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Merge pull request #1989 from hiura2023/master 

Fix Virtual DHCP Server: Correct DHCP Sequence
This commit is contained in:
Ilya Shipitsin 2024-05-04 20:47:48 +02:00 committed by GitHub
parent 99e277aa71 bcb896b178
commit 9378c341f7
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GPG Key ID: B5690EEEBB952194
1 changed files with 93 additions and 34 deletions
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127
src/Cedar/Virtual.c
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@ -9340,20 +9340,75 @@ UINT ServeDhcpDiscoverEx(VH *v, UCHAR *mac, UINT request_ip, bool is_static_ip)
return 0;
}
UINT ret = 0;
DHCP_LEASE *d = SearchDhcpLeaseByIp(v, request_ip);
if (d != NULL)
{
// The requested IP address is used already
return 0;
// If an entry for the same IP address already exists,
// check whether it is a request from the same MAC address
if (Cmp(mac, d->MacAddress, 6) == 0)
{
// Examine whether the specified IP address is within the range of assignment
if (Endian32(v->DhcpIpStart) > Endian32(request_ip) ||
Endian32(request_ip) > Endian32(v->DhcpIpEnd))
{
// Accept if within the range
ret = request_ip;
}
}
else {
// Duplicated IPV4 address found. The DHCP server replies to DHCPREQUEST with DHCP NAK.
char ipstr[MAX_HOST_NAME_LEN + 1] = { 0 };
char macstr[128] = { 0 };
IPToStr32(ipstr, sizeof(ipstr), request_ip);
BinToStr(macstr, sizeof(macstr), d->MacAddress, 6);
Debug("Virtual DHC Server: Duplicated IP address detected. Static IP: %s, Used by MAC:%s\n", ipstr, macstr);
return ret;
}
}
// For static IP, the requested IP address must NOT be within the range of the DHCP pool
if (Endian32(request_ip) < Endian32(v->DhcpIpStart) || Endian32(request_ip) > Endian32(v->DhcpIpEnd))
else
{
return request_ip;
// Examine whether the specified IP address is within the range of assignment
if (Endian32(v->DhcpIpStart) > Endian32(request_ip) ||
Endian32(request_ip) > Endian32(v->DhcpIpEnd))
{
// Accept if within the range
ret = request_ip;
}
else
{
// Propose an IP in the range since it's a Discover although It is out of range
}
}
if (ret == 0)
{
// If there is any entry with the same MAC address
// that are already registered, use it with priority
DHCP_LEASE *d = SearchDhcpLeaseByMac(v, mac);
if (d != NULL)
{
// Examine whether the found IP address is in the allocation region
if (Endian32(v->DhcpIpStart) > Endian32(d->IpAddress) ||
Endian32(d->IpAddress) > Endian32(v->DhcpIpEnd))
{
// Use the IP address if it's found within the range
ret = d->IpAddress;
}
}
}
if (ret == 0)
{
// For static IP, the requested IP address must NOT be within the range of the DHCP pool
if (Endian32(v->DhcpIpStart) > Endian32(request_ip) ||
Endian32(request_ip) > Endian32(v->DhcpIpEnd))
{
ret = request_ip;
}
}
return 0;
return ret;
}
// Take an appropriate IP addresses that can be assigned newly
@ -9710,36 +9765,40 @@ void VirtualDhcpServer(VH *v, PKT *p)
}
else
{
// There is no IP address that can be provided
DHCP_OPTION_LIST ret;
LIST *o;
Zero(&ret, sizeof(ret));
ret.Opcode = DHCP_NACK;
ret.ServerAddress = v->HostIP;
StrCpy(ret.DomainName, sizeof(ret.DomainName), v->DhcpDomain);
ret.SubnetMask = v->DhcpMask;
// Build the DHCP option
o = BuildDhcpOption(&ret);
if (o != NULL)
// Reply of DHCP_REQUEST must be either DHCP_ACK or DHCP_NAK.
if (opt->Opcode == DHCP_REQUEST)
{
BUF *b = BuildDhcpOptionsBuf(o);
if (b != NULL)
{
UINT dest_ip = p->L3.IPv4Header->SrcIP;
if (dest_ip == 0)
{
dest_ip = 0xffffffff;
}
// Transmission
VirtualDhcpSend(v, tran_id, dest_ip, Endian16(p->L4.UDPHeader->SrcPort),
ip, dhcp->ClientMacAddress, b, dhcp->HardwareType, dhcp->HardwareAddressSize);
// There is no IP address that can be provided
DHCP_OPTION_LIST ret;
LIST *o;
Zero(&ret, sizeof(ret));
// Release the memory
FreeBuf(b);
ret.Opcode = DHCP_NACK;
ret.ServerAddress = v->HostIP;
StrCpy(ret.DomainName, sizeof(ret.DomainName), v->DhcpDomain);
ret.SubnetMask = v->DhcpMask;
// Build the DHCP option
o = BuildDhcpOption(&ret);
if (o != NULL)
{
BUF *b = BuildDhcpOptionsBuf(o);
if (b != NULL)
{
UINT dest_ip = p->L3.IPv4Header->SrcIP;
if (dest_ip == 0)
{
dest_ip = 0xffffffff;
}
// Transmission
VirtualDhcpSend(v, tran_id, dest_ip, Endian16(p->L4.UDPHeader->SrcPort),
ip, dhcp->ClientMacAddress, b, dhcp->HardwareType, dhcp->HardwareAddressSize);
// Release the memory
FreeBuf(b);
}
FreeDhcpOptions(o);
}
FreeDhcpOptions(o);
}
}
}