If binding to specified network adress fails, daemon defaults back to 0.0.0.0

[Sian]

Observed behaviour:

If binding to the specified network adress fails, the dæmon silently ignores the setting and binds to 0.0.0.0, thus using any available network interface.

Problem: In certain use cases, this behavior is not preferable. Quote from the  forums:

This is a problem because I (and I guess, many people who might want to use it) want my p2p traffic to go exclusively through my VPN. Another use case is people with a 3G connection; you might want to bind to wlan0 when you're at home and traffic is free, but definitely don't want it to go through the cell interface.

Related to this: Would it be possible to allow not only IP adress as valid input in the specified network adress input field, but either interface names (ath0, eth1, etc.) or host names? Combined with some sort of internal check and update mechanism, deluge could bind dynamically to IP adresses. So users wouldn't need to really on an external script to update the adress to bind to (as tried in the forum thread linked above).