Module candidate 

Candidates as the agent holds them: priority, foundation and base (RFC 8445 §5.1.1.3, §5.1.2.1, §7.1.1; spec §4, §5).

sipx_sdp::ice::Candidate is the a=candidate line. It is what crosses the wire and it knows nothing about which socket a check would leave from, because sipx-sdp owns no sockets. The two types here add exactly that: a LocalCandidate carries the LocalBase the driver bound, and a RemoteCandidate carries a foundation that a peer-reflexive candidate can also have — §7.3.1.3 gives one “an arbitrary value, different from the foundations of all other remote candidates”, which is not a value any a=candidate line ever supplied.

Structs

CandidateIds

Allocates the identities of LocalCandidates and RemoteCandidates.

Foundations

Allocates foundations over the candidates as they are gathered (§5.1.1.3).

Gathered

A candidate the driver gathered, before the agent has priced it.

LocalBase

Which socket the driver bound, named so the agent never has to hold one.

LocalCandidate

A local candidate: what the driver gathered, plus what §5.1.1.3 and §5.1.2.1 make of it.

LocalFoundation

A local candidate’s foundation (§5.1.1.3).

LocalId

A local candidate’s identity.

PairFoundation

A candidate pair’s foundation: §6.1.2.6’s “combination of the foundations of the local and remote candidates in the pair”.

RemoteCandidate

A remote candidate: one the peer signalled, or one §7.3.1.3 learned from a check.

RemoteId

A remote candidate’s identity, allocated and stable — see LocalId.

Enums

RemoteFoundation

A remote candidate’s foundation.

Constants

HOST_PREFERENCE

Type preference for a host candidate (§5.1.2.2’s recommended value; spec §4).

MAX_TYPE_PREFERENCE

The largest type preference §5.1.2.1 admits: “an integer from 0 … to 126 … inclusive”.

PEER_REFLEXIVE_PREFERENCE

Type preference for a peer-reflexive candidate. §5.1.2.1 makes it a MUST that this is higher than the server-reflexive one, and it is the preference every PRIORITY attribute uses whatever the candidate actually is (§7.1.1, check_priority).

RELAYED_PREFERENCE

Type preference for a relayed candidate: last resort, because it costs a relay’s bandwidth.

SERVER_REFLEXIVE_PREFERENCE

Type preference for a server-reflexive candidate (§5.1.2.2’s recommended value).

SINGLE_ADDRESS_PREFERENCE

The local preference for a candidate that is the only one of its type for its component. §5.1.2.1: “When there is only a single IP address, this value SHOULD be set to 65535.”

Functions

assign_local_preferences

Assign §5.1.2.1’s local preferences across a gathered set, and price every candidate.

check_priority

The PRIORITY a connectivity check carries (§7.1.1).

find_local

The local candidate with this identity, if it is still known.

find_remote

The remote candidate with this identity, if it is still known.

pair_priority

§6.1.2.3’s pair priority, with controlling the priority of the controlling agent’s candidate and controlled the controlled agent’s:

priority

§5.1.2.1’s formula, exactly as it is printed:

type_preference

§5.1.2.2’s recommended type preference for a candidate of this type (spec §4’s table).