info: initial implementation

Read INFO characteristic as the first action after discovering device.
Save information about server and device certificates, i.e. whether they
were already provisioned.

Reading INFO characteristic replaces reading server cert serial number,
since the same information is provided.

When device certificate provisioned flag is set, this reduces overhead by
about 350ms (with default configuration of pouch device).

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

Author: mniestroj

.github/workflows/bsim.yml

@@ -71,6 +71,7 @@ jobs:
         run: |
           uv pip install                                  \
             -r pouch/requirements.txt                     \
+            -r pouch-gateway/requirements.txt             \
             -r zephyr/scripts/requirements-base.txt       \
             -r zephyr/scripts/requirements-build-test.txt \
             -r zephyr/scripts/requirements-run-test.txt   \

.github/workflows/build.yml

@@ -82,6 +82,7 @@ jobs:
       - name: Install pip packages
         run: |
           uv pip install \
+            -r pouch-gateway/requirements.txt \
             -r zephyr/scripts/requirements-base.txt
 
           uv pip install            \

include/pouch_gateway/bt/info.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2025 Golioth, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+struct bt_conn;
+
+/**
+ * Start reading info characteristic for the given Bluetooth connection.
+ *
+ * @param conn The Bluetooth connection.
+ */
+void pouch_gateway_info_read_start(struct bt_conn *conn);

include/pouch_gateway/info.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2025 Golioth, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+struct pouch_gateway_info_context;
+
+/**
+ * @brief Flag indicating that the device certificate is provisioned.
+ */
+#define POUCH_GATEWAY_INFO_FLAG_DEVICE_PROVISIONED BIT(0)
+
+/**
+ * @brief Start info read operation.
+ *
+ * @return Pointer to the info context, or NULL on failure.
+ */
+struct pouch_gateway_info_context *pouch_gateway_info_start(void);
+/**
+ * @brief Push data to the info context.
+ *
+ * @param context The info context.
+ * @param data The data to push.
+ * @param len The length of the data.
+ * @return 0 on success, negative on error.
+ */
+int pouch_gateway_info_push(struct pouch_gateway_info_context *context,
+                            const void *data,
+                            size_t len);
+/**
+ * @brief Abort the info read operation.
+ *
+ * @param context The info context.
+ */
+void pouch_gateway_info_abort(struct pouch_gateway_info_context *context);
+/**
+ * @brief Finish the info read operation.
+ *
+ * @param context The info context.
+ * @param[out] server_cert_provisioned Set to true if server cert is provisioned.
+ * @param[out] device_cert_provisioned Set to true if device cert is provisioned.
+ * @return 0 on success, negative on error.
+ */
+int pouch_gateway_info_finish(struct pouch_gateway_info_context *context,
+                              bool *server_cert_provisioned,
+                              bool *device_cert_provisioned);

include/pouch_gateway/types.h

@@ -44,8 +44,11 @@ struct pouch_gateway_node_info
     void *server_cert_scratch;
     struct pouch_gatt_packetizer *packetizer;
     struct pouch_gateway_uplink *uplink;
+    struct pouch_gateway_info_context *info_ctx;
     struct pouch_gateway_device_cert_context *device_cert_ctx;
     struct pouch_gateway_server_cert_context *server_cert_ctx;
+    bool server_cert_provisioned;
+    bool device_cert_provisioned;
 };
 
 /**

lib/CMakeLists.txt

@@ -3,11 +3,14 @@ zephyr_library()
 zephyr_library_sources(bt/cert.c)
 zephyr_library_sources(bt/connect.c)
 zephyr_library_sources(bt/downlink.c)
+zephyr_library_sources(bt/info.c)
 zephyr_library_sources(bt/scan.c)
 zephyr_library_sources(bt/uplink.c)
 zephyr_library_sources(block.c)
 zephyr_library_sources(cert.c)
 zephyr_library_sources(downlink.c)
+zephyr_library_sources(info.c)
+zephyr_library_sources(info_decode.c)
 zephyr_library_sources(uplink.c)
 
 zephyr_library_link_libraries(mbedTLS)
@@ -23,3 +26,18 @@ endif()
 generate_inc_file_for_target(${lib_name}
   ${cert_name}
   ${ZEPHYR_BINARY_DIR}/include/generated/pouch_gateway_server.pem.inc)
+
+message("${ZEPHYR_POUCH_MODULE_DIR}/src/transport/gatt/info.cddl")
+
+add_custom_command(OUTPUT info_decode.c
+    COMMAND zcbor code
+      -c ${ZEPHYR_POUCH_MODULE_DIR}/src/transport/gatt/info.cddl
+      -s
+      -t pouch_gatt_info
+      -d --include-prefix cddl/
+      --output-c ${CMAKE_CURRENT_BINARY_DIR}/info_decode.c
+      --output-h ${CMAKE_CURRENT_BINARY_DIR}/include/cddl/info_decode.h
+    BYPRODUCTS include/cddl/info_decode.h include/cddl/info_decode_types.h
+    DEPENDS ${ZEPHYR_POUCH_MODULE_DIR}/src/transport/gatt/info.cddl)
+
+zephyr_library_include_directories(${CMAKE_CURRENT_BINARY_DIR}/include)

lib/bt/cert.c

@@ -51,72 +51,6 @@ static void server_cert_cleanup(struct bt_conn *conn)
     }
 }
 
-static uint8_t server_cert_read_cb(struct bt_conn *conn,
-                                   uint8_t err,
-                                   struct bt_gatt_read_params *params,
-                                   const void *data,
-                                   uint16_t length)
-{
-    if (err)
-    {
-        LOG_ERR("Failed to read BLE GATT %s (err %d)", "server cert", err);
-        return BT_GATT_ITER_STOP;
-    }
-
-    if (length == 0)
-    {
-        gateway_server_cert_write_start(conn);
-        return BT_GATT_ITER_STOP;
-    }
-
-    bool is_first = false;
-    bool is_last = false;
-    const void *payload = NULL;
-    ssize_t payload_len = pouch_gatt_packetizer_decode(data, length, &payload, &is_first, &is_last);
-    if (payload_len < 0)
-    {
-        LOG_ERR("Failed to decode BLE GATT %s (err %d)", "server cert", (int) payload_len);
-        server_cert_cleanup(conn);
-        pouch_gateway_bt_finished(conn);
-        return BT_GATT_ITER_STOP;
-    }
-
-    if (data)
-    {
-        LOG_HEXDUMP_DBG(data, length, "[READ] BLE GATT server cert");
-    }
-
-    if (is_last)
-    {
-        uint8_t serial[CERT_SERIAL_MAXLEN];
-        size_t serial_len = sizeof(serial);
-
-        pouch_gateway_server_cert_get_serial(serial, &serial_len);
-
-        if (payload_len > 0 && payload_len == serial_len
-            && memcmp(serial, payload, payload_len) == 0)
-        {
-            LOG_DBG("server cert match");
-            gateway_device_cert_read_start(conn);
-        }
-        else
-        {
-            LOG_DBG("server cert mismatch");
-            gateway_server_cert_write_start(conn);
-        }
-
-        return BT_GATT_ITER_STOP;
-    }
-
-    err = bt_gatt_read(conn, params);
-    if (err)
-    {
-        LOG_ERR("BT (re)read request failed: %d", err);
-        return BT_GATT_ITER_STOP;
-    }
-
-    return BT_GATT_ITER_STOP;
-}
 
 static void device_cert_cleanup(struct bt_conn *conn)
 {
@@ -262,6 +196,7 @@ static void write_response_cb(struct bt_conn *conn,
         {
             // There was certificate update in the meantime, so send it once again.
             LOG_INF("Noticed certificate update, sending once again");
+            node->server_cert_provisioned = false;
             gateway_server_cert_write_start(conn);
         }
     }
@@ -301,6 +236,12 @@ static void gateway_server_cert_write_start(struct bt_conn *conn)
 {
     struct pouch_gateway_node_info *node = pouch_gateway_get_node_info(conn);
 
+    if (node->server_cert_provisioned)
+    {
+        gateway_device_cert_read_start(conn);
+        return;
+    }
+
     if (0 == node->attr_handles[POUCH_GATEWAY_GATT_ATTR_SERVER_CERT].value)
     {
         LOG_ERR("%s characteristic undiscovered", "server cert");
@@ -325,28 +266,15 @@ static void gateway_server_cert_write_start(struct bt_conn *conn)
     write_server_cert_characteristic(conn);
 }
 
-static void gateway_server_cert_serial_read_start(struct bt_conn *conn)
+static void gateway_device_cert_read_start(struct bt_conn *conn)
 {
     struct pouch_gateway_node_info *node = pouch_gateway_get_node_info(conn);
 
-    struct bt_gatt_read_params *read_params = &node->read_params;
-    memset(read_params, 0, sizeof(*read_params));
-
-    read_params->func = server_cert_read_cb;
-    read_params->handle_count = 1;
-    read_params->single.handle = node->attr_handles[POUCH_GATEWAY_GATT_ATTR_SERVER_CERT].value;
-    int err = bt_gatt_read(conn, read_params);
-    if (err)
+    if (node->device_cert_provisioned)
     {
-        LOG_ERR("BT read request failed: %d", err);
-        server_cert_cleanup(conn);
-        pouch_gateway_bt_finished(conn);
+        pouch_gateway_uplink_start(conn);
+        return;
     }
-}
-
-static void gateway_device_cert_read_start(struct bt_conn *conn)
-{
-    struct pouch_gateway_node_info *node = pouch_gateway_get_node_info(conn);
 
     struct bt_gatt_read_params *read_params = &node->read_params;
     memset(read_params, 0, sizeof(*read_params));
@@ -367,5 +295,5 @@ static void gateway_device_cert_read_start(struct bt_conn *conn)
 
 void pouch_gateway_cert_exchange_start(struct bt_conn *conn)
 {
-    gateway_server_cert_serial_read_start(conn);
+    gateway_server_cert_write_start(conn);
 }

lib/bt/connect.c

@@ -17,6 +17,7 @@
 #include <pouch_gateway/bt/connect.h>
 #include <pouch_gateway/bt/cert.h>
 #include <pouch_gateway/bt/downlink.h>
+#include <pouch_gateway/bt/info.h>
 #include <pouch_gateway/bt/scan.h>
 #include <pouch_gateway/bt/uplink.h>
 
@@ -79,7 +80,7 @@ static uint8_t discover_descriptors(struct bt_conn *conn,
     if (node->attr_handles[POUCH_GATEWAY_GATT_ATTR_SERVER_CERT].value
         && node->attr_handles[POUCH_GATEWAY_GATT_ATTR_DEVICE_CERT].value)
     {
-        pouch_gateway_cert_exchange_start(conn);
+        pouch_gateway_info_read_start(conn);
     }
     else
     {