credentials

type AuthInfo interface {
	AuthType() string
}

type Credentials interface {
	// GetRequestMetadata gets the current request metadata, refreshing
	// tokens if required. This should be called by the transport layer on
	// each request, and the data should be populated in headers or other
	// context. uri is the URI of the entry point for the request. When
	// supported by the underlying implementation, ctx can be used for
	// timeout and cancellation.
	// TODO(zhaoq): Define the set of the qualified keys instead of leaving
	// it as an arbitrary string.
	GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error)
	// RequireTransportSecurity indicates whether the credentails requires
	// transport security.
	RequireTransportSecurity() bool
}

type ProtocolInfo struct {
	// ProtocolVersion is the gRPC wire protocol version.
	ProtocolVersion string
	// SecurityProtocol is the security protocol in use.
	SecurityProtocol string
	// SecurityVersion is the security protocol version.
	SecurityVersion string
}

type TLSInfo struct {
	State tls.ConnectionState
}

type TransportAuthenticator interface {
	// ClientHandshake does the authentication handshake specified by the corresponding
	// authentication protocol on rawConn for clients. It returns the authenticated
	// connection and the corresponding auth information about the connection.
	ClientHandshake(addr string, rawConn net.Conn, timeout time.Duration) (net.Conn, AuthInfo, error)
	// ServerHandshake does the authentication handshake for servers. It returns
	// the authenticated connection and the corresponding auth information about
	// the connection.
	ServerHandshake(rawConn net.Conn) (net.Conn, AuthInfo, error)
	// Info provides the ProtocolInfo of this TransportAuthenticator.
	Info() ProtocolInfo
	Credentials
}