e2e: parse sync_key_counts to decide on key sending

The server returns the count of one-time-keys that it has,
we parse that and detect if we need to send more.

It's a little tricky in that a server that doesn't have
any keys will send an empty response, so force sending in
that case.

If we get to the point of multiple types of keys this will
need reworking to make sure we only send the key types needed.

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>

2 files changed, 45 insertions, 0 deletions

diff --git a/matrix-e2e.c b/matrix-e2e.c
index c4c2cfa..f12c19f 100644
--- a/matrix-e2e.c
+++ b/matrix-e2e.c
@@ -298,6 +298,44 @@ static int get_id_keys(PurpleConnection *pc, OlmAccount *account, gchar ***algor
     return n_keys;
 }
 
+/* Called from sync with an object of the form:
+ *           "device_one_time_keys_count" : {
+ *               "signed_curve25519" : 100
+ *           },
+ */
+void matrix_e2e_handle_sync_key_counts(PurpleConnection *pc, JsonObject *count_object,
+                                       gboolean force_send)
+{
+    gboolean need_to_send = force_send;
+    gboolean valid_counts = FALSE;
+    MatrixConnectionData *conn = purple_connection_get_protocol_data(pc);
+    size_t max_keys = olm_account_max_number_of_one_time_keys(conn->e2e->oa);
+    size_t to_create = max_keys;
+
+    if (!force_send) {
+        JsonObjectIter iter;
+        const gchar *key_algo;
+        JsonNode *key_count_node;
+        json_object_iter_init(&iter, count_object);
+        while (json_object_iter_next(&iter, &key_algo, &key_count_node)) {
+            valid_counts = TRUE;
+            gint64 count = matrix_json_node_get_int(key_count_node);
+            if (count < max_keys / 2) {
+                to_create = (max_keys / 2) - count;
+                need_to_send = TRUE;
+            }
+            purple_debug_info("matrixprpl", "%s: %s: %ld\n",
+                           __func__, key_algo, count);
+        }
+    }
+
+    need_to_send |= !valid_counts;
+    if (need_to_send) {
+        purple_debug_info("matrixprpl", "%s: need to send\n",__func__);
+        // TODO send_one_time_keys(conn, to_create);
+    }
+}
+
 static void key_upload_callback(MatrixConnectionData *conn,
                                 gpointer user_data,
                                 struct _JsonNode *json_root,
@@ -457,4 +495,9 @@ void matrix_e2e_cleanup_connection(MatrixConnectionData *conn)
 {
 }
 
+void matrix_e2e_handle_sync_key_counts(PurpleConnection *pc, JsonObject *count_object,
+                                       gboolean force_send)
+{
+}
+
 #endif
diff --git a/matrix-e2e.h b/matrix-e2e.h
index 48afca3..d2f0f4b 100644
--- a/matrix-e2e.h
+++ b/matrix-e2e.h
@@ -19,11 +19,13 @@
 #ifndef MATRIX_E2E_H
 #define MATRIX_E2E_H
 
+#include <json-glib/json-glib.h>
 #include "matrix-connection.h"
 
 typedef struct _MatrixE2EData MatrixE2EData;
 
 int matrix_e2e_get_device_keys(MatrixConnectionData *conn, const gchar *device_id);
 void matrix_e2e_cleanup_connection(MatrixConnectionData *conn);
+void matrix_e2e_handle_sync_key_counts(struct _PurpleConnection *pc, struct _JsonObject *count_object, gboolean force_send);
 
 #endif