implement auth, closed and close envelopes

pkg/encoders/envelopes/process.go

@@ -0,0 +1,41 @@
+package envelopes
+
+import (
+	"io"
+)
+
+// Marshaller is a function signature the same as the codec.JSON Marshal but
+// without the requirement of there being a full implementation or declared
+// receiver variable of this interface. Used here to encapsulate one or more
+// other data structures into an envelope.
+type Marshaller func(dst []byte) (b []byte)
+
+// Marshal is a parser for dynamic typed arrays like nosttr codec.Envelope
+// types.
+func Marshal(dst []byte, label string, m Marshaller) (b []byte) {
+	b = dst
+	b = append(b, '[', '"')
+	b = append(b, label...)
+	b = append(b, '"', ',')
+	b = m(b)
+	b = append(b, ']')
+	return
+}
+
+// SkipToTheEnd scans forward after all fields in an envelope have been read to
+// find the closing bracket.
+func SkipToTheEnd(dst []byte) (rem []byte, err error) {
+	if len(dst) == 0 {
+		return
+	}
+	rem = dst
+	// we have everything, just need to snip the end
+	for ; len(rem) > 0; rem = rem[1:] {
+		if rem[0] == ']' {
+			rem = rem[:0]
+			return
+		}
+	}
+	err = io.EOF
+	return
+}