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

214 HP-UX C SIP Stack Programmer’s Guide
Transmitter API
Via Branch
A branch parameter that will be added to the top Via header of an outgoing
Request message. The application can set the branch parameter to the
transmitter before sending a Request message. When the Request is sent, if the
message already has a branch, it will be replaced with the branch set to the
transmitter. If no branch was set to the transmitter and the top Via header of the
message does not include a branch, the transmitter will generate a new branch
and set it in the top Via header. This parameter has a Set function only.
Ignore Outbound Proxy Flag
Instructs the transmitter to ignore its outbound proxy when sending a request.
When the message includes one or more Route headers, the transmitter will
always ignore its outbound proxy. If there are no Route headers and an outbound
proxy is configured, it will be used as the remote address of the message.
In some cases, the application will want the transmitter to ignore the outbound
proxy even if it is configured to use one. An example is the case of strict routing
when a single Route header becomes the message request URI, and therefore the
message does not include any Route headers but the transmitter still needs to
ignore its outbound proxy.
Use First Route Flag
Instructs the transmitter to use the first Route header as the remote address and
not the Request-URI. The message should be sent to the first route header and
not to the Request-URI when the message is sent to a loose route proxy.
Fix Via Flag
Indicates that the transmitter should update the “sent-by” parameter of the top
Via header before sending the message. The “sent-by” parameter should be
updated according to the local address from which the request will be sent. This
address is determined according to the remote address transport and address
types.
In many cases, the application does not know the remote party IP, transport and
address types in advance, and therefore cannot know which local address will be
used. In this case, the application might want the transmitter to update the top
Via automatically and therefore should call the
RvSipTransmitterSetFixViaFlag() function.
The default value of the Fix Via parameter is RV_FALSE and it should remain
RV_FALSE if the application updates the top Via by itself.