Race Condition Examples

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Race Condition Examples draft-hasebe-sipping-race-
examples-00.txt Miki Hasebe NTT-east Corporation
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• Represented a basic idea to explain race
  conditions
• Made a figure of the dialog state transition to
  reveal the underlying structure of race
  conditions.
• Organize and reclassify examples in race
  condition
• Examples in the previous draft is organized into
  categories based on the figure of dialog state
  transition.

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The dialog state transition in race conditions

• A race condition is generated in a situation
  where the dialog state differs between UAC and
  UAS.

Alice
Bob
INVITE
180
Early
Early
200
CANCEL
Confirmed
Confirmed
ACK
BYE
Terminated
Terminated
200
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Dialog State Machine

• This figure is based on the RFC4235(dialog event
  package)

Preparative
3xx-6xx
2xx
Trying
1xx no-tag
1xx with tag
Proceeding
1xx no-tag
Early
3xx-6xx
BYE
1xx with tag
2xx
Confirmed
Terminated
Moratorium
Mortal
BYE
2xx
BYE
Timeout
ACK
Established
Morgue
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3. Race condition 3.1 Receiving message in the
Moratorium State 3.1.1 Receiving Initial INVITE
retransmission(Trying state) 3.1.2 Receiving
CANCEL(Trying state) 3.1.3 Receiving
CANCEL(Trying state) via a stateful proxy 3.1.4
Receiving BYE (Early state) 3.1.5 Receiving
re-INVITE (Established state) 3.1.6 Receiving
BYE (Established state) 3.2 Receiving message
in the Mortal State 3.2.1 Receiving
BYE(Established state) 3.2.2 Receiving
re-INVITE(Established state) 3.2.3 Receiving
REFER(Established state) 3.2.4 Receiving 200OK
for re-INVITE(Established state) 3.2.5
Receiving ACK (Moratorium state) 3.3 other
race condition
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• Let me hear your candid opinion of my proposal.
• The idea of causing race conditions arising from
  the dialog state transition.
• Classification of examples based on that idea.

Proposal

• I hope to promote discussions on the draft as a
  WG item.