Index: src/OFDNSResolver.m
==================================================================
--- src/OFDNSResolver.m
+++ src/OFDNSResolver.m
@@ -66,10 +66,11 @@
 @interface OFDNSResolver_context: OFObject
 {
 	OFString *_host;
 	OFArray OF_GENERIC(OFString *) *_nameServers, *_searchDomains;
 	size_t _nameServersIndex, _searchDomainsIndex;
+	OFNumber *_ID;
 	OFMutableData *_queryData;
 	id _target;
 	SEL _selector;
 	id _userContext;
 }
@@ -77,18 +78,20 @@
 @property (readonly, nonatomic) OFString *host;
 @property (readonly, nonatomic) OFArray OF_GENERIC(OFString *) *nameServers;
 @property (readonly, nonatomic) OFArray OF_GENERIC(OFString *) *searchDomains;
 @property (nonatomic) size_t nameServersIndex;
 @property (nonatomic) size_t searchDomainsIndex;
+@property (readonly, nonatomic) OFNumber *ID;
 @property (readonly, nonatomic) OFMutableData *queryData;
 @property (readonly, nonatomic) id target;
 @property (readonly, nonatomic) SEL selector;
 @property (readonly, nonatomic) id userContext;
 
 - (instancetype)initWithHost: (OFString *)host
 		 nameServers: (OFArray OF_GENERIC(OFString *) *)nameServers
 	       searchDomains: (OFArray OF_GENERIC(OFString *) *)searchDomains
+			  ID: (OFNumber *)ID
 		   queryData: (OFMutableData *)queryData
 		      target: (id)target
 		    selector: (SEL)selector
 		 userContext: (id)userContext;
 @end
@@ -488,16 +491,18 @@
 
 @implementation OFDNSResolver_context
 @synthesize host = _host, nameServers = _nameServers;
 @synthesize searchDomains = _searchDomains;
 @synthesize nameServersIndex = _nameServersIndex;
-@synthesize searchDomainsIndex = _searchDomainsIndex, queryData = _queryData;
-@synthesize target = _target, selector = _selector, userContext = _userContext;
+@synthesize searchDomainsIndex = _searchDomainsIndex, ID = _ID;
+@synthesize queryData = _queryData, target = _target, selector = _selector;
+@synthesize userContext = _userContext;
 
 - (instancetype)initWithHost: (OFString *)host
 		 nameServers: (OFArray OF_GENERIC(OFString *) *)nameServers
 	       searchDomains: (OFArray OF_GENERIC(OFString *) *)searchDomains
+			  ID: (OFNumber *)ID
 		   queryData: (OFMutableData *)queryData
 		      target: (id)target
 		    selector: (SEL)selector
 		 userContext: (id)userContext
 {
@@ -505,10 +510,11 @@
 
 	@try {
 		_host = [host copy];
 		_nameServers = [nameServers copy];
 		_searchDomains = [searchDomains copy];
+		_ID = [ID retain];
 		_queryData = [queryData retain];
 		_target = [target retain];
 		_selector = selector;
 		_userContext = [userContext retain];
 	} @catch (id e) {
@@ -522,10 +528,11 @@
 - (void)dealloc
 {
 	[_host release];
 	[_nameServers release];
 	[_searchDomains release];
+	[_ID release];
 	[_queryData release];
 	[_target release];
 	[_userContext release];
 
 	[super dealloc];
@@ -997,15 +1004,27 @@
 
 - (size_t)of_socket: (OFUDPSocket *)sock
       didSendBuffer: (void **)buffer
 	  bytesSent: (size_t)bytesSent
 	   receiver: (of_socket_address_t *)receiver
-	    context: (id)context
+	    context: (id)DNSResolverContext
 	  exception: (id)exception
 {
-	if (exception != nil)
+	if (exception != nil) {
+		id target = [[[DNSResolverContext target] retain] autorelease];
+		SEL selector = [DNSResolverContext selector];
+		void (*callback)(id, SEL, OFArray *, id, id) =
+		    (void (*)(id, SEL, OFArray *, id, id))
+		    [target methodForSelector: selector];
+
+		[_queries removeObjectForKey: [DNSResolverContext ID]];
+
+		callback(target, selector, nil,
+		    [DNSResolverContext userContext], exception);
+
 		return 0;
+	}
 
 	[sock asyncReceiveIntoBuffer: [self allocMemoryWithSize: 512]
 			      length: 512
 			      target: self
 			    selector: @selector(of_socket:didReceiveIntoBuffer:
@@ -1102,10 +1121,11 @@
 
 	DNSResolverContext = [[[OFDNSResolver_context alloc]
 	    initWithHost: host
 	     nameServers: _nameServers
 	   searchDomains: _searchDomains
+		      ID: ID
 	       queryData: data
 		  target: target
 		selector: selector
 	     userContext: context] autorelease];
 	[_queries setObject: DNSResolverContext
@@ -1118,19 +1138,21 @@
 	if (address.address.ss_family == AF_INET6) {
 		if (_IPv6Socket == nil) {
 			_IPv6Socket = [[OFUDPSocket alloc] init];
 			[_IPv6Socket bindToHost: @"::"
 					   port: 0];
+			[_IPv6Socket setBlocking: false];
 		}
 
 		sock = _IPv6Socket;
 	} else {
 #endif
 		if (_IPv4Socket == nil) {
 			_IPv4Socket = [[OFUDPSocket alloc] init];
 			[_IPv4Socket bindToHost: @"0.0.0.0"
 					   port: 0];
+			[_IPv4Socket setBlocking: false];
 		}
 
 		sock = _IPv4Socket;
 #ifdef OF_HAVE_IPV6
 	}
@@ -1140,11 +1162,11 @@
 		       length: [data count]
 		     receiver: address
 		       target: self
 		     selector: @selector(of_socket:didSendBuffer:bytesSent:
 				   receiver:context:exception:)
-		      context: nil];
+		      context: DNSResolverContext];
 
 	objc_autoreleasePoolPop(pool);
 }
 
 - (void)close