gcoap: Add file server

examples/filesystem/Makefile

@@ -24,6 +24,14 @@ USEMODULE += shell
 USEMODULE += shell_commands
 USEMODULE += ps
 
+ifeq (${NETWORK},1)
+USEMODULE += gcoap
+USEMODULE += coapfileserver
+USEMODULE += gnrc_ipv6_default
+USEMODULE += gnrc_netdev_default
+USEMODULE += auto_init_gnrc_netif
+endif
+
 # Use MTD (flash layer)
 USEMODULE += mtd
 # USEMODULE += mtd_sdcard

examples/filesystem/README.md

@@ -76,3 +76,21 @@ Hello World!
 cat /const/hello-riot
 Hello RIOT!
 ```
+
+## Network file server
+
+If ``NETWORK=1`` is passed to make, the board's default network setup is
+enabled, and a CoAP server is started that exports the file system at the path
+``/vfs``.
+
+You can access the file system from another board that runs the gcoap example:
+
+```
+> coap get fe80::3c63:beff:fe85:ca96%6 5683 /vfs/const/
+<hello-world>,<hello-riot>
+> coap get fe80::3c63:beff:fe85:ca96%6 5683 /vfs/const/hello-riot
+--- blockwise start ---
+gcoap: response Success, code 2.05, 13 bytes
+00000000  48  65  6C  6C  6F  20  52  49  4F  54  21  0A  00
+--- blockwise complete ---
+```

examples/filesystem/main.c

@@ -26,6 +26,11 @@
 #include "shell.h"
 #include "board.h" /* MTD_0 is defined in board.h */
 
+#ifdef MODULE_COAPFILESERVER
+#include <net/gcoap.h>
+#include <net/coapfileserver.h>
+#endif
+
 /* Configure MTD device for SD card if none is provided */
 #if !defined(MTD_0) && MODULE_MTD_SDCARD
 #include "mtd_sdcard.h"
@@ -309,6 +314,26 @@ static const shell_command_t shell_commands[] = {
     { NULL, NULL, NULL }
 };
 
+#ifdef MODULE_COAPFILESERVER
+/* Export all the file system */
+static const struct coapfileserver_entry vfs = { "", 1 };
+
+/* CoAP resources. Must be sorted by path (ASCII order). */
+static const coap_resource_t _resources[] = {
+    { "/vfs", COAP_GET | COAP_MATCH_SUBTREE, coapfileserver_handler, (void*)&vfs },
+};
+
+static gcoap_listener_t _listener = {
+    &_resources[0],
+    ARRAY_SIZE(_resources),
+    NULL,
+    NULL
+};
+
+#define MAIN_QUEUE_SIZE (4)
+static msg_t _main_msg_queue[MAIN_QUEUE_SIZE];
+#endif
+
 int main(void)
 {
 #if defined(MTD_0) && (defined(MODULE_SPIFFS) || defined(MODULE_LITTLEFS) || defined(MODULE_LITTLEFS2))
@@ -326,6 +351,11 @@ int main(void)
         puts("constfs mounted successfully");
     }
 
+#ifdef MODULE_COAPFILESERVER
+    msg_init_queue(_main_msg_queue, MAIN_QUEUE_SIZE);
+    gcoap_register_listener(&_listener);
+#endif
+
     char line_buf[SHELL_DEFAULT_BUFSIZE];
     shell_run(shell_commands, line_buf, SHELL_DEFAULT_BUFSIZE);
 

sys/Makefile

@@ -179,6 +179,9 @@ endif
 ifneq (,$(filter ztimer_xtimer_compat,$(USEMODULE)))
   FILTER += xtimer
 endif
+ifneq (,$(filter coapfileserver,$(USEMODULE)))
+    DIRS += net/application_layer/coapfileserver
+endif
 
 DIRS += $(dir $(wildcard $(addsuffix /Makefile, $(filter-out $(FILTER), $(USEMODULE)))))
 

sys/Makefile.dep

@@ -760,6 +760,10 @@ ifneq (,$(filter devfs,$(USEMODULE)))
   USEMODULE += vfs
 endif
 
+ifneq (,$(filter coapfileserver,$(USEMODULE)))
+  USEMODULE += vfs
+endif
+
 ifneq (,$(filter vfs,$(USEMODULE)))
   USEMODULE += posix_headers
   ifeq (native, $(BOARD))

sys/include/net/coap.h

@@ -36,6 +36,7 @@ extern "C" {
  * @{
  */
 #define COAP_OPT_URI_HOST       (3)
+#define COAP_OPT_ETAG           (4)
 #define COAP_OPT_OBSERVE        (6)
 #define COAP_OPT_LOCATION_PATH  (8)
 #define COAP_OPT_URI_PATH       (11)

sys/include/net/coapfileserver.h

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2020 chrysn
+ *
+ * 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.
+ */
+
+/**
+ * @ingroup     net_coapfileserver
+ * @{
+ *
+ * @file
+ * @brief       Resource handler for the CoAP file system server
+ *
+ * @author      chrysn <chrysn@fsfe.org>
+ *
+ * @}
+ */
+
+#ifndef NET_COAPFILESERVER_H
+#define NET_COAPFILESERVER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <net/nanocoap.h>
+
+/** File server starting point
+ *
+ * This struct needs to be present at the ctx of a coapfileserver_handler entry
+ * in a resource list.
+ *
+ */
+struct coapfileserver_entry {
+    /** Path in the VFS that should be served.
+     *
+     * This does not need a trailing slash. */
+    char *nameprefix;
+    /** Number of leading path components to ignore as they are the common prefix.
+     *
+     * If the file server is bound to the "/" resource, make this 0; if there
+     * is an entry
+     *
+     * ``{ "/files/sd", COAP_GET | COAP_MATCH_SUBTREE, coapfileserver_handler, files_sd }``
+     *
+     * then ``files_sd.strip_path`` needs to be 2.
+     *
+     * */
+    uint8_t strip_path;
+};
+
+/**
+ * File server handler
+ *
+ * Serve a directory from the VFS as a CoAP resource tree.
+ *
+ * @p ctx pointer to a @ref coapfileserver_entry
+ *
+ * @see net_coapfileserver
+ */
+ssize_t coapfileserver_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len, void *ctx);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_COAPFILESERVER_H */
+
+/** @} */

sys/net/application_layer/coapfileserver/Makefile

@@ -0,0 +1,5 @@
+MODULE = coapfileserver
+
+SRC = coapfileserver.c
+
+include $(RIOTBASE)/Makefile.base