Re: ioctl SIOCGIFADDR bug

Riley Williams (rhw@BigFoot.Com)
Fri, 6 Aug 1999 21:11:36 +0100 (GMT)

Hi Alan.

>> My problem turns out to be an apparently undocumented
>> requirement that the family type must be set in the buffer for
>> SIOCGIFADDR to work (but not for the mask or broadcast commands
>> to work) and if you don't (i.e. all bytes 0) it will return the
>> last four bytes of the network card's MAC address but set this
>> byte (the 18th, at offset 17) to 1 which will cause it to work
>> the next time.

> It returns the entire MAC address if you dont. The world has
> been that way since 4.2 BSD at least.

Presumably his MAC address starts with 00:00 and he didn't notice the
difference as a result...

Best wishes from Riley.

| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |

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