Register the smb service with mDNS if mSDN is supported.

If mDNS is supported, attempt to register the first port we are
listening on for the _smb._tcp service. This provides more reliable
service discovery than NetBIOS browsing.
(This used to be commit 1e7241517d1f55d60af22570e0c9feb280e3fdb5)

1 files changed, 212 insertions, 0 deletions

diff --git a/source3/smbd/dnsregister.c b/source3/smbd/dnsregister.c
new file mode 100644
index 0000000000..fcd97b5dab
--- /dev/null
+++ b/source3/smbd/dnsregister.c
@@ -0,0 +1,212 @@
+/*
+   Unix SMB/CIFS implementation.
+   DNS-SD registration
+   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 <dns_sd.h>
+
+/* Uses DNS service discovery (libdns_sd) to
+ * register the SMB service. SMB service is registered
+ * on ".local" domain via Multicast DNS & any
+ * other unicast DNS domains available.
+ *
+ * Users use the smbclient -B (Browse) option to
+ * browse for advertised SMB services.
+ */
+
+#define DNS_REG_RETRY_INTERVAL (5*60)  /* in seconds */
+
+struct dns_reg_state {
+	DNSServiceRef srv_ref;
+	struct timed_event *retry_handler;
+};
+
+#ifdef WITH_DNSSD_SUPPORT
+
+void dns_register_close(struct dns_reg_state **dns_state_ptr)
+{
+	int mdnsd_conn_fd;
+	struct dns_reg_state *dns_state = *dns_state_ptr;
+
+	if (dns_state == NULL) {
+		return;
+	}
+
+	if (dns_state->srv_ref != NULL) {
+		/* Close connection to the mDNS daemon */
+		DNSServiceRefDeallocate(dns_state->srv_ref);
+		dns_state->srv_ref = NULL;
+	}
+
+	/* Clear event handler */
+	if (dns_state->retry_handler != NULL) {
+		TALLOC_FREE(dns_state->retry_handler);
+		dns_state->retry_handler = NULL;
+	}
+
+	talloc_free(dns_state);
+	*dns_state_ptr = NULL;
+}
+
+static void dns_register_smbd_retry(struct event_context *ctx,
+                                   struct timed_event *te,
+                                   const struct timeval *now,
+                                   void *private_data)
+{
+	struct dns_reg_state *dns_state = (struct dns_reg_state *)private_data;
+
+	/* Clear previous registration state to force new
+	 * registration attempt. Clears event handler.
+	 */
+	dns_register_close(dns_state);
+}
+
+static void schedule_dns_register_smbd_retry(struct dns_reg_state *dns_state,
+		struct timeval *timeout)
+{
+	struct timed_event * event;
+
+	dns_state->srv_ref = NULL;
+	event= event_add_timed(smbd_event_context(),
+			NULL,
+			timeval_current_ofs(DNS_REG_RETRY_INTERVAL, 0),
+			"DNS registration handler",
+			dns_register_smbd_retry,
+			dns_state);
+
+	dns_state->retry_handler = event;
+	get_timed_events_timeout(smbd_event_context(), timeout);
+}
+
+/* Kick off a mDNS request to register the "_smb._tcp" on the specified port.
+ * We really ought to register on all the ports we are listening on. This will
+ * have to be an exercise for some-one who knows the DNS registration API a bit
+ * better.
+ */
+void dns_register_smbd(struct dns_reg_state ** dns_state_ptr,
+		unsigned port,
+		int *maxfd,
+		fd_set *listen_set,
+		struct timeval *timeout)
+{
+	int mdnsd_conn_fd;
+	DNSServiceErrorType err;
+	struct dns_reg_state *dns_state = *dns_state_ptr;
+
+	if (dns_state == NULL) {
+		*dns_state_ptr = dns_state = talloc(NULL, struct dns_reg_state);
+		if (dns_state == NULL) {
+			return;
+		}
+	}
+
+	/* Quit if a re-try attempt has been scheduled.  */
+	if (dns_state->retry_handler != NULL) {
+		return;
+	}
+
+	/* If a registration is active add conn
+	 * fd to select listen_set and return
+	 */
+	if (dns_state->srv_ref != NULL) {
+		mdnsd_conn_fd = DNSServiceRefSockFD(dns_state->srv_ref);
+		FD_SET(mdnsd_conn_fd, listen_set);
+		return;
+	}
+
+	DEBUG(6, ("registering _smb._tcp service on port %d\n", port));
+
+	/* Register service with DNS. Connects with the mDNS
+	 * daemon running on the local system to perform DNS
+	 * service registration.
+	 */
+	err = DNSServiceRegister(&dns_state->srv_ref, 0 /* flags */,
+			kDNSServiceInterfaceIndexAny,
+			NULL /* service name */,
+			"_smb._tcp" /* service type */,
+			NULL /* domain */,
+			"" /* SRV target host name */,
+			htons(port),
+			0 /* TXT record len */,
+			NULL /* TXT record data */,
+			NULL /* callback func */,
+			NULL /* callback context */);
+
+	if (err != kDNSServiceErr_NoError) {
+		/* Failed to register service. Schedule a re-try attempt.
+		 */
+		DEBUG(3, ("unable to register with mDNS (err %d)\n", err));
+		schedule_dns_register_smbd_retry(dns_state, timeout);
+		return;
+	}
+
+	mdnsd_conn_fd = DNSServiceRefSockFD(dns_state->srv_ref);
+	FD_SET(mdnsd_conn_fd, listen_set);
+	*maxfd = MAX(*maxfd, mdnsd_conn_fd);
+	*timeout = timeval_zero();
+
+}
+
+/* Processes reply from mDNS daemon. Returns true if a reply was received */
+bool dns_register_smbd_reply(struct dns_reg_state *dns_state,
+		fd_set *lfds, struct timeval *timeout)
+{
+	int mdnsd_conn_fd = -1;
+
+	if (dns_state->srv_ref == NULL) {
+		return false;
+	}
+
+	mdnsd_conn_fd = DNSServiceRefSockFD(dns_state->srv_ref);
+
+	/* Process reply from daemon. Handles any errors. */
+	if ((mdnsd_conn_fd != -1) && (FD_ISSET(mdnsd_conn_fd,lfds)) ) {
+		DNSServiceErrorType err;
+		
+		err = DNSServiceProcessResult(dns_state->srv_ref);
+		if (err != kDNSServiceErr_NoError) {
+			DEBUG(3, ("failed to process mDNS result (err %d), re-trying\n",
+				    err));
+			schedule_dns_register_smbd_retry(dns_state, timeout);
+		}
+
+		return true;
+	}
+
+	return false;
+}
+
+#else /* WITH_DNSSD_SUPPORT */
+
+ void dns_register_smbd(struct dns_reg_state ** dns_state_ptr,
+		unsigned port,
+		int *maxfd,
+		fd_set *listen_set,
+		struct timeval *timeout)
+{}
+
+ void dns_register_close(struct dns_reg_state ** dns_state_ptr)
+{}
+
+ bool dns_register_smbd_reply(struct dns_reg_state *dns_state,
+		fd_set *lfds, struct timeval *timeout)
+{
+	return false;
+}
+
+#endif /* WITH_DNSSD_SUPPORT */