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windows-nt/Source/XPSP1/NT/net/rras/ip/nathlp/dhcp/dhcpauto.cpp

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/*++
Copyright (c) 1998, Microsoft Corporation
Module Name:
dhcpauto.c
Abstract:
This module contains code for automatic selection of a client address
from a given scope of addresses.
It makes use of a hashing function which accounts for the client's
hardware address.
Author:
Abolade Gbadegesin (aboladeg) 9-Mar-1998
Revision History:
Raghu Gatta (rgatta) 5-Jul-2001
+Changed DhcpIsReservedAddress & DhcpQueryReservedAddress to
handle variable length name strings.
+Added DhcpConvertHostNametoUnicode (mimics DhcpServer effect)
Raghu Gatta (rgatta) 17-Jul-2001
+Added DhcpGetLocalMacAddr
--*/
#include "precomp.h"
#pragma hdrstop
ULONG
DhcpAcquireUniqueAddress(
PCHAR Name,
ULONG NameLength,
PUCHAR HardwareAddress,
ULONG HardwareAddressLength
)
/*++
Routine Description:
This routine is invoked to acquire a unique address for a client
using the given hardware address to decrease the likelihood of collision.
Arguments:
Name - the name of the host for whom the address is being requested.
If this matches the name of a server in the shared-access server-list,
the address reserved for the server is returned.
NameLength - length of 'Name', excluding any terminating 'nul'.
HardwareAddress - the hardware address to be used
HardwareAddressLength - the length of the hardware address
Return Value:
ULONG - the generated IP address
Environment:
Invoked from an arbitrary context.
--*/
{
ULONG AssignedAddress;
ULONG i = 0;
PLIST_ENTRY Link;
ULONG ScopeMask;
ULONG ScopeNetwork;
ULONG Seed = GetTickCount();
BOOLEAN bUnused;
PROFILE("DhcpAcquireUniqueAddress");
EnterCriticalSection(&DhcpGlobalInfoLock);
if (Name &&
(AssignedAddress = DhcpQueryReservedAddress(Name, NameLength))) {
LeaveCriticalSection(&DhcpGlobalInfoLock);
NhTrace(
TRACE_FLAG_DHCP,
"DhcpAcquireUniqueAddress: returning mapping to %s",
INET_NTOA(AssignedAddress)
);
return AssignedAddress;
}
ScopeNetwork = DhcpGlobalInfo->ScopeNetwork;
ScopeMask = DhcpGlobalInfo->ScopeMask;
LeaveCriticalSection(&DhcpGlobalInfoLock);
do {
if (++i > 4) { AssignedAddress = 0; break; }
//
// Generate an address
//
do {
AssignedAddress =
DhcpGenerateAddress(
&Seed,
HardwareAddress,
HardwareAddressLength,
ScopeNetwork,
ScopeMask
);
} while(
(AssignedAddress & ~ScopeMask) == 0 ||
(AssignedAddress & ~ScopeMask) == ~ScopeMask
);
} while(!DhcpIsUniqueAddress(AssignedAddress, &bUnused, NULL, NULL));
return AssignedAddress;
} // DhcpAcquireUniqueAddress
ULONG
DhcpGenerateAddress(
PULONG Seed,
PUCHAR HardwareAddress,
ULONG HardwareAddressLength,
ULONG ScopeNetwork,
ULONG ScopeMask
)
/*++
Routine Description:
This routine is invoked to compute a randomized hash value
for a client IP address using a hardware-address.
Arguments:
Seed - contains (and receives) the seed to 'RtlRandom'
HardwareAddress - the hardware address to be used
HardwareAddressLength - the length of the hardware address
ScopeNetwork - the network into which the generated address
will be constrained
ScopeMask - the mask for the scope network
Return Value:
ULONG - the generated IP address
Environment:
Invoked from an arbitrary context.
Revision History:
Based on 'GrandHashing' from net\sockets\tcpcmd\dhcpm\client\dhcp
by RameshV.
--*/
{
ULONG Hash;
ULONG Shift;
#if 1
Hash = RtlRandom(Seed) & 0xffff0000;
Hash |= RtlRandom(Seed) >> 16;
#else
Seed = GetTickCount();
Seed = Seed * 1103515245 + 12345;
Hash = (Seed) >> 16;
Hash <<= 16;
Seed = Seed * 1103515245 + 12345;
Hash += Seed >> 16;
#endif
Shift = Hash % sizeof(ULONG);
while(HardwareAddressLength--) {
Hash += (*HardwareAddress++) << (8 * Shift);
Shift = (Shift + 1) % sizeof(ULONG);
}
return (Hash & ~ScopeMask) | ScopeNetwork;
} // DnsGenerateAddress
BOOLEAN
DhcpIsReservedAddress(
ULONG Address,
PCHAR Name OPTIONAL,
ULONG NameLength OPTIONAL
)
/*++
Routine Description:
This routine is invoked to determine whether the given IP address
is reserved for another client.
Arguments:
Address - the IP address to be determined
Name - optionally specifies the client on whose behalf the call is made
NameLength - specifies the length of 'Name' excluding the terminating nul
Return Value:
BOOLEAN - TRUE if the address is reserved for another client,
FALSE otherwise.
Environment:
Invoked with 'DhcpGlobalInfoLock' held by the caller.
--*/
{
ULONG Error = NO_ERROR;
PLIST_ENTRY Link;
PNAT_DHCP_RESERVATION Reservation;
PWCHAR pszUnicodeHostName = NULL;
EnterCriticalSection(&NhLock);
if (IsListEmpty(&NhDhcpReservationList)) {
LeaveCriticalSection(&NhLock);
return FALSE;
}
if (Name) {
Error = DhcpConvertHostNametoUnicode(
CP_OEMCP, // atleast Windows clients send it this way
Name,
NameLength,
&pszUnicodeHostName
);
if (NO_ERROR != Error) {
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
//
// we can return true or false on failure
// better we return false - otherwise the client will be in a continuous
// loop trying to get another address when we NACK its request
//
return FALSE;
}
}
for (Link = NhDhcpReservationList.Flink;
Link != &NhDhcpReservationList; Link = Link->Flink) {
Reservation = CONTAINING_RECORD(Link, NAT_DHCP_RESERVATION, Link);
if (Address == Reservation->Address) {
if (lstrcmpiW(pszUnicodeHostName, Reservation->Name)) {
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return TRUE;
} else {
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return FALSE;
}
} else if (lstrcmpiW(pszUnicodeHostName, Reservation->Name) == 0 &&
Address != Reservation->Address) {
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return TRUE;
}
}
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return FALSE;
} // DhcpIsReservedAddress
BOOLEAN
DhcpIsUniqueAddress(
ULONG Address,
PBOOLEAN IsLocal,
PUCHAR ConflictAddress OPTIONAL,
PULONG ConflictAddressLength OPTIONAL
)
/*++
Routine Description:
This routine is invoked to determine whether the given address
is unique on the directly connected subnetworks.
The determination accounts for any configured static addresses
included in the global information.
Arguments:
Address - the address whose uniqueness is to be determined
IsLocal - pointer to BOOLEAN which receives info about whether
the requested address is one of the local interfaces' address
ConflictAddress - optionally receives a copy of the conflicting
hardware address if a conflict is found
ConflictAddressLength - if 'ConflictAddress' is set, receives
the length of the conflicting address.
Return Value:
BOOLEAN - TRUE if unique, FALSE otherwise.
--*/
{
BOOLEAN ConflictFound = FALSE;
ULONG Error;
UCHAR ExistingAddress[MAX_HARDWARE_ADDRESS_LENGTH];
ULONG ExistingAddressLength;
ULONG i;
PDHCP_INTERFACE Interfacep;
BOOLEAN IsNatInterface;
PLIST_ENTRY Link;
ULONG SourceAddress;
PROFILE("DhcpIsUniqueAddress");
*IsLocal = FALSE;
//
// See if this is a static address
//
EnterCriticalSection(&DhcpGlobalInfoLock);
if (DhcpGlobalInfo && DhcpGlobalInfo->ExclusionCount) {
for (i = 0; i < DhcpGlobalInfo->ExclusionCount; i++) {
if (Address == DhcpGlobalInfo->ExclusionArray[i]) {
LeaveCriticalSection(&DhcpGlobalInfoLock);
if (ConflictAddressLength) { *ConflictAddressLength = 0; }
return FALSE;
}
}
}
LeaveCriticalSection(&DhcpGlobalInfoLock);
//
// Try to detect collisions
//
EnterCriticalSection(&DhcpInterfaceLock);
for (Link = DhcpInterfaceList.Flink;
Link != &DhcpInterfaceList;
Link = Link->Flink
) {
Interfacep = CONTAINING_RECORD(Link, DHCP_INTERFACE, Link);
if (DHCP_INTERFACE_DELETED(Interfacep)) { continue; }
ACQUIRE_LOCK(Interfacep);
//
// We send out an ARP request unless
// (a) the interface is a boundary interface
// (b) the interface is not NAT-enabled
// (c) the allocator is not active on the interface
// (d) the interface is not a LAN adapter
// (e) the interface has no bindings.
//
if (!DHCP_INTERFACE_NAT_NONBOUNDARY(Interfacep) ||
!DHCP_INTERFACE_ACTIVE(Interfacep) ||
(Interfacep->Type != PERMANENT) ||
!Interfacep->BindingCount) {
RELEASE_LOCK(Interfacep);
continue;
}
for (i = 0; i < Interfacep->BindingCount; i++) {
SourceAddress = Interfacep->BindingArray[i].Address;
ExistingAddressLength = sizeof(ExistingAddress);
if (SourceAddress == Address)
{
//
// check to see that requested address is not same as
// one of the local addresses on the NAT box
//
NhTrace(
TRACE_FLAG_DHCP,
"DhcpIsUniqueAddress: %s is in use locally",
INET_NTOA(Address)
);
if (ConflictAddress) {
if (DhcpGetLocalMacAddr(
Address,
ExistingAddress,
&ExistingAddressLength
))
{
if (ExistingAddressLength > MAX_HARDWARE_ADDRESS_LENGTH) {
ExistingAddressLength = MAX_HARDWARE_ADDRESS_LENGTH;
}
CopyMemory(
ConflictAddress,
ExistingAddress,
ExistingAddressLength
);
*ConflictAddressLength = ExistingAddressLength;
}
else
{
*ConflictAddressLength = 0;
}
}
*IsLocal = TRUE;
ConflictFound = TRUE;
break;
}
RELEASE_LOCK(Interfacep);
Error =
SendARP(
Address,
SourceAddress,
(PULONG)ExistingAddress,
&ExistingAddressLength
);
ACQUIRE_LOCK(Interfacep);
if (Error) {
NhWarningLog(
IP_AUTO_DHCP_LOG_SENDARP_FAILED,
Error,
"%I%I",
Address,
SourceAddress
);
} else if (ExistingAddressLength &&
ExistingAddressLength <= sizeof(ExistingAddress)) {
NhTrace(
TRACE_FLAG_DHCP,
"DhcpIsUniqueAddress: %s is in use",
INET_NTOA(Address)
);
#if DBG
NhDump(
TRACE_FLAG_DHCP,
ExistingAddress,
ExistingAddressLength,
1
);
#endif
if (ConflictAddress) {
if (ExistingAddressLength > MAX_HARDWARE_ADDRESS_LENGTH) {
ExistingAddressLength = MAX_HARDWARE_ADDRESS_LENGTH;
}
CopyMemory(
ConflictAddress,
ExistingAddress,
ExistingAddressLength
);
*ConflictAddressLength = ExistingAddressLength;
}
ConflictFound = TRUE;
break;
}
}
RELEASE_LOCK(Interfacep);
if (ConflictFound) { break; }
}
LeaveCriticalSection(&DhcpInterfaceLock);
return ConflictFound ? FALSE : TRUE;
} // DhcpIsUniqueAddress
ULONG
DhcpQueryReservedAddress(
PCHAR Name,
ULONG NameLength
)
/*++
Routine Description:
This routine is called to determine whether the given machine name
corresponds to an entry in the list of reserved addresses.
Arguments:
Name - specifies the machine name, which might not be nul-terminated.
NameLength - specifies the length of the given machine name,
not including any terminating nul character.
Return Value:
ULONG - the IP address of the machine, if any.
Environment:
Invoked with 'DhcpGlobalInfoLock' held by the caller.
--*/
{
ULONG Error = NO_ERROR;
PLIST_ENTRY Link;
ULONG ReservedAddress;
PNAT_DHCP_RESERVATION Reservation;
PWCHAR pszUnicodeHostName = NULL;
EnterCriticalSection(&NhLock);
if (IsListEmpty(&NhDhcpReservationList))
{
LeaveCriticalSection(&NhLock);
return FALSE;
}
if (Name) {
Error = DhcpConvertHostNametoUnicode(
CP_OEMCP, // atleast Windows clients send it this way
Name,
NameLength,
&pszUnicodeHostName
);
if (NO_ERROR != Error) {
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return FALSE;
}
}
for (Link = NhDhcpReservationList.Flink;
Link != &NhDhcpReservationList; Link = Link->Flink)
{
Reservation = CONTAINING_RECORD(Link, NAT_DHCP_RESERVATION, Link);
if (lstrcmpiW(pszUnicodeHostName, Reservation->Name)) { continue; }
ReservedAddress = Reservation->Address;
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return ReservedAddress;
}
LeaveCriticalSection(&NhLock);
if (pszUnicodeHostName) {
NH_FREE(pszUnicodeHostName);
}
return 0;
} // DhcpQueryReservedAddress
//
// Utility routines
//
ULONG
DhcpConvertHostNametoUnicode(
UINT CodePage,
CHAR *pHostName,
ULONG HostNameLength,
PWCHAR *ppszUnicode
)
{
//
// make sure to free the returned Unicode hostname
//
DWORD dwSize = 0;
ULONG Error = NO_ERROR;
PCHAR pszHostName = NULL;
LPBYTE pszUtf8HostName = NULL; // copy of pszHostName in Utf8 format
PWCHAR pszUnicodeHostName = NULL;
if (ppszUnicode)
{
*ppszUnicode = NULL;
}
else
{
return ERROR_INVALID_PARAMETER;
}
do
{
//
// create a null terminated copy
//
dwSize = HostNameLength + 4;
pszHostName = reinterpret_cast<PCHAR>(NH_ALLOCATE(dwSize));
if (!pszHostName)
{
NhTrace(
TRACE_FLAG_DNS,
"DhcpConvertHostNametoUnicode: allocation failed for "
"hostname copy buffer"
);
break;
}
ZeroMemory(pszHostName, dwSize);
memcpy(pszHostName, pHostName, HostNameLength);
pszHostName[HostNameLength] = '\0';
//
// convert the given hostname to a Unicode string
//
if (CP_UTF8 == CodePage)
{
pszUtf8HostName = (LPBYTE)pszHostName;
}
else
{
//
// now convert this into UTF8 format
//
if (!ConvertToUtf8(
CodePage,
(LPSTR)pszHostName,
(PCHAR *)&pszUtf8HostName,
&dwSize))
{
Error = GetLastError();
NhTrace(
TRACE_FLAG_DNS,
"DhcpConvertHostNametoUnicode: conversion from "
"CodePage %d to UTF8 for hostname failed "
"with error %ld (0x%08x)",
CodePage,
Error,
Error
);
break;
}
}
//
// now convert UTF8 string into Unicode format
//
if (!ConvertUTF8ToUnicode(
pszUtf8HostName,
(LPWSTR *)&pszUnicodeHostName,
&dwSize))
{
Error = GetLastError();
NhTrace(
TRACE_FLAG_DNS,
"DhcpConvertHostNametoUnicode: conversion from "
"UTF8 to Unicode for hostname failed "
"with error %ld (0x%08x)",
Error,
Error
);
if (pszUnicodeHostName)
{
NH_FREE(pszUnicodeHostName);
}
break;
}
*ppszUnicode = pszUnicodeHostName;
NhTrace(
TRACE_FLAG_DNS,
"DhcpConvertHostNametoUnicode: succeeded! %S",
pszUnicodeHostName
);
} while (FALSE);
if (pszHostName)
{
NH_FREE(pszHostName);
}
if ((CP_UTF8 != CodePage) && pszUtf8HostName)
{
NH_FREE(pszUtf8HostName);
}
return Error;
} // DhcpConvertHostNametoUnicode
BOOL
DhcpGetLocalMacAddr(
ULONG Address,
PUCHAR MacAddr,
PULONG MacAddrLength
)
/*++
Routine Description:
This routine is invoked to determine the local physical MAC address
for the given local IP address.
Arguments:
Address - the local IP address
MacAddr - buffer for holding the MAC addr (upto MAX_HARDWARE_ADDRESS_LENGTH)
MacAddrLength - specifies the length of 'MacAddr'
Return Value:
BOOLEAN - TRUE if we are able to get the MAC address,
FALSE otherwise.
Environment:
Invoked from DhcpIsUniqueAddress().
--*/
{
BOOL bRet = FALSE;
DWORD Error = NO_ERROR;
PMIB_IPNETTABLE IpNetTable = NULL;
PMIB_IPNETROW IpNetRow = NULL;
DWORD dwPhysAddrLen = 0, i;
ULONG dwSize = 0;
do
{
//
// retrieve size of address mapping table
//
Error = GetIpNetTable(
IpNetTable,
&dwSize,
FALSE
);
if (!Error)
{
NhTrace(
TRACE_FLAG_DHCP,
"DhcpGetLocalMacAddr: should NOT have returned %d",
Error
);
break;
}
else
if (ERROR_INSUFFICIENT_BUFFER != Error)
{
NhTrace(
TRACE_FLAG_DHCP,
"DhcpGetLocalMacAddr: GetIpNetTable=%d",
Error
);
break;
}
//
// allocate a buffer
//
IpNetTable = (PMIB_IPNETTABLE)NH_ALLOCATE(dwSize);
if (!IpNetTable)
{
NhTrace(
TRACE_FLAG_DHCP,
"DhcpGetLocalMacAddr: error allocating %d bytes",
dwSize
);
break;
}
//
// retrieve the address mapping table
//
Error = GetIpNetTable(
IpNetTable,
&dwSize,
FALSE
);
if (NO_ERROR != Error)
{
NhTrace(
TRACE_FLAG_DHCP,
"DhcpGetLocalMacAddr: GetIpNetTable=%d size=%d",
Error,
dwSize
);
break;
}
for (i = 0; i < IpNetTable->dwNumEntries; i++)
{
IpNetRow = &IpNetTable->table[i];
if (IpNetRow->dwAddr == Address)
{
dwPhysAddrLen = IpNetRow->dwPhysAddrLen;
if (dwPhysAddrLen > MAX_HARDWARE_ADDRESS_LENGTH)
{
dwPhysAddrLen = MAX_HARDWARE_ADDRESS_LENGTH;
}
CopyMemory(
MacAddr,
IpNetRow->bPhysAddr,
dwPhysAddrLen
);
*MacAddrLength = dwPhysAddrLen;
bRet = TRUE;
break;
}
}
} while (FALSE);
if (IpNetTable)
{
NH_FREE(IpNetTable);
}
return bRet;
} // DhcpGetLocalMacAddr
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