Patch for network-interface-{list,info}

[Alex Plotnick]

I noticed that the functions `network-interface-info' and
`network-interface-list' did not work on Darwin 6.8 (Mac OS X 10.2.8).
After some investigation, I determined that they probably would not work on
some other BSDs as well.  The following patch addresses some of the issues.

The use of ioctl(SIOCGIFCONF) to fetch the list of network interfaces is
prone to some interesting problems.  In particular, the size of the
returned structures (struct ifreq) is not constant on some systems (e.g.,
Darwin), making the buffer resizing and list iteration somewhat tricky.  My
patch fixes these errors, and the SIOCGIFCONF now works properly under both
GNU/Linux and Darwin.  However, it seems to be preferable to just use
getifaddrs() when available, as it's a much cleaner interface.  To my mind,
it's tempting to get rid of the SIOCGIFCONF code all together, but I've
left it in for now.

In the case of `network-interface-info', certain of the requested ioctl()s
are non-existent on Darwin (and, again, presumably on some other BSDs); in
particular, SIOCGIFNETMASK and SIOCGIFHWADDR.  I've got some code that
uses getifaddrs() to fetch all of this info (instead of doing separate
ioctl() calls), but have not included it in this patch.  If people think
this is the correct way to go, I'll send it on.  (For those that care: the
downside of this is the difference between the link-layer sockaddrs on BSD
(struct sockaddr_dl) and Linux (struct sockaddr_ll).)

Comments, suggestions, bug-fixes, and test reports are all welcome.

          -- Alex Plotnick


Index: configure.in
===================================================================
RCS file: /cvsroot/emacs/emacs/configure.in,v
retrieving revision 1.356
diff -u -r1.356 configure.in
--- configure.in        23 Sep 2003 12:39:44 -0000      1.356
+++ configure.in        16 Nov 2003 20:05:24 -0000
@@ -1516,7 +1516,9 @@
                [#include <time.h>])
 AC_CHECK_MEMBERS([struct ifreq.ifr_flags, struct ifreq.ifr_hwaddr, 
                  struct ifreq.ifr_netmask, struct ifreq.ifr_broadaddr,
-                 struct ifreq.ifr_addr], , ,[#include <net/if.h>])
+                 struct ifreq.ifr_addr], , ,[#include <sys/types.h>
+#include <sys/socket.h>
+#include <net/if.h>])
 
 dnl checks for compiler characteristics
 
@@ -2298,7 +2300,7 @@
 rename closedir mkdir rmdir sysinfo \
 random lrand48 bcopy bcmp logb frexp fmod rint cbrt ftime res_init setsid \
 strerror fpathconf select mktime euidaccess getpagesize tzset setlocale \
-utimes setrlimit setpgid getcwd getwd shutdown getaddrinfo \
+utimes setrlimit setpgid getcwd getwd shutdown getaddrinfo getifaddrs \
 __fpending mblen mbrlen mbsinit strsignal setitimer ualarm index rindex \
 sendto recvfrom getsockopt setsockopt getsockname getpeername \
 gai_strerror mkstemp getline getdelim mremap memmove fsync bzero \
Index: src/process.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/process.c,v
retrieving revision 1.416
diff -u -r1.416 process.c
--- src/process.c       27 Sep 2003 00:25:40 -0000      1.416
+++ src/process.c       16 Nov 2003 20:05:26 -0000
@@ -109,6 +109,10 @@
 #endif
 #endif
 
+#ifdef HAVE_GETIFADDRS
+#include <ifaddrs.h>
+#endif
+
 #ifdef IRIS
 #include <sys/sysmacros.h>     /* for "minor" */
 #endif /* not IRIS */
@@ -3353,7 +3357,7 @@
 
 #if defined(HAVE_SOCKETS) && defined(HAVE_NET_IF_H) && 
defined(HAVE_SYS_IOCTL_H)
 
-#ifdef SIOCGIFCONF
+#if defined(HAVE_GETIFADDRS) || defined(SIOCGIFCONF)
 DEFUN ("network-interface-list", Fnetwork_interface_list, 
Snetwork_interface_list, 0, 0, 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
@@ -3361,58 +3365,89 @@
 format; see the description of ADDRESS in `make-network-process'.  */)
      ()
 {
+  Lisp_Object res = Qnil;
+#ifdef HAVE_GETIFADDRS
+  struct ifaddrs *ifap, *ifa;
+
+  if (getifaddrs (&ifap) != 0)
+      return Qnil;
+
+  for (ifa = ifap; ifa != NULL; ifa = ifa->ifa_next)
+    {
+      char namebuf[sizeof (ifa->ifa_name) + 1];
+      if (ifa->ifa_addr->sa_family != AF_INET)
+       continue;
+      bcopy (ifa->ifa_name, namebuf, sizeof (ifa->ifa_name));
+      namebuf[sizeof (ifa->ifa_name)] = 0;
+      res = Fcons (Fcons (build_string (namebuf),
+                         conv_sockaddr_to_lisp (ifa->ifa_addr,
+                                               sizeof (struct sockaddr))),
+                  res);
+    }
+  freeifaddrs(ifap);
+
+#else /* defined(SIOCGIFCONF) */
   struct ifconf ifconf;
-  struct ifreq *ifreqs = NULL;
-  int ifaces = 0;
+  struct ifreq *ifrp, *ifend, *ifnext;
+  char *buf = NULL;
   int buf_size, s;
-  Lisp_Object res;
 
-  s = socket (AF_INET, SOCK_STREAM, 0);
+  s = socket (AF_INET, SOCK_DGRAM, 0);
   if (s < 0)
     return Qnil;
 
+  buf_size = 0;
  again:
-  ifaces += 25;
-  buf_size = ifaces * sizeof(ifreqs[0]);
-  ifreqs = (struct ifreq *)xrealloc(ifreqs, buf_size);
-  if (!ifreqs)
+  buf_size += 1024;
+  buf = (char *) xrealloc (buf, buf_size);
+  if (!buf)
     {
       close (s);
       return Qnil;
     }
 
   ifconf.ifc_len = buf_size;
-  ifconf.ifc_req = ifreqs;
-  if (ioctl (s, SIOCGIFCONF, &ifconf))
+  ifconf.ifc_buf = buf;
+  bzero (buf, buf_size);
+  if (ioctl (s, SIOCGIFCONF, &ifconf) == -1)
     {
       close (s);
+      xfree (buf);
       return Qnil;
     }
 
-  if (ifconf.ifc_len == buf_size)
+  if (buf_size - ifconf.ifc_len < sizeof (struct ifreq))
     goto again;
 
   close (s);
-  ifaces = ifconf.ifc_len / sizeof (ifreqs[0]);
 
-  res = Qnil;
-  while (--ifaces >= 0)
+#ifdef _SIZEOF_ADDR_IFREQ
+#define sizeof_ifreq(IFREQ) _SIZEOF_ADDR_IFREQ (IFREQ)
+#else
+#define sizeof_ifreq(IFREQ) sizeof (struct ifreq)
+#endif
+
+  ifrp = (struct ifreq *) buf;
+  ifend = (struct ifreq *)(buf + ifconf.ifc_len);
+  for ( ; ifrp < ifend; ifrp = ifnext)
     {
-      struct ifreq *ifq = &ifreqs[ifaces];
-      char namebuf[sizeof (ifq->ifr_name) + 1];
-      if (ifq->ifr_addr.sa_family != AF_INET)
+      ifnext = (struct ifreq *) ((char *) ifrp + sizeof_ifreq (*ifrp));
+      char namebuf[sizeof (ifrp->ifr_name) + 1];
+      if (ifrp->ifr_addr.sa_family != AF_INET)
        continue;
-      bcopy (ifq->ifr_name, namebuf, sizeof (ifq->ifr_name));
-      namebuf[sizeof (ifq->ifr_name)] = 0;
+      bcopy (ifrp->ifr_name, namebuf, sizeof (ifrp->ifr_name));
+      namebuf[sizeof (ifrp->ifr_name)] = 0;
       res = Fcons (Fcons (build_string (namebuf),
-                         conv_sockaddr_to_lisp (&ifq->ifr_addr,
+                         conv_sockaddr_to_lisp (&ifrp->ifr_addr,
                                                 sizeof (struct sockaddr))),
                   res);
     }
+  xfree (buf);
+#endif /* SIOCGIFCONF */
 
   return res;
 }
-#endif /* SIOCGIFCONF */
+#endif /* defined(HAVE_GETIFADDRS) || defined(SIOCGIFCONF) */
 
 #if defined(SIOCGIFADDR) || defined(SIOCGIFHWADDR) || defined(SIOCGIFFLAGS)
 
@@ -3473,6 +3508,29 @@
   { 0, 0 }
 };
 
+static Lisp_Object
+conv_ifflags_to_lisp (flags)
+     short int flags;
+{
+  Lisp_Object obj = Qnil;
+  struct ifflag_def *fp;
+  int fnum;
+
+  for (fp = ifflag_table; fp->flag_bit && fp->flag_sym; fp++)
+    {
+      if (flags & fp->flag_bit)
+       {
+         obj = Fcons (intern (fp->flag_sym), obj);
+         flags -= fp->flag_bit;
+       }
+    }
+  for (fnum = 0; flags && fnum < 16; fnum++)
+      if (flags & (1 << fnum))
+       obj = Fcons (make_number (fnum), obj);
+
+  return obj;
+}
+
 DEFUN ("network-interface-info", Fnetwork_interface_info, 
Snetwork_interface_info, 1, 1, 0,
        doc: /* Return information about network interface named IFNAME.
 The return value is a list (ADDR BCAST NETMASK HWADDR FLAGS),
@@ -3499,35 +3557,17 @@
 
   elt = Qnil;
 #if defined(SIOCGIFFLAGS) && defined(HAVE_STRUCT_IFREQ_IFR_FLAGS)
-  if (ioctl (s, SIOCGIFFLAGS, &rq) == 0)
+  if (ioctl (s, SIOCGIFFLAGS, &rq) != -1)
     {
-      int flags = rq.ifr_flags;
-      struct ifflag_def *fp;
-      int fnum;
-
       any++;
-      for (fp = ifflag_table; flags != 0 && fp; fp++)
-       {
-         if (flags & fp->flag_bit)
-           {
-             elt = Fcons (intern (fp->flag_sym), elt);
-             flags -= fp->flag_bit;
-           }
-       }
-      for (fnum = 0; flags && fnum < 32; fnum++)
-       {
-         if (flags & (1 << fnum))
-           {
-             elt = Fcons (make_number (fnum), elt);
-           }
-       }
+      elt = conv_ifflags_to_lisp (rq.ifr_flags);
     }
 #endif
   res = Fcons (elt, res);
 
   elt = Qnil;
 #if defined(SIOCGIFHWADDR) && defined(HAVE_STRUCT_IFREQ_IFR_HWADDR)
-  if (ioctl (s, SIOCGIFHWADDR, &rq) == 0)
+  if (ioctl (s, SIOCGIFHWADDR, &rq) != -1)
     {
       Lisp_Object hwaddr = Fmake_vector (make_number (6), Qnil);
       register struct Lisp_Vector *p = XVECTOR (hwaddr);
@@ -3543,7 +3583,7 @@
 
   elt = Qnil;
 #if defined(SIOCGIFNETMASK) && defined(ifr_netmask)
-  if (ioctl (s, SIOCGIFNETMASK, &rq) == 0)
+  if (ioctl (s, SIOCGIFNETMASK, &rq) != -1)
     {
       any++;
       elt = conv_sockaddr_to_lisp (&rq.ifr_netmask, sizeof (rq.ifr_netmask));
@@ -3553,7 +3593,7 @@
 
   elt = Qnil;
 #if defined(SIOCGIFBRDADDR) && defined(HAVE_STRUCT_IFREQ_IFR_BROADADDR)
-  if (ioctl (s, SIOCGIFBRDADDR, &rq) == 0)
+  if (ioctl (s, SIOCGIFBRDADDR, &rq) != -1)
     {
       any++;
       elt = conv_sockaddr_to_lisp (&rq.ifr_broadaddr, sizeof 
(rq.ifr_broadaddr));
@@ -3563,7 +3603,7 @@
 
   elt = Qnil;
 #if defined(SIOCGIFADDR) && defined(HAVE_STRUCT_IFREQ_IFR_ADDR)
-  if (ioctl (s, SIOCGIFADDR, &rq) == 0)
+  if (ioctl (s, SIOCGIFADDR, &rq) != -1)
     {
       any++;
       elt = conv_sockaddr_to_lisp (&rq.ifr_addr, sizeof (rq.ifr_addr));