NetworkPkg: UefiPxeBcDxe: SECURITY PATCH CVE-2023-45234 Unit Tests

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4539

Unit tests to that the bug..

Buffer overflow when processing DNS Servers option in a DHCPv6 Advertise
message

..has been patched

This contains tests for the following functions:
PxeBcHandleDhcp6Offer
PxeBcCacheDnsServerAddresses

Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>

Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Saloni Kasbekar <saloni.kasbekar@intel.com>

NetworkPkg/UefiPxeBcDxe/GoogleTest/PxeBcDhcp6GoogleTest.h

@@ -0,0 +1,50 @@
+/** @file
+  This file exposes the internal interfaces which may be unit tested
+  for the PxeBcDhcp6Dxe driver.
+
+  Copyright (c) Microsoft Corporation.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef PXE_BC_DHCP6_GOOGLE_TEST_H_
+#define PXE_BC_DHCP6_GOOGLE_TEST_H_
+
+//
+// Minimal includes needed to compile
+//
+#include <Uefi.h>
+#include "../PxeBcImpl.h"
+
+/**
+  Handle the DHCPv6 offer packet.
+
+  @param[in]  Private             The pointer to PXEBC_PRIVATE_DATA.
+
+  @retval     EFI_SUCCESS           Handled the DHCPv6 offer packet successfully.
+  @retval     EFI_NO_RESPONSE       No response to the following request packet.
+  @retval     EFI_OUT_OF_RESOURCES  Failed to allocate resources.
+  @retval     EFI_BUFFER_TOO_SMALL  Can't cache the offer pacet.
+
+**/
+EFI_STATUS
+PxeBcHandleDhcp6Offer (
+  IN PXEBC_PRIVATE_DATA  *Private
+  );
+
+/**
+  Cache the DHCPv6 Server address
+
+  @param[in] Private               The pointer to PXEBC_PRIVATE_DATA.
+  @param[in] Cache6                The pointer to PXEBC_DHCP6_PACKET_CACHE.
+
+  @retval    EFI_SUCCESS           Cache the DHCPv6 Server address successfully.
+  @retval    EFI_OUT_OF_RESOURCES  Failed to allocate resources.
+  @retval    EFI_DEVICE_ERROR      Failed to cache the DHCPv6 Server address.
+**/
+EFI_STATUS
+PxeBcCacheDnsServerAddresses (
+  IN PXEBC_PRIVATE_DATA        *Private,
+  IN PXEBC_DHCP6_PACKET_CACHE  *Cache6
+  );
+
+#endif // PXE_BC_DHCP6_GOOGLE_TEST_H_