examples/protocols: Added URI encoding/decoding feature

  - http_server/simple: Decoding received query
  - esp_http_client: Sending encoded query

examples/common_components/protocol_examples_common/CMakeLists.txt

@@ -1,7 +1,8 @@
 set(srcs "stdin_out.c"
          "addr_from_stdin.c"
          "connect.c"
-         "wifi_connect.c")
+         "wifi_connect.c"
+         "protocol_examples_utils.c")
 
 if(CONFIG_EXAMPLE_PROVIDE_WIFI_CONSOLE_CMD)
     list(APPEND srcs "console_cmd.c")

examples/common_components/protocol_examples_common/include/protocol_examples_utils.h

@@ -0,0 +1,49 @@
+/*
+ * Utility functions for protocol examples
+ *
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/**
+ * @brief Encode an URI
+ *
+ * @param dest       a destination memory location
+ * @param src        the source string
+ * @param len        the length of the source string
+ * @return uint32_t  the count of escaped characters
+ *
+ * @note Please allocate the destination buffer keeping in mind that encoding a
+ *       special character will take up 3 bytes (for '%' and two hex digits).
+ *       In the worst-case scenario, the destination buffer will have to be 3 times
+ *       that of the source string.
+ */
+uint32_t example_uri_encode(char *dest, const char *src, size_t len);
+
+/**
+ * @brief Decode an URI
+ *
+ * @param dest  a destination memory location
+ * @param src   the source string
+ * @param len   the length of the source string
+ *
+ * @note Please allocate the destination buffer keeping in mind that a decoded
+ *       special character will take up 2 less bytes than its encoded form.
+ *       In the worst-case scenario, the destination buffer will have to be
+ *       the same size that of the source string.
+ */
+void example_uri_decode(char *dest, const char *src, size_t len);
+
+#ifdef __cplusplus
+}
+#endif