[#3] signature: Refactor sign and verify

Split methods to separate files, drop redundant intefaces

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

signature/body.go

@@ -0,0 +1,115 @@
+package signature
+
+import (
+	"fmt"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/accounting"
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/container"
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/netmap"
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/reputation"
+	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session"
+)
+
+func serviceMessageBody(req interface{}) stableMarshaler {
+	switch v := req.(type) {
+	default:
+		panic(fmt.Sprintf("unsupported session message %T", req))
+
+		/* Accounting */
+	case *accounting.BalanceRequest:
+		return v.GetBody()
+	case *accounting.BalanceResponse:
+		return v.GetBody()
+
+		/* Session */
+	case *session.CreateRequest:
+		return v.GetBody()
+	case *session.CreateResponse:
+		return v.GetBody()
+
+		/* Container */
+	case *container.PutRequest:
+		return v.GetBody()
+	case *container.PutResponse:
+		return v.GetBody()
+	case *container.DeleteRequest:
+		return v.GetBody()
+	case *container.DeleteResponse:
+		return v.GetBody()
+	case *container.GetRequest:
+		return v.GetBody()
+	case *container.GetResponse:
+		return v.GetBody()
+	case *container.ListRequest:
+		return v.GetBody()
+	case *container.ListResponse:
+		return v.GetBody()
+	case *container.SetExtendedACLRequest:
+		return v.GetBody()
+	case *container.SetExtendedACLResponse:
+		return v.GetBody()
+	case *container.GetExtendedACLRequest:
+		return v.GetBody()
+	case *container.GetExtendedACLResponse:
+		return v.GetBody()
+	case *container.AnnounceUsedSpaceRequest:
+		return v.GetBody()
+	case *container.AnnounceUsedSpaceResponse:
+		return v.GetBody()
+
+		/* Object */
+	case *object.PutRequest:
+		return v.GetBody()
+	case *object.PutResponse:
+		return v.GetBody()
+	case *object.GetRequest:
+		return v.GetBody()
+	case *object.GetResponse:
+		return v.GetBody()
+	case *object.HeadRequest:
+		return v.GetBody()
+	case *object.HeadResponse:
+		return v.GetBody()
+	case *object.SearchRequest:
+		return v.GetBody()
+	case *object.SearchResponse:
+		return v.GetBody()
+	case *object.DeleteRequest:
+		return v.GetBody()
+	case *object.DeleteResponse:
+		return v.GetBody()
+	case *object.GetRangeRequest:
+		return v.GetBody()
+	case *object.GetRangeResponse:
+		return v.GetBody()
+	case *object.GetRangeHashRequest:
+		return v.GetBody()
+	case *object.GetRangeHashResponse:
+		return v.GetBody()
+
+		/* Netmap */
+	case *netmap.LocalNodeInfoRequest:
+		return v.GetBody()
+	case *netmap.LocalNodeInfoResponse:
+		return v.GetBody()
+	case *netmap.NetworkInfoRequest:
+		return v.GetBody()
+	case *netmap.NetworkInfoResponse:
+		return v.GetBody()
+	case *netmap.SnapshotRequest:
+		return v.GetBody()
+	case *netmap.SnapshotResponse:
+		return v.GetBody()
+
+		/* Reputation */
+	case *reputation.AnnounceLocalTrustRequest:
+		return v.GetBody()
+	case *reputation.AnnounceLocalTrustResponse:
+		return v.GetBody()
+	case *reputation.AnnounceIntermediateResultRequest:
+		return v.GetBody()
+	case *reputation.AnnounceIntermediateResultResponse:
+		return v.GetBody()
+	}
+}