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Merge PR #945: Virtual: fix race condition in DHCP server which resulted in multiple clients receiving the same IP

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Davide Beatrici 2019-07-15 09:23:09 +02:00 committed by GitHub
commit 9b20444bb2
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 113 additions and 20 deletions
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130
src/Cedar/Virtual.c
View File

@ -8956,8 +8956,8 @@ void FreeDhcpServer(VH *v)
return;
}
// Remove the all lease entries
for (i = 0;i < LIST_NUM(v->DhcpLeaseList);i++)
// Empty the leases lists
for (i = 0; i < LIST_NUM(v->DhcpLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpLeaseList, i);
FreeDhcpLease(d);
@ -8965,6 +8965,15 @@ void FreeDhcpServer(VH *v)
ReleaseList(v->DhcpLeaseList);
v->DhcpLeaseList = NULL;
for (i = 0; i < LIST_NUM(v->DhcpPendingLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpPendingLeaseList, i);
FreeDhcpLease(d);
}
ReleaseList(v->DhcpPendingLeaseList);
v->DhcpPendingLeaseList = NULL;
}
// Initialize the DHCP server
@ -8978,6 +8987,29 @@ void InitDhcpServer(VH *v)
// Create a list
v->DhcpLeaseList = NewList(CompareDhcpLeaseList);
v->DhcpPendingLeaseList = NewList(CompareDhcpLeaseList);
}
// Search for a pending DHCP lease item by the IP address
DHCP_LEASE *SearchDhcpPendingLeaseByIp(VH *v, UINT ip)
{
UINT i;
// Validate arguments
if (v == NULL)
{
return NULL;
}
for (i = 0; i < LIST_NUM(v->DhcpPendingLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpPendingLeaseList, i);
if (d->IpAddress == ip)
{
return d;
}
}
return NULL;
}
// Search for a DHCP lease item by the IP address
@ -8990,7 +9022,7 @@ DHCP_LEASE *SearchDhcpLeaseByIp(VH *v, UINT ip)
return NULL;
}
for (i = 0;i < LIST_NUM(v->DhcpLeaseList);i++)
for (i = 0; i < LIST_NUM(v->DhcpLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpLeaseList, i);
if (d->IpAddress == ip)
@ -9002,6 +9034,22 @@ DHCP_LEASE *SearchDhcpLeaseByIp(VH *v, UINT ip)
return NULL;
}
// Search for a pending DHCP lease item by the MAC address
DHCP_LEASE *SearchDhcpPendingLeaseByMac(VH *v, UCHAR *mac)
{
DHCP_LEASE *d, t;
// Validate arguments
if (v == NULL || mac == NULL)
{
return NULL;
}
Copy(&t.MacAddress, mac, 6);
d = Search(v->DhcpPendingLeaseList, &t);
return d;
}
// Search for a DHCP lease item by the MAC address
DHCP_LEASE *SearchDhcpLeaseByMac(VH *v, UCHAR *mac)
{
@ -9099,9 +9147,8 @@ void PollingDhcpServer(VH *v)
}
v->LastDhcpPolling = v->Now;
// Remove expired entries
FIRST_LIST:
for (i = 0;i < LIST_NUM(v->DhcpLeaseList);i++)
LIST_CLEANUP:
for (i = 0; i < LIST_NUM(v->DhcpLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpLeaseList, i);
@ -9109,7 +9156,21 @@ FIRST_LIST:
{
FreeDhcpLease(d);
Delete(v->DhcpLeaseList, d);
goto FIRST_LIST;
goto LIST_CLEANUP;
}
}
PENDING_LIST_CLEANUP:
// Remove expired entries
for (i = 0; i < LIST_NUM(v->DhcpPendingLeaseList); ++i)
{
DHCP_LEASE *d = LIST_DATA(v->DhcpPendingLeaseList, i);
if (d->ExpireTime < v->Now)
{
FreeDhcpLease(d);
Delete(v->DhcpPendingLeaseList, d);
goto PENDING_LIST_CLEANUP;
}
}
}
@ -9151,6 +9212,11 @@ UINT ServeDhcpDiscover(VH *v, UCHAR *mac, UINT request_ip)
{
// IP address is specified
DHCP_LEASE *d = SearchDhcpLeaseByIp(v, request_ip);
if (d == NULL)
{
d = SearchDhcpPendingLeaseByIp(v, request_ip);
}
if (d != NULL)
{
// If an entry for the same IP address already exists,
@ -9187,6 +9253,11 @@ UINT ServeDhcpDiscover(VH *v, UCHAR *mac, UINT request_ip)
// 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)
{
d = SearchDhcpPendingLeaseByMac(v, mac);
}
if (d != NULL)
{
// Examine whether the found IP address is in the allocation region
@ -9234,7 +9305,7 @@ UINT GetFreeDhcpIpAddress(VH *v)
for (i = ip_start; i <= ip_end;i++)
{
UINT ip = Endian32(i);
if (SearchDhcpLeaseByIp(v, ip) == NULL)
if (SearchDhcpLeaseByIp(v, ip) == NULL && SearchDhcpPendingLeaseByIp(v, ip) == NULL)
{
// A free IP address is found
return ip;
@ -9284,7 +9355,7 @@ UINT GetFreeDhcpIpAddressByRandom(VH *v, UCHAR *mac)
new_ip = Endian32(ip_start + (rand_int % (ip_end - ip_start + 1)));
if (SearchDhcpLeaseByIp(v, new_ip) == NULL)
if (SearchDhcpLeaseByIp(v, new_ip) == NULL && SearchDhcpPendingLeaseByIp(v, new_ip) == NULL)
{
// A free IP address is found
return new_ip;
@ -9401,8 +9472,9 @@ void VirtualDhcpServer(VH *v, PKT *p)
if (opt->Opcode == DHCP_REQUEST)
{
DHCP_LEASE *d;
char mac[MAX_SIZE];
char str[MAX_SIZE];
char client_mac[MAX_SIZE];
char client_ip[MAX_SIZE];
// Remove old records with the same IP address
d = SearchDhcpLeaseByIp(v, ip);
if (d != NULL)
@ -9411,17 +9483,22 @@ void VirtualDhcpServer(VH *v, PKT *p)
Delete(v->DhcpLeaseList, d);
}
d = SearchDhcpPendingLeaseByIp(v, ip);
if (d != NULL)
{
FreeDhcpLease(d);
Delete(v->DhcpPendingLeaseList, d);
}
// Create a new entry
d = NewDhcpLease(v->DhcpExpire, p->MacAddressSrc,
ip, v->DhcpMask,
opt->Hostname);
d = NewDhcpLease(v->DhcpExpire, p->MacAddressSrc, ip, v->DhcpMask, opt->Hostname);
d->Id = ++v->DhcpId;
Add(v->DhcpLeaseList, d);
MacToStr(mac, sizeof(mac), d->MacAddress);
IPToStr32(str, sizeof(str), d->IpAddress);
MacToStr(client_mac, sizeof(client_mac), d->MacAddress);
IPToStr32(client_ip, sizeof(client_ip), d->IpAddress);
NLog(v, "LH_NAT_DHCP_CREATED", d->Id, mac, str, d->Hostname, v->DhcpExpire / 1000);
NLog(v, "LH_NAT_DHCP_CREATED", d->Id, client_mac, client_ip, d->Hostname, v->DhcpExpire / 1000);
}
// Respond
@ -9510,12 +9587,25 @@ void VirtualDhcpServer(VH *v, PKT *p)
char client_mac[MAX_SIZE];
char client_ip[64];
IP ips;
BinToStr(client_mac, sizeof(client_mac), p->MacAddressSrc, 6);
UINTToIP(&ips, ip);
IPToStr(client_ip, sizeof(client_ip), &ips);
Debug("DHCP %s : %s given %s\n",
ret.Opcode == DHCP_OFFER ? "DHCP_OFFER" : "DHCP_ACK",
client_mac, client_ip);
if (ret.Opcode == DHCP_OFFER)
{
// DHCP_OFFER
DHCP_LEASE *d = NewDhcpLease(5000, p->MacAddressSrc, ip, v->DhcpMask, opt->Hostname);
d->Id = LIST_NUM(v->DhcpPendingLeaseList);
Add(v->DhcpPendingLeaseList, d);
Debug("VirtualDhcpServer(): %s has been marked as pending for %s\n", client_ip, client_mac);
}
else
{
// DHCP_ACK
Debug("VirtualDhcpServer(): %s has been assigned to %s\n", client_ip, client_mac);
}
}
// Build a DHCP option

3
src/Cedar/Virtual.h
View File

@ -296,6 +296,7 @@ struct VH
UINT DhcpDns2; // DNS server address 2
char DhcpDomain[MAX_HOST_NAME_LEN + 1]; // Assigned domain name
LIST *DhcpLeaseList; // DHCP lease list
LIST *DhcpPendingLeaseList; // Pending DHCP lease list
UINT64 LastDhcpPolling; // Time which the DHCP list polled last
bool SaveLog; // Save a log
DHCP_CLASSLESS_ROUTE_TABLE PushRoute; // Pushing routing table
@ -511,7 +512,9 @@ int CompareDhcpLeaseList(void *p1, void *p2);
DHCP_LEASE *NewDhcpLease(UINT expire, UCHAR *mac_address, UINT ip, UINT mask, char *hostname);
void FreeDhcpLease(DHCP_LEASE *d);
DHCP_LEASE *SearchDhcpLeaseByMac(VH *v, UCHAR *mac);
DHCP_LEASE *SearchDhcpPendingLeaseByMac(VH *v, UCHAR *mac);
DHCP_LEASE *SearchDhcpLeaseByIp(VH *v, UINT ip);
DHCP_LEASE *SearchDhcpPendingLeaseByIp(VH *v, UINT ip);
UINT ServeDhcpDiscover(VH *v, UCHAR *mac, UINT request_ip);
UINT GetFreeDhcpIpAddress(VH *v);
UINT GetFreeDhcpIpAddressByRandom(VH *v, UCHAR *mac);