Probe for the availability of AF_INET6 at startup. If it's not

available, default ipv6cp to disabled and refuse to let the user
enable it.

usr.sbin/ppp/bundle.c

@@ -99,6 +99,7 @@
 #include "datalink.h"
 #include "iface.h"
 #include "server.h"
+#include "probe.h"
 #ifdef HAVE_DES
 #include "mppe.h"
 #endif
@@ -809,10 +810,12 @@ bundle_Create(const char *prefix, int type, int unit)
   *bundle.cfg.auth.name = '\0';
   *bundle.cfg.auth.key = '\0';
   bundle.cfg.opt = OPT_IDCHECK | OPT_LOOPBACK | OPT_SROUTES | OPT_TCPMSSFIXUP |
-#ifndef NOINET6
-                   OPT_IPCP | OPT_IPV6CP |
-#endif
                    OPT_THROUGHPUT | OPT_UTMP;
+#ifndef NOINET6
+  bundle.cfg.opt |= OPT_IPCP;
+  if (probe.ipv6_available)
+    bundle.cfg.opt |= OPT_IPV6CP;
+#endif
   *bundle.cfg.label = '\0';
   bundle.cfg.ifqueue = DEF_IFQUEUE;
   bundle.cfg.choked.timeout = CHOKED_TIMEOUT;

usr.sbin/ppp/command.c

@@ -101,6 +101,7 @@
 #include "datalink.h"
 #include "iface.h"
 #include "id.h"
+#include "probe.h"
 
 /* ``set'' values */
 #define	VAR_AUTHKEY	0
@@ -2573,13 +2574,19 @@ OptSet(struct cmdargs const *arg)
   unsigned keep;			/* Keep these bits */
   unsigned add;				/* Add these bits */
 
-  if ((cmd = ident_cmd(arg->argv[arg->argn-2], &keep, &add)) == NULL)
+  if (ident_cmd(arg->argv[arg->argn - 2], &keep, &add) == NULL)
     return 1;
 
+  if (add == NEG_ENABLED && bit == OPT_IPV6CP && !probe.ipv6_available) {
+    log_Printf(LogWARN, "IPv6 is not available on this machine\n");
+    return 1;
+  }
+
   if (add)
     arg->bundle->cfg.opt |= bit;
   else
     arg->bundle->cfg.opt &= ~bit;
+
   return 0;
 }
 

usr.sbin/ppp/main.c

@@ -304,6 +304,8 @@ main(int argc, char **argv)
   struct prompt *prompt;
   struct switches sw;
 
+  probe_Init();
+
   /*
    * We open 3 descriptors to ensure that STDIN_FILENO, STDOUT_FILENO and
    * STDERR_FILENO are always open.  These are closed before DoLoop(),
@@ -531,9 +533,6 @@ DoLoop(struct bundle *bundle)
 {
   fd_set *rfds, *wfds, *efds;
   int i, nfds, nothing_done;
-  struct probe probe;
-
-  probe_Init(&probe);
 
   if ((rfds = mkfdset()) == NULL) {
     log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");

usr.sbin/ppp/probe.c

@@ -27,11 +27,15 @@
  */
 
 #include <sys/time.h>
+#include <sys/socket.h>
+
 #include <unistd.h>
 
 #include "probe.h"
 #include "log.h"
 
+struct probe probe;
+
 /* Does select() alter the passed time value ? */
 static int
 select_changes_time(void)
@@ -44,10 +48,29 @@ select_changes_time(void)
   return t.tv_usec != 100000;
 }
 
-void
-probe_Init(struct probe *p)
+#ifndef NOINET6
+static int
+ipv6_available(void)
 {
-  p->select_changes_time = select_changes_time() ? 1 : 0;
-  log_Printf(LogDEBUG, "Select changes time: %s\n",
-             p->select_changes_time ? "yes" : "no");
+  int s;
+
+  if ((s = ID0socket(AF_INET6, SOCK_DGRAM, 0)) == -1)
+    return 0;
+
+  close(s);
+  return 1;
+}
+#endif
+
+void
+probe_Init()
+{
+  probe.select_changes_time = select_changes_time() ? 1 : 0;
+  log_Printf(LogDEBUG, "Select changes time: %s\n",
+             probe.select_changes_time ? "yes" : "no");
+#ifndef NOINET6
+  probe.ipv6_available = ipv6_available() ? 1 : 0;
+  log_Printf(LogDEBUG, "IPv6 available: %s\n",
+             probe.ipv6_available ? "yes" : "no");
+#endif
 }

usr.sbin/ppp/probe.h

@@ -28,6 +28,11 @@
 
 struct probe {
   unsigned select_changes_time : 1;
+#ifndef NOINET6
+  unsigned ipv6_available : 1;
+#endif
 };
 
-extern void probe_Init(struct probe *);
+extern struct probe probe;
+
+extern void probe_Init(void);