C++插座 - SENDTO - 没有数据收到

Question

的Visual Studio 2017年社区

C++ CLR项目

它应该可以发送一个UDP数据报多播地址。

我发送没有错误。

-------------- 
MULTICAST 
------------------- 
'Project2.exe' (Win32): Loaded 'C:\Windows\SysWOW64\mswsock.dll'. Symbols loaded. 

MULTICAST ---- 
IP:224.0.0.2 
PORT:7125 
------------- 

Sent: 13 


Sent: 13 


Sent: 13 

接收端收到这个输入

{"socketId":0,"data":{},"remoteAddress":"192.168.0.80","remotePort":2535} 

下面是代码

const char *msg = "1 2 3 4 5 6 7"; 


while (sending) { 

    //swprintf(str, L"\nMSG: \n%c ", channels); 
    //OutputDebugString(str); 

    // Send a message to the multicasting address. 
    int ret = sendto(Sock, msg, strlen(msg), 0, (struct sockaddr FAR *) &dest_sin, sizeof(dest_sin)); 

    swprintf(str, L"\nSent: %d \n\n", ret); 
    OutputDebugString(str); 

    if (ret == SOCKET_ERROR) 
    { 
     swprintf(str, L"\nsendto failed! Error: %d ", WSAGetLastError()); 
     OutputDebugString(str); 

     closesocket(Sock); 
     sending = false; 
    } 
    Sleep(66); 
} 

全部插座码的发送部分，如果有帮助

// Sent message string 
TCHAR szError[100];    // Error message string 
SOCKET Sock = INVALID_SOCKET;  // Datagram window socket 

SOCKADDR_IN source_sin,   // Source socket address 
    dest_sin;    // Destination socket address 

WSADATA WSAData;     // Contains details of the 
            // Winsock implementation 


OutputDebugString(L"\n--------------\nMULTICAST\n-------------------\n"); 

// Initialize Winsock. 
if (WSAStartup(MAKEWORD(1, 1), &WSAData) != 0) 
{ 
    swprintf(str, TEXT("WSAStartup failed! Error: %d"), WSAGetLastError()); 
    OutputDebugString(str); 
    return FALSE; 
} 

// Create a datagram window socket, Sock. 
if ((Sock = socket(AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET) 
{ 
    swprintf(str, TEXT("Allocating socket failed! Error: %d"), WSAGetLastError()); 
    OutputDebugString(str); 
    return FALSE; 
} 

// Fill out source socket's address information. 
source_sin.sin_family = AF_INET; 
source_sin.sin_port = htons(SOURCE_PORT); 
source_sin.sin_addr.s_addr = htonl(INADDR_ANY); 

// Associate the source socket's address with the socket, Sock. 
if (bind(Sock, 
    (struct sockaddr FAR *) &source_sin, 
    sizeof(source_sin)) == SOCKET_ERROR) 
{ 
    swprintf(str, TEXT("Binding socket failed! Error: %d"), WSAGetLastError()); 
    OutputDebugString(str); 
    closesocket(Sock); 
    return FALSE; 
} 

// Set the Time-to-Live of the multicast. 
int set_sock = setsockopt(Sock, SOL_SOCKET, SO_BROADCAST, (char FAR *)&iOptVal, sizeof(int)); 
if (set_sock == SOCKET_ERROR) 
{ 
    swprintf(str, TEXT("\n`setsockopt` failed! Error: %d\n\n"), WSAGetLastError()); 
    OutputDebugString(str); 
    closesocket(Sock); 
    return FALSE; 
} 


// Fill out the desination socket's address information. 
dest_sin.sin_family = AF_INET; 
dest_sin.sin_port = ntohs(mcast_port); 
dest_sin.sin_addr.s_addr = inet_addr(mcast_ip); 

swprintf(str, L"\nMULTICAST ----\nIP:%s\nPORT:%d\n-------------\n", mcast_ip, mcast_port); 
OutputDebugString(str); 


const char *msg = "1 2 3 4 5 6 7"; 


while (sending) { 

    //swprintf(str, L"\nMSG: \n%c ", channels); 
    //OutputDebugString(str); 

    // Send a message to the multicasting address. 
    int ret = sendto(Sock, msg, strlen(msg), 0, (struct sockaddr FAR *) &dest_sin, sizeof(dest_sin)); 

    swprintf(str, L"\nSent: %d \n\n", ret); 
    OutputDebugString(str); 

    if (ret == SOCKET_ERROR) 
    { 
     swprintf(str, L"\nsendto failed! Error: %d ", WSAGetLastError()); 
     OutputDebugString(str); 

     closesocket(Sock); 
     sending = false; 
    } 
    Sleep(66); 
} 


OutputDebugString(L"\n---------------------\nMULTICAST DONE\n---------------------\n"); 


if (!sending) { 
    // Disable sending on Sock before closing it. 
    shutdown(Sock, 0x01); 

    // Close Sock. 
    closesocket(Sock); 

    WSACleanup(); 
} 

从我已阅读。

const char * msg

应该是正确的？

任何建议表示赞赏。

编辑：

作为每Remy Lebeau

INT set_sock = setsockopt的（袜子，IPPROTO_IP，IP_ADD_MEMBERSHIP，（CHAR FAR *）& iOptVal，的sizeof（INT））;

Error: 10042 -- An unknown, invalid or unsupported option or level was specified in a getsockopt or setsockopt call.

​​

Answer 1

子网广播方式是不一样的东西多播！

您已经实现了广播代码，但是您使用多播IP地址作为广播目标，这将不起作用。

在这种情况下根本不要使用setsockopt(SOL_SOCKET, SO_BROADCAST)。相反，您必须先使用setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP)才能加入多播组，然后才能向/从该组发送/接收数据报。

阅读MSDN了解更多详情：

Multicast Programming

Answer 2

原来...

setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP)不使用setsockopt(SOL_SOCKET, SO_BROADCAST)答案，发送数据。我测试过并且EJP指出。

问题egg on my face是我忘了控制台中的数据总是空的，直到我解析缓冲区，然后数据存在。

谢谢大家。