drafty types refactor with simple ascii packagergdd/sketch

types.go compiles but that is about it, here be dragons.  Pushing so
that we can get an idea of what this refactor would roughly look like.

2 files changed, 67 insertions, 0 deletions

diff --git a/pkg/types/binary/ssh/ssh.go b/pkg/types/binary/ssh/ssh.go
new file mode 100644
index 0000000..9693476
--- /dev/null
+++ b/pkg/types/binary/ssh/ssh.go
@@ -0,0 +1,34 @@
+// package ssh provides selected parts of the SSH data format, see:
+//
+//   - https://github.com/openssh/openssh-portable/blob/master/PROTOCOL.sshsig
+//   - https://datatracker.ietf.org/doc/html/rfc4251#section-5
+//
+package ssh
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// ToSignBlob outputs the raw bytes to be signed for a given namespace and
+// message.  The reserved string is empty and the specified hash is SHA256.
+func ToSignBlob(namespace string, hashedMessage []byte) []byte {
+	buf := bytes.NewBuffer(nil)
+
+	buf.Write([]byte("SSHSIG"))
+	addString(buf, namespace)
+	addString(buf, "")
+	addString(buf, "sha256")
+	addString(buf, string(hashedMessage[:]))
+
+	return buf.Bytes()
+}
+
+func addUint32(buf *bytes.Buffer, num uint32) {
+	binary.Write(buf, binary.BigEndian, num)
+}
+
+func addString(buf *bytes.Buffer, str string) {
+	addUint32(buf, uint32(len(str)))
+	buf.Write([]byte(str))
+}
diff --git a/pkg/types/binary/trunnel/trunnel.go b/pkg/types/binary/trunnel/trunnel.go
new file mode 100644
index 0000000..fbf41f9
--- /dev/null
+++ b/pkg/types/binary/trunnel/trunnel.go
@@ -0,0 +1,33 @@
+// package trunnel provides selected Trunnel primitives, see:
+//
+//   - https://gitlab.torproject.org/tpo/core/trunnel/-/blob/main/doc/trunnel.md
+package trunnel
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+func Uint64(buf *bytes.Buffer, num *uint64) error {
+	if err := binary.Read(buf, binary.BigEndian, num); err != nil {
+		return fmt.Errorf("uint64: %w", err)
+	}
+	return nil
+}
+
+func Array(buf *bytes.Buffer, arr []byte) error {
+	if _, err := io.ReadFull(buf, arr); err != nil {
+		return fmt.Errorf("array[%d]: %w", len(arr), err)
+	}
+	return nil
+}
+
+func AddUint64(buf *bytes.Buffer, num uint64) {
+	binary.Write(buf, binary.BigEndian, num)
+}
+
+func AddArray(buf *bytes.Buffer, arr []byte) {
+	buf.Write(arr[:])
+}