无法在XMPP中发送文件

Question

我在XMPP中遇到了文件发送功能。虽然我能够收到文件。 当用户从spark接收文件时，我的转接套接字连接失败。

- (BOOL)handleServiceDiscoveryRequest:(XMPPIQ*)inIq {

    NSString *from = [inIq toStr];
    NSString *to = [inIq fromStr];
    NSString *uuid = [self.xmppStream generateUUID];

    NSXMLElement *child = [NSXMLElement elementWithName:@"query" xmlns:@"http://jabber.org/protocol/disco#info"];

    XMPPIQ *iq = [XMPPIQ iqWithType:@"get" elementID:uuid child:child];
    [iq addAttributeWithName:@"to" stringValue:to];
    [iq addAttributeWithName:@"from" stringValue:from];
    [self.xmppStream sendElement:iq];

    _fileToSend = [[NSUserDefaults standardUserDefaults] valueForKey:@"FileTranfserData"];
    _fileRecipient = [[NSUserDefaults standardUserDefaults] valueForKey:@"FileRecepient"];
    _sid = [[NSUserDefaults standardUserDefaults] valueForKey:@"senderId"];

    [TURNSocket setProxyCandidates:[[NSArray alloc] initWithObjects:KHostName, nil]];
    turnSocket = [[TURNSocket alloc] initWithStream:self.xmppStream toJID:[XMPPJID jidWithString:to] sid:_sid];
    [turnSocket startWithDelegate:self delegateQueue:dispatch_get_main_queue()];

    return YES;
}

在didReceive方法中收到以下错误

error code="404" remote server not found。

我真的很感激任何帮助。