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Re: [libvirt] [PATCH[ nwfilter: Discard class D and E IP addresses when sniffing



On 08/13/2010 12:38 PM, Stefan Berger wrote:
>  When sniffing the network traffic, discard class D and E IP addresses
> when sniffing traffic. This was a reason why filters were not correctly
> rebuilt on VMs on the local 192.* network when libvirt was restarted and
> those VMs did not use a DHCP request to get its IP address.
> 
> Signed-off-by: Stefan Berger <stefanb us ibm com>
> 
> ---
>  src/nwfilter/nwfilter_learnipaddr.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> Index: libvirt-acl/src/nwfilter/nwfilter_learnipaddr.c
> ===================================================================
> --- libvirt-acl.orig/src/nwfilter/nwfilter_learnipaddr.c
> +++ libvirt-acl/src/nwfilter/nwfilter_learnipaddr.c
> @@ -546,9 +546,12 @@ learnIPAddressThread(void *arg)
>                      struct iphdr *iphdr = (struct iphdr*)(packet +
>                                                            ethHdrSize);
>                      vmaddr = iphdr->saddr;
> -                    // skip eth. bcast and mcast addresses,
> +                    // skip eth. bcast and mcast addresses (224.0.0.0 -
> +                    // 239.255.255.255), class E (255.*)
>                      // and zero address in DHCP Requests
> -                    if ((ntohl(vmaddr) & 0xc0000000) || vmaddr == 0) {
> +                    if ( (ntohl(vmaddr) & 0xe0000000) == 0xe0000000 ||

This line's fine for 224-239.*, but...

> +                         (ntohl(vmaddr) & 0xf0000000) == 0xf0000000 ||

shouldn't this be (ntohl(vmaddr) & 0xff000000) == 0xff000000, so that
you are not excluding 254.*?

ACK with that fix.

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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