RTCIceCandidate: relatedAddress property
The RTCIceCandidate
interface's read-only relatedAddress
property is a
string indicating the related address of a relay or reflexive candidate.
If the candidate is a host candidate (that is, its address
is in fact the real IP address of the remote peer), relatedAddress
is null
.
The relatedAddress
field's value is set from the candidateInfo
options object passed to the RTCIceCandidate()
constructor.
You can't specify the value of relatedAddress
directly in the options object, but its value is automatically extracted from the object's candidate
a-line if it's formatted properly(the rel-address
field).
The related address and port (relatedPort
) are not used at all by ICE itself; they are provided
for analysis and diagnostic purposes only, and their inclusion may be blocked by security systems, so do not rely on them having non-null
values.
Value
A string which contains the candidate's related address. For both peer and server reflexive candidates, the related address (and related port) are the base for that server or peer reflexive candidate. For relay candidates, the related address and port are set to the mapped address selected by the TURN server.
For host candidates, relatedAddress
is null
, meaning the field is not included in the candidate's a-line.
Usage notes
The related address is included in ICE candidates despite not being used by ICE itself.
relatedAddress
can be used for diagnostic purposes; by observing the
relationships between the various types of candidates and their addresses and related
addresses. relatedAddress
can also be used by Quality-of-Service (QoS) mechanisms.
Here's an SDP attribute line (a-line) describing an ICE candidate discovered by the STUN server:
a=candidate:4234997325 1 udp 2043278322 192.168.0.56 6502 typ srflx raddr 192.168.2.77 rport 32768 generation 0
The remote address, relatedAddress
, is the dotted quad (for IPv4) or
colon-delineated 64-bit address (for IPv6) immediately following the text "raddr"
, or "192.168.2.77"
.
Examples
In this example, the candidate's type
is
checked, and then debugging output is presented, based on the candidate type, including
the candidate's ip
and relatedAddress
.
js
switch (candidate.type) {
case "host":
console.log(`Host candidate's IP address is ${candidate.ip}`);
break;
case "srflx":
console.log(
`Server reflexive candidate's base address is ${candidate.relatedAddress}; reachable at ${candidate.ip}`
);
break;
case "prflx":
console.log(
`Peer reflexive candidate's base address is ${candidate.relatedAddress}; reachable at ${candidate.ip}`
);
break;
case "relay":
console.log(
`Relay candidate's address assigned by the TURN server is ${candidate.relatedAddress}; reachable at ${candidate.ip}`
);
break;
}
Specifications
Specification |
---|
WebRTC: Real-Time Communication in Browsers # dom-rtcicecandidate-relatedaddress |
Browser compatibility
BCD tables only load in the browser