#    This file is part of Metasm, the Ruby assembly manipulation suite
#    Copyright (C) 2006-2011 Yoann GUILLOT
#
#    Licence is LGPL, see LICENCE in the top-level directory


# metasm dasm plugin
# scan for a given asm instruction sequence (all encodings)
# add the G dasm-gui shortcut, the input change ';' for line splits

def findgadget_asm_to_regex(asm)
	fullre = ''
	asm = asm.gsub(';', "\n")

	sc = Shellcode.new(@cpu)
	sc.parse asm
	sc.source.each { |i|
		case i
		when Data
			opts_edata = i.encode(@cpu.endianness)
		when Instruction
			opts_edata = @cpu.encode_instruction(sc, i)
		else
			raise "cant scan for #{i}"
		end

		opts_edata = [opts_edata] if opts_edata.kind_of?(EncodedData)

		opts_re = opts_edata.map { |ed|
			# Regexp.escape ed.data, with relocs replaced with '.'
			re = ''
			off = 0
			ed.reloc.sort.each { |o, rel|
				re << Regexp.escape(ed.data[off...o])
				re << ('.' * rel.length)
				off = o + rel.length
			}
			re << Regexp.escape(ed.data[off..-1])
		}
		fullre << '(' << opts_re.join('|') << ')'
	}

	Regexp.new(fullre, Regexp::MULTILINE, 'n')
end

# parse asm to a regexp, return the list of addresses matching
def findgadget_asm(asm)
	pattern_scan(findgadget_asm_to_regex(asm))
end

def findgadget_prompt
	gui.inputbox("source for the gadget - separate with ;") { |asm|
		lst = findgadget_asm(asm)
		list = [['address', 'section']]
		sections = section_info
		list += lst.map { |addr|
			# [name, addr, len, misc]
			if s = sections.find { |s_| s_[1] <= addr and s_[1] + s_[2] > addr }
				s = s[0]
			else
				s = '?'
			end
			[Expression[addr], s]
		}
		gui.listwindow("gadgetscan for #{asm}", list) { |args| gui.focus_addr(args[0]) }
	}
end

if gui
	gui.keyboard_callback[?G] = lambda { |*a| findgadget_prompt }
	w = gui.toplevel
	w.addsubmenu(w.find_menu('Actions'), 'Scan for _Gadget', 'G') { findgadget_prompt }
	w.update_menu
	:success
end