feat(modem): Add support for handling URC

Closes https://github.com/espressif/esp-protocols/issues/180

components/esp_modem/Kconfig

@@ -67,7 +67,13 @@ menu "esp-modem"
         int "Size in bytes for response from AT commands returning textual values (C-API)"
         default 128
         help
-            Some AT commands returns textrual values which C-API copy as c-string to user allocated space,
+            Some AT commands returns textual values which C-API copy as c-string to user allocated space,
             it also truncates the output data to this size. Increase this if some AT answers are truncated.
 
+    config ESP_MODEM_URC_HANDLER
+        bool "Enable support for adding URC handler"
+        default n
+        help
+            If enabled, APIs to add URC handler are available
+
 endmenu

components/esp_modem/include/cxx_include/esp_modem_dce.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -89,6 +89,13 @@ public:
         return dte->recover();
     }
 
+#ifdef CONFIG_ESP_MODEM_URC_HANDLER
+    void set_urc(got_line_cb on_read_cb)
+    {
+        dte->set_urc_cb(on_read_cb);
+    }
+#endif
+
 protected:
     std::shared_ptr<DTE> dte;
     std::shared_ptr<SpecificModule> device;

components/esp_modem/include/cxx_include/esp_modem_dte.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -94,6 +94,17 @@ public:
      */
     void set_error_cb(std::function<void(terminal_error err)> f);
 
+#ifdef CONFIG_ESP_MODEM_URC_HANDLER
+    /**
+     * @brief Allow setting a line callback for all incoming data
+     * @param line_cb
+     */
+    void set_urc_cb(got_line_cb line_cb)
+    {
+        command_cb.urc_handler = std::move(line_cb);
+    }
+#endif
+
     /**
      * @brief Sets the DTE to desired mode (Command/Data/Cmux)
      * @param m Desired operation mode
@@ -191,6 +202,9 @@ private:
      * @brief This abstracts command callback processing and implements its locking, signaling of completion and timeouts.
      */
     struct command_cb {
+#ifdef CONFIG_ESP_MODEM_URC_HANDLER
+        got_line_cb urc_handler {};                             /*!< URC callback if enabled */
+#endif
         static const size_t GOT_LINE = SignalGroup::bit0;       /*!< Bit indicating response available */
         got_line_cb got_line;                                   /*!< Supplied command callback */
         Lock line_lock{};                                       /*!< Command callback locking mechanism */

components/esp_modem/src/esp_modem_dte.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -50,9 +50,11 @@ void DTE::set_command_callbacks()
 {
     primary_term->set_read_cb([this](uint8_t *data, size_t len) {
         Scoped<Lock> l(command_cb.line_lock);
-        if (command_cb.got_line == nullptr) {
+#ifndef CONFIG_ESP_MODEM_URC_HANDLER
-            return false;
+        if (command_cb.got_line == nullptr || command_cb.result != command_result::TIMEOUT) {
+            return false;   // this line has been processed already (got OK or FAIL previously)
         }
+#endif
         if (data) {
             // For terminals which post data directly with the callback (CMUX)
             // we cannot defragment unless we allocate, but
@@ -347,9 +349,14 @@ void DTE::on_read(got_line_cb on_read_cb)
 
 bool DTE::command_cb::process_line(uint8_t *data, size_t consumed, size_t len)
 {
-    if (result != command_result::TIMEOUT) {
+#ifdef CONFIG_ESP_MODEM_URC_HANDLER
+    if (urc_handler) {
+        urc_handler(data, consumed + len);
+    }
+    if (result != command_result::TIMEOUT || got_line == nullptr) {
         return false;   // this line has been processed already (got OK or FAIL previously)
     }
+#endif
     if (memchr(data + consumed, separator, len)) {
         result = got_line(data, consumed + len);
         if (result == command_result::OK || result == command_result::FAIL) {