io.pkts.packet.sip.header

Interface ViaHeader

All Superinterfaces:

Cloneable, Parameters, SipHeader

All Known Implementing Classes:

ViaHeaderImpl

public interface ViaHeader
extends Parameters, SipHeader

Source rfc 3261 section 8.1.1.7

The Via header field indicates the transport used for the transaction and identifies the location where the response is to be sent. A Via header field value is added only after the transport that will be used to reach the next hop has been selected (which may involve the usage of the procedures in [4]).

When the UAC creates a request, it MUST insert a Via into that request. The protocol name and protocol version in the header field MUST be SIP and 2.0, respectively. The Via header field value MUST 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.

The branch parameter value MUST be unique across space and time for all requests sent by the UA. The exceptions to this rule are CANCEL and ACK for non-2xx responses. As discussed below, a CANCEL request will have the same value of the branch parameter as the request it cancels. As discussed in Section 17.1.1.3, an ACK for a non-2xx response will also have the same branch ID as the INVITE whose response it acknowledges.

The uniqueness property of the branch ID parameter, to facilitate its use as a transaction ID, was not part of RFC 2543.

The branch ID inserted by an element compliant with this specification MUST always begin with the characters "z9hG4bK". These 7 characters are used as a magic cookie (7 is deemed sufficient to ensure that an older RFC 2543 implementation would not pick such a value), so that servers receiving the request can determine that the branch ID was constructed in the fashion described by this specification (that is, globally unique). Beyond this requirement, the precise format of the branch token is implementation-defined.

The Via header maddr, ttl, and sent-by components will be set when the request is processed by the transport layer (Section 18).

Via processing for proxies is described in Section 16.6 Item 8 and Section 16.7 Item 3.

Author:

[email protected]

Field Summary

Fields

Modifier and Type	Field and Description
static Buffer	NAME

Method Summary

Methods

Modifier and Type	Method and Description
Buffer	getBranch() The branch-parameter is mandatory and as such should always be there.
Buffer	getHost()
int	getPort()
Buffer	getReceived()
int	getRPort() Get the value of the rport parameter.
Buffer	getTransport() The protocol, which typically is "UDP", "TCP" or "TLS" but can really be anything according to RFC3261.
int	getTTL()
boolean	hasRPort() For a request, the rport value will not be filled out since the downstream element will do so when it discovers the rport parameter on a ViaHeader.
boolean	isSCTP() Convenience method for checking whether the protocol is SCTP or not.
boolean	isTCP() Convenience method for checking whether the protocol is TCP or not.
boolean	isTLS() Convenience method for checking whether the protocol is TLS or not.
boolean	isUDP() Convenience method for checking whether the protocol is UDP or not.
void	setReceived(Buffer received)
void	setRPort(int port)

Methods inherited from interface io.pkts.packet.sip.header.Parameters

getParameter, getParameter, setParameter

Methods inherited from interface io.pkts.packet.sip.header.SipHeader

clone, getBytes, getName, getValue, verify

Field Detail

NAME

static final Buffer NAME

Method Detail

getTransport

Buffer getTransport()

The protocol, which typically is "UDP", "TCP" or "TLS" but can really be anything according to RFC3261.

Returns:

getHost

Buffer getHost()

getPort

int getPort()

getReceived

Buffer getReceived()

setReceived

void setReceived(Buffer received)

hasRPort

boolean hasRPort()

For a request, the rport value will not be filled out since the downstream element will do so when it discovers the rport parameter on a ViaHeader. Hence, if you use getRPort() you will not correctly be able to determine whether this ViaHeader actually has the rport parameter present or if it is simply not set yet. However, this method will return true if the rport parameter exists on the ViaHeader, irrespectively whether it has a value or not.

Returns:

getRPort

int getRPort()

Get the value of the rport parameter. -1 (negative one) will be returned if the value is not set. Note, if you get -1 that doesn't mean that the rport is not present on the ViaHeader. To make sure that the ViaHeader indeed has the rport parameter set, use the hasRPort().

Returns:

setRPort

void setRPort(int port)

getBranch

Buffer getBranch()

The branch-parameter is mandatory and as such should always be there. However, everything is done lazily in this library so there is not a 100% guarantee that the branch header actually is present. Hence, you MUST be prepared to check for null in case the Via-header is bad. If important to your application (and if you are building a stack it probably will be) then please call SipHeader.verify() on your headers since that will guarantee that they conform to whatever the various RFC's mandates.

Returns:

getTTL

int getTTL()

isUDP

boolean isUDP()

Convenience method for checking whether the protocol is UDP or not.

Returns:

isTCP

boolean isTCP()

Convenience method for checking whether the protocol is TCP or not.

Returns:

isTLS

boolean isTLS()

Convenience method for checking whether the protocol is TLS or not.

Returns:

isSCTP

boolean isSCTP()

Convenience method for checking whether the protocol is SCTP or not.

Returns: