ShellPkg/for: Fix potential null pointer deference

[mirror_edk2.git] / OvmfPkg / VirtioNetDxe / SnpMcastIpToMac.c

/** @file\r
\r
  Implementation of the SNP.McastIpToMac() function and its private helpers if\r
  any.\r
\r
  Copyright (C) 2013, Red Hat, Inc.\r
  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License which accompanies this\r
  distribution. The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
\r
**/\r
\r
#include <Library/UefiBootServicesTableLib.h>\r
\r
#include "VirtioNet.h"\r
\r
/**\r
  Converts a multicast IP address to a multicast HW MAC address.\r
\r
  @param  This The protocol instance pointer.\r
  @param  IPv6 Set to TRUE if the multicast IP address is IPv6 [RFC 2460]. Set\r
               to FALSE if the multicast IP address is IPv4 [RFC 791].\r
  @param  IP   The multicast IP address that is to be converted to a multicast\r
               HW MAC address.\r
  @param  MAC  The multicast HW MAC address that is to be generated from IP.\r
\r
  @retval EFI_SUCCESS           The multicast IP address was mapped to the\r
                                multicast HW MAC address.\r
  @retval EFI_NOT_STARTED       The network interface has not been started.\r
  @retval EFI_BUFFER_TOO_SMALL  The Statistics buffer was too small. The\r
                                current buffer size needed to hold the\r
                                statistics is returned in StatisticsSize.\r
  @retval EFI_INVALID_PARAMETER One or more of the parameters has an\r
                                unsupported value.\r
  @retval EFI_DEVICE_ERROR      The command could not be sent to the network\r
                                interface.\r
  @retval EFI_UNSUPPORTED       This function is not supported by the network\r
                                interface.\r
\r
**/\r
\r
EFI_STATUS\r
EFIAPI\r
VirtioNetMcastIpToMac (\r
  IN EFI_SIMPLE_NETWORK_PROTOCOL *This,\r
  IN BOOLEAN                     IPv6,\r
  IN EFI_IP_ADDRESS              *Ip,\r
  OUT EFI_MAC_ADDRESS            *Mac\r
  )\r
{\r
  VNET_DEV   *Dev;\r
  EFI_TPL    OldTpl;\r
  EFI_STATUS Status;\r
\r
  //\r
  // http://en.wikipedia.org/wiki/Multicast_address\r
  //\r
  if (This == NULL || Ip == NULL || Mac == NULL ||\r
      ( IPv6 && (Ip->v6.Addr[0]       ) != 0xFF) || // invalid IPv6 mcast addr\r
      (!IPv6 && (Ip->v4.Addr[0] & 0xF0) != 0xE0)    // invalid IPv4 mcast addr\r
      ) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  Dev = VIRTIO_NET_FROM_SNP (This);\r
  OldTpl = gBS->RaiseTPL (TPL_CALLBACK);\r
  switch (Dev->Snm.State) {\r
  case EfiSimpleNetworkStopped:\r
    Status = EFI_NOT_STARTED;\r
    goto Exit;\r
  case EfiSimpleNetworkStarted:\r
    Status = EFI_DEVICE_ERROR;\r
    goto Exit;\r
  default:\r
    break;\r
  }\r
\r
  //\r
  // http://en.wikipedia.org/wiki/IP_multicast#Layer_2_delivery\r
  //\r
  if (IPv6) {\r
    Mac->Addr[0] = 0x33;\r
    Mac->Addr[1] = 0x33;\r
    Mac->Addr[2] = Ip->v6.Addr[12];\r
    Mac->Addr[3] = Ip->v6.Addr[13];\r
    Mac->Addr[4] = Ip->v6.Addr[14];\r
    Mac->Addr[5] = Ip->v6.Addr[15];\r
  }\r
  else {\r
    Mac->Addr[0] = 0x01;\r
    Mac->Addr[1] = 0x00;\r
    Mac->Addr[2] = 0x5E;\r
    Mac->Addr[3] = Ip->v4.Addr[1] & 0x7F;\r
    Mac->Addr[4] = Ip->v4.Addr[2];\r
    Mac->Addr[5] = Ip->v4.Addr[3];\r
  }\r
  Status = EFI_SUCCESS;\r
\r
Exit:\r
  gBS->RestoreTPL (OldTpl);\r
  return Status;\r
}\r