32
//
// Do-nothing handler for SIGUSR1; the sole purpose of SIGUSR1 is to
// interrupt the data thread if it's blocked in a system call waiting
// for packets to arrive.
//
static void noop_handler(int sign _U_)
{
}
#endif

/*!
        \brief It serializes a network address.

        It accepts a 'sockaddr_storage' structure as input, and it converts it appropriately into a format
        that can be used to be sent on the network. Basically, it applies all the hton()
        conversion required to the input variable.

        \param sockaddrin a 'sockaddr_storage' pointer to the variable that has to be
        serialized. This variable can be both a 'sockaddr_in' and 'sockaddr_in6'.

        \param sockaddrout an 'rpcap_sockaddr' pointer to the variable that will contain
        the serialized data. This variable has to be allocated by the user.

        \warning This function supports only AF_INET and AF_INET6 address families.
*/
static void
daemon_seraddr(struct sockaddr_storage *sockaddrin, struct rpcap_sockaddr *sockaddrout)
{
        memset(sockaddrout, 0, sizeof(struct sockaddr_storage));

        // There can be the case in which the sockaddrin is not available
        if (sockaddrin == NULL) return;

        // Warning: we support only AF_INET and AF_INET6
        switch (sockaddrin->ss_family)
        {
        case AF_INET:
                {
                struct sockaddr_in *sockaddrin_ipv4;
                struct rpcap_sockaddr_in *sockaddrout_ipv4;

                sockaddrin_ipv4 = (struct sockaddr_in *) sockaddrin;
                sockaddrout_ipv4 = (struct rpcap_sockaddr_in *) sockaddrout;
                sockaddrout_ipv4->family = htons(RPCAP_AF_INET);
                sockaddrout_ipv4->port = htons(sockaddrin_ipv4->sin_port);
                memcpy(&sockaddrout_ipv4->addr, &sockaddrin_ipv4->sin_addr, sizeof(sockaddrout_ipv4->addr));
                memset(sockaddrout_ipv4->zero, 0, sizeof(sockaddrout_ipv4->zero));
                break;
                }

#ifdef AF_INET6
        case AF_INET6:
                {
                struct sockaddr_in6 *sockaddrin_ipv6;
                struct rpcap_sockaddr_in6 *sockaddrout_ipv6;

                sockaddrin_ipv6 = (struct sockaddr_in6 *) sockaddrin;
                sockaddrout_ipv6 = (struct rpcap_sockaddr_in6 *) sockaddrout;
                sockaddrout_ipv6->family = htons(RPCAP_AF_INET6);
                sockaddrout_ipv6->port = htons(sockaddrin_ipv6->sin6_port);
                sockaddrout_ipv6->flowinfo = htonl(sockaddrin_ipv6->sin6_flowinfo);
                memcpy(&sockaddrout_ipv6->addr, &sockaddrin_ipv6->sin6_addr, sizeof(sockaddrout_ipv6->addr));
                sockaddrout_ipv6->scope_id = htonl(sockaddrin_ipv6->sin6_scope_id);
                break;
                }
#endif
        }
}


/*!
        \brief Suspends a thread for secs seconds.
*/
void sleep_secs(int secs)
{
#ifdef _WIN32
        Sleep(secs*1000);
#else
        unsigned secs_remaining;

        if (secs <= 0)
                return;
        secs_remaining = secs;
        while (secs_remaining != 0)
                secs_remaining = sleep(secs_remaining);
#endif
}

/*
 * Read the header of a message.
 */
static int
rpcapd_recv_msg_header(SOCKET sock, SSL *ssl, struct rpcap_header *headerp)
{
        int nread;
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors

        nread = sock_recv(sock, ssl, (char *) headerp, sizeof(struct rpcap_header),
            SOCK_RECEIVEALL_YES|SOCK_EOF_ISNT_ERROR, errbuf, PCAP_ERRBUF_SIZE);
        if (nread == -1)
        {
                // Network error.
                rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                return -1;
        }
        if (nread == 0)
        {
                // Immediate EOF; that's treated like a close message.
                return -2;
        }
        headerp->plen = ntohl(headerp->plen);
        return 0;
}

/*
 * Read data from a message.
 * If we're trying to read more data that remains, puts an error
 * message into errmsgbuf and returns -2.  Otherwise, tries to read
 * the data and, if that succeeds, subtracts the amount read from
 * the number of bytes of data that remains.
 * Returns 0 on success, logs a message and returns -1 on a network
 * error.
 */
static int
rpcapd_recv(SOCKET sock, SSL *ssl, char *buffer, size_t toread, uint32 *plen, char *errmsgbuf)
{
        int nread;
        char errbuf[PCAP_ERRBUF_SIZE];          // buffer for network errors

        if (toread > *plen)
        {
                // Tell the client and continue.
                snprintf(errmsgbuf, PCAP_ERRBUF_SIZE, "Message payload is too short");
                return -2;
        }
        nread = sock_recv(sock, ssl, buffer, toread,
            SOCK_RECEIVEALL_YES|SOCK_EOF_IS_ERROR, errbuf, PCAP_ERRBUF_SIZE);
        if (nread == -1)
        {
                rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                return -1;
        }
        *plen -= nread;
        return 0;
}

/*
 * Discard data from a connection.
 * Mostly used to discard wrong-sized messages.
 * Returns 0 on success, logs a message and returns -1 on a network
 * error.
 */
static int
rpcapd_discard(SOCKET sock, SSL *ssl, uint32 len)
{
        char errbuf[PCAP_ERRBUF_SIZE + 1];      // keeps the error string, prior to be printed

        if (len != 0)
        {
                if (sock_discard(sock, ssl, len, errbuf, PCAP_ERRBUF_SIZE) == -1)
                {
                        // Network error.
                        rpcapd_log(LOGPRIO_ERROR, "Read from client failed: %s", errbuf);
                        return -1;
                }
        }
        return 0;
}

//
// Shut down any packet-capture thread associated with the session,
// close the SSL handle for the data socket if we have one, close
// the data socket if we have one, and close the underlying packet
// capture handle if we have one.
//
// We do not, of course, touch the controlling socket that's also
// copied into the session, as the service loop might still use it.
//
static void session_close(struct session *session)
{
        if (session->have_thread)
        {
                //
                // Tell the data connection thread main capture loop to
                // break out of that loop.
                //
                // This may be sufficient to wake up a blocked thread,
                // but it's not guaranteed to be sufficient.
                //
                pcap_breakloop(session->fp);

#ifdef _WIN32
                //
                // Set the event on which a read would block, so that,
                // if it's currently blocked waiting for packets to
                // arrive, it'll wake up, so it can see the "break
                // out of the loop" indication.  (pcap_breakloop()
                // might do this, but older versions don't.  Setting
                // it twice should, at worst, cause an extra wakeup,
                // which shouldn't be a problem.)
                //
                // XXX - what about modules other than NPF?
                //
                SetEvent(pcap_getevent(session->fp));

                //
                // Wait for the thread to exit, so we don't close
                // sockets out from under it.
                //
                // XXX - have a timeout, so we don't wait forever?
                //
                WaitForSingleObject(session->thread, INFINITE);

                //
                // Release the thread handle, as we're done with
                // it.
                //
                CloseHandle(session->thread);
                session->have_thread = 0;
                session->thread = INVALID_HANDLE_VALUE;
#else
                //
                // Send a SIGUSR1 signal to the thread, so that, if
                // it's currently blocked waiting for packets to arrive,
                // it'll wake up (we've turned off SA_RESTART for
                // SIGUSR1, so that the system call in which it's blocked
                // should return EINTR rather than restarting).
                //
                pthread_kill(session->thread, SIGUSR1);

                //
                // Wait for the thread to exit, so we don't close
                // sockets out from under it.
                //
                // XXX - have a timeout, so we don't wait forever?
                //
                pthread_join(session->thread, NULL);
                session->have_thread = 0;
                memset(&session->thread, 0, sizeof(session->thread));
#endif
        }

#ifdef HAVE_OPENSSL
        if (session->data_ssl)
        {
                // Finish using the SSL handle for the socket.
                // This must be done *before* the socket is closed.
                ssl_finish(session->data_ssl);
                session->data_ssl = NULL;
        }
#endif

        if (session->sockdata != INVALID_SOCKET)
        {
                sock_close(session->sockdata, NULL, 0);
                session->sockdata = INVALID_SOCKET;
        }

        if (session->fp)
        {
                pcap_close(session->fp);
                session->fp = NULL;
        }
}

// Check whether a capture source string is a URL or not.
// This includes URLs that refer to a local device; a scheme, followed
// by ://, followed by *another* scheme and ://, is just silly, and
// anybody who supplies that will get an error.
//
static int
is_url(const char *source)
{
        char *colonp;

        /*
         * RFC 3986 says:
         *
         *   URI         = scheme ":" hier-part [ "?" query ] [ "#" fragment ]
         *
         *   hier-part   = "//" authority path-abempty
         *               / path-absolute
         *               / path-rootless
         *               / path-empty
         *
         *   authority   = [ userinfo "@" ] host [ ":" port ]
         *
         *   userinfo    = *( unreserved / pct-encoded / sub-delims / ":" )
         *
         * Step 1: look for the ":" at the end of the scheme.
         * A colon in the source is *NOT* sufficient to indicate that
         * this is a URL, as interface names on some platforms might
         * include colons (e.g., I think some Solaris interfaces
         * might).
         */
        colonp = strchr(source, ':');
        if (colonp == NULL)
        {
                /*
                 * The source is the device to open.  It's not a URL.
                 */
                return (0);
        }

        /*
         * All schemes must have "//" after them, i.e. we only support
         * hier-part   = "//" authority path-abempty, not
         * hier-part   = path-absolute
         * hier-part   = path-rootless
         * hier-part   = path-empty
         *
         * We need that in order to distinguish between a local device
         * name that happens to contain a colon and a URI.
         */
        if (strncmp(colonp + 1, "//", 2) != 0)
        {
                /*
                 * The source is the device to open.  It's not a URL.
                 */
                return (0);
        }

        /*
         * It's a URL.
         */
        return (1);
}