117 lines
3.1 KiB
Go
117 lines
3.1 KiB
Go
package mesh
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import (
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"net"
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)
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type Overlay interface {
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// Enhance a features map with overlay-related features
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AddFeaturesTo(map[string]string)
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// Prepare on overlay connection. The connection should remain
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// passive until it has been Confirm()ed.
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PrepareConnection(OverlayConnectionParams) (OverlayConnection, error)
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// Obtain diagnostic information specific to the overlay
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Diagnostics() interface{}
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}
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type OverlayConnectionParams struct {
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RemotePeer *Peer
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// The local address of the corresponding TCP connection. Used to
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// derive the local IP address for sending. May differ for
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// different overlay connections.
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LocalAddr *net.TCPAddr
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// The remote address of the corresponding TCP connection. Used to
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// determine the address to send to, but only if the TCP
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// connection is outbound. Otherwise the Overlay needs to discover
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// it (e.g. from incoming datagrams).
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RemoteAddr *net.TCPAddr
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// Is the corresponding TCP connection outbound?
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Outbound bool
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// Unique identifier for this connection
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ConnUID uint64
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// Session key, if connection is encrypted; nil otherwise.
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//
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// NB: overlay connections must take care not to use nonces which
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// may collide with those of the main connection. These nonces are
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// 192 bits, with the top most bit unspecified, the next bit set
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// to 1, followed by 126 zero bits, and a message sequence number
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// in the lowest 64 bits.
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SessionKey *[32]byte
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// Function to send a control message to the counterpart
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// overlay connection.
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SendControlMessage func(tag byte, msg []byte) error
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// Features passed at connection initiation
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Features map[string]string
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}
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// All of the machinery to manage overlay connectivity to a particular
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// peer
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type OverlayConnection interface {
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// Confirm that the connection is really wanted, and so the
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// Overlay should begin heartbeats etc. to verify the operation of
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// the overlay connection.
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Confirm()
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// A channel indicating that the overlay connection is
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// established, i.e. its operation has been confirmed.
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EstablishedChannel() <-chan struct{}
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// A channel indicating an error from the overlay connection. The
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// overlay connection is not expected to be operational after the
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// first error, so the channel only needs to buffer a single
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// error.
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ErrorChannel() <-chan error
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Stop()
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// Handle a message from the peer. 'tag' exists for
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// compatibility, and should always be
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// ProtocolOverlayControlMessage for non-sleeve overlays.
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ControlMessage(tag byte, msg []byte)
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// User facing overlay name
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DisplayName() string
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}
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type NullOverlay struct{}
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func (NullOverlay) AddFeaturesTo(map[string]string) {
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}
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func (NullOverlay) PrepareConnection(OverlayConnectionParams) (OverlayConnection, error) {
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return NullOverlay{}, nil
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}
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func (NullOverlay) Diagnostics() interface{} {
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return nil
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}
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func (NullOverlay) Confirm() {
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}
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func (NullOverlay) EstablishedChannel() <-chan struct{} {
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return nil
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}
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func (NullOverlay) ErrorChannel() <-chan error {
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return nil
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}
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func (NullOverlay) Stop() {
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}
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func (NullOverlay) ControlMessage(byte, []byte) {
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}
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func (NullOverlay) DisplayName() string {
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return "null"
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}
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