implement auth, closed and close envelopes

pkg/encoders/envelopes/identify.go

@@ -0,0 +1,38 @@
+package envelopes
+
+// Identify handles determining what kind of codec.Envelope is, by the Label,
+// the first step in identifying the structure of the message. This first step
+// is not sufficient because the same labels are used on several codec.Envelope
+// types in the nostr specification. The rest of the context is in whether this
+// is a client or a relay receiving it.
+func Identify(b []byte) (t string, rem []byte, err error) {
+	var openBrackets, openQuotes, afterQuotes bool
+	var label []byte
+	rem = b
+	for ; len(rem) > 0; rem = rem[1:] {
+		if !openBrackets && rem[0] == '[' {
+			openBrackets = true
+		} else if openBrackets {
+			if !openQuotes && rem[0] == '"' {
+				openQuotes = true
+			} else if afterQuotes {
+				// return the remainder after the comma
+				if rem[0] == ',' {
+					rem = rem[1:]
+					return
+				}
+			} else if openQuotes {
+				for i := range rem {
+					if rem[i] == '"' {
+						label = rem[:i]
+						rem = rem[i:]
+						t = string(label)
+						afterQuotes = true
+						break
+					}
+				}
+			}
+		}
+	}
+	return
+}