[CIFS] clean up upcall handling for dns_resolver keys
[CIFS] clean up upcall handling for dns_resolver keys

We're given the datalen in the downcall, so there's no need to do any
calls to strlen(). Just keep track of the datalen in the key. Finally,
add a sanity check of the data in the downcall to make sure that it
looks like a real IP address.

Signed-off-by: Jeff Layton <4376fbf8623cd7b7c0232225289bb91cedc0a27f@redhat.com>
Acked-by: David Howells <ebac1d06c1688626821bb0e574a037a7a5354e49@redhat.com>
Signed-off-by: Steve French <d47560e3bac353b8d509d093b1d727868ac7ddf3@us.ibm.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs