epmd: support IPv6 node registration

Allow IPv6 nodes to register with and query epmd. On systems with
IPv6 support:

* epmd listens on both the IPv4 and IPv6 ANY or loopback sockets

* the epmd cli client connects to epmd over the IPv6 loopback

* distributed nodes started with "-proto_dist inet6_tcp" will register
  with epmd over IPv6

To work on IPv6 capable systems that have IPv6 support disabled,
epmd ignores errors opening the socket if the protocol is not
supported. Similarly, the epmd client will fall back to IPv4 if the IPv6
socket is not available.

Update the minimum supported version of Windows to Windows Vista to
support IPv6.

1 files changed, 43 insertions, 20 deletions

diff --git a/erts/epmd/src/epmd_int.h b/erts/epmd/src/epmd_int.h
index 26100afc93..09317094c7 100644
--- a/erts/epmd/src/epmd_int.h
+++ b/erts/epmd/src/epmd_int.h
@@ -55,6 +55,7 @@
 #  ifndef WINDOWS_H_INCLUDES_WINSOCK2_H
 #    include <winsock2.h>
 #  endif
+#  include <ws2tcpip.h>
 #  include <windows.h>
 #  include <process.h>
 #endif
@@ -130,6 +131,10 @@
 #  include <systemd/sd-daemon.h>
 #endif /* HAVE_SYSTEMD_DAEMON */
 
+#if defined(HAVE_IN6) && defined(AF_INET6) && defined(HAVE_INET_PTON)
+#  define EPMD6
+#endif
+
 /* ************************************************************************ */
 /* Replace some functions by others by making the function name a macro */
 
@@ -183,33 +188,53 @@
 /* ************************************************************************ */
 /* Macros that let us use IPv6                                              */
 
-#if defined(HAVE_IN6) && defined(AF_INET6) && defined(EPMD6)
+#if HAVE_IN6
+#  if ! defined(HAVE_IN6ADDR_ANY) || ! HAVE_IN6ADDR_ANY
+#    if HAVE_DECL_IN6ADDR_ANY_INIT
+static const struct in6_addr in6addr_any = { { IN6ADDR_ANY_INIT } };
+#    else
+static const struct in6_addr in6addr_any =
+    { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } } };
+#    endif /* HAVE_IN6ADDR_ANY_INIT */
+#  endif /* ! HAVE_DECL_IN6ADDR_ANY */
+
+#  if ! defined(HAVE_IN6ADDR_LOOPBACK) || ! HAVE_IN6ADDR_LOOPBACK
+#    if HAVE_DECL_IN6ADDR_LOOPBACK_INIT
+static const struct in6_addr in6addr_loopback =
+    { { IN6ADDR_LOOPBACK_INIT } };
+#    else
+static const struct in6_addr in6addr_loopback =
+    { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 } } };
+#    endif /* HAVE_IN6ADDR_LOOPBACK_INIT */
+#  endif /* ! HAVE_DECL_IN6ADDR_LOOPBACK */
+#endif /* HAVE_IN6 */
+
+#define IS_ADDR_LOOPBACK(addr) ((addr).s_addr == htonl(INADDR_LOOPBACK))
+
+#if defined(EPMD6)
 
-#define EPMD_SOCKADDR_IN sockaddr_in6
-#define EPMD_IN_ADDR in6_addr
-#define EPMD_S_ADDR s6_addr
-#define EPMD_ADDR_LOOPBACK in6addr_loopback.s6_addr
-#define EPMD_ADDR_ANY in6addr_any.s6_addr
+#define EPMD_SOCKADDR_IN sockaddr_storage
 #define FAMILY AF_INET6
 
-#define SET_ADDR(dst, addr, port) do { \
-    memset((char*)&(dst), 0, sizeof(dst)); \
-    memcpy((char*)&(dst).sin6_addr.s6_addr, (char*)&(addr), 16); \
-    (dst).sin6_family = AF_INET6; \
-    (dst).sin6_flowinfo = 0; \
-    (dst).sin6_port = htons(port); \
+#define SET_ADDR6(dst, addr, port) do { \
+    struct sockaddr_in6 *sa = (struct sockaddr_in6 *)&(dst); \
+    memset(sa, 0, sizeof(dst)); \
+    sa->sin6_family = AF_INET6; \
+    sa->sin6_addr = (addr); \
+    sa->sin6_port = htons(port); \
  } while(0)
 
-#define IS_ADDR_LOOPBACK(addr) \
-    (memcmp((addr).s6_addr, in6addr_loopback.s6_addr, 16) == 0)
+#define SET_ADDR(dst, addr, port) do { \
+    struct sockaddr_in *sa = (struct sockaddr_in *)&(dst); \
+    memset(sa, 0, sizeof(dst)); \
+    sa->sin_family = AF_INET; \
+    sa->sin_addr.s_addr = (addr); \
+    sa->sin_port = htons(port); \
+ } while(0)
 
 #else /* Not IP v6 */
 
 #define EPMD_SOCKADDR_IN sockaddr_in
-#define EPMD_IN_ADDR in_addr
-#define EPMD_S_ADDR s_addr
-#define EPMD_ADDR_LOOPBACK htonl(INADDR_LOOPBACK)
-#define EPMD_ADDR_ANY htonl(INADDR_ANY)
 #define FAMILY AF_INET
 
 #define SET_ADDR(dst, addr, port) do { \
@@ -219,8 +244,6 @@
     (dst).sin_port = htons(port); \
  } while(0)
 
-#define IS_ADDR_LOOPBACK(addr) ((addr).s_addr == htonl(INADDR_LOOPBACK))
-
 #endif /* Not IP v6 */
 
 /* ************************************************************************ */