Class: Syspy::TdsPackageStream

Inherits:
Object
  • Object
show all
Defined in:
lib/tds_package_stream.rb

Instance Method Summary collapse

Constructor Details

#initialize(interface, dst, dst_port) ⇒ TdsPackageStream

Returns a new instance of TdsPackageStream.



11
12
13
14
15
16
 
# File 'lib/tds_package_stream.rb', line 11

def initialize(interface,dst,dst_port)
  @interface = interface
  @dst = dst
  @dst_port = dst_port
  @in,@out = IO.pipe()
end

Instance Method Details

#each_package ⇒ Object 



18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/tds_package_stream.rb', line 18

def each_package()
  Thread.abort_on_exception = true       
  @tcpdump_thread = Thread.new(){       
    IO.popen("tcpdump -q -y EN10MB -U -B 2048 -w - -i #{@interface} tcp and dst #{@dst} and dst port #{@dst_port} 2>/dev/null"){|io|         
      content = ""
      loop(){
        tcp_length = read_ip_header(io)
        Log.debug "Got IP package: #{tcp_length}"
        content_length = read_tcp_header(io,tcp_length)
        Log.debug "Got TCP package: #{content_length}"
        
        if(content_length > 0)        
          content = io.read(content_length)       
          @out.write(content)
          @out.flush      
        end

        Log.debug "Network package done"      
      } 
    }
  }  

  content = ""
  @in.each_byte(){|byte|
    if(byte == 0x0F)                 
      last_packet_indicator = Bytes.uint(@in)          
      length = Bytes.uint16be(@in)
       
      # skip next 4 bytes of the header
      if(Bytes.uint32be(@in) == 0x00)
        content << @in.read(length - 8)
        
        if(last_packet_indicator == 0x1)              
          begin
            io = StringIO.new(content)
            package = handle_package(io)
            yield package if package               
          ensure
            content = ""
          end             
        end
      end
    end           
  }     
end

#handle_package(io) ⇒ Object 



64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
 
# File 'lib/tds_package_stream.rb', line 64

def handle_package(io)    
  token = Bytes.uint(io)
  token_class = TdsTokens.token_class(token)
  if(token_class)
    length = TdsTokens.fixed_length(token)
    unless(length)
      length_field_size = TdsTokens.length_field_size(token)
      if(length_field_size)
        length = Bytes.uintle(io,length_field_size)
      end       
    end
    Log.debug("Got #{TdsTokens.token_name(token)} of #{length} bytes")
    package = token_class.new(io,length)
    return package        
  end
  nil   
end

#read_ip_header(io) ⇒ Object 



82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
 
# File 'lib/tds_package_stream.rb', line 82

def read_ip_header(io)
  count = 0
  loop(){
    network_type = Bytes.uint16be(io)
    break if network_type == 0x800 and count >= 14
    count += 1 
  }    

  # read IP version and header length
  ver_len = Bytes.uint(io)
  version = ver_len >> 4
   
  raise "Invalid IP version: #{version}" unless version == 4 || version == 6

  header_length = (ver_len & 0x0F) * 4
   
  # skip TOS
  Bytes.uint(io)
   
  # get package length
  content_length = Bytes.uint16be(io)

  # consume remaining IP header
  io.read(header_length - 4)
  content_length - header_length
end

#read_tcp_header(io, ip_package_size) ⇒ Object 



109
110
111
112
113
114
115
116
117
118
119
120
 
# File 'lib/tds_package_stream.rb', line 109

def read_tcp_header(io, ip_package_size)
  # skip first 12
  io.read(12)

  # get header length
  tcp_offset = (Bytes.uint(io) >> 4) * 4
   
  # consume remaining tcp header
  io.read(tcp_offset - 13)
  
  ip_package_size - tcp_offset
end