Source code of Windows XP (NT5)
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/*++
Copyright (c) 1996-2001 Microsoft Corporation
Module Name:
rrlist.c
Abstract:
Domain Name System (DNS) Library
Record list manipulation.
Author:
Jim Gilroy (jamesg) January, 1997
Environment:
User Mode - Win32
Revision History:
--*/
#include "local.h"
PDNS_RECORD
Dns_RecordSetDetach(
IN OUT PDNS_RECORD pRR
)
/*++
Routine Description:
Detach first RR set from the rest of the list.
Arguments:
pRR - incoming record set
Return Value:
Ptr to first record of next RR set.
NULL if at end of list.
--*/
{
PDNS_RECORD prr = pRR;
PDNS_RECORD pback; // previous RR in set
WORD type; // first RR set type
DWORD section; // section of first RR set
if ( !prr )
{
return( NULL );
}
//
// loop until find start of new RR set
// - new type or
// - new section or
// - new name
// note that NULL name is automatically considered
// previous name
//
type = prr->wType;
section = prr->Flags.S.Section;
pback = prr;
while ( prr = pback->pNext )
{
if ( prr->wType == type &&
prr->Flags.S.Section == section &&
( prr->pName == NULL ||
Dns_NameComparePrivate(
prr->pName,
pback->pName,
pback->Flags.S.CharSet ) ) )
{
pback = prr;
continue;
}
// should not be detaching nameless record
// - fixup for robustness
if ( !prr->pName )
{
ASSERT( prr->pName );
prr->pName = Dns_NameCopyAllocate(
pRR->pName,
0, // length unknown
pRR->Flags.S.CharSet,
prr->Flags.S.CharSet );
SET_FREE_OWNER( prr );
}
break;
}
// have following RR set, NULL terminate first set
if ( prr )
{
pback->pNext = NULL;
}
return( prr );
}
PDNS_RECORD
WINAPI
Dns_RecordListAppend(
IN OUT PDNS_RECORD pHeadList,
IN PDNS_RECORD pTailList
)
/*++
Routine Description:
Append record list onto another.
Arguments:
pHeadList -- record list to be head
pTailList -- record list to append to pHeadList
Return Value:
Ptr to first record of combined RR set.
- pHeadList UNLESS pHeadList is NULL,
then it is pTailList.
--*/
{
PDNS_RECORD prr = pHeadList;
if ( !prr )
{
return pTailList;
}
// find end of first list and append second list
while ( prr->pNext )
{
prr = prr->pNext;
}
// should be appending new set (with new name)
// or matching previous set
DNS_ASSERT( !pTailList || pTailList->pName ||
(pTailList->wType == prr->wType &&
pTailList->Flags.S.Section == prr->Flags.S.Section) );
prr->pNext = pTailList;
return pHeadList;
}
DWORD
Dns_RecordListCount(
IN PDNS_RECORD pRRList,
IN WORD wType
)
/*++
Routine Description:
Count records in list.
Arguments:
pRRList - incoming record set
Return Value:
Count of records of given type in list.
--*/
{
DWORD count = 0;
//
// loop counting all records that match
// - either direct match
// - or if matching type is ALL
//
while ( pRRList )
{
if ( pRRList->wType == wType ||
wType == DNS_TYPE_ALL )
{
count++;
}
pRRList = pRRList->pNext;
}
return( count );
}
DWORD
Dns_RecordListGetMinimumTtl(
IN PDNS_RECORD pRRList
)
/*++
Routine Description:
Get minimum TTL of record list
Arguments:
pRRList - incoming record set
Return Value:
Minimum TTL of records in list.
--*/
{
PDNS_RECORD prr = pRRList;
DWORD minTtl = MAXDWORD;
DNSDBG( TRACE, (
"Dns_RecordListGetMinimumTtl( %p )\n",
pRRList ));
//
// loop through list build minimum TTL
//
while ( prr )
{
if ( prr->dwTtl < minTtl )
{
minTtl = prr->dwTtl;
}
prr = prr->pNext;
}
return minTtl;
}
//
// Record screening
//
BOOL
Dns_ScreenRecord(
IN PDNS_RECORD pRR,
IN DWORD ScreenFlag
)
/*++
Routine Description:
Screen a record.
Arguments:
pRR - incoming record
ScreenFlag - screeing flag
Return Value:
TRUE if passes screening.
FALSE if record fails screen.
--*/
{
BOOL fsave = TRUE;
DNSDBG( TRACE, (
"Dns_ScreenRecord( %p, %08x )\n",
pRR,
ScreenFlag ));
// section screening
if ( ScreenFlag & SCREEN_OUT_SECTION )
{
if ( IS_ANSWER_RR(pRR) )
{
fsave = !(ScreenFlag & SCREEN_OUT_ANSWER);
}
else if ( IS_AUTHORITY_RR(pRR) )
{
fsave = !(ScreenFlag & SCREEN_OUT_AUTHORITY);
}
else if ( IS_ADDITIONAL_RR(pRR) )
{
fsave = !(ScreenFlag & SCREEN_OUT_ADDITIONAL);
}
if ( !fsave )
{
return FALSE;
}
}
// type screening
if ( ScreenFlag & SCREEN_OUT_NON_RPC )
{
fsave = Dns_IsRpcRecordType( pRR->wType );
}
return fsave;
}
PDNS_RECORD
Dns_RecordListScreen(
IN PDNS_RECORD pRR,
IN DWORD ScreenFlag
)
/*++
Routine Description:
Screen records from record set.
Arguments:
pRR - incoming record set
ScreenFlag - flag with record screening parameters
Return Value:
Ptr to new record set, if successful.
NULL on error.
--*/
{
PDNS_RECORD prr;
PDNS_RECORD pnext;
DNS_RRSET rrset;
DNSDBG( TRACE, (
"Dns_RecordListScreen( %p, %08x )\n",
pRR,
ScreenFlag ));
// init copy rrset
DNS_RRSET_INIT( rrset );
//
// loop through RR list
//
pnext = pRR;
while ( pnext )
{
prr = pnext;
pnext = prr->pNext;
//
// screen
// - reappend record passing screen
// - delete record failing screen
//
if ( Dns_ScreenRecord( prr, ScreenFlag ) )
{
prr->pNext = NULL;
DNS_RRSET_ADD( rrset, prr );
continue;
}
else
{
Dns_RecordFree( prr );
}
}
return( rrset.pFirstRR );
}
//
// End rrlist.c
//