working on todo.md features

deps/udpsclient/udps_client.h

@@ -237,6 +237,20 @@ typedef void (*udps_data_cb)(const udps_frame_t *frame, void *user);
 /** Called on connection state changes and on recoverable errors. */
 typedef void (*udps_event_cb)(udps_event_t event, const char *detail, void *user);
 
+/**
+ * Largest datagram recv() can deliver on the client's socket, and therefore the
+ * most a raw-datagram observer ever sees in one call.
+ */
+#define UDPS_MAX_DATAGRAM_BYTES (65535 + 17)
+
+/** Called for every datagram as recv() returned it, before the magic check,
+ *  reassembly or resequencing: the bytes a capture has to store, and the only
+ *  place malformed or duplicate datagrams are still visible. Runs on the polling
+ *  thread, inside udps_client_poll(), like every other callback. `bytes` is
+ *  valid until the callback returns. */
+typedef void (*udps_datagram_cb)(const uint8_t *bytes, size_t len,
+                                 double recv_time, void *user);
+
 /**
  * @brief Transport configuration.
  *
@@ -286,6 +300,12 @@ void udps_client_set_callbacks(udps_client_t *client,
                                udps_event_cb  on_event,
                                void          *user);
 
+/** Installs the raw-datagram observer. Separate from
+ *  udps_client_set_callbacks(), whose signature has call sites and which a
+ *  capture hook is no reason to change. May be NULL. */
+void udps_client_set_datagram_cb(udps_client_t *client,
+                                 udps_datagram_cb cb, void *user);
+
 /**
  * @brief Drives the client: connects if needed, then waits for and processes
  *        packets for at most @p timeout_ms milliseconds.