#!/usr/bin/env ruby

require 'socket'
require 'timeout'

class JjSrv
	def rrq
		len = @socket.gets.to_i
		@socket.read len
	end

	def srq(a)
		@socket.puts a.length
		@socket.write a
	end

	def initialize(root = '.', host = 'localhost', port = 10987)
		@lsocket = TCPServer.open host, port
		@root = root
	end

	def main_loop
		puts Time.now.strftime('%d/%m %H:%M:%S ') + "server ready"
		loop do
			a = @lsocket.accept
			if fork
				peer = a.peeraddr
				puts Time.now.strftime('%d/%m %H:%M:%S ') + "new connection from #{peer[2].inspect} (#{peer[3]}:#{peer[1]})"
				a.close
				sleep 1
			else
				@lsocket.close
				@socket = a
				client_loop
				@socket.shutdown
				@socket.close
				exit
			end
		end
	end

	def client_loop
		Timeout.timeout(60) {
			loop do
				srq handle_rq(rrq)
			end
		} rescue nil
	end

	def handle_rq(rq)
		case rq.split.first
		when 'read'
			cmd, off, len, path = rq.split(' ', 4)
			check_path path
			File.open(File.join(@root, path), 'rb') { |fd| fd.pos = off.to_i ; fd.read len.to_i }
		when 'dir'
			path = rq.split(' ', 2).last
			check_path path
			Dir.entries(File.join(@root, path)).map { |d| File.directory?(File.join(@root, path, d)) ? d+'/' : d }.join("\n")	# parse error if filename == "foo\nbar" ...
		when 'size'
			path = rq.split(' ', 2).last
			check_path path
			File.size(File.join(@root, path)).to_s
		end
	end

	def check_path(path)
		raise 'Directory traversal' if path.split('/').include? '..'
	end
end

if $0 == __FILE__
	trap('INT') { exit }
	JjSrv.new(*ARGV).main_loop rescue puts($!, "Usage: #$0 [rootdir] [bindhost] [port]")
end