#!/usr/bin/env ruby

# $Id$

msfbase = __FILE__
while File.symlink?(msfbase)
	msfbase = File.expand_path(File.readlink(msfbase), File.dirname(msfbase))
end

$:.unshift(File.join(File.dirname(msfbase), 'lib'))
$:.unshift(ENV['MSF_LOCAL_LIB']) if ENV['MSF_LOCAL_LIB']

require 'rex/elfparsey'
require 'rex/elfscan'
require 'rex/arch/x86'
require 'optparse'

def opt2i(o)
	o.index("0x")==0 ? o.hex : o.to_i
end

opt = OptionParser.new

opt.banner = "Usage: #{$PROGRAM_NAME} [mode] <options> [targets]"
opt.separator('')
opt.separator('Modes:')

worker = nil
param = {}

opt.on('-j', '--jump [regA,regB,regC]', 'Search for jump equivalent instructions') do |t|
	# take csv of register names (like eax,ebx) and convert
	# them to an array of register numbers
	regnums = t.split(',').collect { |o|
		begin
			Rex::Arch::X86.reg_number(o)
		rescue
			puts "Invalid register \"#{o}\""
			exit(1)
		end
	}
	worker = Rex::ElfScan::Scanner::JmpRegScanner
	param['args'] = regnums
end

opt.on('-p', '--poppopret', 'Search for pop+pop+ret combinations') do |t|
	worker = Rex::ElfScan::Scanner::PopPopRetScanner
	param['args'] = t
end

opt.on('-r', '--regex [regex]', 'Search for regex match') do |t|
	worker = Rex::ElfScan::Scanner::RegexScanner
	param['args'] = t
end

opt.on('-a', '--analyze-address [address]', 'Display the code at the specified address') do |t|
	worker = Rex::ElfScan::Search::DumpRVA
	param['args'] = opt2i(t)
end

opt.on('-b', '--analyze-offset [offset]', 'Display the code at the specified offset') do |t|
	worker = Rex::ElfScan::Search::DumpOffset
	param['args'] = opt2i(t)
end

opt.separator('')
opt.separator('Options:')

opt.on('-A', '--after [bytes]', 'Number of bytes to show after match (-a/-b)') do |t|
	param['after'] = opt2i(t)
end

opt.on('-B', '--before [bytes]', 'Number of bytes to show before match (-a/-b)') do |t|
	param['before'] = opt2i(t)
end

opt.on('-I', '--image-base [address]', 'Specify an alternate ImageBase') do |t|
	param['imagebase'] = opt2i(t)
end

opt.on_tail("-h", "--help", "Show this message") do
	puts opt
	exit(1)
end

begin
	opt.parse!
rescue OptionParser::InvalidOption
	puts "Invalid option, try -h for usage"
	exit(1)
end

if (! worker)
	puts opt
	exit(1)
end

ARGV.each do |file|

	param['file'] = file

	begin
		elf = Rex::ElfParsey::Elf.new_from_file(file, true)
	rescue Rex::ElfParsey::ElfHeaderError
		if $!.message == 'Invalid magic number'
			$stderr.puts("Skipping #{file}: #{$!}")
			next
		end
		raise $!
	rescue Errno::ENOENT
		$stderr.puts("File does not exist: #{file}")
		next
	end

	if (param['imagebase'])
		elf.base_addr = param['imagebase'];
	end

	o = worker.new(elf)
	o.scan(param)

	elf.close

end