HP-UX C SIP Stack Programmer's Guide (Novembery 2007)

Working with SIP Messages 167
Handling Messages with Syntax Errors
Figure 9-5 illustrates how the Stack handles a bad-syntax message across layers
when the application chooses the “continue processing” option.
Figure 9-5 Handling a Bad-syntax Message
Parse the message, keep bad syntax parts in
the StrBadSyntax parameter
New message with syntax errors is
received
The message is given to the transaction
manager
Try to create a new transaction, or locate an
existing transaction
Check syntax of headers
relevant for transaction creation:
To, From, CSeq, top Via
Bad
syntax
Reject with 400
Create Transaction
Check syntax of headers
relevant for the transaction
processing such as
Proxy-Authorization, Authorization
Bad syntax
Transaction is given to the Calll-Leg Manager
Transport +
Parser
Handling
TranscMgr
Handling
Transaction
Handling
Create call-leg
Check syntax of
headers relevant for the call-leg processing
such as Refer-To, Route
Bad syntax
Call-leg
Handling
Application
Handling
B.S Callback - Application chooses the
CONTINUE_PROCESS option