create
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... proxy where to send the
request. Registrations are one way to create this information, but
not the only way. Arbitrary mapping functions can be configured at
the discretion of the administrator ...
... proxy, is a
transaction user. When a TU wishes to send a request, it creates a
client transaction ...
... port, and transport to which to send the
request. A TU that creates a client transaction can also cancel it.
...
... addresses. The bindings
can be created and removed in many ways; this specification
defines a REGISTER ...
... user agent client is a logical entity
that creates a new request, and then uses the client
transaction ...
...
When the UAC creates a request, it MUST insert a Via into that
request. The protocol name and protocol version in the header field ...
... contain a branch parameter. This parameter is used to identify the
transaction created by that request. This parameter is used by both
the client and the server.
...
...
After a new request has been created, and the header fields described
above have been properly constructed, any additional optional header
fields ...
... transaction to deliver a new request.
In order to create a request based on a contact address in a 3xx
response, a UAC ...
... URI
parameters (see Section 19.1.1 for a definition of these parameters).
It uses the "header" parameters to create header field values for the
new request, overwriting header field ...
... requests for which a challenge response is issued. If
unauthenticated requests were handled statefully, then malicious
floods of unauthenticated requests could create massive amounts of
transaction ...
... INVITE are responded to immediately,
sending a CANCEL for a non-INVITE request would always create a
race condition.
...
... requests that have already generated a final response. When the
client decides to send the CANCEL, it creates a client transaction
...
... SIP provides a mechanism
for a UA to create a binding explicitly. This mechanism is known as
registration ...
... REGISTER requests or responses, and MUST be ignored
if present. In particular, the UAC MUST NOT create a new route set
based on the presence or absence of a Record ...
... address of record whose
registration is to be created, queried, or modified. The To
header field and the Request-URI ...
... to send a request to the peer. A dialog can also be in the "early"
state, which occurs when it is created with a provisional response,
and then transition to the "confirmed" state when a 2xx final
...
...
Dialogs are created through the generation of non-failure responses
to requests with specific methods. Within this specification, only
...
... Independent of the method, if a request outside of a dialog generates
a non-2xx final response, any early dialogs created through
provisional responses to that request are terminated. The mechanism
for terminating confirmed dialogs is method ...
... INVITE establishes a session, and it also
creates a dialog between the UA that issued the INVITE and the UA ...
...
Once the INVITE has been created, the UAC follows the procedures
defined for sending requests outside of a dialog (Section 8). This
...
... more final responses are received. Provisional responses for an
INVITE request can create "early dialogs". If a provisional response
has a tag in the To field, and if the dialog ID of the response does
...
... UAC
that wants to add a media stream, for example, will create a new
offer that contains this media stream, and send that in an INVITE ...
... INVITE, each 1xx or 2xx response from a distinct UAS creates a
dialog, and if that response completes the offer/answer exchange, it
...
... dialog, and if that response completes the offer/answer exchange, it
also creates a session. As a result, each session is "associated"
...
... INVITE generates a non-2xx final response, that terminates
all sessions (if any) and all dialogs (if any) that were created
through responses to the request. By virtue of completing the
transaction ...
... transaction, a non-2xx final response also prevents further sessions
from being created as a result of the INVITE. The BYE request is
used to terminate a specific session ...
... session, and to terminate any
sessions already created. For the caller's UA, this would imply a
...
... This may consist of obtaining information from a location service
created by a SIP Registrar, reading a database, consulting a presence
server ...
... request with the original request. For the purposes of this model,
this mechanism is a "response context" created by the proxy layer
...
... If this proxy wishes to remain on the path of future requests
in a dialog created by this request (assuming the request
creates a dialog), it MUST insert a Record ...
... in a dialog created by this request (assuming the request
creates a dialog), it MUST insert a Record-Route header field ...
... valid for the lifetime of any dialog created by the transaction
in which it occurs. A dialog-stateful proxy ...
... in the value they use for construction of the branch parameter.
A proxy choosing to detect loops SHOULD create a branch
parameter separable into two parts by the implementation. The
first part MUST satisfy the constraints ...
... proxy and one of those fields
changes, it is treated as a spiral and not a loop (see Section
16.3). A common way to create this value is to compute a
cryptographic hash of the To tag ...
... The proxy locates the "response context" it created before
forwarding the original request using the key described in
Section 16.6. The remaining processing steps take place in
...
... client pending
transactions as described in Section 10, and it MUST NOT create
any new branches in this context.
...
... interface. When the TU wishes to initiate a new transaction, it
creates a client transaction and passes it the SIP request ...
... header field as the branch parameter in the top
Via header field of the request that created the transaction.
...
... this through a state machine. Server transactions are created by the
core when a request is received, and transaction handling is desired
...
... 1. the branch parameter in the request is equal to the one in the
top Via header field of the request that created the
transaction, and
...
...
2. the sent-by value in the top Via of the request is equal to the
one in the request that created the transaction, and
...
... header field match those of the
INVITE request which created the transaction. In this case, the
INVITE ...
... header field match those of the INVITE request which created the
transaction, and the To tag ...
... method), and top Via header field match those of the request that
created the transaction. Matching is done based on the matching
rules defined for each of those header fields ...
... the existing connection to the source of the original request
that created the transaction, if that connection is still open.
...
... certificates from known public
certificate authorities. As an alternative, users MAY create self-
signed certificates. The implications of self-signed certificates ...
... MIME bodies SHOULD be signed by the sender. This creates a
"multipart/signed" MIME body that contains an encrypted ...
... IP endpoints. SIP creates a
number of potential opportunities for distributed denial-of-service
attacks that must be recognized and addressed by the implementers ...
...
Attackers can create bogus requests that contain a falsified source
IP address and a corresponding Via header field that identify a
...
... proxy server -
attackers cannot create spoofed requests that appear to have been
sent through that proxy server.
...
... header field if the two were initially identical. Thus it MAY be
desirable for privacy reasons to create a To header field that
differs from the Request-URI ...
...
The specification instructs the IANA to create four new sub-
registries under http://www.iana.org/assignments/sip-parameters ...