Fix bug in tab completion of directories

[smashery]

This fixes several bugs in local directory tab completion.

The code currently just performs a glob based on the user's current input. This has a bug that effectively prevents it from ever working. It performs a string concatenation to add an asterisk, which alters the str parameter with the in-place-modification method concat. The str parameter is used by the readline library to do its tab completion magic, so suddenly it's got an asterisk on there, and readline's string matching fails. As a practical example:

• The current directory contains the directories 'tools' and 'test'
• We type cd t and press <tab>
• The glob adds an asterisk to str to give it the value t*
• The glob finds both the directories and returns them
• Readline receives these two values, but also uses the modified t* value, because of the in-place modification that occurred as a result of using concat
• Because neither tools nor test start with the literal string t*, it finds no matches, and provides no tab completion to the user.

Steps to reproduce:

• Launch msfconsole from a directory containing at least two folders
• Type cd and press <tab>
• You'll see it pop up ./
• Press <tab> again
• Nothing happens

Expected behaviour:

The tab completion provides options based on the current directory, or absolute directory specified.

Fix:

A simple fix would be to change str.concat(*) to str + '*'. However, this leaves another subtle bug in that it doesn't respect glob-meaningful characters such as *, ?, [ and ]. So if folders actually contain these characters, it would not provide the expected results (as the user is not aware that globbing is used). ? and * work by coincidence, as globbing will use them as wildcards, which will match the literal characters ? and *; but it fails in the case of folder names containing brackets. This is probably a rarer situation, but still a bug.

You could do all sorts of glob backslash escaping, but that starts to get messy, so instead I just implemented directory searching so as to control this behaviour ourselves, in order to keep it Readline-friendly.

After the fix:

msf6 > cd co<tab>
cd config/    cd coverage/  
msf6 > cd /t<tab>
cd /testing/  cd /tmp/      cd /tools/
msf6 > cd /tmp/globtest/a[<tab>
cd /tmp/globtest/a[hi]b/     cd /tmp/globtest/a[there]b/

[bcoles]

This line has been duplicated.

This line has been duplicated.

[smcintyre-r7]

Tested and confirmed that I could reproduce the original issue and that the proposed changes fixes it. Tab completion is always hard to demo but the screenshot is a broadcast group using terminator with the unpatched version on the left with the fixed one on the right.

I'm going to resolve the comment about the duplicate line (I tested it with that removed) and get this landed. Thanks @smashery !

[smcintyre-r7]

Release Notes

This fixes a bug in how msfconsole tab completes directory paths.