<div class="content"><p> </p><p>The <b>R_DhcpEnumFilterV4</b> method enumerates all the
filter records from either allow list or deny list. It also returns a list of
hardware types presently exempted from filtering. These entries are present in
the allow list. Exemption entries have a pattern of <b>Length</b> 0 and <b>IsWildCard</b>
set to TRUE; both are specified in the <b>AddrPatt</b> field of the <span><a href="0b075377-a495-400d-9d8f-94141735ce60" data-linktype="relative-path">DHCP_FILTER_RECORD (section 2.2.1.2.92)</a></span>
structure.</p><dl>
<dd>
<div><pre> DWORD R_DhcpEnumFilterV4(
   [in, unique, string] DHCP_SRV_HANDLE ServerIpAddress,
   [in, out] LPDHCP_ADDR_PATTERN ResumeHandle,
   [in] DWORD PreferredMaximum,
   [in] DHCP_FILTER_LIST_TYPE ListType,
   [out] LPDHCP_FILTER_ENUM_INFO* EnumFilterInfo,
   [out] DWORD* ElementsRead,
   [out] DWORD* ElementsTotal
 );
</pre></div>
</dd></dl><p><b>ServerIpAddress: </b>The IP address/host name of
the DHCP server. This parameter is unused.</p><p><b>ResumeHandle: </b>This is a pointer of type <span><a href="a45ad236-6c42-42eb-9e67-c9335b61b7a7" data-linktype="relative-path">DHCP_ADDR_PATTERN (section 2.2.1.2.89)</a></span>
which identifies the enumeration operation. Initially, this value MUST be set
to zero, with a successful call returning the address/pattern value used for
subsequent enumeration requests.</p><p><b>PreferredMaximum: </b>This is of type <span><a href="../ms-dtyp/262627d8-3418-4627-9218-4ffe110850b2" data-linktype="relative-path">DWORD</a></span>
which specifies the preferred maximum number of bytes to return. If the number
of remaining unenumerated filter information size is less than this value, then
all the filters configured on the specific list on the DHCPv4 server are
returned. The maximum value for this is 64 kilobytes and the minimum value is 1
kilobyte. To retrieve all filter records, 0xFFFFFFFF is specified.</p><p><b>ListType: </b>This is of type <span><a href="0e19e8f5-c954-49dc-953d-79333debd863" data-linktype="relative-path">DHCP_FILTER_LIST_TYPE (section 2.2.1.1.17)</a></span>,
which specifies the list to be enumerated.</p><p><b>EnumFilterInfo: </b>This is a pointer of type <span><a href="2f1426c0-cd0f-4d0d-b66d-32851902928d" data-linktype="relative-path">LPDHCP_FILTER_ENUM_INFO</a></span>
that points to the location in which the link-layer filter info configured on
the DHCPv4 server is returned.</p><p><b>ElementsRead: </b>This is a pointer to a DWORD
value that specifies the number of link-layer filter entries returned in
EnumFilterInfo. The caller must allocate memory for this parameter that is
equal to the size of data type DWORD.</p><p><b>ElementsTotal: </b>This is a pointer to a DWORD
value that specifies the number of link-layer filter entries defined on the
DHCPv4 server that have not yet been enumerated with respect to the resume
handle that is returned. The caller must allocate memory for this parameter
that is equal to the size of data type DWORD.</p><p><b>Return Values: </b>A 32-bit unsigned integer value
that indicates return status. A return value ERROR_NO_MORE_ITEMS (0x00000103)
indicates that the operation was completed successfully. Otherwise, it contains
a Win32 error code, as specified in <span><a href="../ms-erref/1bc92ddf-b79e-413c-bbaa-99a5281a6c90" data-linktype="relative-path">[MS-ERREF]</a></span>.
This error code value can correspond to a DHCP-specific failure, which takes a
value between 20000 and 20099, or any generic failure.</p><dl>
<dd>
<table><thead>
  <tr>
   <th>
   <p>Return value/code</p>
   </th>
   <th>
   <p>Description</p>
   </th>
  </tr>
 </thead><tbody><tr>
  <td>
  <p>0x000000EA</p>
  <p>ERROR_MORE_DATA</p>
  </td>
  <td>
  <p>There are more elements available to enumerate.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x00000103</p>
  <p>ERROR_NO_MORE_ITEMS</p>
  </td>
  <td>
  <p>There are no more elements left to enumerate.</p>
  </td>
 </tr><tr>
  <td>
  <p>0x00004E2D</p>
  <p>ERROR_DHCP_JET_ERROR</p>
  </td>
  <td>
  <p>An error occurred while accessing the DHCP server
  database.</p>
  </td>
 </tr></tbody></table>
</dd></dl><p>The opnum field value for this method is 86.</p><p>When processing this call, the DHCP server MUST do the
following:</p><ul><li><p><span><span> 
</span></span>Validate whether this method is authorized for read access per
section <span><a href="baec2112-1146-4c42-b77e-b706e170a590" data-linktype="relative-path">3.5.4</a></span>. If not,
return error ERROR_ACCESS_DENIED.</p>
</li><li><p><span><span> 
</span></span>Retrieve all the <b>DHCPv4Filter</b> entries in which the <i>ListType</i>
field is equal to the <i>ListType</i> input parameter from the server ADM
element <b>DHCPv4FiltersList</b> and start enumerating from <i>ResumeHandle</i>
filter.</p>
</li><li><p><span><span> 
</span></span>If the <i>ResumeHandle</i> parameter points to 0x00000000, the
enumeration MUST start from the first entry in the retrieved list.</p>
</li><li><p><span><span> 
</span></span>If the <i>ResumeHandle</i> parameter points to a nonzero value,
the server MUST continue enumeration based on the value of <i>ResumeHandle</i>.
If the <i>ResumeHandle</i> is greater than the number of <b>DHCPv4Filter</b>
entries, then return ERROR_NO_MORE_ITEMS.</p>
</li><li><p><span><span> 
</span></span>The <i>PreferredMaximum</i> parameter specifies the maximum
number of bytes that the server can allocate and return to the caller
containing the data related to the configured link-layer filters.</p>
</li><li><p><span><span> 
</span></span>If <i>PreferredMaximum</i> is less than 1024, it is assigned
1024, and if <i>PreferredMaximum</i> is greater than 65536, it is assigned
65536.</p>
</li><li><p><span><span> 
</span></span>Allocate memory for <i>EnumFilterInfo</i> equal to the size of
structure DHCP_FILTER_ENUM_INFO.</p>
</li><li><p><span><span> 
</span></span>Copy the retrieved <b>DHCPv4Filter</b> entries in <i>EnumFilterInfo</i>,
copy the numbers of read <b>DHCPv4Filter</b> entries in <i>ElementsRead</i>,
and copy the numbers of <b>DHCPv4Filter</b> entries that have not been
enumerated in <i>ElementsTotal</i>. Update the <i>ResumeHandle</i> to the <b>AddrPatt</b>
field of the last <b>DHCPv4Filter</b> entry read. If the size of link-layer
filters to be enumerated exceeds <i>PreferredMaximum</i>, enumerate <b>DHCPv4Filter</b>
entries with total size less than or equal to <i>PreferredMaximum</i> and
return ERROR_MORE_DATA. If the size of <b>DHCPv4Filter</b> entries to be
enumerated is less than or equal to <i>PreferredMaximum</i>, enumerate all the <b>DHCPv4Filter</b>
entries and return ERROR_NO_MORE_ITEMS.</p>
</li></ul><p><b>Exceptions Thrown:</b> No exceptions are thrown beyond
those thrown by the underlying RPC protocol <span><a href="../ms-rpce/290c38b1-92fe-4229-91e6-4fc376610c15" data-linktype="relative-path">[MS-RPCE]</a></span>.</p></div>