Extend network-interface-list to return IPv6 and network info

Bug#38218

* src/process.c (Fnetwork_interface_list): Extend argument list to
allow requesting full network info and/or IPv4/IPv6 info.
(network_interface_list) [HAVE_GETIFADDRS]: Use getifaddrs to retrieve
interface IP addresses.

* src/process.h: Update prototype of network_interface_list.

* src/w32.c (g_b_init_get_adapters_addresses): New init flag.
(globals_of_w32): Initialize it.
(GetAdaptersAddresses_Proc): New function typedef.
(get_adapters_addresses): New wrapper function.
(init_winsock): Load htonl and ntohl.
(sys_htonl, sys_ntohl): New wrapper functions.
(network_interface_list): Implement in terms of
get_adapters_addresses.

* nt/inc/sys/socket.h: Add sys_htonl and sys_ntohl prototypes.

* etc/NEWS: Announce IPv4/IPv6 changes in network-interface-list.

* doc/lispref/processes.texi (Misc Network): Document updated arglist
and return values for network-interface-list.

1 files changed, 100 insertions, 58 deletions

diff --git a/src/process.c b/src/process.c
index 9158cfd347c..0f82682ae5f 100644
--- a/src/process.c
+++ b/src/process.c
@@ -4255,73 +4255,86 @@ usage: (make-network-process &rest ARGS)  */)
 }
 
 
-#ifdef HAVE_NET_IF_H
 
-#ifdef SIOCGIFCONF
+#ifdef HAVE_GETIFADDRS
 static Lisp_Object
-network_interface_list (void)
+network_interface_list (bool full, unsigned short match)
 {
-  struct ifconf ifconf;
-  struct ifreq *ifreq;
-  void *buf = NULL;
-  ptrdiff_t buf_size = 512;
-  int s;
-  Lisp_Object res;
-  ptrdiff_t count;
+  Lisp_Object res = Qnil;
+  struct ifaddrs *ifap;
 
-  s = socket (AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
-  if (s < 0)
+  if (getifaddrs (&ifap) == -1)
     return Qnil;
-  count = SPECPDL_INDEX ();
-  record_unwind_protect_int (close_file_unwind, s);
 
-  do
+  for (struct ifaddrs *it = ifap; it != NULL; it = it->ifa_next)
     {
-      buf = xpalloc (buf, &buf_size, 1, INT_MAX, 1);
-      ifconf.ifc_buf = buf;
-      ifconf.ifc_len = buf_size;
-      if (ioctl (s, SIOCGIFCONF, &ifconf))
-        {
-          emacs_close (s);
-          xfree (buf);
-          return Qnil;
-        }
-    }
-  while (ifconf.ifc_len == buf_size);
-
-  res = unbind_to (count, Qnil);
-  ifreq = ifconf.ifc_req;
-  while ((char *) ifreq < (char *) ifconf.ifc_req + ifconf.ifc_len)
-    {
-      struct ifreq *ifq = ifreq;
-#ifdef HAVE_STRUCT_IFREQ_IFR_ADDR_SA_LEN
-#define SIZEOF_IFREQ(sif)                                               \
-      ((sif)->ifr_addr.sa_len < sizeof (struct sockaddr)                \
-       ? sizeof (*(sif)) : sizeof ((sif)->ifr_name) + (sif)->ifr_addr.sa_len)
+      int len;
+      int addr_len;
+      uint32_t *maskp;
+      uint32_t *addrp;
+      Lisp_Object elt = Qnil;
 
-      int len = SIZEOF_IFREQ (ifq);
-#else
-      int len = sizeof (*ifreq);
+      /* BSD can allegedly return interfaces with a NULL address.  */
+      if (it->ifa_addr == NULL)
+        continue;
+      if (match && it->ifa_addr->sa_family != match)
+        continue;
+      if (it->ifa_addr->sa_family == AF_INET)
+        {
+          DECLARE_POINTER_ALIAS (sin1, struct sockaddr_in, it->ifa_netmask);
+          maskp = (uint32_t *)&sin1->sin_addr;
+          DECLARE_POINTER_ALIAS (sin2, struct sockaddr_in, it->ifa_addr);
+          addrp = (uint32_t *)&sin2->sin_addr;
+          len = sizeof (struct sockaddr_in);
+          addr_len = 1;
+        }
+#ifdef AF_INET6
+      else if (it->ifa_addr->sa_family == AF_INET6)
+        {
+          DECLARE_POINTER_ALIAS (sin6_1, struct sockaddr_in6, it->ifa_netmask);
+          maskp = (uint32_t *) &sin6_1->sin6_addr;
+          DECLARE_POINTER_ALIAS (sin6_2, struct sockaddr_in6, it->ifa_addr);
+          addrp = (uint32_t *) &sin6_2->sin6_addr;
+          len = sizeof (struct sockaddr_in6);
+          addr_len = 4;
+        }
 #endif
-      char namebuf[sizeof (ifq->ifr_name) + 1];
-      ifreq = (struct ifreq *) ((char *) ifreq + len);
+      else
+        continue;
 
-      if (ifq->ifr_addr.sa_family != AF_INET)
-        continue;
+      Lisp_Object addr = conv_sockaddr_to_lisp (it->ifa_addr, len);
 
-      memcpy (namebuf, ifq->ifr_name, sizeof (ifq->ifr_name));
-      namebuf[sizeof (ifq->ifr_name)] = 0;
-      res = Fcons (Fcons (build_string (namebuf),
-                          conv_sockaddr_to_lisp (&ifq->ifr_addr,
-                                                 sizeof (struct sockaddr))),
-                   res);
+      if (full)
+        {
+          elt = Fcons (conv_sockaddr_to_lisp (it->ifa_netmask, len), elt);
+          /* There is an it->ifa_broadaddr field, but its contents are
+             unreliable, so always calculate the broadcast address from
+             the address and the netmask.  */
+          int i;
+          uint32_t mask;
+          for (i = 0; i < addr_len; i++)
+            {
+              mask = maskp[i];
+              maskp[i] = (addrp[i] & mask) | ~mask;
+            }
+          elt = Fcons (conv_sockaddr_to_lisp (it->ifa_netmask, len), elt);
+          elt = Fcons (addr, elt);
+        }
+      else
+        {
+          elt = addr;
+        }
+      res = Fcons (Fcons (build_string (it->ifa_name), elt), res);
     }
+#ifdef HAVE_FREEIFADDRS
+  freeifaddrs (ifap);
+#endif
 
-  xfree (buf);
   return res;
 }
-#endif /* SIOCGIFCONF */
+#endif  /* HAVE_GETIFADDRS */
 
+#ifdef HAVE_NET_IF_H
 #if defined (SIOCGIFADDR) || defined (SIOCGIFHWADDR) || defined (SIOCGIFFLAGS)
 
 struct ifflag_def {
@@ -4550,17 +4563,46 @@ network_interface_info (Lisp_Object ifname)
 #endif  /* defined (HAVE_NET_IF_H) */
 
 DEFUN ("network-interface-list", Fnetwork_interface_list,
-       Snetwork_interface_list, 0, 0, 0,
+       Snetwork_interface_list, 0, 2, 0,
        doc: /* Return an alist of all network interfaces and their network address.
-Each element is a cons, the car of which is a string containing the
-interface name, and the cdr is the network address in internal
-format; see the description of ADDRESS in `make-network-process'.
+Each element is cons of the form (IFNAME . IP) where IFNAME is a
+string containing the interface name, and IP is the network address in
+internal format; see the description of ADDRESS in
+`make-network-process'.  The interface name is not guaranteed to be
+unique.
+
+Optional parameter FULL non-nil means return all IP address info for
+each interface.  Each element is then a list of the form
+    (IFNAME IP BCAST MASK)
+where IFNAME is the interface name, IP the IP address,
+BCAST the broadcast address, and MASK the network mask.
+
+Optional parameter FAMILY controls the type of addresses to return.
+The default of nil means both IPv4 and IPv6, symbol `ipv4' means IPv4
+only, symbol `ipv6' means IPv6 only.
+
+See also `network-interface-info', which is limited to IPv4 only.
 
 If the information is not available, return nil.  */)
-  (void)
+  (Lisp_Object full, Lisp_Object family)
 {
-#if (defined HAVE_NET_IF_H && defined SIOCGIFCONF) || defined WINDOWSNT
-  return network_interface_list ();
+#if defined HAVE_GETIFADDRS || defined WINDOWSNT
+  unsigned short match;
+  bool full_info = false;
+
+  if (! NILP (full))
+    full_info = true;
+  if (NILP (family))
+    match = 0;
+  else if (EQ (family, Qipv4))
+    match = AF_INET;
+#ifdef AF_INET6
+  else if (EQ (family, Qipv6))
+    match = AF_INET6;
+#endif
+  else
+    error ("Unsupported address family");
+  return network_interface_list (full_info, match);
 #else
   return Qnil;
 #endif