Bug#537271: netcfg: new version of gateway reachability patch

[Robert Edmonds <edmonds@debian.org>]

Christian PERRIER wrote:
> To Robert: thanks for the patches and the finally fruitful discussion
> with Matthew (it started a little bit hot but you guys managed to
> handle it. That deserves applauses).

here is a new version of the patch.  this one makes the reachability
test conditional on !is_wireless_iface(), since wireless interfaces
don't have the 802.1d forwarding delay problem.

-- 
Robert Edmonds
edmonds@debian.org

diff -Npru netcfg-1.60.orig/netcfg-common.c netcfg-1.60/netcfg-common.c
--- netcfg-1.60.orig/netcfg-common.c	2011-02-05 20:42:06.000000000 -0500
+++ netcfg-1.60/netcfg-common.c	2011-02-08 21:14:29.855940300 -0500
@@ -1035,23 +1035,40 @@ void netcfg_update_entropy (void)
  */
 int netcfg_detect_link(struct debconfclient *client, const char *if_name)
 {
-    int wait_count, rv = 0;
+    char arping[256];
+    char s_gateway[INET_ADDRSTRLEN];
+    int count, rv = 0;
+    int link_waits = NETCFG_LINK_WAIT_TIME * 4;
+    int gw_tries = NETCFG_GATEWAY_REACHABILITY_TRIES;
+
+    if (gateway.s_addr) {
+        inet_ntop(AF_INET, &gateway, s_gateway, sizeof(s_gateway));
+        sprintf(arping, "arping -c 1 -w 1 -f -I %s %s", if_name, s_gateway);
+    }
     
     debconf_capb(client, "progresscancel");
     debconf_subst(client, "netcfg/link_detect_progress", "interface", if_name);
-    debconf_progress_start(client, 0, NETCFG_LINK_WAIT_TIME * 4, "netcfg/link_detect_progress");
-    for (wait_count = 0; wait_count < NETCFG_LINK_WAIT_TIME * 4; wait_count++) {
+    debconf_progress_start(client, 0, 100, "netcfg/link_detect_progress");
+    for (count = 0; count < link_waits; count++) {
         usleep(250000);
-        if (debconf_progress_step(client, 1) == 30) {
+        if (debconf_progress_set(client, 50 * count / link_waits) == 30) {
             /* User cancelled on us... bugger */
             rv = 0;
             break;
         }
-        if (ethtool_lite (if_name) == 1) /* ethtool-lite's CONNECTED */ {
-            debconf_progress_set(client, NETCFG_LINK_WAIT_TIME * 4);
+        if (ethtool_lite(if_name) == 1) /* ethtool-lite's CONNECTED */ {
+            if (gateway.s_addr && !is_wireless_iface(if_name)) {
+                for (count = 0; count < gw_tries; count++) {
+                    if (di_exec_shell_log(arping) == 0)
+                        break;
+                    if (debconf_progress_set(client, 50 + 50 * count / gw_tries) == 30)
+                        break;
+                }
+            }
             rv = 1;
             break;
         }
+        debconf_progress_set(client, 100);
     }
 
     debconf_progress_stop(client);
diff -Npru netcfg-1.60.orig/netcfg.h netcfg-1.60/netcfg.h
--- netcfg-1.60.orig/netcfg.h	2011-02-05 20:42:06.000000000 -0500
+++ netcfg-1.60/netcfg.h	2011-02-07 01:32:02.895935476 -0500
@@ -47,6 +47,11 @@
  */
 #define NETCFG_LINK_WAIT_TIME 3
 
+/* The number of times to attempt to verify gateway reachability.
+ * Each try invokes arping with a one second timeout.
+ */
+#define NETCFG_GATEWAY_REACHABILITY_TRIES 50
+
 #ifndef MAXHOSTNAMELEN
 #define MAXHOSTNAMELEN 63
 #endif