1 files changed, 248 insertions, 0 deletions
diff --git a/vendor/github.com/fullsailor/pkcs7/ber.go b/vendor/github.com/fullsailor/pkcs7/ber.go
new file mode 100644
index 000000000..89e96d30c
--- /dev/null
+++ b/vendor/github.com/fullsailor/pkcs7/ber.go
@@ -0,0 +1,248 @@
+package pkcs7
+
+import (
+	"bytes"
+	"errors"
+)
+
+// var encodeIndent = 0
+
+type asn1Object interface {
+	EncodeTo(writer *bytes.Buffer) error
+}
+
+type asn1Structured struct {
+	tagBytes []byte
+	content  []asn1Object
+}
+
+func (s asn1Structured) EncodeTo(out *bytes.Buffer) error {
+	//fmt.Printf("%s--> tag: % X\n", strings.Repeat("| ", encodeIndent), s.tagBytes)
+	//encodeIndent++
+	inner := new(bytes.Buffer)
+	for _, obj := range s.content {
+		err := obj.EncodeTo(inner)
+		if err != nil {
+			return err
+		}
+	}
+	//encodeIndent--
+	out.Write(s.tagBytes)
+	encodeLength(out, inner.Len())
+	out.Write(inner.Bytes())
+	return nil
+}
+
+type asn1Primitive struct {
+	tagBytes []byte
+	length   int
+	content  []byte
+}
+
+func (p asn1Primitive) EncodeTo(out *bytes.Buffer) error {
+	_, err := out.Write(p.tagBytes)
+	if err != nil {
+		return err
+	}
+	if err = encodeLength(out, p.length); err != nil {
+		return err
+	}
+	//fmt.Printf("%s--> tag: % X length: %d\n", strings.Repeat("| ", encodeIndent), p.tagBytes, p.length)
+	//fmt.Printf("%s--> content length: %d\n", strings.Repeat("| ", encodeIndent), len(p.content))
+	out.Write(p.content)
+
+	return nil
+}
+
+func ber2der(ber []byte) ([]byte, error) {
+	if len(ber) == 0 {
+		return nil, errors.New("ber2der: input ber is empty")
+	}
+	//fmt.Printf("--> ber2der: Transcoding %d bytes\n", len(ber))
+	out := new(bytes.Buffer)
+
+	obj, _, err := readObject(ber, 0)
+	if err != nil {
+		return nil, err
+	}
+	obj.EncodeTo(out)
+
+	// if offset < len(ber) {
+	//	return nil, fmt.Errorf("ber2der: Content longer than expected. Got %d, expected %d", offset, len(ber))
+	//}
+
+	return out.Bytes(), nil
+}
+
+// encodes lengths that are longer than 127 into string of bytes
+func marshalLongLength(out *bytes.Buffer, i int) (err error) {
+	n := lengthLength(i)
+
+	for ; n > 0; n-- {
+		err = out.WriteByte(byte(i >> uint((n-1)*8)))
+		if err != nil {
+			return
+		}
+	}
+
+	return nil
+}
+
+// computes the byte length of an encoded length value
+func lengthLength(i int) (numBytes int) {
+	numBytes = 1
+	for i > 255 {
+		numBytes++
+		i >>= 8
+	}
+	return
+}
+
+// encodes the length in DER format
+// If the length fits in 7 bits, the value is encoded directly.
+//
+// Otherwise, the number of bytes to encode the length is first determined.
+// This number is likely to be 4 or less for a 32bit length. This number is
+// added to 0x80. The length is encoded in big endian encoding follow after
+//
+// Examples:
+//  length | byte 1 | bytes n
+//  0      | 0x00   | -
+//  120    | 0x78   | -
+//  200    | 0x81   | 0xC8
+//  500    | 0x82   | 0x01 0xF4
+//
+func encodeLength(out *bytes.Buffer, length int) (err error) {
+	if length >= 128 {
+		l := lengthLength(length)
+		err = out.WriteByte(0x80 | byte(l))
+		if err != nil {
+			return
+		}
+		err = marshalLongLength(out, length)
+		if err != nil {
+			return
+		}
+	} else {
+		err = out.WriteByte(byte(length))
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+func readObject(ber []byte, offset int) (asn1Object, int, error) {
+	//fmt.Printf("\n====> Starting readObject at offset: %d\n\n", offset)
+	tagStart := offset
+	b := ber[offset]
+	offset++
+	tag := b & 0x1F // last 5 bits
+	if tag == 0x1F {
+		tag = 0
+		for ber[offset] >= 0x80 {
+			tag = tag*128 + ber[offset] - 0x80
+			offset++
+		}
+		tag = tag*128 + ber[offset] - 0x80
+		offset++
+	}
+	tagEnd := offset
+
+	kind := b & 0x20
+	/*
+		if kind == 0 {
+			fmt.Print("--> Primitive\n")
+		} else {
+			fmt.Print("--> Constructed\n")
+		}
+	*/
+	// read length
+	var length int
+	l := ber[offset]
+	offset++
+	indefinite := false
+	if l > 0x80 {
+		numberOfBytes := (int)(l & 0x7F)
+		if numberOfBytes > 4 { // int is only guaranteed to be 32bit
+			return nil, 0, errors.New("ber2der: BER tag length too long")
+		}
+		if numberOfBytes == 4 && (int)(ber[offset]) > 0x7F {
+			return nil, 0, errors.New("ber2der: BER tag length is negative")
+		}
+		if 0x0 == (int)(ber[offset]) {
+			return nil, 0, errors.New("ber2der: BER tag length has leading zero")
+		}
+		//fmt.Printf("--> (compute length) indicator byte: %x\n", l)
+		//fmt.Printf("--> (compute length) length bytes: % X\n", ber[offset:offset+numberOfBytes])
+		for i := 0; i < numberOfBytes; i++ {
+			length = length*256 + (int)(ber[offset])
+			offset++
+		}
+	} else if l == 0x80 {
+		indefinite = true
+	} else {
+		length = (int)(l)
+	}
+
+	//fmt.Printf("--> length        : %d\n", length)
+	contentEnd := offset + length
+	if contentEnd > len(ber) {
+		return nil, 0, errors.New("ber2der: BER tag length is more than available data")
+	}
+	//fmt.Printf("--> content start : %d\n", offset)
+	//fmt.Printf("--> content end   : %d\n", contentEnd)
+	//fmt.Printf("--> content       : % X\n", ber[offset:contentEnd])
+	var obj asn1Object
+	if indefinite && kind == 0 {
+		return nil, 0, errors.New("ber2der: Indefinite form tag must have constructed encoding")
+	}
+	if kind == 0 {
+		obj = asn1Primitive{
+			tagBytes: ber[tagStart:tagEnd],
+			length:   length,
+			content:  ber[offset:contentEnd],
+		}
+	} else {
+		var subObjects []asn1Object
+		for (offset < contentEnd) || indefinite {
+			var subObj asn1Object
+			var err error
+			subObj, offset, err = readObject(ber, offset)
+			if err != nil {
+				return nil, 0, err
+			}
+			subObjects = append(subObjects, subObj)
+
+			if indefinite {
+				terminated, err := isIndefiniteTermination(ber, offset)
+				if err != nil {
+					return nil, 0, err
+				}
+
+				if terminated {
+					break
+				}
+			}
+		}
+		obj = asn1Structured{
+			tagBytes: ber[tagStart:tagEnd],
+			content:  subObjects,
+		}
+	}
+
+	// Apply indefinite form length with 0x0000 terminator.
+	if indefinite {
+		contentEnd = offset + 2
+	}
+
+	return obj, contentEnd, nil
+}
+
+func isIndefiniteTermination(ber []byte, offset int) (bool, error) {
+	if len(ber) - offset < 2 {
+		return false, errors.New("ber2der: Invalid BER format")
+	}
+
+	return bytes.Index(ber[offset:], []byte{0x0, 0x0}) == 0, nil
+}