chore: remove code for 0.12 backwards compatibility in protocol support (#5622)

internal/daemon/worker/handler.go

@@ -30,17 +30,10 @@ import (
 	"github.com/hashicorp/nodeenrollment"
 	"github.com/hashicorp/nodeenrollment/types"
 	"google.golang.org/protobuf/proto"
-	"google.golang.org/protobuf/types/known/anypb"
 	"google.golang.org/protobuf/types/known/timestamppb"
 	"nhooyr.io/websocket"
 )
 
-var GetProtocolContext = nilProtocolContext
-
-func nilProtocolContext(context.Context, string, session.Session, string) (*anypb.Any, error) {
-	return nil, nil
-}
-
 type HandlerProperties struct {
 	ListenerConfig *listenerutil.ListenerConfig
 }
@@ -267,14 +260,6 @@ func (w *Worker) handleProxy(listenerCfg *listenerutil.ListenerConfig, sessionMa
 			return
 		}
 		protocolCtx := acResp.GetProtocolContext()
-		if protocolCtx == nil {
-			// TODO: Remove this if block once pre v0.12.0 controllers are no longer supported.
-			if protocolCtx, err = GetProtocolContext(ctx, workerId, sess, endpointUrl.Scheme); err != nil {
-				conn.Close(proxyHandlers.WebsocketStatusProtocolSetupError, "unable to get proxy context")
-				event.WriteError(ctx, op, err)
-				return
-			}
-		}
 
 		pDialer, err := proxyHandlers.GetEndpointDialer(ctx, endpointUrl.Host, workerId, acResp, w.downstreamReceiver, proxyHandlers.WithDnsServerAddress(w.conf.WorkerDnsServer))
 		if err != nil {