Tweak the SIOCGIFCONF code once again.

diff --git a/common/discover.c b/common/discover.c
index 6c3c8d9145a2d7dba123076f2fd21784ece01dca..6619fb27396768417a0f45bfdcb98f6c2f9fe4a7 100644 (file)
--- a/common/discover.c
+++ b/common/discover.c
@@ -43,7 +43,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: discover.c,v 1.41 2001/04/09 01:03:12 mellon Exp $ Copyright (c) 1995-2001 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: discover.c,v 1.42 2001/05/02 06:36:54 mellon Exp $ Copyright (c) 1995-2001 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -159,8 +159,7 @@ void discover_interfaces (state)
 
        /* Get the interface configuration information... */
 
-#ifdef SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN
-
+#ifdef SIOCGIFCONF_ZERO_PROBE
        /* linux will only tell us how long a buffer it wants if we give it
         * a null buffer first. So, do a dry run to figure out the length.
         * 
@@ -171,24 +170,13 @@ void discover_interfaces (state)
 
        ic.ifc_len = 0;
        ic.ifc_ifcu.ifcu_buf = (caddr_t)NULL;
-
-       i = ioctl(sock, SIOCGIFCONF, &ic);
-       if (i < 0)
-               log_fatal ("ioctl: SIOCGIFCONF: %m");
-
-       ic.ifc_ifcu.ifcu_buf = dmalloc ((size_t)ic.ifc_len, MDL);
-       if (!ic.ifc_ifcu.ifcu_buf)
-               log_fatal ("Can't allocate SIOCGIFCONF buffer.");
-
-#else /* SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN */
-
+#else
        /* otherwise, we just feed it a starting size, and it'll tell us if
         * it needs more */
 
        ic.ifc_len = sizeof buf;
        ic.ifc_ifcu.ifcu_buf = (caddr_t)buf;
-
-#endif /* SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN */
+#endif
 
       gifconf_again:
        i = ioctl(sock, SIOCGIFCONF, &ic);
@@ -198,13 +186,23 @@ void discover_interfaces (state)
 
        /* If the SIOCGIFCONF resulted in more data than would fit in
           a buffer, allocate a bigger buffer. */
-       if (ic.ifc_ifcu.ifcu_buf == buf &&
-           ic.ifc_len > sizeof buf) {
+       if ((ic.ifc_ifcu.ifcu_buf == buf 
+#ifdef SIOCGIFCONF_ZERO_PROBE
+            || ic.ifc_ifcu.ifcu_buf == 0
+#endif
+               ) && ic.ifc_len > sizeof buf) {
                ic.ifc_ifcu.ifcu_buf = dmalloc ((size_t)ic.ifc_len, MDL);
                if (!ic.ifc_ifcu.ifcu_buf)
                        log_fatal ("Can't allocate SIOCGIFCONF buffer.");
                goto gifconf_again;
+#ifdef SIOCGIFCONF_ZERO_PROBE
+       } else if (ic.ifc_ifcu.ifcu_buf == 0) {
+               ic.ifc_ifcu.ifcu_buf = (caddr_t)buf;
+               if.ifc_len = sizeof buf;
+               goto gifconf_again;
+#endif
        }
+
                
        /* If we already have a list of interfaces, and we're running as
           a DHCP server, the interfaces were requested. */