Basic DHT functions

1 files changed, 103 insertions, 0 deletions

diff --git a/dht/krpc.go b/dht/krpc.go
new file mode 100644
index 0000000..a926e81
--- /dev/null
+++ b/dht/krpc.go
@@ -0,0 +1,103 @@
+package dht
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"net"
+)
+
+const transIDBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+func newTransactionID() string {
+	b := make([]byte, 2)
+	for i := range b {
+		b[i] = transIDBytes[rand.Int63()%int64(len(transIDBytes))]
+	}
+	return string(b)
+}
+
+// makeQuery returns a query-formed data.
+func makeQuery(t, q string, a map[string]interface{}) map[string]interface{} {
+	return map[string]interface{}{
+		"t": t,
+		"y": "q",
+		"q": q,
+		"a": a,
+	}
+}
+
+// makeResponse returns a response-formed data.
+func makeResponse(t string, r map[string]interface{}) map[string]interface{} {
+	return map[string]interface{}{
+		"t": t,
+		"y": "r",
+		"r": r,
+	}
+}
+
+// parseMessage parses the basic data received from udp.
+// It returns a map value.
+func parseMessage(data interface{}) (map[string]interface{}, error) {
+	response, ok := data.(map[string]interface{})
+	if !ok {
+		return nil, errors.New("response is not dict")
+	}
+
+	if err := checkKeys(response, [][]string{{"t", "string"}, {"y", "string"}}); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+// parseKeys parses keys. It just wraps parseKey.
+func checkKeys(data map[string]interface{}, pairs [][]string) (err error) {
+	for _, args := range pairs {
+		key, t := args[0], args[1]
+		if err = checkKey(data, key, t); err != nil {
+			break
+		}
+	}
+	return err
+}
+
+// parseKey parses the key in dict data. `t` is type of the keyed value.
+// It's one of "int", "string", "map", "list".
+func checkKey(data map[string]interface{}, key string, t string) error {
+	val, ok := data[key]
+	if !ok {
+		return fmt.Errorf("krpc: missing key %s", key)
+	}
+
+	switch t {
+	case "string":
+		_, ok = val.(string)
+	case "int":
+		_, ok = val.(int)
+	case "map":
+		_, ok = val.(map[string]interface{})
+	case "list":
+		_, ok = val.([]interface{})
+	default:
+		return errors.New("krpc: invalid type")
+	}
+
+	if !ok {
+		return errors.New("krpc: key type mismatch")
+	}
+
+	return nil
+}
+
+// Swiped from nictuku
+func compactNodeInfoToString(cni string) string {
+	if len(cni) == 6 {
+		return fmt.Sprintf("%d.%d.%d.%d:%d", cni[0], cni[1], cni[2], cni[3], (uint16(cni[4])<<8)|uint16(cni[5]))
+	} else if len(cni) == 18 {
+		b := []byte(cni[:16])
+		return fmt.Sprintf("[%s]:%d", net.IP.String(b), (uint16(cni[16])<<8)|uint16(cni[17]))
+	} else {
+		return ""
+	}
+}