[Patch] MdeModulePkg: Support classless IP for DHCPv4 TransmitReceive()

[Jiaxin Wu <jiaxin.wu@intel.com>]

The IP address should not be treated as classful one if DHCP options
contain a classless IP with its true subnet mask. Otherwise, DHCPv4
TransmitReceive() will failed. This real subnet mask will be parsed
and recorded in DhcpSb->Netmask. So, we need check it before get the
IP's corresponding subnet mask.

Cc: Santhapur Naveen <naveens@amiindia.co.in>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
---
 .../Universal/Network/Dhcp4Dxe/Dhcp4Impl.c         | 28 +++++++++++++++-------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c
index 4f491b4..79f7cde 100644
--- a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c
+++ b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c
@@ -1,9 +1,9 @@
 /** @file
   This file implement the EFI_DHCP4_PROTOCOL interface.
 
-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
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php
 
@@ -1186,18 +1186,20 @@ Dhcp4InstanceConfigUdpIo (
   IN UDP_IO       *UdpIo,
   IN VOID         *Context
   )
 {
   DHCP_PROTOCOL                     *Instance;
+  DHCP_SERVICE                      *DhcpSb;
   EFI_DHCP4_TRANSMIT_RECEIVE_TOKEN  *Token;
   EFI_UDP4_CONFIG_DATA              UdpConfigData;
   IP4_ADDR                          ClientAddr;
   IP4_ADDR                          Ip;   
   INTN                              Class; 
   IP4_ADDR                          SubnetMask;
 
   Instance = (DHCP_PROTOCOL *) Context;
+  DhcpSb   = Instance->Service;
   Token    = Instance->Token;
 
   ZeroMem (&UdpConfigData, sizeof (EFI_UDP4_CONFIG_DATA));
 
   UdpConfigData.AcceptBroadcast    = TRUE;
@@ -1206,14 +1208,19 @@ Dhcp4InstanceConfigUdpIo (
   UdpConfigData.DoNotFragment      = TRUE;
 
   ClientAddr = EFI_NTOHL (Token->Packet->Dhcp4.Header.ClientAddr);
   Ip = HTONL (ClientAddr);
   CopyMem (&UdpConfigData.StationAddress, &Ip, sizeof (EFI_IPv4_ADDRESS));
-  
-  Class = NetGetIpClass (ClientAddr);
-  ASSERT (Class < IP4_ADDR_CLASSE);
-  SubnetMask = gIp4AllMasks[Class << 3];
+
+  if (DhcpSb->Netmask == 0) {
+    Class = NetGetIpClass (ClientAddr);
+    ASSERT (Class < IP4_ADDR_CLASSE);
+    SubnetMask = gIp4AllMasks[Class << 3];
+  } else {
+    SubnetMask = DhcpSb->Netmask;
+  }
+
   Ip = HTONL (SubnetMask);
   CopyMem (&UdpConfigData.SubnetMask, &Ip, sizeof (EFI_IPv4_ADDRESS));
 
   if ((Token->ListenPointCount == 0) || (Token->ListenPoints[0].ListenPort == 0)) {
     UdpConfigData.StationPort = DHCP_CLIENT_PORT;
@@ -1574,16 +1581,21 @@ EfiDhcp4TransmitReceive (
     EndPoint.RemotePort = DHCP_SERVER_PORT;
   } else {
     EndPoint.RemotePort = Token->RemotePort;
   }
 
+  if (DhcpSb->Netmask == 0) {
+    Class = NetGetIpClass (ClientAddr);
+    ASSERT (Class < IP4_ADDR_CLASSE);
+    SubnetMask = gIp4AllMasks[Class << 3];
+  } else {
+    SubnetMask = DhcpSb->Netmask;
+  }
+  
   //
   // Get the gateway.
   //
-  Class = NetGetIpClass (ClientAddr);
-  ASSERT (Class < IP4_ADDR_CLASSE);
-  SubnetMask = gIp4AllMasks[Class << 3];
   ZeroMem (&Gateway, sizeof (Gateway));
   if (!IP4_NET_EQUAL (ClientAddr, EndPoint.RemoteAddr.Addr[0], SubnetMask)) {
     CopyMem (&Gateway.v4, &Token->GatewayAddress, sizeof (EFI_IPv4_ADDRESS));
     Gateway.Addr[0] = NTOHL (Gateway.Addr[0]);
   }
-- 
1.9.5.msysgit.1