166 lines
4 KiB
Ruby
166 lines
4 KiB
Ruby
require_relative 'array'
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require_relative 'network'
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require_relative 'bytes'
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class NetChunk
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attr_reader :next, :data, :msg, :sys, :flags
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@@sent_vital_chunks = 0
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def initialize(data)
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@next = nil
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@flags = {}
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@size = 0
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parse_header(data[0..2])
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chunk_end = CHUNK_HEADER_SIZE + @size
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# puts "data[0]: " + str_hex(data[0])
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@data = data[CHUNK_HEADER_SIZE...chunk_end]
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@msg = @data[0].unpack("C*").first
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@sys = @msg & 1 == 1 ? true : false
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@msg >>= 1
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@next = data[chunk_end..] if data.size > chunk_end
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end
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def to_s
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"NetChunk\n" +
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" msg=#{msg} sys=#{sys}\n" +
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" #{@flags}\n" +
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" data: #{str_hex(data)}"
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end
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##
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# Create int array ready to be send over the network
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#
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# Given the flags hash (vital/resend)
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# the size
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# the sequence number
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#
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# It will create a 3 byte chunk header
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# represented as an Array of 3 integers
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def self.create_vital_header(flags, size, seq = nil)
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@@sent_vital_chunks += 1
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if seq.nil?
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seq = @@sent_vital_chunks
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end
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flag_bits = '00'
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flag_bits[0] = flags[:resend] ? '1' : '0'
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flag_bits[1] = flags[:vital] ? '1' : '0'
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size_bits = size.to_s(2).rjust(12, '0')
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# size_bits[0..5]
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# size_bits[6..]
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seq_bits = seq.to_s(2).rjust(10, '0')
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# seq_bits[0..1]
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# seq_bits[2..]
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# The vital chunk header is 3 bytes
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# containing flags, size and sequence
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# in the following format
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#
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# f=flag
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# s=size
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# q=sequence
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#
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# ffss ssss qqss ssss qqqq qqqq
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header_bits =
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flag_bits +
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size_bits[0..5] +
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seq_bits[0..1] +
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size_bits[6..] +
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seq_bits[2..]
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header_bits.chars.groups_of(8).map do |eigth_bits|
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eigth_bits.join('').to_i(2)
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end
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end
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def parse_header(data)
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# flags
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flags = data[0].unpack("B*").first
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flags = flags[0..1]
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@flags[:resend] = flags[0] == "1"
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@flags[:vital] = flags[1] == "1"
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# size
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size = data[0..1].unpack("B*").first
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size_bytes = size.chars.groups_of(8)
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# trim first 2 bits of both bytes
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# Size: 2 bytes (..00 0000 ..00 0010)
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size_bytes.map! {|b| b[2..].join('') }
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@size = size_bytes.join('').to_i(2)
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# sequence number
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# in da third byte but who needs seq?!
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end
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def flags_vital
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@flags[:vital]
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end
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def flags_resend
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@flags[:resend]
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end
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end
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MAX_NUM_CHUNKS = 1024
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class BigChungusTheChunkGetter
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def self.get_chunks(data)
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chunks = []
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chunk = NetChunk.new(data)
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chunks.push(chunk)
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while chunk.next
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chunk = NetChunk.new(chunk.next)
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chunks.push(chunk)
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if chunks.size > MAX_NUM_CHUNKS
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# inf loop guard case
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puts "Warning: abort due to max num chunks bein reached"
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break
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end
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end
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chunks
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end
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end
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def todo_make_this_an_rspec_test
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# handcrafted fake packet
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# two empty motd chunks
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data = [
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0x40, 0x02, 0x02, 0x02, 0x00,
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0x40, 0x02, 0x02, 0x02, 0x00
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].pack("C*")
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chunks = BigChungusTheChunkGetter.get_chunks(data)
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p chunks.size == 2
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p chunks[0].msg == NETMSGTYPE_SV_MOTD
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p chunks[1].msg == NETMSGTYPE_SV_MOTD
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p chunks[0].sys == false
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# actual packet server sends
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data = [
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0x40, 0x02, 0x02, 0x02, 0x00, # motd
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0x40, 0x07, 0x03, 0x22, 0x01, 0x00, 0x01, 0x00, 0x01, 0x08, # server settings
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0x40, 0x01, 0x04, 0x0b # ready
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].pack("C*")
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chunks = BigChungusTheChunkGetter.get_chunks(data)
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p chunks.size == 3
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p chunks[0].msg == NETMSGTYPE_SV_MOTD
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p chunks[1].msg == NETMSGTYPE_SV_SERVERSETTINGS
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# actual mapchange the server sends
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map_change = [
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0x40, 0x32, 0x01, 0x05, 0x62, 0x72, 0x69, 0x64, 0x67, 0x65, 0x00,
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0xee, 0xcb, 0xd0, 0xd7, 0x02, 0x9c, 0x0e, 0x08, 0xa8, 0x15, 0x1a, 0xb3, 0xbb, 0xb1, 0xd4, 0x04,
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0x75, 0x68, 0xec, 0xe3, 0x41, 0x6e, 0x83, 0x20, 0xaf, 0x97, 0x0f, 0x49, 0xbe, 0x4f, 0x3c, 0x61,
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0x04, 0xf4, 0xbe, 0x60, 0xd2, 0x87, 0x39, 0x91, 0x59, 0xab
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].pack("C*")
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chunks = BigChungusTheChunkGetter.get_chunks(map_change)
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p chunks.size == 1
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p chunks[0].sys == true
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end
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def test2
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p NetChunk.create_vital_header({vital: true}, 20, 5) == [64, 20, 5]
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end
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