examples: make udhcpc script handle /32 netmasks

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 25 insertions, 5 deletions

diff --git a/examples/udhcp/sample.bound b/examples/udhcp/sample.bound
index 7c9d857e0..efd98cf15 100755
--- a/examples/udhcp/sample.bound
+++ b/examples/udhcp/sample.bound
@@ -18,11 +18,18 @@ then
         metric=0
         for i in $router
         do
+                if [ "$subnet" = "255.255.255.255" ]; then
+                        # special case for /32 subnets:
+                        # /32 instructs kernel to always use routing for all outgoing packets
+                        # (they can never be sent to local subnet - there is no local subnet for /32).
+                        # Used in datacenters, avoids the need for private ip-addresses between two hops.
+                        /sbin/ip route add $i dev $interface
+                fi
                 /sbin/route add default gw $i dev $interface metric $((metric++))
         done
 fi
 
-# Only replace resolv.conf is we have at least one DNS server
+# Only replace resolv.conf if we have at least one DNS server
 if [ -n "$dns" ]
 then
         echo -n > $RESOLV_CONF
diff --git a/examples/udhcp/sample.renew b/examples/udhcp/sample.renew
index 4dce8486a..efd98cf15 100755
--- a/examples/udhcp/sample.renew
+++ b/examples/udhcp/sample.renew
@@ -1,5 +1,5 @@
 #!/bin/sh
-# Sample udhcpc bound script
+# Sample udhcpc renew script
 
 RESOLV_CONF="/etc/udhcpc/resolv.conf"
 
@@ -18,11 +18,18 @@ then
         metric=0
         for i in $router
         do
+                if [ "$subnet" = "255.255.255.255" ]; then
+                        # special case for /32 subnets:
+                        # /32 instructs kernel to always use routing for all outgoing packets
+                        # (they can never be sent to local subnet - there is no local subnet for /32).
+                        # Used in datacenters, avoids the need for private ip-addresses between two hops.
+                        /sbin/ip route add $i dev $interface
+                fi
                 /sbin/route add default gw $i dev $interface metric $((metric++))
         done
 fi
 
-# Only replace resolv.conf is we have at least one DNS server
+# Only replace resolv.conf if we have at least one DNS server
 if [ -n "$dns" ]
 then
         echo -n > $RESOLV_CONF
diff --git a/examples/udhcp/simple.script b/examples/udhcp/simple.script
index 2a917eb6c..e4c1f2d76 100755
--- a/examples/udhcp/simple.script
+++ b/examples/udhcp/simple.script
@@ -29,8 +29,14 @@ case "$1" in
                         metric=0
                         for i in $router ; do
                                 echo "Adding router $i"
-                                route add default gw $i dev $interface metric $metric
-                                : $(( metric += 1 ))
+                                if [ "$subnet" = "255.255.255.255" ]; then
+        # special case for /32 subnets:
+        # /32 instructs kernel to always use routing for all outgoing packets
+        # (they can never be sent to local subnet - there is no local subnet for /32).
+        # Used in datacenters, avoids the need for private ip-addresses between two hops.
+                                        ip route add $i dev $interface
+                                fi
+                                route add default gw $i dev $interface metric $((metric++))
                         done
                 fi