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# -*- coding: binary -*-
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module Msf
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# This mixin provides helper functions for building Git repositories
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module Exploit::Git
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  class GitObject
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    attr_reader :type, :content, :sha1, :path, :compressed
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    def initialize(type, content, sha1, compressed)
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      @type = type
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      @content = content
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      @sha1 = sha1
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      @compressed = compressed
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      @path = "#{@sha1[0...2]}/#{@sha1[2..40]}"
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    end
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    # Wrapper for `build_object()` to create
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    # a GitObject of type `commit`
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    # @param [ Hash ] containing sha1s for the tree,
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    # (optional) parent sha1 and optional data
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    # such as commit message, committer name,
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    # company name, and email address
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    def self.build_commit_object(opts = {})
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      full_name = opts[:name] || Faker::Name.name
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      email = opts[:email] || Faker::Internet.email(name: full_name, separators: ['-', '_'])
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      company = opts[:company] || Faker::Company.name
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      commit_text = opts[:message] || "Initial commit to open git repository for #{company}!"
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      tree_sha1 = opts[:tree_sha1]
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      parent_sha1 = opts[:parent_sha1]
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      tstamp = Time.now.to_i
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      author_time = rand(tstamp)
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      commit_time = rand(author_time)
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      tz_off = rand(10)
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      commit_msg = "tree #{tree_sha1}\n"
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      commit_msg << "parent #{parent_sha1}\n" unless parent_sha1.nil?
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      commit_msg << "author #{full_name} <#{email}> #{author_time} -0#{tz_off}00\n"
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      commit_msg << "committer #{full_name} <#{email}> #{commit_time} -0#{tz_off}00\n"
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      commit_msg << "\n"
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      commit_msg << "#{commit_text}\n"
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      sha1, compressed = build_object('commit', commit_msg)
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      GitObject.new('commit', commit_msg, sha1, compressed)
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    end
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    # Wrapper for `build_object()` to create
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    # a GitObject of type `blob`
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    # @param [ String ] the data that the object
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    # will represent
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    def self.build_blob_object(content)
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      sha1, compressed = build_object('blob', content)
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      GitObject.new('blob', content, sha1, compressed)
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    end
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    # Creates a GitObject of type `tree`
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    # @param [ Hash ] entries containing
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    # the file mode, name, and sha1 from
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    # a previously-created `blob` object
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    # Ex:
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    # {
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    #   mode: '100755', file_name: 'hooks',
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    #   sha1: 'a372436ad8331b380e20e8c9861f547063d76a46'
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    # }
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    def self.build_tree_object(tree_entries)
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      tree = ''
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      unless tree_entries.is_a?(Array)
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        tree_entries = [ tree_entries ]
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      end
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      tree_entries.each do |entry|
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        tree += "#{entry[:mode]} #{entry[:file_name]}\0#{[entry[:sha1]].pack('H*')}"
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      end
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      sha1, compressed = build_object('tree', tree)
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      GitObject.new('tree', tree, sha1, compressed)
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    end
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    # Generates a git object of the specified
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    # type, ex: blob, tree, commit
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    #
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    # @param [ String ] type of object to create
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    # @param [ String ] the data that the resulting
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    # object will represent
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    # Returns an Array containing the sha1 hash
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    # and Zlib-compressed data
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    def self.build_object(type, content)
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      # taken from http://schacon.github.io/gitbook/7_how_git_stores_objects.html
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      header = "#{type} #{content.size}\0"
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      store = header + content
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      [Digest::SHA1.hexdigest(store), Rex::Text.zlib_deflate(store, Zlib::DEFAULT_COMPRESSION)]
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    end
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    # Given a sha1 and list of Git objects
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    # find the object with the matching sha1
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    #
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    # @param [ String ] sha1 of the object to find
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    # @param [ Array ] list of GitObjects to search
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    # @return GitObject with the matching sha1, nil otherwise
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    def self.find_object(sha1, objs = [])
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      return nil if objs.empty?
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      objs.find { |obj| obj.sha1 == sha1 }
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    end
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  end
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end
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end
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