source: trunk/ETSI-Testsuites/ETSI_auto_IOT/adapter/src/Dispatcher/README.txt @ 32

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