[Patch 1/3] MdeModulePkg: Update NetLib interface to support classless addressing.

[Fu Siyuan <siyuan.fu@intel.com>]

The classful addressing (IP class A/B/C) has been deprecated according to
RFC4632. This patch updates the NetLib NetGetIpClass() and NetIp4IsUnicast()
accordingly.

NetGetIpClass()
The function is kept for compatibility, while the caller of this function
could only check the returned value against with IP4_ADDR_CLASSD (multicast)
or IP4_ADDR_CLASSE (reserved) now. The function has been updated to note this.

NetIp4IsUnicast()
The NetMask becomes a required parameter to check the unicast address.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Zhang Lubo <lubo.zhang@intel.com>
Cc: Wu Jiaxin <jiaxin.wu@intel.com>
---
 MdeModulePkg/Include/Library/NetLib.h      | 22 +++++++++++++---------
 MdeModulePkg/Library/DxeNetLib/DxeNetLib.c | 26 ++++++++++++--------------
 2 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/MdeModulePkg/Include/Library/NetLib.h b/MdeModulePkg/Include/Library/NetLib.h
index 87f393e..4c4f0bf 100644
--- a/MdeModulePkg/Include/Library/NetLib.h
+++ b/MdeModulePkg/Include/Library/NetLib.h
@@ -43,9 +43,9 @@ typedef UINT16          TCP_PORTNO;
 //
 // The address classification
 //
-#define  IP4_ADDR_CLASSA       1
-#define  IP4_ADDR_CLASSB       2
-#define  IP4_ADDR_CLASSC       3
+#define  IP4_ADDR_CLASSA       1     // Deprecated
+#define  IP4_ADDR_CLASSB       2     // Deprecated
+#define  IP4_ADDR_CLASSC       3     // Deprecated
 #define  IP4_ADDR_CLASSD       4
 #define  IP4_ADDR_CLASSE       5
 
@@ -379,6 +379,11 @@ NetGetMaskLength (
   Return the class of the IP address, such as class A, B, C.
   Addr is in host byte order.
 
+  [ATTENTION]
+  Classful addressing (IP class A/B/C) has been deprecated according to RFC4632.
+  Caller of this function could only check the returned value against
+  IP4_ADDR_CLASSD (multicast) or IP4_ADDR_CLASSE (reserved) now.
+
   The address of class A  starts with 0.
   If the address belong to class A, return IP4_ADDR_CLASSA.
   The address of class B  starts with 10.
@@ -404,17 +409,16 @@ NetGetIpClass (
 
 /**
   Check whether the IP is a valid unicast address according to
-  the netmask. If NetMask is zero, use the IP address's class to get the default mask.
+  the netmask. 
 
-  If Ip is 0, IP is not a valid unicast address.
-  Class D address is used for multicasting and class E address is reserved for future. If Ip
-  belongs to class D or class E, Ip is not a valid unicast address.
-  If all bits of the host address of Ip are 0 or 1, Ip is not a valid unicast address.
+  ASSERT if NetMask is zero.
+  
+  If all bits of the host address of IP are 0 or 1, IP is also not a valid unicast address.
 
   @param[in]  Ip                    The IP to check against.
   @param[in]  NetMask               The mask of the IP.
 
-  @return TRUE if Ip is a valid unicast address on the network, otherwise FALSE.
+  @return TRUE if IP is a valid unicast address on the network, otherwise FALSE.
 
 **/
 BOOLEAN
diff --git a/MdeModulePkg/Library/DxeNetLib/DxeNetLib.c b/MdeModulePkg/Library/DxeNetLib/DxeNetLib.c
index 7700f0ff..83a99e5 100644
--- a/MdeModulePkg/Library/DxeNetLib/DxeNetLib.c
+++ b/MdeModulePkg/Library/DxeNetLib/DxeNetLib.c
@@ -580,6 +580,11 @@ NetGetMaskLength (
   Return the class of the IP address, such as class A, B, C.
   Addr is in host byte order.
 
+  [ATTENTION]
+  Classful addressing (IP class A/B/C) has been deprecated according to RFC4632.
+  Caller of this function could only check the returned value against
+  IP4_ADDR_CLASSD (multicast) or IP4_ADDR_CLASSE (reserved) now.
+
   The address of class A  starts with 0.
   If the address belong to class A, return IP4_ADDR_CLASSA.
   The address of class B  starts with 10.
@@ -628,11 +633,10 @@ NetGetIpClass (
 
 /**
   Check whether the IP is a valid unicast address according to
-  the netmask. If NetMask is zero, use the IP address's class to get the default mask.
+  the netmask. 
 
-  If Ip is 0, IP is not a valid unicast address.
-  Class D address is used for multicasting and class E address is reserved for future. If Ip
-  belongs to class D or class E, IP is not a valid unicast address.
+  ASSERT if NetMask is zero.
+  
   If all bits of the host address of IP are 0 or 1, IP is also not a valid unicast address.
 
   @param[in]  Ip                    The IP to check against.
@@ -648,18 +652,12 @@ NetIp4IsUnicast (
   IN IP4_ADDR               NetMask
   )
 {
-  INTN                      Class;
-
-  Class = NetGetIpClass (Ip);
-
-  if ((Ip == 0) || (Class >= IP4_ADDR_CLASSD)) {
+  ASSERT (NetMask != 0);
+  
+  if (Ip == 0) {
     return FALSE;
   }
-
-  if (NetMask == 0) {
-    NetMask = gIp4AllMasks[Class << 3];
-  }
-
+  
   if (((Ip &~NetMask) == ~NetMask) || ((Ip &~NetMask) == 0)) {
     return FALSE;
   }
-- 
2.7.4.windows.1