cryptobyte: add uint48 methods
Adds uint48 methods for cryptobyte.Builder and cryptobyte.String.
Supporting 48-bit unsigned integers is useful for working with protocols
that use them for sequence numbers, such as DTLS.
Fixes golang/go#61275
Change-Id: Ibe49422d37644b9212b28b123dc5e01850f7b05b
GitHub-Last-Rev: 11b388c240109c8f4ac23880645c901ce6d2f093
GitHub-Pull-Request: golang/crypto#265
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/508675
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Run-TryBot: Roland Shoemaker <roland@golang.org>
Auto-Submit: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/cryptobyte/builder.go b/cryptobyte/builder.go
index c05ac7d..cf254f5 100644
--- a/cryptobyte/builder.go
+++ b/cryptobyte/builder.go
@@ -95,6 +95,11 @@
b.add(byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
}
+// AddUint48 appends a big-endian, 48-bit value to the byte string.
+func (b *Builder) AddUint48(v uint64) {
+ b.add(byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
+}
+
// AddUint64 appends a big-endian, 64-bit value to the byte string.
func (b *Builder) AddUint64(v uint64) {
b.add(byte(v>>56), byte(v>>48), byte(v>>40), byte(v>>32), byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
diff --git a/cryptobyte/cryptobyte_test.go b/cryptobyte/cryptobyte_test.go
index dc90e81..9b55d52 100644
--- a/cryptobyte/cryptobyte_test.go
+++ b/cryptobyte/cryptobyte_test.go
@@ -179,6 +179,27 @@
}
}
+func TestUint48(t *testing.T) {
+ var b Builder
+ var u uint64 = 0xfefcff3cfdfc
+ b.AddUint48(u)
+ if err := builderBytesEq(&b, 254, 252, 255, 60, 253, 252); err != nil {
+ t.Error(err)
+ }
+
+ var s String = b.BytesOrPanic()
+ var v uint64
+ if !s.ReadUint48(&v) {
+ t.Error("ReadUint48() = false, want true")
+ }
+ if v != u {
+ t.Errorf("v = %x, want %x", v, u)
+ }
+ if len(s) != 0 {
+ t.Errorf("len(s) = %d, want 0", len(s))
+ }
+}
+
func TestUint64(t *testing.T) {
var b Builder
b.AddUint64(0xf2fefefcff3cfdfc)
diff --git a/cryptobyte/string.go b/cryptobyte/string.go
index 0531a3d..10692a8 100644
--- a/cryptobyte/string.go
+++ b/cryptobyte/string.go
@@ -81,6 +81,17 @@
return true
}
+// ReadUint48 decodes a big-endian, 48-bit value into out and advances over it.
+// It reports whether the read was successful.
+func (s *String) ReadUint48(out *uint64) bool {
+ v := s.read(6)
+ if v == nil {
+ return false
+ }
+ *out = uint64(v[0])<<40 | uint64(v[1])<<32 | uint64(v[2])<<24 | uint64(v[3])<<16 | uint64(v[4])<<8 | uint64(v[5])
+ return true
+}
+
// ReadUint64 decodes a big-endian, 64-bit value into out and advances over it.
// It reports whether the read was successful.
func (s *String) ReadUint64(out *uint64) bool {
