404 lines
6.9 KiB
C
404 lines
6.9 KiB
C
/*++
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Copyright (c) 1996-2001 Microsoft Corporation
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Module Name:
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rrlist.c
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Abstract:
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Domain Name System (DNS) Library
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Record list manipulation.
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Author:
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Jim Gilroy (jamesg) January, 1997
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Environment:
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User Mode - Win32
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Revision History:
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--*/
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#include "local.h"
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PDNS_RECORD
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Dns_RecordSetDetach(
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IN OUT PDNS_RECORD pRR
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)
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/*++
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Routine Description:
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Detach first RR set from the rest of the list.
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Arguments:
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pRR - incoming record set
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Return Value:
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Ptr to first record of next RR set.
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NULL if at end of list.
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--*/
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{
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PDNS_RECORD prr = pRR;
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PDNS_RECORD pback; // previous RR in set
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WORD type; // first RR set type
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DWORD section; // section of first RR set
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if ( !prr )
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{
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return( NULL );
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}
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//
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// loop until find start of new RR set
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// - new type or
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// - new section or
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// - new name
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// note that NULL name is automatically considered
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// previous name
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//
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type = prr->wType;
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section = prr->Flags.S.Section;
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pback = prr;
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while ( prr = pback->pNext )
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{
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if ( prr->wType == type &&
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prr->Flags.S.Section == section &&
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( prr->pName == NULL ||
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Dns_NameComparePrivate(
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prr->pName,
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pback->pName,
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pback->Flags.S.CharSet ) ) )
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{
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pback = prr;
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continue;
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}
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// should not be detaching nameless record
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// - fixup for robustness
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if ( !prr->pName )
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{
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ASSERT( prr->pName );
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prr->pName = Dns_NameCopyAllocate(
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pRR->pName,
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0, // length unknown
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pRR->Flags.S.CharSet,
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prr->Flags.S.CharSet );
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SET_FREE_OWNER( prr );
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}
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break;
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}
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// have following RR set, NULL terminate first set
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if ( prr )
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{
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pback->pNext = NULL;
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}
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return( prr );
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}
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PDNS_RECORD
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WINAPI
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Dns_RecordListAppend(
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IN OUT PDNS_RECORD pHeadList,
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IN PDNS_RECORD pTailList
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)
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/*++
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Routine Description:
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Append record list onto another.
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Arguments:
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pHeadList -- record list to be head
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pTailList -- record list to append to pHeadList
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Return Value:
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Ptr to first record of combined RR set.
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- pHeadList UNLESS pHeadList is NULL,
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then it is pTailList.
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--*/
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{
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PDNS_RECORD prr = pHeadList;
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if ( !prr )
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{
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return pTailList;
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}
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// find end of first list and append second list
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while ( prr->pNext )
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{
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prr = prr->pNext;
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}
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// should be appending new set (with new name)
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// or matching previous set
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DNS_ASSERT( !pTailList || pTailList->pName ||
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(pTailList->wType == prr->wType &&
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pTailList->Flags.S.Section == prr->Flags.S.Section) );
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prr->pNext = pTailList;
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return pHeadList;
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}
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DWORD
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Dns_RecordListCount(
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IN PDNS_RECORD pRRList,
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IN WORD wType
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)
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/*++
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Routine Description:
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Count records in list.
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Arguments:
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pRRList - incoming record set
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Return Value:
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Count of records of given type in list.
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--*/
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{
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DWORD count = 0;
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//
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// loop counting all records that match
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// - either direct match
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// - or if matching type is ALL
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//
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while ( pRRList )
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{
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if ( pRRList->wType == wType ||
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wType == DNS_TYPE_ALL )
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{
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count++;
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}
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pRRList = pRRList->pNext;
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}
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return( count );
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}
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DWORD
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Dns_RecordListGetMinimumTtl(
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IN PDNS_RECORD pRRList
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)
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/*++
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Routine Description:
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Get minimum TTL of record list
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Arguments:
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pRRList - incoming record set
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Return Value:
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Minimum TTL of records in list.
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--*/
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{
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PDNS_RECORD prr = pRRList;
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DWORD minTtl = MAXDWORD;
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DNSDBG( TRACE, (
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"Dns_RecordListGetMinimumTtl( %p )\n",
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pRRList ));
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//
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// loop through list build minimum TTL
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//
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while ( prr )
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{
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if ( prr->dwTtl < minTtl )
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{
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minTtl = prr->dwTtl;
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}
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prr = prr->pNext;
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}
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return minTtl;
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}
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//
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// Record screening
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//
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BOOL
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Dns_ScreenRecord(
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IN PDNS_RECORD pRR,
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IN DWORD ScreenFlag
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)
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/*++
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Routine Description:
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Screen a record.
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Arguments:
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pRR - incoming record
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ScreenFlag - screeing flag
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Return Value:
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TRUE if passes screening.
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FALSE if record fails screen.
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--*/
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{
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BOOL fsave = TRUE;
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DNSDBG( TRACE, (
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"Dns_ScreenRecord( %p, %08x )\n",
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pRR,
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ScreenFlag ));
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// section screening
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if ( ScreenFlag & SCREEN_OUT_SECTION )
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{
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if ( IS_ANSWER_RR(pRR) )
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{
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fsave = !(ScreenFlag & SCREEN_OUT_ANSWER);
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}
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else if ( IS_AUTHORITY_RR(pRR) )
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{
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fsave = !(ScreenFlag & SCREEN_OUT_AUTHORITY);
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}
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else if ( IS_ADDITIONAL_RR(pRR) )
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{
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fsave = !(ScreenFlag & SCREEN_OUT_ADDITIONAL);
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}
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if ( !fsave )
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{
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return FALSE;
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}
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}
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// type screening
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if ( ScreenFlag & SCREEN_OUT_NON_RPC )
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{
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fsave = Dns_IsRpcRecordType( pRR->wType );
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}
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return fsave;
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}
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PDNS_RECORD
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Dns_RecordListScreen(
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IN PDNS_RECORD pRR,
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IN DWORD ScreenFlag
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)
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/*++
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Routine Description:
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Screen records from record set.
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Arguments:
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pRR - incoming record set
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ScreenFlag - flag with record screening parameters
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Return Value:
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Ptr to new record set, if successful.
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NULL on error.
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--*/
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{
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PDNS_RECORD prr;
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PDNS_RECORD pnext;
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DNS_RRSET rrset;
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DNSDBG( TRACE, (
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"Dns_RecordListScreen( %p, %08x )\n",
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pRR,
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ScreenFlag ));
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// init copy rrset
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DNS_RRSET_INIT( rrset );
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//
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// loop through RR list
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//
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pnext = pRR;
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while ( pnext )
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{
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prr = pnext;
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pnext = prr->pNext;
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//
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// screen
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// - reappend record passing screen
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// - delete record failing screen
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//
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if ( Dns_ScreenRecord( prr, ScreenFlag ) )
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{
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prr->pNext = NULL;
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DNS_RRSET_ADD( rrset, prr );
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continue;
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}
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else
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{
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Dns_RecordFree( prr );
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}
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}
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return( rrset.pFirstRR );
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}
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//
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// End rrlist.c
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//
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