Merge branch 'SoftEtherVPN:master' into master

Fix memory access error when IPv6 prefix reading, should resolve #1972

src/Cedar/IPC.c

@@ -1517,7 +1517,9 @@ void IPCProcessL3EventsEx(IPC *ipc, UINT64 now)
 									// We save the router advertisement data for later use
 									IPCIPv6AddRouterPrefixes(ipc, &p->ICMPv6HeaderPacketInfo.OptionList, src_mac, &ip_src);
 									IPCIPv6AssociateOnNDTEx(ipc, &ip_src, src_mac, true);
+									if (p->ICMPv6HeaderPacketInfo.OptionList.SourceLinkLayer != NULL) {
 										IPCIPv6AssociateOnNDTEx(ipc, &ip_src, p->ICMPv6HeaderPacketInfo.OptionList.SourceLinkLayer->Address, true);
+									}
 									ndtProcessed = true;
 									header_size = sizeof(ICMPV6_ROUTER_ADVERTISEMENT_HEADER);
 									break;
@@ -2354,7 +2356,14 @@ void IPCIPv6AddRouterPrefixes(IPC *ipc, ICMPV6_OPTION_LIST *recvPrefix, UCHAR *m
 				IntToSubnetMask6(&newRA->RoutedMask, recvPrefix->Prefix[i]->SubnetLength);
 				CopyIP(&newRA->RouterAddress, ip);
 				Copy(newRA->RouterMacAddress, macAddress, 6);
+				if (recvPrefix->SourceLinkLayer != NULL)
+				{
 					Copy(newRA->RouterLinkLayerAddress, recvPrefix->SourceLinkLayer->Address, 6);
+				}
+				else
+				{
+					Zero(newRA->RouterLinkLayerAddress, 6);
+				}
 				Add(ipc->IPv6RouterAdvs, newRA);
 			}
 		}
@@ -2657,7 +2666,7 @@ void IPCIPv6SendUnicast(IPC *ipc, void *data, UINT size, IP *next_ip)
 		}
 
 		destMac = ra.RouterMacAddress;
-		if (!IsMacUnicast(destMac) && !IsMacInvalid(ra.RouterMacAddress))
+		if (!IsMacUnicast(destMac) && !IsMacInvalid(ra.RouterLinkLayerAddress))
 		{
 			destMac = ra.RouterLinkLayerAddress;
 		}

src/Cedar/Virtual.c

@@ -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;
-	}
-
-	// 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))
+		// 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)
 		{
-		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 {
+			// 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;
+		}
+	}
+	else
+	{
+		// 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