forked from rainliu/sip
/
FromHeader.go
138 lines (82 loc) · 4.27 KB
/
FromHeader.go
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package header
/**
* The From header field indicates the logical identity of the initiator
* of the request, possibly the user's address-of-record. This may be different
* from the initiator of the dialog. Requests sent by the callee to the caller
* use the callee's address in the From header field.
* <p>
* Like the To header field, it contains a URI and optionally a display name,
* encapsulated in a {@link javax.sip.address.Address}. It is used by SIP
* elements to determine which processing rules to apply to a request (for
* example, automatic call rejection). As such, it is very important that the
* From URI not contain IP addresses or the FQDN of the host on which the UA is
* running, since these are not logical names.
* <p>
* The From header field allows for a display name. A UAC SHOULD use
* the display name "Anonymous", along with a syntactically correct, but
* otherwise meaningless URI (like sip:thisis@anonymous.invalid), if the
* identity of the client is to remain hidden.
* <p>
* Usually, the value that populates the From header field in requests
* generated by a particular UA is pre-provisioned by the user or by the
* administrators of the user's local domain. If a particular UA is used by
* multiple users, it might have switchable profiles that include a URI
* corresponding to the identity of the profiled user. Recipients of requests
* can authenticate the originator of a request in order to ascertain that
* they are who their From header field claims they are.
* <p>
* Two From header fields are equivalent if their URIs match, and their
* parameters match. Extension parameters in one header field, not present in
* the other are ignored for the purposes of comparison. This means that the
* display name and presence or absence of angle brackets do not affect
* matching.
* <ul>
* <li> The "Tag" parameter - is used in the To and From header fields of SIP
* messages. It serves as a general mechanism to identify a dialog, which is
* the combination of the Call-ID along with two tags, one from each
* participant in the dialog. When a User Agent sends a request outside of a dialog,
* it contains a From tag only, providing "half" of the dialog ID. The dialog
* is completed from the response(s), each of which contributes the second half
* in the To header field. When a tag is generated by a User Agent for insertion into
* a request or response, it MUST be globally unique and cryptographically
* random with at least 32 bits of randomness. Besides the requirement for
* global uniqueness, the algorithm for generating a tag is implementation
* specific. Tags are helpful in fault tolerant systems, where a dialog is to
* be recovered on an alternate server after a failure. A UAS can select the
* tag in such a way that a backup can recognize a request as part of a dialog
* on the failed server, and therefore determine that it should attempt to
* recover the dialog and any other state associated with it.
* </ul>
* For Example:<br>
* <code>From: "Bob" sips:bob@biloxi.com ;tag=a48s<br>
* From: sip:+12125551212@phone2net.com;tag=887s<br>
* From: Anonymous sip:c8oqz84zk7z@privacy.org;tag=hyh8</code>
*/
type FromHeader interface {
ParametersHeader
AddressHeader
/**
* Sets the tag parameter of the FromHeader. The tag in the From field of a
* request identifies the peer of the dialog. When a UA sends a request
* outside of a dialog, it contains a From tag only, providing "half" of
* the dialog Identifier.
* <p>
* The From Header MUST contain a new "tag" parameter, chosen by the UAC
* applicaton. Once the initial From "tag" is assigned it should not be
* manipulated by the application. That is on the client side for outbound
* requests the application is responsible for Tag assigmennment, after
* dialog establishment the stack will take care of Tag assignment.
*
* @param tag - the new tag of the FromHeader
* @throws ParseException which signals that an error has been reached
* unexpectedly while parsing the Tag value.
*/
SetTag(tag string) (ParseException error)
/**
* Gets the tag of FromHeader. The Tag parameter identified the Peer of the
* dialogue and must always be present.
*
* @return the tag parameter of the FromHeader.
*/
GetTag() string
}