Add support for rule position 'p'

[mhasbini]

The loop condition in RULE_OP_REJECT_CONTAINS was changed to be compatible with JtR.

echo 'remember' | ./hashcat --stdout -j '/e op3'
r3member

echo 'remember' |  ./hashcat --stdout -j '%2m ip!'
reme!mber

echo 'remember' |  ./hashcat --stdout -j '%3e op3 %2e op3 /e op3'
r3m3mb3r

Using p without using / or % before it, would result in an invalid rule.
E.g. echo 'remember' | ./hashcat --stdout -j 'op3' will return empty response with exit status 1.

This may not close #1035. I thought it's nice to have.

[jsteube]

Thanks for your contributions. Please see my comments below:

1. In the changes.txt:

+- Rules: Support added for position 'p'

This should be modified to reflect this change will work only for the CPU rule enging by using -j and -k, but not on GPU

2. The macro name convention:

 #define RULE_OP_REJECT_EQUAL_AT         '=' // reject plains that do not contain char X at position N
 #define RULE_OP_REJECT_CONTAINS         '%' // reject plains that contain char X less than N times
 #define RULE_OP_REJECT_MEMORY           'Q' // reject plains that match the plain saved (see M), i.e. if unchanged
-
+#define RULE_REJECT_SAVED_POS           'p' // position of the character last found with '/' or '%'

I'm wondering if the "REJECT" substring is correct, or is it really working only for reject cases?

[mhasbini]

@jsteube Thanks for checking!

1. In the changes.txt:

I'll update the changelog entry to be:

• Rules: Support added for position 'p' in host mode (using -j or -k)

What do you think?

2. The macro name convention

I wasn't sure about the name.
p will only work if it's preceded by / or %, and will have the position of the last matched character as value.

Maybe RULE_LAST_REJECTED_SAVED_POS or RULE_CONTAINS_SAVED_POS?

[jsteube]

1. OK
2. OK. RULE_LAST_REJECTED_SAVED_POS sounds good to me.

[roycewilliams]

Examples are now documented here: https://hashcat.net/wiki/doku.php?id=rule_based_attack#using_p_nth_instance_of_a_character_with_positional_rules