[#83] pkg/client: Support status returns

Make all `Client` methods to return structured values and error. Parse v2
status messages in all RPC and provide status getter from all result
structures. Returns status failures as status result instead of error.

Interface changes:
  * all methods return `<method>Res` structure;
  * rename some methods to be more clear;
  * unify TZ and SHA256 objecy payload hashing in single method.

Behavior changes:
  * client doesn't verify object header structure received via Object.Head.
    If the caller was tied to verification, now it must do it explicitly.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

client/netmap.go

@@ -17,10 +17,10 @@ type Netmap interface {
 	// EndpointInfo returns attributes, address and public key of the node, specified
 	// in client constructor via address or open connection. This can be used as a
 	// health check to see if node is alive and responses to requests.
-	EndpointInfo(context.Context, ...CallOption) (*EndpointInfo, error)
+	EndpointInfo(context.Context, ...CallOption) (*EndpointInfoRes, error)
 
 	// NetworkInfo returns information about the NeoFS network of which the remote server is a part.
-	NetworkInfo(context.Context, ...CallOption) (*netmap.NetworkInfo, error)
+	NetworkInfo(context.Context, ...CallOption) (*NetworkInfoRes, error)
 }
 
 // EACLWithSignature represents eACL table/signature pair.
@@ -40,10 +40,24 @@ func (e *EndpointInfo) NodeInfo() *netmap.NodeInfo {
 	return e.ni
 }
 
+type EndpointInfoRes struct {
+	statusRes
+
+	info *EndpointInfo
+}
+
+func (x EndpointInfoRes) Info() *EndpointInfo {
+	return x.info
+}
+
+func (x *EndpointInfoRes) setInfo(info *EndpointInfo) {
+	x.info = info
+}
+
 // EndpointInfo returns attributes, address and public key of the node, specified
 // in client constructor via address or open connection. This can be used as a
 // health check to see if node is alive and responses to requests.
-func (c *clientImpl) EndpointInfo(ctx context.Context, opts ...CallOption) (*EndpointInfo, error) {
+func (c *clientImpl) EndpointInfo(ctx context.Context, opts ...CallOption) (*EndpointInfoRes, error) {
 	// apply all available options
 	callOptions := c.defaultCallOptions()
 
@@ -67,26 +81,52 @@ func (c *clientImpl) EndpointInfo(ctx context.Context, opts ...CallOption) (*End
 		return nil, fmt.Errorf("transport error: %w", err)
 	}
 
-	// handle response meta info
-	if err := c.handleResponseInfoV2(callOptions, resp); err != nil {
-		return nil, err
-	}
+	var (
+		res     = new(EndpointInfoRes)
+		procPrm processResponseV2Prm
+		procRes processResponseV2Res
+	)
 
-	err = v2signature.VerifyServiceMessage(resp)
-	if err != nil {
-		return nil, fmt.Errorf("can't verify response message: %w", err)
+	procPrm.callOpts = callOptions
+	procPrm.resp = resp
+
+	procRes.statusRes = res
+
+	// process response in general
+	if c.processResponseV2(&procRes, procPrm) {
+		if procRes.cliErr != nil {
+			return nil, procRes.cliErr
+		}
+
+		return res, nil
 	}
 
 	body := resp.GetBody()
 
-	return &EndpointInfo{
+	res.setInfo(&EndpointInfo{
 		version: version.NewFromV2(body.GetVersion()),
 		ni:      netmap.NewNodeInfoFromV2(body.GetNodeInfo()),
-	}, nil
+	})
+
+	return res, nil
+}
+
+type NetworkInfoRes struct {
+	statusRes
+
+	info *netmap.NetworkInfo
+}
+
+func (x NetworkInfoRes) Info() *netmap.NetworkInfo {
+	return x.info
+}
+
+func (x *NetworkInfoRes) setInfo(info *netmap.NetworkInfo) {
+	x.info = info
 }
 
 // NetworkInfo returns information about the NeoFS network of which the remote server is a part.
-func (c *clientImpl) NetworkInfo(ctx context.Context, opts ...CallOption) (*netmap.NetworkInfo, error) {
+func (c *clientImpl) NetworkInfo(ctx context.Context, opts ...CallOption) (*NetworkInfoRes, error) {
 	// apply all available options
 	callOptions := c.defaultCallOptions()
 
@@ -110,15 +150,27 @@ func (c *clientImpl) NetworkInfo(ctx context.Context, opts ...CallOption) (*netm
 		return nil, fmt.Errorf("v2 NetworkInfo RPC failure: %w", err)
 	}
 
-	// handle response meta info
-	if err := c.handleResponseInfoV2(callOptions, resp); err != nil {
-		return nil, err
+	var (
+		res     = new(NetworkInfoRes)
+		procPrm processResponseV2Prm
+		procRes processResponseV2Res
+	)
+
+	procPrm.callOpts = callOptions
+	procPrm.resp = resp
+
+	procRes.statusRes = res
+
+	// process response in general
+	if c.processResponseV2(&procRes, procPrm) {
+		if procRes.cliErr != nil {
+			return nil, procRes.cliErr
+		}
+
+		return res, nil
 	}
 
-	err = v2signature.VerifyServiceMessage(resp)
-	if err != nil {
-		return nil, fmt.Errorf("response message verification failed: %w", err)
-	}
+	res.setInfo(netmap.NewNetworkInfoFromV2(resp.GetBody().GetNetworkInfo()))
 
-	return netmap.NewNetworkInfoFromV2(resp.GetBody().GetNetworkInfo()), nil
+	return res, nil
 }