* dhcp: don't bring down an interface to delete old addresses / route

  / ARP cache information, but just flush those using the ip command.
  Bringing down wireless interfaces causes wpa_supplicant to fail and
  never recover ("wpa_supplicant: l2_packet_receive - recvfrom:
  Network is down").  This made associating with a wireless network
  rather unreliable and timing-dependant.  It seems to work a lot
  better now.

svn path=/nixpkgs/trunk/; revision=17514

2 files changed, 86 insertions, 2 deletions

diff --git a/pkgs/tools/networking/dhcp/default.nix b/pkgs/tools/networking/dhcp/default.nix
index 15d06e9d42d..de6e08df7b6 100644
--- a/pkgs/tools/networking/dhcp/default.nix
+++ b/pkgs/tools/networking/dhcp/default.nix
@@ -8,6 +8,13 @@ stdenv.mkDerivation rec {
     sha256 = "0il966bcls7nfd93qfqrgvd2apkm0kv7pk35lnl1nvbm7fyrik7z";
   };
 
+  patches =
+    [ # Don't bring down interfaces, because wpa_supplicant doesn't
+      # recover when the wlan interface goes down.  Instead just flush
+      # all addresses, routes and neighbours of the interface.
+      ./flush-if.patch
+    ];
+
   # Fixes "socket.c:591: error: invalid application of 'sizeof' to
   # incomplete type 'struct in6_pktinfo'".  See
   # http://www.mail-archive.com/blfs-book@linuxfromscratch.org/msg13013.html
@@ -24,10 +31,11 @@ stdenv.mkDerivation rec {
         "${nettools}/bin:${nettools}/sbin:${iputils}/bin:${stdenv.coreutils}/bin:${stdenv.gnused}/bin"
     '';
 
-  preConfigure = ''
+  preConfigure =
+    ''
       sed -i "includes/dhcpd.h" \
 	-"es|^ *#define \+_PATH_DHCLIENT_SCRIPT.*$|#define _PATH_DHCLIENT_SCRIPT \"$out/sbin/dhclient-script\"|g"
-  '';
+    '';
 
   meta = {
     description = "Dynamic Host Configuration Protocol (DHCP) tools";
diff --git a/pkgs/tools/networking/dhcp/flush-if.patch b/pkgs/tools/networking/dhcp/flush-if.patch
new file mode 100644
index 00000000000..a6d914231ee
--- /dev/null
+++ b/pkgs/tools/networking/dhcp/flush-if.patch
@@ -0,0 +1,76 @@
+diff --exclude '*~' -rc dhcp-4.1.0p1-orig/client/scripts/linux dhcp-4.1.0p1/client/scripts/linux
+*** dhcp-4.1.0p1-orig/client/scripts/linux	2008-05-23 15:56:07.000000000 +0200
+--- dhcp-4.1.0p1/client/scripts/linux	2009-09-29 17:56:57.000000000 +0200
+***************
+*** 67,72 ****
+--- 67,80 ----
+    exit $exit_status
+  }
+  
++ # Delete the old addresses, routes and ARP information for this
++ # interface.
++ flush_if() {
++   ${ip} address flush dev $interface
++   ${ip} route flush dev $interface
++   ${ip} neighbour flush dev $interface
++ }
++ 
+  # Invoke the local dhcp client enter hooks, if they exist.
+  if [ -f /etc/dhclient-enter-hooks ]; then
+    exit_status=0
+***************
+*** 150,159 ****
+      ifconfig $interface:0- inet 0
+    fi
+    if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
+!     # IP address changed. Bringing down the interface will delete all routes,
+!     # and clear the ARP cache.
+!     ifconfig $interface inet 0 down
+! 
+    fi
+    if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
+       [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then
+--- 158,165 ----
+      ifconfig $interface:0- inet 0
+    fi
+    if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
+!     # IP address changed.
+!     flush_if
+    fi
+    if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
+       [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then
+***************
+*** 189,196 ****
+      ifconfig $interface:0- inet 0
+    fi
+    if [ x$old_ip_address != x ]; then
+!     # Shut down interface, which will delete routes and clear arp cache.
+!     ifconfig $interface inet 0 down
+    fi
+    if [ x$alias_ip_address != x ]; then
+      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
+--- 195,201 ----
+      ifconfig $interface:0- inet 0
+    fi
+    if [ x$old_ip_address != x ]; then
+!     flush_if
+    fi
+    if [ x$alias_ip_address != x ]; then
+      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
+***************
+*** 225,231 ****
+      make_resolv_conf
+      exit_with_hooks 0
+    fi
+!   ifconfig $interface inet 0 down
+    exit_with_hooks 1
+  fi
+  
+--- 230,236 ----
+      make_resolv_conf
+      exit_with_hooks 0
+    fi
+!   flush_if
+    exit_with_hooks 1
+  fi
+