Declare variables for username, password and delegate.

Implement getters and setters for declared variables.
Fix deallocation issue when sockets are not configured.
Fix issue with username and password when they are nil.

OpenVPN Adapter/OpenVPNAdapter.mm

@@ -29,7 +29,12 @@ NSString * const OpenVPNAdapterErrorFatalKey = @"me.ss-abramchuk.openvpn-adapter
 NSString * const OpenVPNAdapterErrorEventKey = @"me.ss-abramchuk.openvpn-adapter.error-key.event";
 
 
-@interface OpenVPNAdapter ()
+@interface OpenVPNAdapter () {
+    NSString *_username;
+    NSString *_password;
+    
+    __weak id<OpenVPNAdapterDelegate> _delegate;
+}
 
 @property OpenVPNClient *vpnClient;
 
@@ -290,10 +295,31 @@ static void socketCallback(CFSocketRef socket, CFSocketCallBackType type, CFData
 
 @implementation OpenVPNAdapter (Provider)
 
-@dynamic username;
+#pragma mark Properties Gettters/Setters
-@dynamic password;
 
-@dynamic delegate;
+- (void)setUsername:(NSString *)username {
+    _username = username;
+}
+
+- (NSString *)username {
+    return _username;
+}
+
+- (void)setPassword:(NSString *)password {
+    _password = password;
+}
+
+- (NSString *)password {
+    return _password;
+}
+
+- (void)setDelegate:(id<OpenVPNAdapterDelegate>)delegate {
+    _delegate = delegate;
+}
+
+- (id<OpenVPNAdapterDelegate>)delegate {
+    return _delegate;
+}
 
 #pragma mark Client Configuration
 
@@ -321,10 +347,9 @@ static void socketCallback(CFSocketRef socket, CFSocketCallBackType type, CFData
         return NO;
     }
 
-    // TODO: Check whether nil values can be used for username and password or not
     ClientAPI::ProvideCreds creds;
-    creds.username = [self.username UTF8String];
+    creds.username = self.username == nil? "" : [self.username UTF8String];
-    creds.password = [self.password UTF8String];
+    creds.password = self.password == nil ? "" : [self.password UTF8String];
     
     ClientAPI::Status creds_status = self.vpnClient->provide_creds(creds);
     if (creds_status.error) {
@@ -378,6 +403,19 @@ static void socketCallback(CFSocketRef socket, CFSocketCallBackType type, CFData
 
 @implementation OpenVPNAdapter
 
+#pragma mark Initialization
+
+- (instancetype)init
+{
+    self = [super init];
+    if (self) {
+        _username = nil;
+        _password = nil;
+        _delegate = nil;
+    }
+    return self;
+}
+
 #pragma mark TUN -> OpenVPN
 
 - (void)readTUNPackets {
@@ -427,11 +465,15 @@ static void socketCallback(CFSocketRef socket, CFSocketCallBackType type, CFData
 - (void)dealloc {
     delete self.vpnClient;
     
+    if (self.vpnSocket) {
         CFSocketInvalidate(self.vpnSocket);
-    CFSocketInvalidate(self.tunSocket);
-    
         CFRelease(self.vpnSocket);
+    }
+    
+    if (self.tunSocket) {
+        CFSocketInvalidate(self.tunSocket);
         CFRelease(self.tunSocket);
+    }
 }
 
 @end