Question

I’ve been using WifiInfo.getMacAddress string as seen on my nexus one or any other mobile device I’ve been able to use, i.e. in the format of 01:02:03:04:05:06

But one of the users of my app just reported a crash on a Toshiba Folio100, my MAC address parsing failed. Since I’ve not any log files and the report is anonymous, I cannot contact that man, so I ask here if you know how it’s encoded in such kind of device.

I suppose it could be like 010203040506 but I’m not so confident.

Answer 1

Although I can’t comment on The Toshiba Folio specifically, I would urge you to reconsider how you parse the MAC address string.

I wrote code many years ago to get the MAC addresses from NICs in PCs – as it used the cards’ PC drivers, the format could vary depending on manufacturer. The docs for WifiInfo.getMACAddress() don’t actually give a guarantee of how this string is returned so consider preparing for all eventualities.

I saw the following formats…

01:02:03:04:05:06 // Delimited with ':' and padded to 2 chars
1:2:3:4:5:6 // Delimited but if < 16, there was no leading '0'
010203040506 // No delimiters but octets ALWAYS pre-padded with '0' when < 16

NOTE: Also the alphabetic characters may have been upper or lower case (although consistent in each case, i.e., all upper or all lower case). Example…

0A0B0C0D0E0F
0a0b0c0d0e0f
A:B:C:D:E:F
a:b:c:d:e:f

To cope with the above, I first forced the string toLower().

I then checked for presence of ‘:’. If it existed I’d split the string into an array and I’d then check the length of each ‘octet string’ in the array and if length = 1 then padding wasn’t used so I’d prefix ‘0’. Finally I’d reassemble the string by concatenating each of the array elements using ‘:’ as a delimiter.

If the string didn’t contain ‘:’ then I’d confirm that its length = 12, at this point I’d rebuild the string using each pair of characters and delimit with ‘:’.

If the string wasn’t delimited and its length wan’t 12 then it would be impossible to parse correctly and I had to assume that requesting the MAC address string had failed and I reported a bad MAC address.