1 files changed, 103 insertions, 0 deletions
diff --git a/vendor/gopkg.in/asn1-ber.v1/identifier.go b/vendor/gopkg.in/asn1-ber.v1/identifier.go
new file mode 100644
index 000000000..f7672a844
--- /dev/null
+++ b/vendor/gopkg.in/asn1-ber.v1/identifier.go
@@ -0,0 +1,103 @@
+package ber
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"math"
+)
+
+func readIdentifier(reader io.Reader) (Identifier, int, error) {
+	identifier := Identifier{}
+	read := 0
+
+	// identifier byte
+	b, err := readByte(reader)
+	if err != nil {
+		if Debug {
+			fmt.Printf("error reading identifier byte: %v\n", err)
+		}
+		return Identifier{}, read, err
+	}
+	read++
+
+	identifier.ClassType = Class(b) & ClassBitmask
+	identifier.TagType = Type(b) & TypeBitmask
+
+	if tag := Tag(b) & TagBitmask; tag != HighTag {
+		// short-form tag
+		identifier.Tag = tag
+		return identifier, read, nil
+	}
+
+	// high-tag-number tag
+	tagBytes := 0
+	for {
+		b, err := readByte(reader)
+		if err != nil {
+			if Debug {
+				fmt.Printf("error reading high-tag-number tag byte %d: %v\n", tagBytes, err)
+			}
+			return Identifier{}, read, err
+		}
+		tagBytes++
+		read++
+
+		// Lowest 7 bits get appended to the tag value (x.690, 8.1.2.4.2.b)
+		identifier.Tag <<= 7
+		identifier.Tag |= Tag(b) & HighTagValueBitmask
+
+		// First byte may not be all zeros (x.690, 8.1.2.4.2.c)
+		if tagBytes == 1 && identifier.Tag == 0 {
+			return Identifier{}, read, errors.New("invalid first high-tag-number tag byte")
+		}
+		// Overflow of int64
+		// TODO: support big int tags?
+		if tagBytes > 9 {
+			return Identifier{}, read, errors.New("high-tag-number tag overflow")
+		}
+
+		// Top bit of 0 means this is the last byte in the high-tag-number tag (x.690, 8.1.2.4.2.a)
+		if Tag(b)&HighTagContinueBitmask == 0 {
+			break
+		}
+	}
+
+	return identifier, read, nil
+}
+
+func encodeIdentifier(identifier Identifier) []byte {
+	b := []byte{0x0}
+	b[0] |= byte(identifier.ClassType)
+	b[0] |= byte(identifier.TagType)
+
+	if identifier.Tag < HighTag {
+		// Short-form
+		b[0] |= byte(identifier.Tag)
+	} else {
+		// high-tag-number
+		b[0] |= byte(HighTag)
+
+		tag := identifier.Tag
+
+		highBit := uint(63)
+		for {
+			if tag&(1<<highBit) != 0 {
+				break
+			}
+			highBit--
+		}
+
+		tagBytes := int(math.Ceil(float64(highBit) / 7.0))
+		for i := tagBytes - 1; i >= 0; i-- {
+			offset := uint(i) * 7
+			mask := Tag(0x7f) << offset
+			tagByte := (tag & mask) >> offset
+			if i != 0 {
+				tagByte |= 0x80
+			}
+			b = append(b, byte(tagByte))
+		}
+	}
+	return b
+}