session: implement gRPC session creator

session/create.go

@@ -0,0 +1,67 @@
+package session
+
+import (
+	"context"
+	"crypto/ecdsa"
+
+	"github.com/nspcc-dev/neofs-api-go/internal"
+	"github.com/nspcc-dev/neofs-api-go/service"
+	crypto "github.com/nspcc-dev/neofs-crypto"
+	"google.golang.org/grpc"
+)
+
+type gRPCCreator struct {
+	conn *grpc.ClientConn
+
+	key *ecdsa.PrivateKey
+
+	clientFunc func(*grpc.ClientConn) SessionClient
+}
+
+const ErrNilCreateParamsSource = internal.Error("create params source is nil")
+
+const ErrNilGPRCClientConn = internal.Error("gRPC client connection is nil")
+
+// NewGRPCCreator unites virtual gRPC client with private ket and returns Creator interface.
+//
+// If passed ClientConn is nil, ErrNilGPRCClientConn returns.
+// If passed private key is nil, crypto.ErrEmptyPrivateKey returns.
+func NewGRPCCreator(conn *grpc.ClientConn, key *ecdsa.PrivateKey) (Creator, error) {
+	if conn == nil {
+		return nil, ErrNilGPRCClientConn
+	} else if key == nil {
+		return nil, crypto.ErrEmptyPrivateKey
+	}
+
+	return &gRPCCreator{
+		conn: conn,
+
+		key: key,
+
+		clientFunc: NewSessionClient,
+	}, nil
+}
+
+// Create constructs message, signs it with private key and sends it to a gRPC client.
+//
+// If passed CreateParamsSource is nil, ErrNilCreateParamsSource returns.
+// If message could not be signed, an error returns.
+func (s gRPCCreator) Create(ctx context.Context, p CreateParamsSource) (CreateResult, error) {
+	if p == nil {
+		return nil, ErrNilCreateParamsSource
+	}
+
+	// create and fill a message
+	req := new(CreateRequest)
+	req.SetOwnerID(p.GetOwnerID())
+	req.SetCreationEpoch(p.CreationEpoch())
+	req.SetExpirationEpoch(p.ExpirationEpoch())
+
+	// sign with private key
+	if err := service.SignDataWithSessionToken(s.key, req); err != nil {
+		return nil, err
+	}
+
+	// make gRPC call
+	return s.clientFunc(s.conn).Create(ctx, req)
+}