first commit

pkg/htools/UUID.go

@@ -0,0 +1,102 @@
+package htools
+
+import (
+	crand "crypto/rand"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	mrand "math/rand"
+	"regexp"
+	"strings"
+)
+
+// seeded indicates if math/rand has been seeded
+var seeded bool = false
+
+// uuidRegex matches the UUID string
+var uuidRegex *regexp.Regexp = regexp.MustCompile(`^\{?([a-fA-F0-9]{8})-?([a-fA-F0-9]{4})-?([a-fA-F0-9]{4})-?([a-fA-F0-9]{4})-?([a-fA-F0-9]{12})\}?$`)
+
+// UUID type.
+type UUID [16]byte
+
+// Hex returns a hex string representation of the UUID in xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx format.
+func (this UUID) Hex() string {
+
+	x := [16]byte(this)
+
+	return fmt.Sprintf("%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
+		x[0], x[1], x[2], x[3], x[4],
+		x[5], x[6],
+		x[7], x[8],
+		x[9], x[10], x[11], x[12], x[13], x[14], x[15])
+}
+
+// Rand generates a new version 4 UUID.
+func Rand() UUID {
+	var x [16]byte
+	randBytes(x[:])
+	x[6] = (x[6] & 0x0F) | 0x40
+	x[8] = (x[8] & 0x3F) | 0x80
+	return x
+}
+
+// FromStr returns a UUID based on a string.
+// The string could be in the following format:
+//
+// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+//
+// xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+//
+// {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+//
+// If the string is not in one of these formats, it'll return an error.
+func FromStr(s string) (id UUID, err error) {
+	if s == "" {
+		err = errors.New("Empty string")
+		return
+	}
+
+	parts := uuidRegex.FindStringSubmatch(s)
+	if parts == nil {
+		err = errors.New("Invalid string format")
+		return
+	}
+
+	var array [16]byte
+	slice, _ := hex.DecodeString(strings.Join(parts[1:], ""))
+	copy(array[:], slice)
+	id = array
+	return
+}
+
+// MustFromStr behaves similarly to FromStr except that it'll panic instead of
+// returning an error.
+func MustFromStr(s string) UUID {
+	id, err := FromStr(s)
+	if err != nil {
+		panic(err)
+	}
+	return id
+}
+
+// randBytes uses crypto random to get random numbers. If fails then it uses math random.
+func randBytes(x []byte) {
+
+	length := len(x)
+	n, err := crand.Read(x)
+
+	if n != length || err != nil {
+		for length > 0 {
+			length--
+			x[length] = byte(mrand.Int31n(256))
+		}
+	}
+}
+
+func GetUUID() string {
+
+	var uuid UUID = Rand()
+
+	return uuid.Hex()
+
+}