From 8c5f78a2cc15199e3f77ae4b156023af366fd6c7 Mon Sep 17 00:00:00 2001
From: Jiaxin Wu <jiaxin.wu@intel.com>
Date: Thu, 18 Aug 2016 13:31:07 +0800
Subject: [PATCH] MdeModulePkg: Support classless IP for DHCPv4
 TransmitReceive()

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>
Reviewed-by: Fu Siyuan <siyuan.fu@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 4f491b4bba..79f7cded8d 100644
--- a/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c
+++ b/MdeModulePkg/Universal/Network/Dhcp4Dxe/Dhcp4Impl.c
@@ -1,7 +1,7 @@
 /** @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
@@ -1188,6 +1188,7 @@ Dhcp4InstanceConfigUdpIo (
   )
 {
   DHCP_PROTOCOL                     *Instance;
+  DHCP_SERVICE                      *DhcpSb;
   EFI_DHCP4_TRANSMIT_RECEIVE_TOKEN  *Token;
   EFI_UDP4_CONFIG_DATA              UdpConfigData;
   IP4_ADDR                          ClientAddr;
@@ -1196,6 +1197,7 @@ Dhcp4InstanceConfigUdpIo (
   IP4_ADDR                          SubnetMask;
 
   Instance = (DHCP_PROTOCOL *) Context;
+  DhcpSb   = Instance->Service;
   Token    = Instance->Token;
 
   ZeroMem (&UdpConfigData, sizeof (EFI_UDP4_CONFIG_DATA));
@@ -1208,10 +1210,15 @@ Dhcp4InstanceConfigUdpIo (
   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));
 
@@ -1576,12 +1583,17 @@ EfiDhcp4TransmitReceive (
     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));