Visual C++ :: Using The Same Port For 2 UDP Multicast Groups?
Jun 20, 2014
I habe a program, that can send and receive UDP Multicast telegrams. When I open the socket then I bind my multicast group address and the local port to a specified networkcard (our PC has 2 network cards). Now I have a special constellation:
Our PC has 2 network cards. Multicast group 1 shall use card 1 and group shall use card 2. As long as both groups use different local ports it works fine. But when both group want to use the same port number then I can receive and send telegrams only through the first group that was created. For the second one I don't even get a FD_READ event at all.
Code:
SrvAddr.sin_family = AF_INET;
SrvAddr.sin_port = htons( (WORD) nLocalPort );
SrvAddr.sin_addr.s_addr = inet_addr(strOwnIpAddress); // bind multicast group socket to a specified networkcard
// If bind socket to port failed
if( bind( hSocket,
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//Construct a Zone Query packet // 4 bytes - Signature "Ohz " = 0x6f, 0x68, 0x7a, 0x20 // 1 bytes - Version = 1 // 1 bytes - Type (0 = Zone Query, 1 = Zone Uri) // 2 bytes - Entire message length = 12 + zone length // 4 bytes - Length in bytes of the zone ID // n bytes - Zone ID to query
[Code] ....
The errors that I get are:
error: invalid conversion from ‘short int’ to ‘const void*’ [-fpermissive] memcpy(buffer + 6, packetLength, sizeof(packetLength)); ^ [Code] ....
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[Code] ....
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Code:
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