fix(ec): return the served shard identity and validate it client-side

The encode identity was only enforced server-side, so a pre-upgrade server
ignored the request field and served bytes unchecked. Echo the served
shard's EncodeTsNs on every read response chunk and have the client reject a
mismatch (including 0 from an old server), so the guard holds regardless of
server version; a rejected read recovers from parity.

weed/pb/volume_server.proto

@@ -486,6 +486,7 @@ message VolumeEcShardReadRequest {
 message VolumeEcShardReadResponse {
     bytes data = 1;
     bool is_deleted = 2;
+    int64 encode_ts_ns = 3; // identity of the shard actually served; client rejects a mismatch (0 = pre-upgrade server)
 }
 
 message VolumeEcBlobDeleteRequest {

weed/pb/volume_server_pb/volume_server.pb.go

@@ -3992,6 +3992,7 @@ type VolumeEcShardReadResponse struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Data          []byte                 `protobuf:"bytes,1,opt,name=data,proto3" json:"data,omitempty"`
 	IsDeleted     bool                   `protobuf:"varint,2,opt,name=is_deleted,json=isDeleted,proto3" json:"is_deleted,omitempty"`
+	EncodeTsNs    int64                  `protobuf:"varint,3,opt,name=encode_ts_ns,json=encodeTsNs,proto3" json:"encode_ts_ns,omitempty"` // identity of the shard actually served; client rejects a mismatch (0 = pre-upgrade server)
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -4040,6 +4041,13 @@ func (x *VolumeEcShardReadResponse) GetIsDeleted() bool {
 	return false
 }
 
+func (x *VolumeEcShardReadResponse) GetEncodeTsNs() int64 {
+	if x != nil {
+		return x.EncodeTsNs
+	}
+	return 0
+}
+
 type VolumeEcBlobDeleteRequest struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	VolumeId      uint32                 `protobuf:"varint,1,opt,name=volume_id,json=volumeId,proto3" json:"volume_id,omitempty"`
@@ -7289,11 +7297,13 @@ const file_volume_server_proto_rawDesc = "" +
 	"\x04size\x18\x04 \x01(\x03R\x04size\x12\x19\n" +
 	"\bfile_key\x18\x05 \x01(\x04R\afileKey\x12 \n" +
 	"\fencode_ts_ns\x18\a \x01(\x03R\n" +
-	"encodeTsNsJ\x04\b\x06\x10\a\"N\n" +
+	"encodeTsNsJ\x04\b\x06\x10\a\"p\n" +
 	"\x19VolumeEcShardReadResponse\x12\x12\n" +
 	"\x04data\x18\x01 \x01(\fR\x04data\x12\x1d\n" +
 	"\n" +
-	"is_deleted\x18\x02 \x01(\bR\tisDeleted\"\x8d\x01\n" +
+	"is_deleted\x18\x02 \x01(\bR\tisDeleted\x12 \n" +
+	"\fencode_ts_ns\x18\x03 \x01(\x03R\n" +
+	"encodeTsNs\"\x8d\x01\n" +
 	"\x19VolumeEcBlobDeleteRequest\x12\x1b\n" +
 	"\tvolume_id\x18\x01 \x01(\rR\bvolumeId\x12\x1e\n" +
 	"\n" +

weed/server/volume_grpc_erasure_coding.go

@@ -686,7 +686,8 @@ func (vs *VolumeServer) VolumeEcShardRead(req *volume_server_pb.VolumeEcShardRea
 		_, size, _ := ecVolume.FindNeedleFromEcx(types.Uint64ToNeedleId(req.FileKey))
 		if size.IsDeleted() {
 			return stream.Send(&volume_server_pb.VolumeEcShardReadResponse{
-				IsDeleted: true,
+				IsDeleted:  true,
+				EncodeTsNs: ecVolume.EncodeTsNs,
 			})
 		}
 	}
@@ -714,7 +715,8 @@ func (vs *VolumeServer) VolumeEcShardRead(req *volume_server_pb.VolumeEcShardRea
 				bytesread = int(bytesToRead)
 			}
 			err = stream.Send(&volume_server_pb.VolumeEcShardReadResponse{
-				Data: buffer[:bytesread],
+				Data:       buffer[:bytesread],
+				EncodeTsNs: ecVolume.EncodeTsNs,
 			})
 			if err != nil {
 				// println("sending", bytesread, "bytes err", err.Error())

weed/storage/store_ec.go

@@ -590,6 +590,12 @@ func (s *Store) doReadRemoteEcShardInterval(sourceDataNode pb.ServerAddress, nee
 			if receiveErr != nil {
 				return fmt.Errorf("receiving ec shard %d.%d from %s: %v", vid, shardId, sourceDataNode, receiveErr)
 			}
+			// Validate the served shard's identity client-side, so the guard holds
+			// even against a pre-upgrade server that ignored the request field (it
+			// returns 0). A mismatch fails the read; the caller recovers from parity.
+			if expectedEncodeTsNs != 0 && resp.EncodeTsNs != expectedEncodeTsNs {
+				return fmt.Errorf("ec shard %d.%d from %s belongs to a different encode run (want %d, got %d)", vid, shardId, sourceDataNode, expectedEncodeTsNs, resp.EncodeTsNs)
+			}
 			if resp.IsDeleted {
 				is_deleted = true
 			}