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#include "ifaddrs.h"
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef _WIN32
#include <arpa/inet.h>
#include <net/if.h>
#include <ifaddrs.h>
#include <endian.h>
#include <sys/types.h>
#include <sys/socket.h>
#else
#include <winsock2.h>
#include <ws2ipdef.h>
#include <ws2tcpip.h>
#endif
#define DISCOVERY_MULTICAST_GROUP "ff12:b6a4:6b1f:969:caee:acc2:5c93:73e1"
uint32_t * join_multicast(int fd, size_t * count)
{
size_t capacity = 16;
*count = 0;
uint32_t * interfaces = malloc(sizeof(uint32_t) * capacity);
#ifdef _WIN32
interfaces[0] = 0;
*count = 1;
#else
struct ifaddrs * addrs;
if (getifaddrs(&addrs) < 0)
return 0;
for (struct ifaddrs * ifa = addrs; ifa; ifa = ifa->ifa_next) {
if( ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET6 &&
! (ifa->ifa_flags & IFF_LOOPBACK) &&
(ifa->ifa_flags & IFF_MULTICAST) &&
! IN6_IS_ADDR_LINKLOCAL( & ((struct sockaddr_in6 *) ifa->ifa_addr)->sin6_addr ) ){
int idx = if_nametoindex(ifa->ifa_name);
bool seen = false;
for (size_t i = 0; i < *count; i++) {
if (interfaces[i] == idx) {
seen = true;
break;
}
}
if (seen)
continue;
if (*count + 1 >= capacity) {
capacity *= 2;
uint32_t * nret = realloc(interfaces, sizeof(uint32_t) * capacity);
if (nret) {
interfaces = nret;
} else {
free(interfaces);
*count = 0;
return NULL;
}
}
interfaces[*count] = idx;
(*count)++;
}
}
freeifaddrs(addrs);
#endif
for (size_t i = 0; i < *count; i++) {
struct ipv6_mreq group;
group.ipv6mr_interface = interfaces[i];
inet_pton(AF_INET6, DISCOVERY_MULTICAST_GROUP, &group.ipv6mr_multiaddr);
int ret = setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
(const void *) &group, sizeof(group));
if (ret < 0)
fprintf(stderr, "IPV6_ADD_MEMBERSHIP failed: %s\n", strerror(errno));
}
return interfaces;
}
#ifndef _WIN32
uint32_t * broadcast_addresses(void)
{
struct ifaddrs * addrs;
if (getifaddrs(&addrs) < 0)
return 0;
size_t capacity = 16, count = 0;
uint32_t * ret = malloc(sizeof(uint32_t) * capacity);
for (struct ifaddrs * ifa = addrs; ifa; ifa = ifa->ifa_next) {
if (ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET &&
ifa->ifa_flags & IFF_BROADCAST) {
if (count + 2 >= capacity) {
capacity *= 2;
uint32_t * nret = realloc(ret, sizeof(uint32_t) * capacity);
if (nret) {
ret = nret;
} else {
free(ret);
return 0;
}
}
ret[count] = ((struct sockaddr_in*)ifa->ifa_broadaddr)->sin_addr.s_addr;
count++;
}
}
freeifaddrs(addrs);
ret[count] = 0;
return ret;
}
#else // _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#pragma comment(lib, "ws2_32.lib")
uint32_t * broadcast_addresses(void)
{
uint32_t * ret = NULL;
SOCKET wsock = INVALID_SOCKET;
struct WSAData wsaData;
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
return NULL;
wsock = WSASocket(AF_INET, SOCK_DGRAM, IPPROTO_UDP, NULL, 0, 0);
if (wsock == INVALID_SOCKET)
goto cleanup;
INTERFACE_INFO InterfaceList[32];
unsigned long nBytesReturned;
if (WSAIoctl(wsock, SIO_GET_INTERFACE_LIST, 0, 0,
InterfaceList, sizeof(InterfaceList),
&nBytesReturned, 0, 0) == SOCKET_ERROR)
goto cleanup;
int numInterfaces = nBytesReturned / sizeof(INTERFACE_INFO);
size_t capacity = 16, count = 0;
ret = malloc(sizeof(uint32_t) * capacity);
for (int i = 0; i < numInterfaces && count < capacity - 1; i++)
if (InterfaceList[i].iiFlags & IFF_BROADCAST)
ret[count++] = InterfaceList[i].iiBroadcastAddress.AddressIn.sin_addr.s_addr;
ret[count] = 0;
cleanup:
if (wsock != INVALID_SOCKET)
closesocket(wsock);
WSACleanup();
return ret;
}
#endif
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