Remove custom internal contextID codec in favour of multicodec

Use the same multicodec that identifies transport over graphsync for
filecoinv1 internally to encode context ID as CID, used by the
standalone retrieval server implemented in cardatatransfer.

Because the transport they use is the same as what the multicodec
represents.

cardatatransfer/cardatatransfer.go

@@ -42,11 +42,6 @@ type carDataTransfer struct {
 	stores   *stores.ReadOnlyBlockstores
 }
 
-// TBD: this is really for internal use only
-// -- maybe we find something that doesn't overlap a protocol range?
-
-const ContextIDCodec multicodec.Code = 0x300001
-
 func StartCarDataTransfer(dt datatransfer.Manager, supplier BlockStoreSupplier) error {
 	cdt := &carDataTransfer{
 		dt:       dt,
@@ -72,7 +67,7 @@ func StartCarDataTransfer(dt datatransfer.Manager, supplier BlockStoreSupplier)
 func MetadataFromContextID(contextID []byte) (stiapi.Metadata, error) {
 	pieceCid, err := cid.Prefix{
 		Version:  1,
-		Codec:    uint64(ContextIDCodec),
+		Codec:    uint64(multicodec.TransportGraphsyncFilecoinv1),
 		MhType:   multihash.IDENTITY,
 		MhLength: -1,
 	}.Sum(contextID)
@@ -148,7 +143,7 @@ func (cdt *carDataTransfer) attemptAcceptDeal(providerDealID ProviderDealID, pro
 
 	// get contextID
 	prefix := proposal.PieceCID.Prefix()
-	if prefix.Codec != uint64(ContextIDCodec) {
+	if prefix.Codec != uint64(multicodec.TransportGraphsyncFilecoinv1) {
 		return DealStatusErrored, errors.New("incorrect Piece CID codec")
 	}
 	if prefix.MhType != multihash.IDENTITY {

cmd/provider/import.go

@@ -11,6 +11,7 @@ import (
 	"github.com/filecoin-project/index-provider/cardatatransfer"
 	adminserver "github.com/filecoin-project/index-provider/server/admin/http"
 	stiapi "github.com/filecoin-project/storetheindex/api/v0"
+	"github.com/multiformats/go-multicodec"
 	"github.com/urfave/cli/v2"
 )
 
@@ -32,7 +33,7 @@ var (
 		Action:  doImportCar,
 	}
 	metadata = stiapi.Metadata{
-		ProtocolID: cardatatransfer.ContextIDCodec,
+		ProtocolID: multicodec.TransportGraphsyncFilecoinv1,
 	}
 )
 

engine/engine.go

@@ -10,7 +10,6 @@ import (
 	"github.com/filecoin-project/go-legs/dtsync"
 	"github.com/filecoin-project/go-legs/httpsync"
 	provider "github.com/filecoin-project/index-provider"
-	"github.com/filecoin-project/index-provider/cardatatransfer"
 	"github.com/filecoin-project/index-provider/engine/chunker"
 	stiapi "github.com/filecoin-project/storetheindex/api/v0"
 	"github.com/filecoin-project/storetheindex/api/v0/ingest/schema"
@@ -21,6 +20,7 @@ import (
 	logging "github.com/ipfs/go-log/v2"
 	"github.com/ipld/go-ipld-prime"
 	cidlink "github.com/ipld/go-ipld-prime/linking/cid"
+	"github.com/multiformats/go-multicodec"
 )
 
 const (
@@ -410,7 +410,7 @@ func (e *Engine) publishAdvForIndex(ctx context.Context, contextID []byte, metad
 		// The advertisement still requires a valid metadata even though
 		// metadata is not used for removal.  Create a valid empty metadata.
 		metadata = stiapi.Metadata{
-			ProtocolID: cardatatransfer.ContextIDCodec,
+			ProtocolID: multicodec.TransportGraphsyncFilecoinv1,
 		}
 	}