From 815a33de95fccbe5be1814e18c7f89d641754f20 Mon Sep 17 00:00:00 2001
From: David Robles <master-nevi@users.noreply.github.com>
Date: Sun, 22 Mar 2015 16:09:38 -0700
Subject: [PATCH] Allow the option to receive multicast SSDP notifications (not
 just send) by not supplying a network interface to bind the socket to.
 Implement [SSDPServiceBrowser _notifyDelegateWithRemovedService] for
 reporting removed devices.

---
 Classes/SSDPService.m        |  2 +-
 Classes/SSDPServiceBrowser.h | 17 +++++++-------
 Classes/SSDPServiceBrowser.m | 44 ++++++++++++++++++++++++++++--------
 3 files changed, 44 insertions(+), 19 deletions(-)

diff --git a/Classes/SSDPService.m b/Classes/SSDPService.m
index 80a93d8..4358567 100644
--- a/Classes/SSDPService.m
+++ b/Classes/SSDPService.m
@@ -30,7 +30,7 @@ - (id)initWithHeaders:(NSDictionary *)headers {
     self = [super init];
     if (self) {
         _location = [NSURL URLWithString:[headers objectForKey:@"location"]];
-        _serviceType = [headers objectForKey:@"st"];
+        _serviceType = [headers objectForKey:@"st"] ? [headers objectForKey:@"st"] : [headers objectForKey:@"nt"];
         _uniqueServiceName = [headers objectForKey:@"usn"];
         _server = [headers objectForKey:@"server"];
     }
diff --git a/Classes/SSDPServiceBrowser.h b/Classes/SSDPServiceBrowser.h
index c6f355c..507accb 100644
--- a/Classes/SSDPServiceBrowser.h
+++ b/Classes/SSDPServiceBrowser.h
@@ -27,9 +27,9 @@
 @class SSDPService;
 
 @protocol SSDPServiceBrowserDelegate
-- (void) ssdpBrowser:(SSDPServiceBrowser *)browser didNotStartBrowsingForServices:(NSError *)error;
-- (void) ssdpBrowser:(SSDPServiceBrowser *)browser didFindService:(SSDPService *)service;
-- (void) ssdpBrowser:(SSDPServiceBrowser *)browser didRemoveService:(SSDPService *)service;
+- (void)ssdpBrowser:(SSDPServiceBrowser *)browser didNotStartBrowsingForServices:(NSError *)error;
+- (void)ssdpBrowser:(SSDPServiceBrowser *)browser didFindService:(SSDPService *)service;
+- (void)ssdpBrowser:(SSDPServiceBrowser *)browser didRemoveService:(SSDPService *)service;
 @end
 
 
@@ -39,13 +39,12 @@
 @property(readonly, nonatomic) NSString *networkInterface;
 @property(assign, nonatomic) id<SSDPServiceBrowserDelegate> delegate;
 
-- (id) initWithServiceType:(NSString *)serviceType onInterface:(NSString *)networkInterface;
-- (id) initWithServiceType:(NSString *)serviceType;
+- (id)initWithServiceType:(NSString *)serviceType onInterface:(NSString *)networkInterface;
+- (id)initWithServiceType:(NSString *)serviceType;
 
-- (void) startBrowsingForServices;
-- (void) stopBrowsingForServices;
+- (void)startBrowsingForServices;
+- (void)stopBrowsingForServices;
 
-
-+ (NSDictionary *) availableNetworkInterfaces;
++ (NSDictionary *)availableNetworkInterfaces;
 
 @end
diff --git a/Classes/SSDPServiceBrowser.m b/Classes/SSDPServiceBrowser.m
index 66e0c81..8b18cf5 100644
--- a/Classes/SSDPServiceBrowser.m
+++ b/Classes/SSDPServiceBrowser.m
@@ -59,7 +59,7 @@ @interface SSDPServiceBrowser () {
 
 @implementation SSDPServiceBrowser
 
-- (id) initWithServiceType:(NSString *)serviceType onInterface:(NSString *)networkInterface {
+- (id)initWithServiceType:(NSString *)serviceType onInterface:(NSString *)networkInterface {
     self = [super init];
     if (self) {
         _serviceType = [serviceType copy];
@@ -112,13 +112,23 @@ - (void)startBrowsingForServices {
 
     NSDictionary *interfaces = [SSDPServiceBrowser availableNetworkInterfaces];
     NSData *sourceAddress = _networkInterface? [interfaces objectForKey:_networkInterface] : nil;
-    if( !sourceAddress ) sourceAddress = [[interfaces allValues] firstObject];
-
-    if(![_socket bindToAddress:sourceAddress error:&err]) {
-        [self _notifyDelegateWithError:err];
-        return;
+    
+    if(sourceAddress) {
+        // Bind to address to receive unicast datagrams only
+        if(![_socket bindToAddress:sourceAddress error:&err]) {
+            [self _notifyDelegateWithError:err];
+            return;
+        }
+    }
+    else {
+        // Bind to port to receive unicast and multicast datagrams
+        if(![_socket bindToPort:SSDPMulticastUDPPort error:&err]) {
+            [self _notifyDelegateWithError:err];
+            return;
+        }
     }
 
+    // Join multicast group in order to receive multicast datagrams
     if(![_socket joinMulticastGroup:SSDPMulticastGroupAddress error:&err]) {
         [self _notifyDelegateWithError:err];
         return;
@@ -157,10 +167,18 @@ - (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
     NSString *msg = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
     if( msg ) {
         NSDictionary *headers = [self _parseHeadersFromMessage:msg];
-        if( [headers objectForKey:SSDPResponseStatusKey] ) {
-            SSDPService *service = [[SSDPService alloc] initWithHeaders:headers];
+        SSDPService *service = [[SSDPService alloc] initWithHeaders:headers];
+        if( [[headers objectForKey:SSDPResponseStatusKey] isEqualToString:@"200"] ) {
             [self _notifyDelegateWithFoundService:service];
         }
+        else if ([[headers objectForKey:SSDPRequestMethodKey] isEqualToString:@"NOTIFY"]) {
+            if ([[headers objectForKey:@"nts"] isEqualToString:@"ssdp:alive"]) {
+                [self _notifyDelegateWithFoundService:service];
+            }
+            else if ([[headers objectForKey:@"nts"] isEqualToString:@"ssdp:byebye"]) {
+                [self _notifyDelegateWithRemovedService:service];
+            }
+        }
     }
     else {
         NSString *host = nil;
@@ -231,8 +249,16 @@ - (void)_notifyDelegateWithFoundService:(SSDPService *)service
     });
 }
 
+- (void)_notifyDelegateWithRemovedService:(SSDPService *)service
+{
+    dispatch_async(dispatch_get_main_queue(), ^{
+        @autoreleasepool {
+            [_delegate ssdpBrowser:self didRemoveService:service];
+        }
+    });
+}
 
-+ (NSDictionary *) availableNetworkInterfaces {
++ (NSDictionary *)availableNetworkInterfaces {
     NSMutableDictionary *addresses = [NSMutableDictionary dictionary];
     struct ifaddrs *interfaces = NULL;
     struct ifaddrs *ifa = NULL;