Struct InstanceId 

pub struct InstanceId(/* private fields */);

A device identity that outlives a reboot, a re-address and a change of network (§4.1).

§4.1 requires the value to be “persistent”, which is the whole point: the registrar uses it to recognise that a new registration replaces an old one for the same device rather than adding a second contact for it. A UA that mints a fresh instance on every start accumulates dead bindings at the registrar and looks, to it, like a growing crowd of identical phones.

§4.1 says a UA “SHOULD” use a UUID URN (RFC 4122), which is what InstanceId::generate makes — but the type accepts any URN, because §4.1 permits other schemes and a UA that persisted one has to be able to present it again.

Implementations

impl InstanceId

pub fn generate() -> Self

A fresh random UUID URN (§4.1, RFC 4122 §4.4 — version 4).

Generate this once and store it. Calling it on every start satisfies the syntax and defeats the mechanism.

pub fn parse(value: &str) -> Option<Self>

Adopt an instance ID a UA persisted earlier.

Rejects anything that is not a URN: §4.1’s grammar is instance-val = urn, and a value that is not one would be quoted into the Contact and rejected by the registrar rather than by us.

pub fn urn(&self) -> &str

The URN itself.

pub fn contact_param(&self) -> String

The Contact header parameter, quoted and bracketed as §4.1’s grammar requires: +sip.instance="<urn:uuid:…>".

The angle brackets are inside the quotes. Both are load-bearing — the URN contains colons, which would otherwise terminate the parameter value.

Trait Implementations

impl Clone for InstanceId

fn clone(&self) -> InstanceId

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for InstanceId

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for InstanceId

fn eq(&self, other: &InstanceId) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for InstanceId

impl StructuralPartialEq for InstanceId