[libvirt] [PATCH v5] network: bridge: Don't start network if it collides with host routing
Cole Robinson
crobinso at redhat.com
Thu May 27 22:07:23 UTC 2010
On 05/27/2010 05:09 PM, Jim Meyering wrote:
> Cole Robinson wrote:
>> Fedora bug https://bugzilla.redhat.com/show_bug.cgi?id=235961
>>
>> If using the default virtual network, an easy way to lose guest network
>> connectivity is to install libvirt inside the VM. The autostarted
>> default network inside the guest collides with host virtual network
>> routing. This is a long standing issue that has caused users quite a
>> bit of pain and confusion.
>>
>> On network startup, parse /proc/net/route and compare the requested
>> IP+netmask against host routing destinations: if any matches are found,
>> refuse to start the network.
>>
>> v2: Drop sscanf, fix a comment typo, comment that function could use
>> libnl instead of /proc
>>
>> v3: Consider route netmask. Compare binary data rather than convert to
>> string.
>>
>> v4: Return to using sscanf, drop inet functions in favor of virSocket,
>> parsing safety checks. Don't make parse failures fatal, in case
>> expected format changes.
>>
>> v5: Try and continue if we receive unexpected. Delimit parsed lines to
>> prevent scanning past newline
> ...
>> + while (cur) {
>> + char iface[17], dest[128], mask[128];
>> + unsigned int addr_val, mask_val;
>> + int num;
>> +
>> + /* NUL-terminate the line, so sscanf doesn't go beyond a newline. */
>> + char *nl = strchr(cur, '\n');
>> + if (nl) {
>> + *nl++ = '\0';
>> + }
>> +
>> + num = sscanf(cur, "%16s %127s %*s %*s %*s %*s %*s %127s",
>> + iface, dest, mask);
>> + cur = nl;
>
> Glad you incremented nl above and hoisted the "cur" update to here.
>
> ACK.
Thanks, I've pushed this now.
- Cole
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