Hi,
I tried to send an ipv6 multicast packet through my network. The sending seems to work, since it arrives on the destination PC - at least it appears in the logged network traffic in WireShark. But it does not arrive in my server program. When I send a packet from the same PC that should receive it, it does work though.
This is the code for sending:
UDPBroadcastSocket = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
BOOL Yes = 1;
setsockopt(UDPBroadcastSocket, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&Yes, sizeof(BOOL));
int32_t hops = 50;
setsockopt(UDPBroadcastSocket, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, (char*)&hops, sizeof(hops));
uint32_t IF = 0;
setsockopt(UDPBroadcastSocket, IPPROTO_IPV6, IPV6_MULTICAST_IF, (char*)&IF, sizeof(IF));
struct sockaddr_in6 sock_in;
struct addrinfo *result = NULL;
struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET6;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
hints.ai_flags = AI_NUMERICHOST;
getaddrinfo("FF18::1243", "12346", &hints, &result);
unsigned char buffer[MAXBUF];
int PacketSize = 8;
int sinlen = int(result->ai_addrlen);
memcpy(&sock_in, result->ai_addr, result->ai_addrlen);
freeaddrinfo(result);
sendto(UDPBroadcastSocket, (char*)buffer, PacketSize, 0, (sockaddr *)&sock_in, sinlen);
And this is the code for receiving the packet:
std::vector<uint32_t> GetNetworkInterfaceIndices(){
std::vector<uint32_t> Result = { 0 };
/* Declare and initialize variables */
DWORD dwSize = 0;
DWORD dwRetVal = 0;
unsigned int i = 0;
// Set the flags to pass to GetAdaptersAddresses
ULONG flags = GAA_FLAG_INCLUDE_PREFIX;
// default to unspecified address family (both)
ULONG family = AF_UNSPEC;
LPVOID lpMsgBuf = NULL;
PIP_ADAPTER_ADDRESSES pAddresses = NULL;
ULONG outBufLen = 0;
ULONG Iterations = 0;
PIP_ADAPTER_ADDRESSES pCurrAddresses = NULL;
PIP_ADAPTER_UNICAST_ADDRESS pUnicast = NULL;
PIP_ADAPTER_ANYCAST_ADDRESS pAnycast = NULL;
PIP_ADAPTER_MULTICAST_ADDRESS pMulticast = NULL;
IP_ADAPTER_DNS_SERVER_ADDRESS *pDnServer = NULL;
IP_ADAPTER_PREFIX *pPrefix = NULL;
family = AF_INET6;
// Allocate a 15 KB buffer to start with.
outBufLen = WORKING_BUFFER_SIZE;
do {
pAddresses = (IP_ADAPTER_ADDRESSES *)MALLOC(outBufLen);
if (pAddresses == NULL) {
return{ 0 };
}
dwRetVal =
GetAdaptersAddresses(family, flags, NULL, pAddresses, &outBufLen);
if (dwRetVal == ERROR_BUFFER_OVERFLOW) {
FREE(pAddresses);
pAddresses = NULL;
}
else {
break;
}
Iterations++;
} while ((dwRetVal == ERROR_BUFFER_OVERFLOW) && (Iterations < MAX_TRIES));
if (dwRetVal == NO_ERROR) {
// If successful, output some information from the data we received
pCurrAddresses = pAddresses;
while (pCurrAddresses) {
Result.emplace_back(pCurrAddresses->IfIndex);
pCurrAddresses = pCurrAddresses->Next;
}
}
else {
return{ 0 };
}
if (pAddresses) {
FREE(pAddresses);
}
return Result;
}
UDPSocket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
sockaddr_in6 UDP_Sock_in;
memset(&UDP_Sock_in, 0, sizeof(sockaddr_in6));
UDP_Sock_in.sin6_addr = in6addr_any;
UDP_Sock_in.sin6_port = htons(Settings::GetPort()+1);
UDP_Sock_in.sin6_family = PF_INET6;
setsockopt(UDPSocket, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&No, sizeof(BOOL));
bind(UDPSocket, (sockaddr*)&UDP_Sock_in, sizeof(UDP_Sock_in));
ipv6_mreq BroadcastGroup;
memset(&BroadcastGroup, 0, sizeof(ipv6_mreq));
const auto IfIndices = GetNetworkInterfaceIndices();
BroadcastGroup.ipv6mr_multiaddr.u.Byte[0] = 0xFF;
BroadcastGroup.ipv6mr_multiaddr.u.Byte[1] = 0x18;
BroadcastGroup.ipv6mr_multiaddr.u.Byte[14] = 0x12;
BroadcastGroup.ipv6mr_multiaddr.u.Byte[15] = 0x43;
for (const auto& Index : IfIndices) {
BroadcastGroup.ipv6mr_interface = Index;
setsockopt(UDPSocket, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, (char*)&BroadcastGroup, sizeof(ipv6_mreq));
}
socklen_t fromLength = sizeof(sockaddr_in6);
pollfd PollFd;
PollFd.events = POLLIN;
PollFd.fd = UDPSocket;
PollFd.revents = -1;
WSAPoll(&PollFd, 1, -1);
recvfrom(UDPSocket, (char*)buffer, MAXBUF, 0, (sockaddr*)&from, &fromLength);
I basically tried specifying every single network interface index and the packet still does not arrive in the server. I have no idea what could be wrong. And why does it work when sender and receiver are on the same PC? I don't understand this. Does anyone have an idea? I'm trying this for like 5 hours now and I'm frustrated.
