| [22] | 1 | README: |
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| 2 | ====== |
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| 3 | |
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| 4 | For each protocol layer: |
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| 5 | - Dispatcher instanciates a new Dissector for this layer. |
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| 6 | - Dispatcher asks Dissector to parse the captured packet. |
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| 7 | - Dissector determines if packet must be reassembled. |
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| 8 | - If reassembly is required, packet is tranfered to reassembly, |
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| 9 | which may result in a complete packet |
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| 10 | - If packet is complete, then dispatch filters are querried to |
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| 11 | eliminate components for which this packet is not suitable |
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| 12 | - Upper layer dispatcher is selected based on Dissector information |
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| 13 | (Implicitely registered Upper Layers) or based on Upper Layer |
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| 14 | Filters (Explicitely registered Upper Layers). Packet and component |
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| 15 | list are transmitted to first available Upper Layer Dispatcher. |
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| 16 | - If no Upper Layer Dispatcher is available, then payload and |
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| 17 | component list are returned. |
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| 18 | |
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| 19 | |
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| 20 | Dispatchers are Singletons, and all inherit from Dispatcher class. |
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| 21 | |
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| 22 | Dispatcher |
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| 23 | ^---EthernetDispatcher |
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| 24 | |---IpDispatcher |
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| 25 | |---TcpDispatcher |
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| 26 | |---UdpDispatcher |
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| 27 | |---SipDispatcher |
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| 28 | |---... |
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| 29 | |
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| 30 | Dispatcher instances can be retrieved via pseudo-factory DispatcherFactory |
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| 31 | using method Get("<Layer>"). |
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| 32 | Example: DispatcherFactory::Instance().Get("UDP"); |
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| 33 | |
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| 34 | |
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| 35 | Dissectors all inherits from Dissectors |
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| 36 | |
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| 37 | Dissector |
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| 38 | ^---EthernetDissector |
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| 39 | |---IpDissector |
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| 40 | |---TcpDissector |
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| 41 | |---UdpDissector |
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| 42 | |---SipDissector |
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| 43 | |---... |
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| 44 | |
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| 45 | Dissectors are created via DissectorFactory using method Create(<Layer>). |
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| 46 | Example: DissectorFactory::Instance().Create("Ethernet"); |
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| 47 | |
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| 48 | |
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| 49 | TODO: |
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| 50 | ==== |
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| 51 | |
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| 52 | * Implement Dispatch filters: |
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| 53 | => Dispatch filters are created using Dispatcher's RegisterFilter() |
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| 54 | method. |
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| 55 | => Each Dispatch filter should be associated with a ComponentId. |
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| 56 | => the Match() method should receive a Dissector as parameter. |
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| 57 | => if none of a ComponentId filters matches, then this ComponentId |
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| 58 | should be removed from Dispatcher's ComponentId list. |
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| 59 | => if a ComponentId has no associated filter, then this ComponentId |
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| 60 | remains in the list. |
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| 61 | => if Dispatcher's ComponentId list gets empty, then it means that |
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| 62 | captured packet does not match any Component filter... Oooops |
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| 63 | => All filters are always processed, thus Dispatch filter |
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| 64 | registration order has no impact. |
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| 65 | => Example: |
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| 66 | |
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| 67 | Configuration: |
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| 68 | Components: CompA, CompB, CompC |
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| 69 | |
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| 70 | Dispatcher: IP |
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| 71 | Filters: |
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| 72 | - CompA, addr, @1 |
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| 73 | - CompB, addr, @1 |
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| 74 | - CompB, addr, @2 |
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| 75 | |
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| 76 | Dispatcher: UDP/TCP |
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| 77 | Filters: |
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| 78 | b - CompA, port, 5060 |
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| 79 | - CompB, port, 53 |
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| 80 | - CompB, port, 5060 |
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| 81 | - CompC, port, 80 |
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| 82 | |
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| 83 | |
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| 84 | Captured Packets: |
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| 85 | a/ SIP (addr=@1, port=5060) |
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| 86 | b/ DNS (addr=@1, port=53) |
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| 87 | c/ SIP (addr=@2, port=5060) |
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| 88 | d/ HTTP (addr=@1, port=80) |
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| 89 | |
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| 90 | Results: |
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| 91 | a/ Init: CompA, CompB, CompC |
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| 92 | Eth: CompA, CompB, CompC |
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| 93 | IP: CompA, CompB, CompC |
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| 94 | UDP: CompA, CompB |
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| 95 | Enqueued on CompA and CompB |
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| 96 | |
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| 97 | b/ Init: CompA, CompB, CompC |
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| 98 | Eth: CompA, CompB, CompC |
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| 99 | IP: CompA, CompB, CompC |
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| 100 | UDP: CompB |
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| 101 | Enqueued on CompB |
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| 102 | |
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| 103 | c/ Init: CompA, CompB, CompC |
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| 104 | Eth: CompA, CompB, CompC |
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| 105 | IP: CompB, CompC |
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| 106 | UDP: CompB |
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| 107 | Enqueued on CompB |
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| 108 | |
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| 109 | d/ Init: CompA, CompB, CompC |
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| 110 | Eth: CompA, CompB, CompC |
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| 111 | IP: CompA, CompB, CompC |
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| 112 | TCP: CompC |
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| 113 | |
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| 114 | * Implement UpperLayer filters: |
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| 115 | => Explicit Upper Layers are registered using Dispatcher's method |
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| 116 | AddExplicitUpperLayer(). |
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| 117 | => Upper Layers can be selected using Upper Layer filters |
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| 118 | => Dispatcher will transmit current packet to first registered |
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| 119 | Upper Layer having a matching UL filter. IMPORTANT: null filter |
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| 120 | (=no filter) always match. As a consequence, registration order |
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| 121 | is important |
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| 122 | => Example 1: |
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| 123 | |
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| 124 | Configuration: |
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| 125 | Dispatcher: Ethernet |
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| 126 | Implicitely registered Upper Layers: IP |
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| 127 | |
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| 128 | Dispatcher: IP |
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| 129 | Implicitely registered Upper Layers: TCP, UDP |
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| 130 | |
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| 131 | Captured Packets: |
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| 132 | a/ Eth-IP-UDP-SIP |
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| 133 | b/ Eth-IP-TCP-SIP |
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| 134 | c/ Eth-IP-UDP-DNS |
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| 135 | |
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| 136 | Results: |
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| 137 | a/ Dispatchers called: |
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| 138 | - Eth |
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| 139 | - IP |
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| 140 | - UDP |
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| 141 | SIP dispatcher no called! |
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| 142 | |
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| 143 | b/ Dispatchers called: |
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| 144 | - Eth |
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| 145 | - IP |
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| 146 | - TCP |
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| 147 | SIP dispatcher no called! |
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| 148 | (SIP messages not Reassembled !!!) |
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| 149 | |
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| 150 | c/ Dispatchers called: |
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| 151 | - Eth |
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| 152 | - IP |
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| 153 | - TCP |
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| 154 | DNS dispatcher no called! |
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| 155 | |
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| 156 | => Example 2: |
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| 157 | |
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| 158 | Configuration: |
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| 159 | Dispatcher: Ethernet |
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| 160 | Implicitely registered Upper Layers: IP |
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| 161 | |
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| 162 | Dispatcher: IP |
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| 163 | Implicitely registered Upper Layers: TCP, UDP |
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| 164 | |
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| 165 | Dispatcher: UDP |
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| 166 | Explicitely registered Upper Layers: |
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| 167 | - SIP (Filter: none) |
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| 168 | - DNS (Filter: port=53) |
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| 169 | |
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| 170 | Dispatcher: TCP |
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| 171 | Explicitely registered Upper Layers: |
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| 172 | - SIP (Filter: none) |
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| 173 | |
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| 174 | Captured Packets: |
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| 175 | a/ Eth-IP-UDP-SIP |
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| 176 | b/ Eth-IP-TCP-SIP |
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| 177 | c/ Eth-IP-UDP-DNS |
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| 178 | |
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| 179 | Results: |
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| 180 | a/ Dispatchers called: |
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| 181 | - Eth |
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| 182 | - IP |
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| 183 | - UDP |
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| 184 | - SIP |
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| 185 | |
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| 186 | b/ Dispatchers called: |
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| 187 | - Eth |
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| 188 | - IP |
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| 189 | - TCP |
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| 190 | - SIP |
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| 191 | SIP dispatcher called => SIP messages Reassembled !!! |
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| 192 | |
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| 193 | c/ Dispatchers called: |
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| 194 | - Eth |
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| 195 | - IP |
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| 196 | - UDP |
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| 197 | - SIP |
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| 198 | DNS dispatcher no called! |
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| 199 | SIP dispatcher called!!! |
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| 200 | => first dispatcher with matching filter |
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| 201 | has been called... Oooops |
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| 202 | |
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| 203 | |
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| 204 | => Example 3: |
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| 205 | |
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| 206 | Configuration: |
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| 207 | Dispatcher: Ethernet |
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| 208 | Implicitely registered Upper Layers: IP |
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| 209 | |
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| 210 | Dispatcher: IP |
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| 211 | Implicitely registered Upper Layers: TCP, UDP |
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| 212 | |
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| 213 | Dispatcher: UDP |
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| 214 | Explicitely registered Upper Layers: |
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| 215 | - SIP (Filter: none) |
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| 216 | - DNS (Filter: port=53) |
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| 217 | |
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| 218 | Dispatcher: TCP |
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| 219 | Explicitely registered Upper Layers: |
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| 220 | - SIP (Filter: none) |
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| 221 | |
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| 222 | Captured Packets: |
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| 223 | a/ Eth-IP-UDP-SIP |
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| 224 | b/ Eth-IP-TCP-SIP |
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| 225 | c/ Eth-IP-UDP-DNS |
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| 226 | |
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| 227 | Results: |
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| 228 | a/ Dispatchers called: |
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| 229 | - Eth |
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| 230 | - IP |
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| 231 | - UDP |
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| 232 | - SIP |
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| 233 | |
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| 234 | b/ Dispatchers called: |
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| 235 | - Eth |
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| 236 | - IP |
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| 237 | - TCP |
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| 238 | - SIP |
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| 239 | DNS dispatcher no called (filter does not match) |
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| 240 | SIP dispatcher called => SIP messages Reassembled !!! |
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| 241 | |
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| 242 | c/ Dispatchers called: |
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| 243 | - Eth |
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| 244 | - IP |
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| 245 | - UDP |
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| 246 | - DNS |
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| 247 | DNS dispatcher called, OK! |
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| 248 | |
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| 249 | * Implement Sip Dissector: |
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| 250 | => SipDissector should be able to partially parse SIP message in |
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| 251 | order to get its length and determine if it is complete or need |
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| 252 | reassembly. |
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| 253 | => Reassemble should proceed to SIP message reassembly (simple |
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| 254 | concatenation, as TCP guaranties packet order). |
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| 255 | => Refer to IpDissector for example of reassembly. |
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| 256 | |
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| 257 | |
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