First attempt at mdns

registry/mdns/encoding.go

@@ -0,0 +1,124 @@
+package mdns
+
+import (
+	"bytes"
+	"compress/zlib"
+	"encoding/hex"
+	"encoding/json"
+	"io/ioutil"
+
+	"github.com/micro/go-micro/registry"
+)
+
+func encode(buf []byte) string {
+	var b bytes.Buffer
+	defer b.Reset()
+
+	w := zlib.NewWriter(&b)
+	if _, err := w.Write(buf); err != nil {
+		return ""
+	}
+	w.Close()
+
+	return hex.EncodeToString(b.Bytes())
+}
+
+func decode(d string) []byte {
+	hr, err := hex.DecodeString(d)
+	if err != nil {
+		return nil
+	}
+
+	br := bytes.NewReader(hr)
+	zr, err := zlib.NewReader(br)
+	if err != nil {
+		return nil
+	}
+
+	rbuf, err := ioutil.ReadAll(zr)
+	if err != nil {
+		return nil
+	}
+
+	return rbuf
+}
+
+func encodeEndpoints(en []*registry.Endpoint) []string {
+	var tags []string
+	for _, e := range en {
+		if b, err := json.Marshal(e); err == nil {
+			tags = append(tags, "e-"+encode(b))
+		}
+	}
+	return tags
+}
+
+func decodeEndpoints(tags []string) []*registry.Endpoint {
+	var en []*registry.Endpoint
+
+	for _, tag := range tags {
+		if len(tag) == 0 || tag[0] != 'e' || tag[1] != '-' {
+			continue
+		}
+
+		buf := decode(tag[2:])
+
+		var e *registry.Endpoint
+		if err := json.Unmarshal(buf, &e); err == nil {
+			en = append(en, e)
+		}
+	}
+	return en
+}
+
+func encodeMetadata(md map[string]string) []string {
+	var tags []string
+	for k, v := range md {
+		if b, err := json.Marshal(map[string]string{
+			k: v,
+		}); err == nil {
+			// new encoding
+			tags = append(tags, "t-"+encode(b))
+		}
+	}
+	return tags
+}
+
+func decodeMetadata(tags []string) map[string]string {
+	md := make(map[string]string)
+
+	for _, tag := range tags {
+		if len(tag) == 0 || tag[0] != 't' || tag[1] != '-' {
+			continue
+		}
+
+		buf := decode(tag[2:])
+
+		var kv map[string]string
+
+		// Now unmarshal
+		if err := json.Unmarshal(buf, &kv); err == nil {
+			for k, v := range kv {
+				md[k] = v
+			}
+		}
+	}
+	return md
+}
+
+func encodeVersion(v string) []string {
+	return []string{
+		// new encoding,
+		"v-" + encode([]byte(v)),
+	}
+}
+
+func decodeVersion(tags []string) (string, bool) {
+	for _, tag := range tags {
+		if len(tag) < 2 || tag[0] != 'v' || tag[1] != '-' {
+			continue
+		}
+		return string(decode(tag[2:])), true
+	}
+	return "", false
+}