Workaround to ignore interfaces whose name got truncated by netstat

[hellais]

When interface names are longer than 7 characters netstat will truncate
them to the first 7 chars which leads to looking up an invalid interface
name.

This workaround ignores interfaces that are too long.

This fixes #147

[guedou]

While a fix to #147 is really important, I am not a big fan of ignoring truncated interface names. It should be the ultimate solution.
Instead, a better fix will be to first try to fix truncated interface names using output from ifconfig -l, then fail if its not possible.

We are still working on a good way to add unit tests to functions such as read_routes(). PR #127 fixes read_routes6() on OS X and add unit tests to other platforms using the mock module.

[dark-lbp]

May be try netiface for that problem?
netifaces

[guedou]

@dark-lbp there is no need to rely on an external module. I think that @hellais should be able to implement my proposal quite easily.

[hellais]

Rebased and pushed with support for guessing the interface name.

[p-l-]

This is inefficient. Maybe this would be better?

from __future__ import with_statement

[...]

    with os.popen('ifconfig -l') as fdesc:
        ifaces = fdesc.readline().strip().split()
    for iface in ifaces:
        if iface.startswith(netif):
            return iface

[hellais]

Ok, I can change to use the with statement.

Regarding:

    for iface in ifaces:
        if iface.startswith(netif):
            return iface

I want to avoid returning an interface name when there are multiple matches as that means that I am actually not sure what interface is the correct one.

[p-l-]

OK. Anyway, please avoid filter + lambda: matches = [iface for iface in ifaces if iface.startswith(netif)]

[guedou]

@Osso does this fix your bug ?

@hellais could you share the output of netsat and get_if_list(), I would like to add a mocked unit tests to our regressions.

[Osso]

Yes this fixes my bug
I get this warning but all is good:
WARNING: Could not guess partial interface name None

[guedou]

It might be interesting to assign the returned value to fixed_netif in order to display a correct warning. See @Osso comment.

[guedou]

read_routes6()might be also broken.
Could you share the output of netstat -rn -f inet6 ?

Thanks.

[Osso]

I bet it is broken too but the default vagrant configuration is without ipv6.
As a result on my ipv6 netstat I do not have any truncated interface.

[guedou]

@hellais could you apply my comment ?

[guedou]

Due to no recent activity on this PR, I modified the original patch and created PR #260.