emailler/server/lib/tftp_server.rb

222 lines
8.6 KiB
Ruby

#
# minimal TFTP server implementation for use with netboot65
#
# supports RRQ, WRQ and a custom DIR request (opcode 0x65 - returns null terminated list of filenames that match specified filemask)
# Jonno Downes (jonno@jamtronix.com) - January, 2009
#
# TFTP spec : http://www.ietf.org/rfc/rfc1350.txt
require 'socket'
class Netboot65TFTPServer
TFTP_OPCODES={
1=>'RRQ', #read request
2=>'WRQ', #write request
3=>'DATA',
4=>'ACK',
5=>'ERROR',
0x65=>'DIR',
}
TFTP_ERRORCODES={
1 =>'File not found.',
2 =>'Access violation.',
3 =>'Disk full or allocation exceeded.',
4 =>'Illegal TFTP operation.',
5 =>'Unknown transfer ID.',
6 =>'File already exists.',
7 =>'No such user.',
}
TFTP_MAX_RESENDS=10
attr_reader :bootfile_dir,:port,:server_thread
def initialize(bootfile_dir,port=69)
@bootfile_dir=bootfile_dir
@port=port
@server_thread=nil
@current_connection={}
end
def send_error(client_ip,client_port,error_code,error_msg)
packet=[5,error_code,error_msg,0].pack("nnA#{error_msg.length}c")
socket=UDPSocket.open.send(packet,0,client_ip,client_port)
log_msg("sent error #{error_code}:'#{error_msg}' to #{client_ip}:#{client_port}")
end
def send_data(client_ip,client_port,filename,data_to_send)
client_sock=UDPSocket.open
client_sock.connect(client_ip,client_port)
blocks_to_send=1+(data_to_send.length.to_f/512.0).floor
log_msg("sending #{filename} to #{client_ip}:#{client_port} (#{blocks_to_send} blocks)")
blocks_to_send.times do |block_number|
block_data=data_to_send[block_number*512,512]
packet=[3,block_number+1,block_data].pack("nnA*")
got_ack=false
TFTP_MAX_RESENDS.times do |attempt_number|
log_msg("sending block #{block_number+1}/#{blocks_to_send} of #{filename} to #{client_ip}:#{client_port} - #{block_data.length} bytes - attempt #{attempt_number+1}")
client_sock.send(packet,0,client_ip,client_port)
if (IO.select([client_sock], nil, nil, 1)) then
data,addr_info=client_sock.recvfrom(4096)
client_ip=addr_info[3]
client_port=addr_info[1]
opcode=data[0,2].unpack("n")[0]
opcode_description=TFTP_OPCODES[opcode]
if opcode==4 then
acked_block_number=data[2,2].unpack("n")[0]
log_msg "TFTP: ACK from #{client_ip}:#{client_port} - block #{acked_block_number}"
got_ack=true if acked_block_number==block_number+1
else
opcode_description="[UNK]" if opcode_description.nil?
log_msg "TFTP: response from #{client_ip}:#{client_port} - opcode #{opcode} : #{opcode_description}"
end
end
break if got_ack
end
if !got_ack then
log_msg "TFTP: timed out waiting for ACK of block #{block_number} from #{client_ip}"
break
end
end
end
def recv_data(client_ip,client_port,filename,file_handle)
client_sock=UDPSocket.open
client_sock.connect(client_ip,client_port)
client_id="#{client_ip}:#{client_port}"
if @current_connection[client_id]==true then
log_msg("already sending to #{client_id}" )
end
@current_connection[client_id]=true
log_msg("receiving #{filename} from #{client_ip}:#{client_port}")
got_last_block=false
finished=false
block_number=0
finished
until finished do
packet=[4,block_number].pack("nn")
got_block=false
TFTP_MAX_RESENDS.times do |attempt_number|
log_msg("ACKing block #{block_number} of #{filename} from #{client_ip}:#{client_port} - attempt #{attempt_number+1}")
client_sock.send(packet,0,client_ip,client_port)
if got_last_block then
puts "last block received"
finished=true
break
else
if (IO.select([client_sock], nil, nil, 1)) then
data,addr_info=client_sock.recvfrom(4096)
client_ip=addr_info[3]
client_port=addr_info[1]
opcode=data[0,2].unpack("n")[0]
opcode_description=TFTP_OPCODES[opcode]
if opcode==3 then
recved_block_number=data[2,2].unpack("n")[0]
block_data=data[4,512]
got_last_block=(block_data.length!=512)
log_msg "TFTP: DATA from #{client_ip}:#{client_port} - block #{recved_block_number} - #{block_data.length} bytes"
if recved_block_number==block_number+1
got_block=true
file_handle<<block_data
end
else
opcode_description="[UNK]" if opcode_description.nil?
log_msg "TFTP: response from #{client_ip}:#{client_port} - opcode #{opcode} : #{opcode_description}"
end
end
break if got_block
end
end
if !got_block && !finished then
log_msg "TFTP: timed out waiting for DATA for block #{block_number+1} from #{client_ip}"
finished=true
break
end
block_number+=1
end
file_handle.close
@current_connection[client_id]=false
end
def start()
log_msg "TFTP: serving #{bootfile_dir} on port #{port}"
Socket.do_not_reverse_lookup = true
@server_thread=Thread.start do
loop do
socket=UDPSocket.open
socket.setsockopt Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1
log_msg "waiting for TFTP client to connect"
socket.bind("",port)
data,addr_info=socket.recvfrom(4096)
client_ip=addr_info[3]
client_port=addr_info[1]
opcode=data[0,2].unpack("n")[0]
opcode_description=TFTP_OPCODES[opcode]
opcode_description="[UNK]" if opcode_description.nil?
log_msg "TFTP: connect from #{client_ip}:#{client_port} - opcode #{opcode} : #{opcode_description}"
case opcode
when 1 : #READ REQUEST
opcode,filename_and_mode=data.unpack("nA*")
filename,mode=filename_and_mode.split(0.chr)
log_msg "RRQ for #{filename} (#{mode})"
if filename=~/^\./ || filename=~/\.\./ then #looks like something dodgy - either a dotfile or a directory traversal attempt
send_error(client_ip,client_port,1,"'#{filename}' invalid filename")
else
full_filename="#{bootfile_dir}/#{filename}"
if File.file?(full_filename) then
data_to_send=File.open(full_filename,"rb").read
Thread.new {send_data(client_ip,client_port,full_filename,data_to_send)}
else
send_error(client_ip,client_port,1,"'#{filename}' not found")
end
end
when 2 : #WRITE REQUEST
opcode,filename_and_mode=data.unpack("nA*")
filename,mode=filename_and_mode.split(0.chr)
log_msg "WRQ for #{filename} (#{mode})"
if filename=~/^\./ || filename=~/\.\./ then #looks like something dodgy - either a dotfile or a directory traversal attempt
send_error(client_ip,client_port,1,"'#{filename}' invalid filename")
else
full_filename="#{bootfile_dir}/#{filename}"
begin
file_handle=File.open(full_filename,"wb")
Thread.new {recv_data(client_ip,client_port,full_filename,file_handle)}
rescue Exception=>e
send_error(client_ip,client_port,2,"error writing to '#{filename}':#{e.to_s}")
end
end
when 0x65 : #DIR REQUEST
opcode,filemask_and_mode=data.unpack("nA*")
filemask,mode=filemask_and_mode.split(0.chr)
log_msg "DIR for #{filemask} (#{mode})"
if filename=~/^\./ || filename=~/\.\./ then #looks like something dodgy - either a dotfile or a directory traversal attempt
send_error(client_ip,client_port,1,"'#{filemask}' invalid filename")
else
data_to_send=""
Dir.chdir(bootfile_dir) do
Dir.glob(filemask).each {|filename| data_to_send<<"#{filename}\000"}
end
data_to_send<<0.chr
Thread.new {send_data(client_ip,client_port,"DIR of #{filemask}",data_to_send)}
end
else
send_error(client_ip,client_port,4,"opcode #{opcode} not supported")
end
socket.close
end
end
# @server_thread.join
end
def shutdown()
log_msg "TFTP: stopping"
server_thread.kill
end
end