Allow IPV6 only in iOS to connect to game server not behind a firewall

lib/enet/unix.c

@@ -60,6 +60,9 @@ static enet_uint32 timeBase = 0;
 
 #ifdef IOS_STK
 extern void iOSInitialize(void);
+extern int isIPV6Only(void);
+extern void getSynthesizedAddress(const ENetAddress* ea, struct sockaddr_in6* in6);
+extern void getIPV4FromSynthesized(const struct sockaddr_in6* in6, ENetAddress* ea);
 #endif
 
 int
@@ -195,6 +198,21 @@ enet_address_get_host (const ENetAddress * address, char * name, size_t nameLeng
 
 int
 enet_socket_bind (ENetSocket socket, const ENetAddress * address)
+{
+#ifdef IOS_STK
+    // In STK we only bind port and listen to any address
+    if (isIPV6Only())
+    {
+        struct sockaddr_in6 sin;
+        memset (&sin, 0, sizeof (struct sockaddr_in6));
+        sin.sin6_family = AF_INET6;
+        sin.sin6_addr = in6addr_any;
+        sin.sin6_port = ENET_HOST_TO_NET_16 (address -> port);
+        return bind (socket, (struct sockaddr *) & sin,
+                     sizeof (struct sockaddr_in6));
+    }
+    else
+#endif
     {
         struct sockaddr_in sin;
 
@@ -217,6 +235,7 @@ enet_socket_bind (ENetSocket socket, const ENetAddress * address)
                      (struct sockaddr *) & sin,
                      sizeof (struct sockaddr_in));
     }
+}
 
 int
 enet_socket_get_address (ENetSocket socket, ENetAddress * address)
@@ -242,7 +261,12 @@ enet_socket_listen (ENetSocket socket, int backlog)
 ENetSocket
 enet_socket_create (ENetSocketType type)
 {
-    return socket (PF_INET, type == ENET_SOCKET_TYPE_DATAGRAM ? SOCK_DGRAM : SOCK_STREAM, 0);
+#ifdef IOS_STK
+    int af_family = isIPV6Only() == 1 ? PF_INET6 : PF_INET;
+#else
+    int af_family = PF_INET;
+#endif
+    return socket (af_family, type == ENET_SOCKET_TYPE_DATAGRAM ? SOCK_DGRAM : SOCK_STREAM, 0);
 }
 
 int
@@ -384,11 +408,24 @@ enet_socket_send (ENetSocket socket,
 {
     struct msghdr msgHdr;
     struct sockaddr_in sin;
+#ifdef IOS_STK
+    struct sockaddr_in6 sin6;
+#endif
     int sentLength;
 
     memset (& msgHdr, 0, sizeof (struct msghdr));
 
     if (address != NULL)
+    {
+#ifdef IOS_STK
+        if (isIPV6Only())
+        {
+            getSynthesizedAddress(address, &sin6);
+            msgHdr.msg_name = & sin6;
+            msgHdr.msg_namelen = sizeof (struct sockaddr_in6);
+        }
+        else
+#endif
         {
             memset (& sin, 0, sizeof (struct sockaddr_in));
 
@@ -399,6 +436,7 @@ enet_socket_send (ENetSocket socket,
             msgHdr.msg_name = & sin;
             msgHdr.msg_namelen = sizeof (struct sockaddr_in);
         }
+    }
 
     msgHdr.msg_iov = (struct iovec *) buffers;
     msgHdr.msg_iovlen = bufferCount;
@@ -424,15 +462,28 @@ enet_socket_receive (ENetSocket socket,
 {
     struct msghdr msgHdr;
     struct sockaddr_in sin;
+#ifdef IOS_STK
+    struct sockaddr_in6 sin6;
+#endif
     int recvLength;
 
     memset (& msgHdr, 0, sizeof (struct msghdr));
 
     if (address != NULL)
+    {
+#ifdef IOS_STK
+        if (isIPV6Only())
+        {
+            msgHdr.msg_name = & sin6;
+            msgHdr.msg_namelen = sizeof (struct sockaddr_in6);
+        }
+        else
+#endif
         {
             msgHdr.msg_name = & sin;
             msgHdr.msg_namelen = sizeof (struct sockaddr_in);
         }
+    }
 
     msgHdr.msg_iov = (struct iovec *) buffers;
     msgHdr.msg_iovlen = bufferCount;
@@ -453,10 +504,19 @@ enet_socket_receive (ENetSocket socket,
 #endif
 
     if (address != NULL)
+    {
+#ifdef IOS_STK
+        if (isIPV6Only())
+        {
+            getIPV4FromSynthesized(&sin6, address);
+        }
+        else
+#endif
         {
             address -> host = (enet_uint32) sin.sin_addr.s_addr;
             address -> port = ENET_NET_TO_HOST_16 (sin.sin_port);
         }
+    }
 
     return recvLength;
 }

src/network/ios_ipv6.cpp

@@ -20,13 +20,10 @@
 #ifdef IOS_STK
 
 #include "network/ios_ipv6.hpp"
-#include "config/stk_config.hpp"
+#include "network/transport_address.hpp"
-#include "config/user_config.hpp"
 #include "utils/string_utils.hpp"
 #include "utils/log.hpp"
 
-#include <enet/enet.h>
-
 #include <arpa/inet.h>
 #include <err.h>
 #include <netdb.h>
@@ -48,8 +45,9 @@
 #define NAME_SVR_LEN (10)
 
 
-bool g_ipv6_only;
+int g_ipv6_only;
-ENetAddress g_connected_address;
+struct sockaddr_in6 g_connected_ipv6;
+ENetAddress g_connected_ipv4;
 
 namespace Mars
 {
@@ -273,7 +271,7 @@ namespace Mars
     }
 }
 
-bool isIPV6Only()
+int isIPV6Only()
 {
     return g_ipv6_only;
 }
@@ -281,13 +279,86 @@ bool isIPV6Only()
 void iOSInitialize()
 {
     // Clear previous setting, in case user changed wifi or mobile data
-    g_ipv6_only = false;
+    g_ipv6_only = 0;
-    g_connected_address.host = 0;
+    g_connected_ipv4.host = 0;
-    g_connected_address.port = 0;
+    g_connected_ipv4.port = 0;
+    memset(&g_connected_ipv6, 0, sizeof(struct sockaddr_in6));
 
     using namespace Mars;
     int ipstack = local_ipstack_detect();
-    g_ipv6_only = ipstack == ELocalIPStack_IPv6;
+    if (ipstack == ELocalIPStack_IPv6)
-
+        g_ipv6_only = 1;
 }   // iOSInitialize
+
+void getSynthesizedAddress(const ENetAddress* ea, struct sockaddr_in6* in6)
+{
+    if (ea->host != g_connected_ipv4.host &&
+        ea->port != g_connected_ipv4.port)
+    {
+        g_connected_ipv4.host = ea->host;
+        g_connected_ipv4.port = ea->port;
+        memset(&g_connected_ipv6, 0, sizeof(struct sockaddr_in6));
+        g_connected_ipv6.sin6_family = AF_INET6;
+        TransportAddress addr(*ea);
+        // The ability to synthesize IPv6 addresses was added to getaddrinfo in iOS 9.2
+        struct addrinfo hints, *res;
+
+        memset(&hints, 0, sizeof hints);
+        hints.ai_family = AF_UNSPEC;
+        hints.ai_socktype = SOCK_STREAM;
+
+        // Resolve the stun server name so we can send it a STUN request
+        const std::string& ipv4 = addr.toString(false/*show_port*/);
+        int status = getaddrinfo(ipv4.c_str(), StringUtils::toString(ea->port).c_str(),
+            &hints, &res);
+        if (status != 0)
+        {
+            Log::error("STKHost", "Error in getaddrinfo for synthesizing ipv6"
+                       " %s: %s", ipv4.c_str(), gai_strerror(status));
+            return;
+        }
+        assert(res != NULL);
+        for (const struct addrinfo* addr = res; addr != NULL; addr = addr->ai_next)
+        {
+            if (addr->ai_family == AF_INET6)
+            {
+                struct sockaddr_in6* ipv6 = (struct sockaddr_in6*)addr->ai_addr;
+                g_connected_ipv6.sin6_addr = ipv6->sin6_addr;
+                // Workaround in iOS 9 where port is not written (fixed in iOS 10)
+                if (ipv6->sin6_port == 0)
+                    ipv6->sin6_port = htons(ea->port);
+                g_connected_ipv6.sin6_port = ipv6->sin6_port;
+                break;
+            }
+        }
+        freeaddrinfo(res);
+    }
+    memcpy(in6, &g_connected_ipv6, sizeof(struct sockaddr_in6));
+}
+
+bool sameIPV6(const struct in6_addr* a, const struct in6_addr* b)
+{
+    for (unsigned i = 0; i < sizeof(struct in6_addr); i++)
+    {
+        if (a->s6_addr[i] != b->s6_addr[i])
+            return false;
+    }
+    return true;
+}
+
+void getIPV4FromSynthesized(const struct sockaddr_in6* in6, ENetAddress* ea)
+{
+    if (sameIPV6(&(in6->sin6_addr), &(g_connected_ipv6.sin6_addr)) &&
+        in6->sin6_port == g_connected_ipv6.sin6_port)
+    {
+        ea->host = g_connected_ipv4.host;
+        ea->port = g_connected_ipv4.port;
+    }
+    else
+    {
+        ea->host = 0;
+        ea->port = 0;
+    }
+}
+
 #endif

src/network/ios_ipv6.hpp

@@ -15,11 +15,15 @@
 //  along with this program; if not, write to the Free Software
 //  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
+#include <enet/enet.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
-bool isIPV6Only();
+int isIPV6Only();
 void iOSInitialize();
+void getSynthesizedAddress(const ENetAddress* ea, struct sockaddr_in6* in6);
+void getIPV4FromSynthesized(const struct sockaddr_in6* in6, ENetAddress* ea);
 #ifdef __cplusplus
 }
 #endif

src/network/stk_host.cpp

@@ -23,6 +23,7 @@
 #include "io/file_manager.hpp"
 #include "network/event.hpp"
 #include "network/game_setup.hpp"
+#include "network/ios_ipv6.hpp"
 #include "network/network_config.hpp"
 #include "network/network_console.hpp"
 #include "network/network_player_profile.hpp"
@@ -369,6 +370,16 @@ void STKHost::shutdown()
  */
 void STKHost::setPublicAddress()
 {
+#ifdef IOS_STK
+    if (isIPV6Only())
+    {
+        // IPV6 only in iOS doesn't support connection to firewalled server,
+        // so no need to test STUN
+        Log::info("STKHost", "IPV6 only environment detected.");
+        m_public_address = TransportAddress("169.254.0.0:65535");
+        return;
+    }
+#endif
     std::vector<std::pair<std::string, uint32_t> > untried_server;
     for (auto& p : UserConfigParams::m_stun_servers)
         untried_server.push_back(p);