Windows DNS SD : add port knocking like other implementations

Both the Linux and Mac implemations of DNS SD ensures something is there
before passing the host information up the stack. The Windows
implemnation was missing this, so add it. Add locking since it's needed
by those functions.

Fix #559

Signed-off-by: Robin Getz <[email protected]>

Author: rgetz

dns_sd_windows.c

@@ -16,6 +16,7 @@
 
 #include "debug.h"
 #include "dns_sd.h"
+#include "iio-lock.h"
 #include "iio-private.h"
 #include "mdns.h"
 
@@ -189,6 +190,7 @@ int dnssd_find_hosts(struct dns_sd_discovery_data **ddata)
 	WSADATA wsaData;
 	const char service[] = "_iio._tcp.local";
 	size_t records, capacity = 2048;
+	struct dns_sd_discovery_data *d;
 	unsigned int i, isock, num_sockets;
 	void *buffer;
 	int sockets[32];
@@ -202,14 +204,19 @@ int dnssd_find_hosts(struct dns_sd_discovery_data **ddata)
 
 	IIO_DEBUG("DNS SD: Start service discovery.\n");
 
-	*ddata = zalloc(sizeof(**ddata));
-	if (!*ddata)
+	d = zalloc(sizeof(*d));
+	if (!d)
 		goto out_wsa_cleanup;
+	/* pass the structure back, so it can be freed if err */
+	*ddata = d;
 
+	d->lock = iio_mutex_create();
+	if (!d->lock)
+		goto out_wsa_cleanup;
 
 	buffer = malloc(capacity);
 	if (!buffer)
-		goto out_wsa_cleanup;
+		goto out_destroy_lock;
 
 	IIO_DEBUG("Sending DNS-SD discovery\n");
 
@@ -250,7 +257,7 @@ int dnssd_find_hosts(struct dns_sd_discovery_data **ddata)
 
 				records += mdns_query_recv(sockets[isock],
 							   buffer, capacity,
-							   query_callback, *ddata,
+							   query_callback, d,
 							   transaction_id[isock]);
 			}
 		} while (records);
@@ -266,9 +273,14 @@ int dnssd_find_hosts(struct dns_sd_discovery_data **ddata)
 
 	IIO_DEBUG("Closed socket%s\n", (num_sockets > 1) ? "s" : "");
 
+	port_knock_discovery_data(&d);
+	remove_dup_discovery_data(&d);
+
 	ret = 0;
 out_free_buffer:
 	free(buffer);
+out_destroy_lock:
+	iio_mutex_destroy(d->lock);
 out_wsa_cleanup:
 	WSACleanup();
 	return ret;