在IOS上使用CFSocket进行UDP广播

Question

一直在做一些谷歌搜索和一些关于这个主题的阅读，但无论我花了多少时间搜索，似乎都无法得到正确的结果。

我想要做的是通过广告我对他们提供的服务的兴趣来接收连接在我的网络上的设备的广播消息。使用wireshark，我可以看到我想要连接的网络设备通过我的网络发送的广播/通知消息，但看不到我对其服务感兴趣的广播搜索。 但是通过网络实用程序，我可以看到套接字已创建，但不知道它处于哪种状态，是侦听还是已连接。

是的，我知道有一些库可以用来执行此操作，但我想从头开始构建自己的东西，并更好地了解它是如何工作的。

MySocket.h

#import <Foundation/Foundation.h>
#import <CoreFoundation/CoreFoundation.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#if TARGET_OS_IPHONE
#import <CFNetwork/CFNetwork.h>
#endif

 @interface MySocket : NSObject
 {
    NSString* _message;
    CFSocketRef cfSocket;
    CFRunLoopSourceRef cfSource;

 }

 - (void)listen;
 @end

MySocket.m

#import "MySocket.h"

#define MAX_UDP_DATAGRAM_SIZE 65507

@implementation MySocket


static void socketCallback(CFSocketRef cfSocket, CFSocketCallBackType
                           type, CFDataRef address, const void *data, void *userInfo)
{
    NSLog(@"socketCAllBAck was called");
}    

- (void)listen
{
    //Enable broadcast to network hosts        
    int yes = 1;
    int setSockResult = 0;
    _message = [[NSMutableString alloc ] initWithString: @"M-SEARCH *HTTP/1.1\r\nHOST:239.255.255.250:1900\r\nMAN:\"ssdp:discover\"\r\nST:ssdp:all\r\nMX:1\r\n\r\n"];

    CFSocketContext socketContext = {0, self, NULL, NULL, NULL};

    /* Create the server socket as a UDP IPv4 socket and set a callback */
    /* for calls to the socket's lower-level accept() function */
    cfSocket = CFSocketCreate(NULL, PF_INET, SOCK_DGRAM, IPPROTO_UDP,
                              kCFSocketAcceptCallBack | kCFSocketDataCallBack , (CFSocketCallBack)socketCallback, &socketContext);
    if (cfSocket == NULL)
        NSLog(@"UDP socket could not be created\n");

    /* Re-use local addresses, if they're still in TIME_WAIT */
   setSockResult = setsockopt(CFSocketGetNative(cfSocket), SOL_SOCKET, SO_BROADCAST, (void *)&yes, sizeof(yes));

    if(setSockResult < 0)
        NSLog(@"Could not setsockopt for broabcast");

    /* Set the port and address we want to listen on */
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_len = sizeof(addr);
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("239.255.255.250");
    //inet_pton(AF_INET, "239.255.255.250", &(addr.sin_addr));

    addr.sin_port = htons(1900);
    //addr.sin_addr.s_addr = htonl(INADDR_ANY);

    NSData *address = [ NSData dataWithBytes: &addr length: sizeof(addr) ];
    if (address != nil && CFSocketSetAddress(cfSocket, (CFDataRef) address) != kCFSocketSuccess) {
        NSLog(@"CFSocketSetAddress() failed\n");
        CFRelease(cfSocket);
    }      

    CFDataRef data = CFDataCreate(NULL, (const UInt8*)[_message UTF8String], [_message lengthOfBytesUsingEncoding:NSUTF8StringEncoding]);

    setSockResult = CFSocketSendData(cfSocket, (CFDataRef)address, data, 0.0);
    if(kCFSocketSuccess != setSockResult) NSLog(@"Unable to send data, %i", setSockResult);
    else NSLog(@"Sending data");

    cfSource = CFSocketCreateRunLoopSource(kCFAllocatorDefault, cfSocket, 0); 

    if(cfSource == NULL)
        NSLog(@"CFRunLoopSourceRef is null");

    CFRunLoopAddSource(CFRunLoopGetCurrent(), cfSource, kCFRunLoopDefaultMode);

    NSLog(@"Socket listening on port 1900");

        CFRelease(cfSource);
    CFRelease(cfSocket);
    [address release];
    data = nil;
    CFRunLoopRun();
}

- (void)dealloc
{
    CFRunLoopRemoveSource(CFRunLoopGetCurrent(), cfSource, kCFRunLoopDefaultMode);
    CFRelease(cfSource);
    CFRelease(cfSocket);
    [_message release];
    [super dealloc];
}

@end

编辑： 一切运行良好，直到调用发送数据。

为了让它发挥作用，我是否缺少一些小但重要的东西？ 或者我错过了大局？

任何帮助或指导表示赞赏。 提前致谢，祝周末愉快

Answer 1

删除 SetAdress，一切都会正常工作。我现在已经测试过了；

Answer 2

如何将这个初始化与地址一起使用

CFDataRef address=CFDataCreate(kCFAllocatorDefault,(UInt8 *)&addr,sizeof(addr));