1 files changed, 22 insertions, 0 deletions
diff --git a/pesto.h b/pesto.h
index e9b329f..3c93d3e 100644
--- a/pesto.h
+++ b/pesto.h
@@ -9,4 +9,26 @@
 #ifndef PESTO_H
 #define PESTO_H
 
+#include <assert.h>
+#include <stdint.h>
+
+#define PESTO_SERVER_MAGIC	"basil:s"
+
+/* Version 0 is reserved for unreleased / unsupported experimental versions */
+#define PESTO_PROTOCOL_VERSION	1
+
+/**
+ * struct pesto_hello - Server introduction message
+ * @magic:	PESTO_SERVER_MAGIC
+ * @version:	Version number
+ */
+struct pesto_hello {
+	char magic[8];
+	uint32_t version;
+} __attribute__ ((__packed__));
+
+static_assert(sizeof(PESTO_SERVER_MAGIC)
+	      == sizeof(((struct pesto_hello *)0)->magic),
+	      "PESTO_SERVER_MAGIC has wrong size");
+
 #endif /* PESTO_H */