Local discovery with IPv6

Changelog: Local discovery with IPv6

3 files changed, 106 insertions, 9 deletions

diff --git a/src/Erebos/Network.hs b/src/Erebos/Network.hs
index 1e06008..2064d1c 100644
--- a/src/Erebos/Network.hs
+++ b/src/Erebos/Network.hs
@@ -54,6 +54,9 @@ import GHC.Conc.Sync (unsafeIOToSTM)
 import Network.Socket hiding (ControlMessage)
 import qualified Network.Socket.ByteString as S
 
+import Foreign.C.Types
+import Foreign.Marshal.Alloc
+
 import Erebos.Channel
 #ifdef ENABLE_ICE_SUPPORT
 import Erebos.ICE
@@ -71,6 +74,9 @@ import Erebos.Storage.Merge
 discoveryPort :: PortNumber
 discoveryPort = 29665
 
+discoveryMulticastGroup :: HostAddress6
+discoveryMulticastGroup = tupleToHostAddress6 (0xff12, 0xb6a4, 0x6b1f, 0x0969, 0xcaee, 0xacc2, 0x5c93, 0x73e1) -- ff12:b6a4:6b1f:969:caee:acc2:5c93:73e1
+
 announceIntervalSeconds :: Int
 announceIntervalSeconds = 60
 
@@ -249,8 +255,6 @@ startServer opt serverOrigHead logd' serverServices = do
         either (atomically . logd) return =<< runExceptT =<<
             atomically (readTQueue serverIOActions)
 
-    broadcastAddreses <- getBroadcastAddresses discoveryPort
-
     let open addr = do
             sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
             putMVar serverSocket sock
@@ -261,9 +265,14 @@ startServer opt serverOrigHead logd' serverServices = do
             return sock
 
         loop sock = do
-            when (serverLocalDiscovery opt) $ forkServerThread server $ forever $ do
-                atomically $ writeFlowBulk serverControlFlow $ map (SendAnnounce . DatagramAddress) broadcastAddreses
-                threadDelay $ announceIntervalSeconds * 1000 * 1000
+            when (serverLocalDiscovery opt) $ forkServerThread server $ do
+                announceAddreses <- fmap concat $ sequence $
+                    [ map (SockAddrInet6 discoveryPort 0 discoveryMulticastGroup) <$> joinMulticast sock
+                    , getBroadcastAddresses discoveryPort
+                    ]
+                forever $ do
+                    atomically $ writeFlowBulk serverControlFlow $ map (SendAnnounce . DatagramAddress) announceAddreses
+                    threadDelay $ announceIntervalSeconds * 1000 * 1000
 
             let announceUpdate identity = do
                     st <- derivePartialStorage serverStorage
@@ -944,9 +953,19 @@ runPeerServiceOn mbservice peer handler = liftIO $ do
             logd $ "unhandled service '" ++ show (toUUID svc) ++ "'"
 
 
+foreign import ccall unsafe "Network/ifaddrs.h join_multicast" cJoinMulticast :: CInt -> Ptr CSize -> IO (Ptr Word32)
 foreign import ccall unsafe "Network/ifaddrs.h broadcast_addresses" cBroadcastAddresses :: IO (Ptr Word32)
 foreign import ccall unsafe "stdlib.h free" cFree :: Ptr Word32 -> IO ()
 
+joinMulticast :: Socket -> IO [ Word32 ]
+joinMulticast sock =
+    withFdSocket sock $ \fd ->
+    alloca $ \pcount -> do
+        ptr <- cJoinMulticast fd pcount
+        count <- fromIntegral <$> peek pcount
+        forM [ 0 .. count - 1 ] $ \i ->
+            peekElemOff ptr i
+
 getBroadcastAddresses :: PortNumber -> IO [SockAddr]
 getBroadcastAddresses port = do
     ptr <- cBroadcastAddresses
diff --git a/src/Erebos/Network/ifaddrs.c b/src/Erebos/Network/ifaddrs.c
index efeca18..70685bc 100644
--- a/src/Erebos/Network/ifaddrs.c
+++ b/src/Erebos/Network/ifaddrs.c
@@ -1,13 +1,89 @@
 #include "ifaddrs.h"
 
-#ifndef _WIN32
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
+#ifndef _WIN32
 #include <arpa/inet.h>
-#include <ifaddrs.h>
 #include <net/if.h>
-#include <stdlib.h>
-#include <sys/types.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)) {
+			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)
 {
diff --git a/src/Erebos/Network/ifaddrs.h b/src/Erebos/Network/ifaddrs.h
index 06d26ec..8852ec6 100644
--- a/src/Erebos/Network/ifaddrs.h
+++ b/src/Erebos/Network/ifaddrs.h
@@ -1,3 +1,5 @@
+#include <stddef.h>
 #include <stdint.h>
 
+uint32_t * join_multicast(int fd, size_t * count);
 uint32_t * broadcast_addresses(void);