all: sync with master; upd chlog

internal/client/client.go

@@ -3,3 +3,52 @@
 //
 // TODO(a.garipov): Expand.
 package client
+
+import (
+	"encoding"
+	"fmt"
+)
+
+// Source represents the source from which the information about the client has
+// been obtained.
+type Source uint8
+
+// Clients information sources.  The order determines the priority.
+const (
+	SourceNone Source = iota
+	SourceWHOIS
+	SourceARP
+	SourceRDNS
+	SourceDHCP
+	SourceHostsFile
+	SourcePersistent
+)
+
+// type check
+var _ fmt.Stringer = Source(0)
+
+// String returns a human-readable name of cs.
+func (cs Source) String() (s string) {
+	switch cs {
+	case SourceWHOIS:
+		return "WHOIS"
+	case SourceARP:
+		return "ARP"
+	case SourceRDNS:
+		return "rDNS"
+	case SourceDHCP:
+		return "DHCP"
+	case SourceHostsFile:
+		return "etc/hosts"
+	default:
+		return ""
+	}
+}
+
+// type check
+var _ encoding.TextMarshaler = Source(0)
+
+// MarshalText implements encoding.TextMarshaler for the Source.
+func (cs Source) MarshalText() (text []byte, err error) {
+	return []byte(cs.String()), nil
+}