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windows-nt/Source/XPSP1/NT/ds/dns/dnsapi/servlist.c

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/*++
Copyright (c) 1997-2001 Microsoft Corporation
Module Name:
servlist.c
Abstract:
Domain Name System (DNS) API
DNS network info routines.
Author:
Jim Gilroy (jamesg) January, 1997
Glenn Curtis (glennc) May, 1997
Revision History:
Jim Gilroy (jamesg) March 2000 slowly cleaning up
--*/
#include "local.h"
#include "registry.h" // Registry reading definitions
//
// Keep copy of DNS server/network info
//
#define CURRENT_ADAPTER_LIST_TIMEOUT (10) // 10 seconds
//
// Registry info
//
#define DNS_REG_READ_BUF_SIZE (1000)
#define LOCALHOST "127.0.0.1"
DNS_STATUS
ParseNameServerList(
IN OUT PIP_ARRAY aipServers,
IN LPSTR pBuffer,
IN BOOL IsMultiSzString
)
/*++
Routine Description:
Parse DNS server list from registry into IP address array.
Arguments:
aipServers -- IP array of DNS servers
pBuffer -- buffer with IP addresses in dotted format
IsMultiSzString -- Determines how to interpret data in buffer
Return Value:
ERROR_SUCCESS if successful.
Error code on failure.
--*/
{
DWORD stringLength;
LPSTR pstring;
DWORD cchBufferSize = 0;
CHAR ch;
PUCHAR pchIpString;
IP_ADDRESS ip;
DWORD countServers = aipServers->AddrCount;
DNSDBG( NETINFO, (
"Parsing name server list %s\n",
pBuffer ));
//
// MULTI_SZ string
//
// IPs are given as individual strings with double NULL termination
//
if ( IsMultiSzString )
{
pstring = pBuffer;
while ( ( stringLength = strlen( pstring ) ) != 0 &&
countServers < DNS_MAX_NAME_SERVERS )
{
ip = inet_addr( pstring );
if ( ip != INADDR_ANY && ip != INADDR_NONE )
{
aipServers->AddrArray[ countServers ] = ip;
countServers++;
}
pstring += (stringLength + 1);
}
}
else
{
//
// extract each IP string in buffer, convert to IP address,
// and add to server IP array
//
cchBufferSize = strlen( pBuffer );
while( ch = *pBuffer && countServers < DNS_MAX_NAME_SERVERS )
{
// skip leading whitespace, find start of IP string
while( cchBufferSize > 0 &&
( ch == ' ' || ch == '\t' || ch == ',' ) )
{
ch = *++pBuffer;
cchBufferSize--;
}
pchIpString = pBuffer;
//
// find end of string and NULL terminate
//
ch = *pBuffer;
while( cchBufferSize > 0 &&
( ch != ' ' && ch != '\t' && ch != '\0' && ch != ',' ) )
{
ch = *++pBuffer;
cchBufferSize--;
}
*pBuffer = '\0';
// at end of buffer
if ( pBuffer == pchIpString )
{
DNS_ASSERT( cchBufferSize == 1 || cchBufferSize == 0 );
break;
}
//
// get IP address for string
// - zero or broadcast addresses are bogus
//
ip = inet_addr( pchIpString );
if ( ip == INADDR_ANY || ip == INADDR_NONE )
{
break;
}
aipServers->AddrArray[ countServers ] = ip;
countServers++;
// if more continue
if ( cchBufferSize > 0 )
{
pBuffer++;
cchBufferSize--;
continue;
}
break;
}
}
// reset server count
aipServers->AddrCount = countServers;
if ( aipServers->AddrCount )
{
return( ERROR_SUCCESS );
}
else
{
return( DNS_ERROR_NO_DNS_SERVERS );
}
}
//
// Network info structure routines
//
#if 0
PSEARCH_LIST
Dns_GetDnsSearchList(
IN LPSTR pszPrimaryDomainName,
IN HKEY hKey,
IN PDNS_NETINFO pNetworkInfo,
IN BOOL fUseDomainNameDevolution,
IN BOOL fUseDotLocalDomain
)
/*++
Dumb stub because this function is exposed in dnslib.h
and in stmpdns\servlist.cpp in iis project
DCR: eliminate this routine (stupid)
--*/
{
return SearchList_Build(
pszPrimaryDomainName,
NULL, // no reg session
hKey,
pNetworkInfo,
fUseDomainNameDevolution,
fUseDotLocalDomain );
}
#endif
VOID
Dns_ResetNetworkInfo(
IN PDNS_NETINFO pNetworkInfo
)
/*++
Routine Description:
Clear the flags for each adapter.
Arguments:
pNetworkInfo -- pointer to a DNS network info structure.
Return Value:
Nothing
--*/
{
DWORD iter;
DNSDBG( TRACE, ( "Dns_ResetNetworkInfo()\n" ));
if ( ! pNetworkInfo )
{
return;
}
for ( iter = 0; iter < pNetworkInfo->AdapterCount; iter++ )
{
pNetworkInfo->AdapterArray[iter]->RunFlags = 0;
}
pNetworkInfo->ReturnFlags = 0;
}
BOOL
Dns_DisableTimedOutAdapters(
IN OUT PDNS_NETINFO pNetworkInfo
)
/*++
Routine Description:
For each adapter with status ERROR_TIMEOUT, disable it from
further retry queries till Dns_ResetNetworkInfo is called.
Arguments:
pNetworkInfo -- pointer to a DNS network info structure.
Return Value:
True if a timed out adapter was found and disabled
--*/
{
DWORD iter;
PDNS_ADAPTER padapter;
BOOL fSetAdapter = FALSE;
DNSDBG( TRACE, ( "Dns_DisableTimedOutAdapters()\n" ));
if ( ! pNetworkInfo )
{
return FALSE;
}
for ( iter = 0; iter < pNetworkInfo->AdapterCount; iter++ )
{
padapter = pNetworkInfo->AdapterArray[iter];
if ( padapter->Status == ERROR_TIMEOUT )
{
//
// See if the given adapters are really timing out or not.
//
// Sometimes a given name query will take a long time and
// we timeout waiting for the response, though the server
// will quicky respond to other name queries. Other times
// the default gateway doesn't let us reach the DNS servers
// on a given adapter, or they are plain dead.
//
// Pinging the given DNS servers to see if they can respond
// to a simple query helps to avoid the confusion.
//
if ( !Dns_PingAdapterServers( padapter ) )
{
padapter->RunFlags |= RUN_FLAG_IGNORE_ADAPTER;
padapter->RunFlags |= RUN_FLAG_RESET_SERVER_PRIORITY;
fSetAdapter = TRUE;
}
}
}
if ( fSetAdapter )
{
pNetworkInfo->ReturnFlags = RUN_FLAG_RESET_SERVER_PRIORITY;
}
return fSetAdapter;
}
BOOL
Dns_ShouldNameErrorBeCached(
IN PDNS_NETINFO pNetworkInfo
)
/*++
Routine Description:
This routine is used in conjuction with a given query's NAME_ERROR
response to see if the error was one that occured on all adapters.
This is used to decide if the name error response should be cached
or not. If the machine was multihomed, and one of the adapters had
a timeout error, then the name error should not be cached as a
negative response.
Arguments:
pNetworkInfo -- pointer to a DNS network info structure.
Return Value:
False if a timed out adapter was found, and name error should not
be negatively cached.
--*/
{
DWORD iter;
PDNS_ADAPTER padapter;
DNSDBG( TRACE, ( "Dns_DidNameErrorOccurEverywhere()\n" ));
if ( ! pNetworkInfo )
{
return TRUE;
}
if ( pNetworkInfo->ReturnFlags & RUN_FLAG_RESET_SERVER_PRIORITY )
{
for ( iter = 0; iter < pNetworkInfo->AdapterCount; iter++ )
{
padapter = pNetworkInfo->AdapterArray[iter];
if ( !( padapter->InfoFlags & DNS_FLAG_IGNORE_ADAPTER ) &&
padapter->Status == ERROR_TIMEOUT )
{
return FALSE;
}
}
}
return TRUE;
}
BOOL
Dns_PingAdapterServers(
IN PDNS_ADAPTER pAdapterInfo
)
//
// DCR: Dns_PingAdapterServers() is stupid
// why are we doing this?
//
{
BOOL fPing = TRUE;
PDNS_NETINFO pnetworkInfo = NULL;
PDNS_ADAPTER padapterCopy = NULL;
DNS_STATUS Status = NO_ERROR;
DNSDBG( TRACE, ( "Dns_PingAdapterServers()\n" ));
pnetworkInfo = NetInfo_Alloc( 1 );
if ( !pnetworkInfo )
{
return FALSE;
}
padapterCopy = AdapterInfo_Copy( pAdapterInfo );
if ( !padapterCopy )
{
NetInfo_Free( pnetworkInfo );
return FALSE;
}
padapterCopy->InfoFlags = DNS_FLAG_IS_AUTONET_ADAPTER;
NetInfo_AddAdapter(
pnetworkInfo,
padapterCopy );
//
// query adapter's DNS servers
// - query for loopback which always exists
//
Status = QueryDirectEx(
NULL, // no message
NULL, // no results
NULL, // no header
0, // no header counts
"1.0.0.127.in-addr.arpa.",
DNS_TYPE_PTR,
NULL, // no input records
DNS_QUERY_ACCEPT_PARTIAL_UDP |
DNS_QUERY_NO_RECURSION,
NULL, // no server list
pnetworkInfo );
NetInfo_Free( pnetworkInfo );
if ( Status == ERROR_TIMEOUT )
{
fPing = FALSE;
}
return fPing;
}
#if 0
//
// this is some stuff Glenn wrote for the case where you
// don't have a DNS server list and will get it through mcast
//
// it was in the middle of the NetworkInfo building routine
//
else
{
//
// DCR: functionalize multicast query attempt
//
//
// See if we can find a DNS server address to put on this
// adapter by multicasting for it . . .
//
// LevonE is still debating this method for
// server detection. If this is ultimately utilized, it
// might be better to direct the multicast query out the
// specific adapter IP address to try to get an address
// relevant to the specific adapter's network. This
// could be done by building a dummy pNetworkInfo
// parameter to pass down to Dns_QueryLib. The helper
// routine Dns_SendAndRecvMulticast could be revised to
// support specific adapter multicasting, etc.
PDNS_RECORD pServer = NULL;
status = Dns_QueryLib(
NULL,
&pServer,
(PDNS_NAME) MULTICAST_DNS_SRV_RECORD_NAME,
DNS_TYPE_SRV,
DNS_QUERY_MULTICAST_ONLY,
NULL,
NULL, // May want to specify network!
0 );
if ( status )
{
//
// This adapter is not going to have any configured
// DNS servers. No point trying any DNS queries on
// it then.
//
adapterFlags |= DNS_FLAG_IGNORE_ADAPTER;
}
else
{
if ( pServer &&
pServer->Flags.S.Section == DNSREC_ANSWER &&
pServer->wType == DNS_TYPE_SRV &&
pServer->Data.SRV.wPort == DNS_PORT_HOST_ORDER )
{
PDNS_RECORD pNext = pServer->pNext;
while ( pNext )
{
if ( pNext->Flags.S.Section == DNSREC_ADDITIONAL &&
pNext->wType == DNS_TYPE_A &&
Dns_NameCompare( pServer ->
Data.SRV.pNameTarget,
pNext->pName ) )
{
pserverIpArray->AddrCount = 1;
pserverIpArray->AddrArray[0] =
pNext->Data.A.IpAddress;
adapterFlags |= DNS_FLAG_AUTO_SERVER_DETECTED;
break;
}
pNext = pNext->pNext;
}
}
Dns_RecordListFree( pServer );
if ( pserverIpArray->AddrCount == 0 )
{
//
// This adapter is not going to have any configured
// DNS servers. No point trying any DNS queries on
// it then.
//
adapterFlags |= DNS_FLAG_IGNORE_ADAPTER;
}
}
}
#endif // multicast attempt
//
// End servlist.c
//
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