sys/net/application_layer/gcoap/include: add internal proxy header

sys/net/application_layer/gcoap/include/forward_proxy_internal.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2024 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for
+ * more details.
+ */
+
+/**
+ * @defgroup    net_gcoap_forward_proxy_thread    GCoAP Forward Proxy Thread
+ * @ingroup     net_gcoap
+ * @brief       Forward proxy thread implementation for GCoAP
+ *
+ * @{
+ *
+ * @file
+ * @brief       Definitions for the GCoAP forward proxy internal communication
+ *
+ * @author      Mariem Charrada <[email protected]>
+ */
+
+#ifndef NET_GCOAP_FORWARD_PROXY_INTERNAL_H
+#define NET_GCOAP_FORWARD_PROXY_INTERNAL_H
+
+#include <stdint.h>
+#include "net/coap.h"
+#include "net/gcoap.h"
+#include "net/sock/udp.h"
+#include "ztimer.h"
+#include "event.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   client ep structure
+ */
+typedef struct {
+    coap_pkt_t pdu;                         /**< forward CoAP PDU */
+    sock_udp_ep_t server_ep;                /**< forward Server endpoint */
+    sock_udp_ep_t ep;                       /**< client endpoint */
+    uint16_t mid;                           /**< message ID */
+    uint8_t flags;                          /**< client flags */
+#if IS_USED(MODULE_NANOCOAP_CACHE)
+    uint8_t req_etag[COAP_ETAG_LENGTH_MAX]; /**< request ETag */
+#endif
+    ztimer_t empty_ack_timer;               /**< empty ACK timer */
+    event_t event;                          /**< client event */
+} client_ep_t;
+
+/**
+ * @brief Stack size for the forward proxy thread
+ *
+ */
+#ifndef GCOAP_PROXY_STACK_SIZE
+#define GCOAP_PROXY_STACK_SIZE (THREAD_STACKSIZE_DEFAULT + DEBUG_EXTRA_STACKSIZE \
+                                + sizeof(coap_pkt_t) + GCOAP_DTLS_EXTRA_STACKSIZE)
+#endif
+
+/**
+ * @brief Definition of forward proxy thread msgs.
+ */
+enum {
+    GCOAP_FORWARD_PROXY_MSG_SEND,
+};
+
+/**
+ * @brief   Initialize the forward proxy thread
+ */
+void gcoap_forward_proxy_thread_init(void);
+
+/**
+ * @brief Forward the CoAP request to the server
+ *        The client endpoint is passed as an argument
+ *        and freed if the send failed.
+ *
+ * @param[in] cep   client endpoint
+ * @return          @ref gcoap_req_send
+ */
+int gcoap_forward_proxy_req_send(client_ep_t *cep);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GCOAP_FORWARD_PROXY_INTERNAL_H */
+/**
+ * @}
+ */