add compile time option to disable IPv6 support

include/libtorrent/config.hpp

@@ -84,6 +84,8 @@ POSSIBILITY OF SUCH DAMAGE.
 #define TORRENT_BSD
 #endif
 
+#define TORRENT_USE_IPV6 1
+
 // should wpath or path be used?
 #if defined UNICODE && !defined BOOST_FILESYSTEM_NARROW_ONLY \
 	&& BOOST_VERSION >= 103400 && !defined __APPLE__

include/libtorrent/policy.hpp

@@ -125,8 +125,14 @@ namespace libtorrent
 			size_type total_upload() const;
 
 			tcp::endpoint ip() const { return tcp::endpoint(addr, port); }
+
+#if TORRENT_USE_IPV6
 			void set_ip(tcp::endpoint const& endp)
 			{ addr = endp.address(); port = endp.port(); }
+#else
+			void set_ip(tcp::endpoint const& endp)
+			{ addr = endp.address().to_v4(); port = endp.port(); }
+#endif
 
 			// this is the accumulated amount of
 			// uploaded and downloaded data to this
@@ -141,7 +147,11 @@ namespace libtorrent
 			size_type prev_amount_download;
 
 			// the ip address this peer is or was connected on
+#if TORRENT_USE_IPV6
 			address addr;
+#else
+			address_v4 addr;
+#endif
 
 			// the time when this peer was optimistically unchoked
 			// the last time.

src/enum_net.cpp

@@ -91,6 +91,7 @@ namespace libtorrent { namespace
 		return address_v4(b);
 	}
 
+#if TORRENT_USE_IPV6
 	address inaddr6_to_address(in6_addr const* ina6)
 	{
 		typedef asio::ip::address_v6::bytes_type bytes_t;
@@ -98,13 +99,16 @@ namespace libtorrent { namespace
 		std::memcpy(&b[0], ina6, b.size());
 		return address_v6(b);
 	}
+#endif
 
 	address sockaddr_to_address(sockaddr const* sin)
 	{
 		if (sin->sa_family == AF_INET)
 			return inaddr_to_address(&((sockaddr_in const*)sin)->sin_addr);
+#if TORRENT_USE_IPV6
 		else if (sin->sa_family == AF_INET6)
 			return inaddr6_to_address(&((sockaddr_in6 const*)sin)->sin6_addr);
+#endif
 		return address();
 	}
 
@@ -192,7 +196,11 @@ namespace libtorrent { namespace
 		if (sa == 0
 			|| rti_info[RTAX_DST] == 0
 			|| rti_info[RTAX_NETMASK] == 0
-			|| (sa->sa_family != AF_INET && sa->sa_family != AF_INET6))
+			|| (sa->sa_family != AF_INET
+#if TORRENT_USE_IPV6
+				&& sa->sa_family != AF_INET6
+#endif
+				))
 			return false;
 
 		rt_info->gateway = sockaddr_to_address(rti_info[RTAX_GATEWAY]);
@@ -209,8 +217,11 @@ namespace libtorrent { namespace
 	{
 		return (sin->sin_len == sizeof(sockaddr_in)
 			&& sin->sin_family == AF_INET)
+#if TORRENT_USE_IPV6
 			|| (sin->sin_len == sizeof(sockaddr_in6)
-				&& sin->sin_family == AF_INET6);
+				&& sin->sin_family == AF_INET6)
+#endif
+			;
 	}
 #endif
 
@@ -274,7 +285,10 @@ namespace libtorrent
 			ifreq const& item = *reinterpret_cast<ifreq*>(ifr);
 
 			if (item.ifr_addr.sa_family == AF_INET
-				|| item.ifr_addr.sa_family == AF_INET6)
+#if TORRENT_USE_IPV6
+				|| item.ifr_addr.sa_family == AF_INET6
+#endif
+				)
 			{
 				ip_interface iface;
 				iface.interface_address = sockaddr_to_address(&item.ifr_addr);

src/policy.cpp

@@ -1183,7 +1183,11 @@ namespace libtorrent
 	policy::peer::peer(const tcp::endpoint& ip_, peer::connection_type t, int src)
 		: prev_amount_upload(0)
 		, prev_amount_download(0)
+#if TORRENT_USE_IPV6
 		, addr(ip_.address())
+#else
+		, addr(ip_.address().to_v4())
+#endif
 		, last_optimistically_unchoked(min_time())
 		, connected(min_time())
 		, connection(0)

src/session_impl.cpp

@@ -725,6 +725,7 @@ namespace aux {
 				async_accept(s.sock);
 			}
 
+#if TORRENT_USE_IPV6
 #ifdef TORRENT_WINDOWS
 			// only try to open the IPv6 port if IPv6 is installed
 			SOCKADDR_STORAGE storage;
@@ -746,6 +747,7 @@ namespace aux {
 #ifdef TORRENT_WINDOWS
 			}
 #endif
+#endif // TORRENT_USE_IPV6
 		}
 		else
 		{