This change adapts pion/ice to use a new interface for most network
related operations. The interface was formerly a simple struct vnet.Net
which was originally intended to facilicate testing. By replacing it
with an interface we have greater flexibility and allow users to hook
into the networking stack by providing their own implementation of
the interface.
Before a SessionDescription was assumed to be Plan-B if it contained a
MediaName of `audio` or `video`. This PR Changes that behavior.
If SDPSemantics is UnifiedPlan the SessionDescription must contain a
MediaDescription with two SSRCes to be considered a Plan-B. Before if
the MediaDescription had name of `audio` or `video` it was assumed to be
Plan-B.
If SDPSemantics is PlanB or UnifiedPlanWithFallback it maintains the
existing behavior.
Resolves#2193
Instead of having logic in pion/webrtc and pion/sdp move all logic to
pion/ice. Users of pion/ice don't want to import these packages to use
basic pion/ice functionality.
By default, we should be using unified-plan as the
SDP format of choice. This patch adds a PeerConnection
configuration option to allow the user to specify that
they want plan-b only, unified-plan only, or a special
compatibility mode where a plan-b answer will be generated
IFF a plan-b offer is received.
