1 files changed, 80 insertions, 0 deletions
diff --git a/src/lib/dispatch/msgtypes.h b/src/lib/dispatch/msgtypes.h
new file mode 100644
index 0000000000..01d969dcb5
--- /dev/null
+++ b/src/lib/dispatch/msgtypes.h
@@ -0,0 +1,80 @@
+/* Copyright (c) 2001, Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file msgtypes.h
+ * \brief Types used for messages in the dispatcher code.
+ **/
+
+#ifndef TOR_DISPATCH_MSGTYPES_H
+#define TOR_DISPATCH_MSGTYPES_H
+
+#include <stdint.h>
+
+#include "ext/tor_queue.h"
+
+/**
+ * These types are aliases for subsystems, channels, and message IDs.
+ **/
+typedef uint16_t subsys_id_t;
+typedef uint16_t channel_id_t;
+typedef uint16_t message_id_t;
+
+/**
+ * This identifies a C type that can be sent along with a message.
+ **/
+typedef uint16_t msg_type_id_t;
+
+/**
+ * An ID value returned for *_type_t when none exists.
+ */
+#define ERROR_ID 65535
+
+/**
+ * Auxiliary (untyped) data sent along with a message.
+ *
+ * We define this as a union of a pointer and a u64, so that the integer
+ * types will have the same range across platforms.
+ **/
+typedef union {
+  void *ptr;
+  uint64_t u64;
+} msg_aux_data_t;
+
+/**
+ * Structure of a received message.
+ **/
+typedef struct msg_t {
+  TOR_SIMPLEQ_ENTRY(msg_t) next;
+  subsys_id_t sender;
+  channel_id_t channel;
+  message_id_t msg;
+  /** We could omit this field, since it is implicit in the message type, but
+   * IMO let's leave it in for safety. */
+  msg_type_id_t type;
+  /** Untyped auxiliary data. You shouldn't have to mess with this
+   * directly. */
+  msg_aux_data_t aux_data__;
+} msg_t;
+
+/**
+ * A function that a subscriber uses to receive a message.
+ **/
+typedef void (*recv_fn_t)(const msg_t *m);
+
+/**
+ * Table of functions to use for a given C type.  Any omitted (NULL) functions
+ * will be treated as no-ops.
+ **/
+typedef struct dispatch_typefns_t {
+  /** Release storage held for the auxiliary data of this type. */
+  void (*free_fn)(msg_aux_data_t);
+  /** Format and return a newly allocated string describing the contents
+   * of this data element. */
+  char *(*fmt_fn)(msg_aux_data_t);
+} dispatch_typefns_t;
+
+#endif /* !defined(TOR_DISPATCH_MSGTYPES_H) */