Mac C++ Broadcast -> more then one network-interface - macos

Question

I have a broadcast program on my mac, everything is working fine, but if i have more then one network interface, he didn't recieve anything.
So what i now want to do is:
Check which network interfaces are activ on the mac
send to every activ interface a broadcast ( so i have to select which interface i want to use)
recieve the answer (if there is one :) )
Interesting:
the broadcast client is on my WLAN (with a router beetween the devices) and a normal internet connection is on my LAN. If i deactivate the LAN in the system configs, he also didn't find my other device, but if i pull the cable he found the other device... So maybe i didn't have to look which interface is activ and have a look to which interface is connected.
Do u have some tipps or good google keywords for me to do that?

Answer 1

Long time ago, but if someone find my post, here is my solution:
#include <stdint.h>
static uint32 Inet_AtoN(const char * buf)
{
// net_server inexplicably doesn't have this function; so I'll just fake it
uint32 ret = 0;
int shift = 24; // fill out the MSB first
bool startQuad = true;
while ((shift >= 0) && (*buf))
{
if (startQuad)
{
unsigned char quad = (unsigned char)atoi(buf);
ret |= (((uint32)quad) << shift);
shift -= 8;
}
startQuad = (*buf == '.');
buf++;
}
return ret;
}
int Broadcast::BroadcastToAllInterfaces()
{
DEBUG_LOG(1,"Start Broadcast To All Interfaces", "DEv1");
globalDatabase->SetInBroadcast();
moreThenOne = 0;
#if defined(USE_GETIFADDRS)
struct ifaddrs * ifap;
if (getifaddrs(&ifap) == 0)
{
struct ifaddrs * p = ifap;
while (p)
{
uint32 ifaAddr = SockAddrToUint32(p->ifa_addr);
uint32 maskAddr = SockAddrToUint32(p->ifa_netmask);
uint32 dstAddr = SockAddrToUint32(p->ifa_dstaddr);
if (ifaAddr > 0)
{
char ifaAddrStr[32]; Inet_NtoA(ifaAddr, ifaAddrStr);
char maskAddrStr[32]; Inet_NtoA(maskAddr, maskAddrStr);
char dstAddrStr[32]; Inet_NtoA(dstAddr, dstAddrStr);
std::stringstream addr, descss;
std::string addrs, descs;
addr << dstAddrStr;
descss << p->ifa_name;
descss >> descs;
addr >> addrs;
DoABroadcast(dstAddr);
}
p = p->ifa_next;
}
freeifaddrs(ifap);
}
#elif defined(WIN32)
// Windows XP style implementation
// Adapted from example code at http://msdn2.microsoft.com/en-us/library/aa365917.aspx
// Now get Windows' IPv4 addresses table. Once again, we gotta call GetIpAddrTable()
// multiple times in order to deal with potential race conditions properly.
MIB_IPADDRTABLE * ipTable = NULL;
{
ULONG bufLen = 0;
for (int i = 0; i<5; i++)
{
DWORD ipRet = GetIpAddrTable(ipTable, &bufLen, false);
if (ipRet == ERROR_INSUFFICIENT_BUFFER)
{
free(ipTable); // in case we had previously allocated it STILL_RUN
ipTable = (MIB_IPADDRTABLE *)malloc(bufLen);
}
else if (ipRet == NO_ERROR) break;
else
{
free(ipTable);
ipTable = NULL;
break;
}
}
}
if (ipTable)
{
IP_ADAPTER_INFO * pAdapterInfo = NULL;
{
ULONG bufLen = 0;
for (int i = 0; i<5; i++)
{
DWORD apRet = GetAdaptersInfo(pAdapterInfo, &bufLen);
if (apRet == ERROR_BUFFER_OVERFLOW)
{
free(pAdapterInfo); // in case we had previously allocated it
pAdapterInfo = (IP_ADAPTER_INFO *)malloc(bufLen);
}
else if (apRet == ERROR_SUCCESS) break;
else
{
free(pAdapterInfo);
pAdapterInfo = NULL;
break;
}
}
}
for (DWORD i = 0; i<ipTable->dwNumEntries; i++)
{
const MIB_IPADDRROW & row = ipTable->table[i];
// Now lookup the appropriate adaptor-name in the pAdaptorInfos, if we can find it
const char * name = NULL;
const char * desc = NULL;
if (pAdapterInfo)
{
IP_ADAPTER_INFO * next = pAdapterInfo;
while ((next) && (name == NULL))
{
IP_ADDR_STRING * ipAddr = &next->IpAddressList;
while (ipAddr)
{
if (Inet_AtoN(ipAddr->IpAddress.String) == ntohl(row.dwAddr))
{
name = next->AdapterName;
desc = next->Description;
break;
}
ipAddr = ipAddr->Next;
}
next = next->Next;
}
}
char buf[128];
int setUnnamed = 0;
if (name == NULL)
{
sprintf(buf, "unnamed");
name = buf;
setUnnamed = 1;
}
uint32 ipAddr = ntohl(row.dwAddr);
uint32 netmask = ntohl(row.dwMask);
uint32 baddr = ipAddr & netmask;
if (row.dwBCastAddr) baddr |= ~netmask;
char ifaAddrStr[32]; Inet_NtoA(ipAddr, ifaAddrStr);
char maskAddrStr[32]; Inet_NtoA(netmask, maskAddrStr);
char dstAddrStr[32]; Inet_NtoA(baddr, dstAddrStr);
std::stringstream addr, descss;
std::string addrs, descs;
if (setUnnamed == 0)
{
addr << dstAddrStr;
descss << desc;
descss >> descs;
addr >> addrs;
DoABroadcast(baddr);
}
}
free(pAdapterInfo);
free(ipTable);
}
#else
// Dunno what we're running on here!
# error "Don't know how to implement PrintNetworkInterfaceInfos() on this OS!"
#endif
globalDatabase->SetLeaveBroadcast();
return 1;
}
int Broadcast::DoABroadcast(uint32 broadAddr)
{
int askSinlen = sizeof(struct sockaddr_in);
int askBuflen = MAXBUF;
int message;
char buf[512];
int status;
char askBuffer[MAXBUF];
struct sockaddr_in sock_in, client_adress, client_adress2;
#ifdef __APPLE__
socklen_t clientLength;
int askYes = 1;
#else
char askYes = 1;
int clientLength;
WSADATA w;
int result = WSAStartup(MAKEWORD(2, 2), &w);
#endif
int recSocket = socket(AF_INET, SOCK_DGRAM, 0);
if (recSocket <0)
{
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return 10;
}
sock_in.sin_addr.s_addr = htonl(INADDR_ANY);
sock_in.sin_port = htons(4028);
sock_in.sin_family = PF_INET;
client_adress.sin_family = PF_INET;
client_adress.sin_port = htons(4029);
client_adress.sin_addr.s_addr = htonl(broadAddr);
askSinlen = sizeof(sock_in);
client_adress2.sin_family = AF_INET;
client_adress2.sin_port = htons(4028);
client_adress2.sin_addr.s_addr = htonl(0xc0a8b2ff);
status = setsockopt(recSocket, SOL_SOCKET, SO_BROADCAST, &askYes, sizeof(askYes));
if (status < 0)
{
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return 10;
}
status = bind(recSocket, (struct sockaddr *)&sock_in, askSinlen);
if (status < 0)
{
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return 10;
}
askBuflen = sprintf(askBuffer, "Ciao Mac ist hier");
status = sendto(recSocket, askBuffer, askBuflen, 0, (struct sockaddr *)&client_adress, sizeof(client_adress));
fd_set fds;
struct timeval tv;
tv.tv_sec = 2;
tv.tv_usec = 0;
FD_ZERO(&fds);
FD_SET(recSocket, &fds);
int ret;
if ((ret = select(recSocket +1, &fds, NULL, NULL, &tv)) > 0)
{
int e = 0;
while ((ret = select(recSocket + 1, &fds, NULL, NULL, &tv)) > 0)
{
clientLength = sizeof(client_adress2);
message = recvfrom(recSocket, buf, sizeof(buf), 0, (struct sockaddr*) &client_adress2, &clientLength);
if (message == -1)
{
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return -5;
}
else
{
std::string hereisyourbroadcast(buf);
}
}
}
else
{
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return -6;
}
#ifdef __APPLE__
close(recSocket);
#else
closesocket(recSocket);
#endif
inBroadcast = false;
return 1;
}