micro/registry/mdns/encoding.go

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
}