The buf[i] < 3 condition in use previously allowed all chars (signed on x86)
through that had the 0x80 high-bit set after reconstructing from the two
bytes of the netbios name, resulting in escaped non-ascii content in
the logs.
Fixes more of #2742
Fixes to `decode_netbios_name`:
* Improve validation that input string is a NetBIOS encoding
(32 bytes, with characters ranging from 'A' to 'P'). This helps
prevent Undefined Behavior of left-shifting negative values.
Invalid encodings now cause a return-value of an empty string.
* More liberal in what decoded characters are allowed. Namely,
spaces are now allowed (but any trailing null-bytes and spaces
are trimmed, similar to before).
Fixes to `decode_netbios_name_type`:
* Improve validation that input string is a NetBIOS encoding
(32 bytes, with characters ranging from 'A' to 'P'). This helps
prevent Undefined Behavior of left-shifting negative values and
a heap-buffer-overread when the input string is too small.
Invalid encodings now cause a return-value of 256.
With this patch the model is:
- "print" cleans the data so that non-printable characters get
escaped. This is not necessarily reversible.
- to print in a reversible way, one can go through
escape_string(); this escapes backslashes as well to make the
decoding non-ambigious.
- Logging always escapes similar to escape_string(), making it
reversible.
Compared to master, we also change the escaping as follows:
- We now only escape with "\xXX", no more "^X" or "\0". Exception:
backslashes.
- We escape backlashes as "\\".
- There's no "alternative" output style anymore, i.e., fmt() '%A'
qualifier is gone.
Baselines in testing/btest are updated, external tests not yet.
Addresses BIT-1333.
