source: vendor/3.5.4/source3/client/dnsbrowse.c

/*
   Unix SMB/CIFS implementation.
   DNS-SD browse client
   Copyright (C) Rishi Srivatsavai 2007

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "client/client_proto.h"

#ifdef WITH_DNSSD_SUPPORT

#include <dns_sd.h>

/* Holds service instances found during DNS browse */
struct mdns_smbsrv_result
{
        char *serviceName;
        char *regType;
        char *domain;
        uint32_t ifIndex;
        struct mdns_smbsrv_result *nextResult;
};

/* Maintains state during DNS browse */
struct mdns_browse_state
{
        struct mdns_smbsrv_result *listhead; /* Browse result list head */
        int browseDone;

};


static void
do_smb_resolve_reply (DNSServiceRef sdRef, DNSServiceFlags flags,
                uint32_t interfaceIndex, DNSServiceErrorType errorCode,
                const char *fullname, const char *hosttarget, uint16_t port,
                uint16_t txtLen, const unsigned char *txtRecord, void *context)
{
        printf("SMB service available on %s port %u\n",
                hosttarget, ntohs(port));
}


static void do_smb_resolve(struct mdns_smbsrv_result *browsesrv)
{
        DNSServiceRef mdns_conn_sdref = NULL;
        int mdnsfd;
        int fdsetsz;
        int ret;
        fd_set *fdset = NULL;
        struct timeval tv;
        DNSServiceErrorType err;

        TALLOC_CTX * ctx = talloc_tos();

        err = DNSServiceResolve(&mdns_conn_sdref, 0 /* flags */,
                browsesrv->ifIndex,
                browsesrv->serviceName, browsesrv->regType, browsesrv->domain,
                do_smb_resolve_reply, NULL);

        if (err != kDNSServiceErr_NoError) {
                return;
        }

        mdnsfd = DNSServiceRefSockFD(mdns_conn_sdref);
        for (;;)  {
                if (fdset != NULL) {
                        TALLOC_FREE(fdset);
                }

                fdsetsz = howmany(mdnsfd + 1, NFDBITS) * sizeof(fd_mask);
                fdset = TALLOC_ZERO(ctx, fdsetsz);
                FD_SET(mdnsfd, fdset);

                tv.tv_sec = 1;
                tv.tv_usec = 0;

                /* Wait until response received from mDNS daemon */
                ret = sys_select(mdnsfd + 1, fdset, NULL, NULL, &tv);
                if (ret <= 0 && errno != EINTR) {
                        break;
                }

                if (FD_ISSET(mdnsfd, fdset)) {
                        /* Invoke callback function */
                        DNSServiceProcessResult(mdns_conn_sdref);
                        break;
                }
        }

        TALLOC_FREE(fdset);
        DNSServiceRefDeallocate(mdns_conn_sdref);
}


static void
do_smb_browse_reply(DNSServiceRef sdRef, DNSServiceFlags flags,
        uint32_t interfaceIndex, DNSServiceErrorType errorCode,
        const char  *serviceName, const char *regtype,
        const char  *replyDomain, void  *context)
{
        struct mdns_browse_state *bstatep = (struct mdns_browse_state *)context;
        struct mdns_smbsrv_result *bresult;

        if (bstatep == NULL) {
                return;
        }

        if (errorCode != kDNSServiceErr_NoError) {
                bstatep->browseDone = 1;
                return;
        }

        if (flags & kDNSServiceFlagsMoreComing) {
                bstatep->browseDone = 0;
        } else {
                bstatep->browseDone = 1;
        }

        if (!(flags & kDNSServiceFlagsAdd)) {
                return;
        }

        bresult = TALLOC_ARRAY(talloc_tos(), struct mdns_smbsrv_result, 1);
        if (bresult == NULL) {
                return;
        }

        if (bstatep->listhead != NULL) {
                bresult->nextResult = bstatep->listhead;
        }

        bresult->serviceName = talloc_strdup(talloc_tos(), serviceName);
        bresult->regType = talloc_strdup(talloc_tos(), regtype);
        bresult->domain = talloc_strdup(talloc_tos(), replyDomain);
        bresult->ifIndex = interfaceIndex;
        bstatep->listhead = bresult;
}

int do_smb_browse(void)
{
        int mdnsfd;
        int fdsetsz;
        int ret;
        fd_set *fdset = NULL;
        struct mdns_browse_state bstate;
        struct mdns_smbsrv_result *resptr;
        struct timeval tv;
        DNSServiceRef mdns_conn_sdref = NULL;
        DNSServiceErrorType err;

        TALLOC_CTX * ctx = talloc_stackframe();

        ZERO_STRUCT(bstate);

        err = DNSServiceBrowse(&mdns_conn_sdref, 0, 0, "_smb._tcp", "",
                        do_smb_browse_reply, &bstate);

        if (err != kDNSServiceErr_NoError) {
                d_printf("Error connecting to the Multicast DNS daemon\n");
                TALLOC_FREE(ctx);
                return 1;
        }

        mdnsfd = DNSServiceRefSockFD(mdns_conn_sdref);
        for (;;)  {
                if (fdset != NULL) {
                        TALLOC_FREE(fdset);
                }

                fdsetsz = howmany(mdnsfd + 1, NFDBITS) * sizeof(fd_mask);
                fdset = TALLOC_ZERO(ctx, fdsetsz);
                FD_SET(mdnsfd, fdset);

                tv.tv_sec = 1;
                tv.tv_usec = 0;

                /* Wait until response received from mDNS daemon */
                ret = sys_select(mdnsfd + 1, fdset, NULL, NULL, &tv);
                if (ret <= 0 && errno != EINTR) {
                        break;
                }

                if (FD_ISSET(mdnsfd, fdset)) {
                        /* Invoke callback function */
                        if (DNSServiceProcessResult(mdns_conn_sdref)) {
                                break;
                        }
                        if (bstate.browseDone) {
                                break;
                        }
                }
        }

        DNSServiceRefDeallocate(mdns_conn_sdref);

        if (bstate.listhead != NULL) {
                resptr = bstate.listhead;
                while (resptr != NULL) {
                        struct mdns_smbsrv_result *oldresptr;
                        oldresptr = resptr;

                        /* Resolve smb service instance */
                        do_smb_resolve(resptr);

                        resptr = resptr->nextResult;
                }
        }

        TALLOC_FREE(ctx);
        return 0;
}

#else /* WITH_DNSSD_SUPPORT */

int do_smb_browse(void)
{
    d_printf("DNS-SD browsing is not supported on this platform\n");
    return 1;
}

#endif /* WITH_DNSSD_SUPPORT */