Merge pull request #38 from XeroHawk/alpha2_fix
Ported over the Issue 3190 SVN changes for unicode_mixed, an old bug that was hiding out in Redmine.
This commit is contained in:
Tod Beardsley
commit
6b06df0d7d
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@ -8,6 +8,7 @@ module Alpha2
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class Generic
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# Note: 'A' is presumed to be accepted, but excluded from the accepted characters, because it serves as the terminator
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def Generic.default_accepted_chars ; ('a' .. 'z').to_a + ('B' .. 'Z').to_a + ('0' .. '9').to_a ; end
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def Generic.gen_decoder_prefix(reg, offset)
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@ -22,14 +23,6 @@ class Generic
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return ''
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end
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def Generic.gen_base_set(ignored_max=0x0f)
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# 0xf is max for XOR encodings - non-unicode
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max = 0x0f
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Rex::Text.shuffle_a(
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[* ( (0..(max)).map { |i| i *= 0x10 } ) ]
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)
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end
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def Generic.gen_second(block, base)
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# XOR encoder for ascii - unicode uses additive
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(block^base)
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@ -37,58 +30,41 @@ class Generic
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def Generic.encode_byte(block, badchars)
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accepted_chars = default_accepted_chars.dup
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# Remove bad chars from the accepted_chars list. Sadly 'A' must be
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# an accepted char or we'll certainly fail at this point. This could
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# be fixed later maybe with some recalculation of the encoder stubs...
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# - Puss
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(badchars || '').unpack('C*').map { |c| accepted_chars.delete([c].pack('C')) }
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first = 0
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second = 1
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randbase = 0
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found = nil
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gen_base_set(block).each do |randbase_|
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second = gen_second(block, randbase_)
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next if second < 0
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if accepted_chars.include?([second].pack('C'))
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found = second
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randbase = randbase_
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break
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end
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badchars.each_char {|c| accepted_chars.delete(c) } if badchars
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# No, not nipple.
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nibble_chars = Array.new(0x10) {[]}
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accepted_chars.each {|c| nibble_chars[c.unpack('C')[0] & 0x0F].push(c) }
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poss_encodings = []
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block_low_nibble = block & 0x0F
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block_high_nibble = block >> 4
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# Get list of chars suitable for expressing lower part of byte
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first_chars = nibble_chars[block_low_nibble]
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# Build a list of possible encodings
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first_chars.each do |first_char|
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first_high_nibble = first_char.unpack('C')[0] >> 4
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# In the decoding process, the low nibble of the second char gets combined
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# (either ADDed or XORed depending on the encoder) with the high nibble of the first char,
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# and we want the high nibble of our input byte to result
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second_low_nibble = gen_second(block_high_nibble, first_high_nibble) & 0x0F
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# Find valid second chars for this first char and add each combination to our possible encodings
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second_chars = nibble_chars[second_low_nibble]
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second_chars.each {|second_char| poss_encodings.push(second_char + first_char) }
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end
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if not found
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msg = "No valid base found for #{"0x%.2x" % block}"
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if not accepted_chars.include?([second].pack('C'))
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msg << ": BadChar to #{second}"
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elsif second < 1
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msg << ": Negative"
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end
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raise RuntimeError, msg
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if poss_encodings.empty?
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raise RuntimeError, "No encoding of #{"0x%.2X" % block} possible with limited character set"
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end
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if (randbase > 0xa0)
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# first num must be 4
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first = (randbase/0x10) + 0x40
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elsif (randbase == 0x00) || (randbase == 0x10)
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# first num must be 5
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first = (randbase/0x10) + 0x50
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else
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# pick one at "random"
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first = (randbase/0x10)
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if (first % 2) > 0
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first += 0x40
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else
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first += 0x50
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end
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end
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# now add our new bytes :)
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[first.to_i, second].pack('CC')
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# Return a random encoding
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poss_encodings[rand(poss_encodings.length)]
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end
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def Generic.encode(buf, reg, offset, badchars = '')
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@ -97,10 +73,10 @@ class Generic
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buf.each_byte {
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|block|
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encoded += encode_byte(block, badchars)
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encoded << encode_byte(block, badchars)
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}
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encoded += add_terminator()
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encoded << add_terminator()
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return encoded
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end
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@ -7,12 +7,6 @@ module Encoder
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module Alpha2
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class UnicodeMixed < Generic
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def self.gen_base_set(max)
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Rex::Text.shuffle_a(
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[* ( (0..(max-1)).map { |i| i *= 0x10 } ) ]
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)
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end
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def self.gen_second(block, base)
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# unicode uses additive encoding
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@ -20,8 +14,8 @@ class UnicodeMixed < Generic
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end
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def self.gen_decoder_prefix(reg, offset)
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if (offset > 28)
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raise "Critical: Offset is greater than 28"
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if (offset > 21)
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raise "Critical: Offset is greater than 21"
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end
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# offset untested for unicode :(
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@ -8,12 +8,6 @@ module Alpha2
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class UnicodeUpper < Generic
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def self.default_accepted_chars ; ('B' .. 'Z').to_a + ('0' .. '9').to_a ; end
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def self.gen_base_set(max)
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Rex::Text.shuffle_a(
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[* ( (0..(max-1)).map { |i| i *= 0x10 } ) ]
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)
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end
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def self.gen_second(block, base)
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# unicode uses additive encoding
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@ -21,8 +15,8 @@ class UnicodeUpper < Generic
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end
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def self.gen_decoder_prefix(reg, offset)
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if (offset > 8)
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raise "Critical: Offset is greater than 8"
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if (offset > 6)
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raise "Critical: Offset is greater than 6"
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end
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# offset untested for unicode :(
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