ShellPkg: Update 'ifconfig -r' implementation

This patch is used to update ifconfig -r implementation
to sync with UEFI Shell 2.2.

option -r means to reconfigure all or specified interface,
and set DHCP policy. If specified interface is already set
to DHCP, then refresh the IPv4 configuration.

If the interface name is specified
with '-r', DHCP DORA process will be triggered by the policy
transition (static -> dhcp).

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Carsey Jaben <jaben.carsey@intel.com>
Cc: El-Haj-Mahmoud Samer <samer.el-haj-mahmoud@hpe.com>
Cc: Subramanian Sriram <sriram-s@hpe.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Sriram Subramanian <sriram-s@hpe.com>
Reviewed-by: Jaben Carsey <Jaben.carsey@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>

ShellPkg/Library/UefiShellNetwork1CommandsLib/Ifconfig.c

@@ -2,7 +2,7 @@
   The implementation for Shell command ifconfig based on IP4Config2 protocol.
 
   (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.<BR>
-  Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
 
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -710,6 +710,7 @@ IfConfigShowInterfaceInfo (
   The clean process of the ifconfig command to clear interface info.
 
   @param[in]   IfList    The pointer of IfList(interface list).
+  @param[in]   IfName    The pointer of interface name.
 
   @retval SHELL_SUCCESS  The ifconfig command clean processed successfully.
   @retval others         The ifconfig command clean process failed.
@@ -717,7 +718,8 @@ IfConfigShowInterfaceInfo (
 **/
 SHELL_STATUS
 IfConfigClearInterfaceInfo (
-  IN LIST_ENTRY    *IfList
+  IN LIST_ENTRY    *IfList,
+  IN CHAR16        *IfName
   )
 {
   EFI_STATUS                Status;  
@@ -727,7 +729,6 @@ IfConfigClearInterfaceInfo (
   IFCONFIG_INTERFACE_CB     *IfCb;
   EFI_IP4_CONFIG2_POLICY    Policy;
   
-  Policy = Ip4Config2PolicyDhcp;
   Status = EFI_SUCCESS;
   ShellStatus = SHELL_SUCCESS;
 
@@ -737,10 +738,30 @@ IfConfigClearInterfaceInfo (
 
   //
   // Go through the interface list.
+  // If the interface name is specified, DHCP DORA process will be 
+  // triggered by the policy transition (static -> dhcp).
   //
   NET_LIST_FOR_EACH_SAFE (Entry, Next, IfList) {
     IfCb = NET_LIST_USER_STRUCT (Entry, IFCONFIG_INTERFACE_CB, Link);
 
+    if ((IfName != NULL) && (StrCmp (IfName, IfCb->IfInfo->Name) == 0)) {
+      Policy = Ip4Config2PolicyStatic;
+      
+      Status = IfCb->IfCfg->SetData (
+                              IfCb->IfCfg,
+                              Ip4Config2DataTypePolicy,
+                              sizeof (EFI_IP4_CONFIG2_POLICY),
+                              &Policy
+                              );
+      if (EFI_ERROR (Status)) {
+        ShellPrintHiiEx (-1, -1, NULL, STRING_TOKEN (STR_GEN_ERR_AD), gShellNetwork1HiiHandle, L"ifconfig");
+        ShellStatus = SHELL_ACCESS_DENIED;
+        break;
+      }  
+    }
+
+    Policy = Ip4Config2PolicyDhcp;
+    
     Status = IfCb->IfCfg->SetData (
                             IfCb->IfCfg,
                             Ip4Config2DataTypePolicy,
@@ -1143,7 +1164,7 @@ IfConfig (
     break;
 
   case IfConfigOpClear:
-    ShellStatus = IfConfigClearInterfaceInfo (&Private->IfList);
+    ShellStatus = IfConfigClearInterfaceInfo (&Private->IfList, Private->IfName);
     break;
 
   case IfConfigOpSet: