1 files changed, 169 insertions, 0 deletions
diff --git a/src/Erebos/Network/ifaddrs.c b/src/Erebos/Network/ifaddrs.c
new file mode 100644
index 0000000..637716e
--- /dev/null
+++ b/src/Erebos/Network/ifaddrs.c
@@ -0,0 +1,169 @@
+#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