Initial commit: crypto.go and protocol.go implementation + unit tests

protocol.go

@@ -0,0 +1,47 @@
+package ownwire_sdk
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+type SessionInit struct {
+	SessionId       string
+	ServerPubKeyB64 string
+	SaltB64         string
+	SeqOut          uint64
+	SeqInMax        uint64
+}
+
+// ParseSessionInit parses:
+// "/session:<id>:<server_pubkey_b64>:<salt_b64>:<seq_out>:<seq_in_max>"
+func ParseSessionInit(line string) (SessionInit, error) {
+	if !strings.HasPrefix(line, "/session:") {
+		return SessionInit{}, fmt.Errorf("invalid session line prefix: %q", line)
+	}
+
+	parts := strings.Split(line, ":")
+	if len(parts) < 6 || parts[0] != "/session" {
+		return SessionInit{}, fmt.Errorf("invalid session line: %q", line)
+	}
+
+	seq_out, err := strconv.ParseUint(parts[4], 10, 64)
+	if err != nil {
+		return SessionInit{}, fmt.Errorf("invalid seq_out: %w", err)
+	}
+
+	seq_in_max, err := strconv.ParseUint(parts[5], 10, 64)
+	if err != nil {
+		return SessionInit{}, fmt.Errorf("invalid seq_in_max: %w", err)
+	}
+
+	out := SessionInit{
+		SessionId:       parts[1],
+		ServerPubKeyB64: parts[2],
+		SaltB64:         parts[3],
+		SeqOut:          seq_out,
+		SeqInMax:        seq_in_max,
+	}
+	return out, nil
+}