1 files changed, 66 insertions, 0 deletions
diff --git a/vendor/github.com/getlantern/hidden/hidden.go b/vendor/github.com/getlantern/hidden/hidden.go
new file mode 100644
index 0000000..0c52b08
--- /dev/null
+++ b/vendor/github.com/getlantern/hidden/hidden.go
@@ -0,0 +1,66 @@
+// Package hidden provides the ability to "hide" binary data in a string using
+// a hex encoding with non-printing characters. Hidden data is demarcated with
+// a leading and trailing NUL character.
+package hidden
+
+import (
+	"bytes"
+	"fmt"
+	"regexp"
+
+	"github.com/getlantern/hex"
+)
+
+// 16 non-printing characters
+const hextable = "\x01\x02\x03\x04\x05\x06\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17"
+
+var (
+	hexencoding = hex.NewEncoding(hextable)
+
+	re *regexp.Regexp
+)
+
+func init() {
+	var err error
+	re, err = regexp.Compile(fmt.Sprintf("\x00[%v]+\x00", hextable))
+	if err != nil {
+		panic(err)
+	}
+}
+
+// ToString encodes the given data as a hidden string, including leadnig and
+// trailing NULs.
+func ToString(data []byte) string {
+	buf := bytes.NewBuffer(make([]byte, 0, 2+hex.EncodedLen(len(data))))
+	// Leading NUL
+	buf.WriteByte(0)
+	buf.WriteString(hexencoding.EncodeToString(data))
+	// Trailing NUL
+	buf.WriteByte(0)
+	return buf.String()
+}
+
+// FromString extracts the hidden data from a string, which is expected to
+// contain leading and trailing NULs.
+func FromString(str string) ([]byte, error) {
+	return hexencoding.DecodeString(str[1 : len(str)-1])
+}
+
+// Extract extracts all hidden data from an arbitrary string.
+func Extract(str string) ([][]byte, error) {
+	m := re.FindAllString(str, -1)
+	result := make([][]byte, 0, len(m))
+	for _, s := range m {
+		b, err := FromString(s)
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, b)
+	}
+	return result, nil
+}
+
+// Clean removes any hidden data from an arbitrary string.
+func Clean(str string) string {
+	return re.ReplaceAllString(str, "")
+}