[#577] cmd/node: Add node section to config

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-node/config/node/config.go

@@ -0,0 +1,81 @@
+package nodeconfig
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+
+	"github.com/nspcc-dev/neofs-node/cmd/neofs-node/config"
+	"github.com/nspcc-dev/neofs-node/pkg/network"
+)
+
+const (
+	subsection = "node"
+
+	attributePrefix = "attribute"
+)
+
+var (
+	errKeyNotSet     = errors.New("empty/not set key address, see `node.key` section")
+	errAddressNotSet = errors.New("empty/not set bootstrap address, see `node.address` section")
+)
+
+// Key returns value of "key" config parameter
+// from "node" section.
+//
+// Panics if value is not a non-empty string.
+func Key(c *config.Config) string {
+	v := config.StringSafe(c.Sub(subsection), "key")
+	if v == "" {
+		panic(errKeyNotSet)
+	}
+
+	// TODO: add string -> `ecdsa.PrivateKey` parsing logic
+	// after https://github.com/nspcc-dev/neofs-node/pull/569.
+
+	return v
+}
+
+// BootstrapAddress returns value of "address" config parameter
+// from "node" section as network.Address.
+//
+// Panics if value is not a valid NeoFS network address
+func BootstrapAddress(c *config.Config) *network.Address {
+	v := config.StringSafe(c.Sub(subsection), "address")
+	if v == "" {
+		panic(errAddressNotSet)
+	}
+
+	addr, err := network.AddressFromString(v)
+	if err != nil {
+		panic(fmt.Errorf("could not convert bootstrap address %s to %T: %w", v, addr, err))
+	}
+
+	return addr
+}
+
+// Attributes returns list of config parameters
+// from "node" section that are set in "attribute_i" format,
+// where i in range [0,100).
+func Attributes(c *config.Config) (attrs []string) {
+	const maxAttributes = 100
+
+	for i := 0; i < maxAttributes; i++ {
+		attr := config.StringSafe(c.Sub(subsection), attributePrefix+"_"+strconv.Itoa(i))
+		if attr == "" {
+			return
+		}
+
+		attrs = append(attrs, attr)
+	}
+
+	return
+}
+
+// Relay returns value of "relay" config parameter
+// from "node" section.
+//
+// Returns false if value is not set.
+func Relay(c *config.Config) bool {
+	return config.BoolSafe(c.Sub(subsection), "relay")
+}