Just need to check the last byte. (#89)

Author: robxyy

id.go

@@ -265,6 +265,10 @@ func decode(id *ID, src []byte) bool {
 	_ = id[11]
 
 	id[11] = dec[src[17]]<<6 | dec[src[18]]<<1 | dec[src[19]]>>4
+	// check the last byte
+	if encoding[(id[11]<<4)&0x1F] != src[19] {
+		return false
+	}
 	id[10] = dec[src[16]]<<3 | dec[src[17]]>>2
 	id[9] = dec[src[14]]<<5 | dec[src[15]]
 	id[8] = dec[src[12]]<<7 | dec[src[13]]<<2 | dec[src[14]]>>3
@@ -276,16 +280,7 @@ func decode(id *ID, src []byte) bool {
 	id[2] = dec[src[3]]<<4 | dec[src[4]]>>1
 	id[1] = dec[src[1]]<<6 | dec[src[2]]<<1 | dec[src[3]]>>4
 	id[0] = dec[src[0]]<<3 | dec[src[1]]>>2
-
-	// Validate that there are no discarer bits (padding) in src that would
-	// cause the string-encoded id not to equal src.
-	var check [4]byte
-
-	check[3] = encoding[(id[11]<<4)&0x1F]
-	check[2] = encoding[(id[11]>>1)&0x1F]
-	check[1] = encoding[(id[11]>>6)&0x1F|(id[10]<<2)&0x1F]
-	check[0] = encoding[id[10]>>3]
-	return bytes.Equal([]byte(src[16:20]), check[:])
+	return true
 }
 
 // Time returns the timestamp part of the id.

id_test.go

@@ -63,6 +63,23 @@ func TestIDPartsExtraction(t *testing.T) {
 	}
 }
 
+func TestPadding(t *testing.T) {
+	for i := 0; i < 100000; i++ {
+		wantBytes := make([]byte, 20)
+		wantBytes[19] = encoding[0]                       // 0
+		copy(wantBytes[0:13], []byte("c6e52g2mrqcjl")[:]) // c6e52g2mrqcjl44hf170
+		for j := 0; j < 6; j++ {
+			wantBytes[13+j] = encoding[rand.Intn(32)]
+		}
+		want := string(wantBytes)
+		id, _ := FromString(want)
+		got := id.String()
+		if got != want {
+			t.Errorf("String() = %v, want %v %v", got, want, wantBytes)
+		}
+	}
+}
+
 func TestNew(t *testing.T) {
 	// Generate 10 ids
 	ids := make([]ID, 10)