Hi All,
I have been looking into openslp code and i found a few changes that
might make things better in openslp. I dont have patches to share, but i will
create them if everyone here agrees.
- Multiple Binding Issue: I observed that, when the list of interfaces is not
specified in the config file, the slpd daemon reads all interface information
and binds to all address of all interfaces. I feel this is a overkill. When no
specific interfaces are given, its much easier to bind to :: or INADDR_ANY.
Proposal: In SLPDIncomingInit() function all the address are bound.
if (G_SlpdProperty.interfaces != NULL)
SLPIfaceGetInfo(G_SlpdProperty.interfaces, &ifaces, &G_SLPDProcInfo,
AF_UNSPEC);
else
ifaces.iface_count = 0;
When the interfaces are found to be NULL, we can assume that slpd must bind to
all inetfaces. So depending on the config file we have 3 cases.
Case 1: Only IPv4 enabled. We can create TCP/UDP sockets with INADDR_ANY.
Case 2: Only IPv6 enabled. We can create TCP/UDP sockets with ::
Case 3: Both IPv6 & IPv4 enabled. We can create sockets with :: but use
IPV6_V6ONLY option set.
This way we will have only 1 or 2 sockets listening instead of all. Improves
performance as well. My only doubt is how this works with Windows. Iam no
expert in that.
If the interfaces are specified then we do exactly what is done now. Is that ok
with everyone?
- Wrong Representation Of Interfaces In Config File: Although it looked at
first as a minor issue, this has caused multiple problems to basic
functionality. Openslp takes in ipaddress without the need for interface
information.
This leads to major issues. The function v6GetScope() is faulty function.
There can be cases when interfaces can have same ips. Eg:
eth2 Link encap:Ethernet HWaddr 00:06:29:55:60:81
inet6 addr: fe80::206:29ff:fe55:6081/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:4037 errors:0 dropped:0 overruns:0 frame:0
TX packets:134395 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:436006 (425.7 KiB) TX bytes:14655216 (13.9 MiB)
Interrupt:16 Base address:0x2200
eth2.30 Link encap:Ethernet HWaddr 00:06:29:55:60:81
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: 3001::1/128 Scope:Global
inet6 addr: fe80::206:29ff:fe55:6081/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:367 errors:0 dropped:0 overruns:0 frame:0
TX packets:15830 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:40872 (39.9 KiB) TX bytes:1650541 (1.5 MiB)
The LL address of both interfaces are same, In which case it becomes clear
viewing the v6GetScope() code that the scope id returned will be same for both
interface but in reality it is different. This results in binding to
only one interface. This is wrong. This has to be changed. This also is the
case with ips specified in the config file.
net.slp.interfaces = fe80::206:29ff:fe55:6081
There is no way of saying which interface this must bind to.
Proposal: The posix standard must be adopted to fix the issue. The interface
must be specified.
net.slp.interfaces = fe80::206:29ff:fe55:6081%eth2.30,2001::1%eth1,10.0.0.1%eth0
The <ip>%<iface> is standard posix method. This will greatly help in getting
the correct scopeid.
I have already looked into the code and made a temporary fix for the above
problem. But i want to rewrite that patch to make it better. If everyone is ok
with the above i will start working on it. Please reply back with any
issues. I have no windows programming knowledge, so if iam making a blunder
here, do let me know.
Regards,
Varun
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