gcoap: Add file server

examples/gcoap_fileserver/Makefile

@@ -0,0 +1,35 @@
+# name of your application
+APPLICATION = gcoap_fileserver
+
+# If no BOARD is found in the environment, use this default:
+BOARD ?= native
+
+# This has to be the absolute path to the RIOT base directory:
+RIOTBASE ?= $(CURDIR)/../..
+
+# Comment this out to disable code in RIOT that does safety checking
+# which is not needed in a production environment but helps in the
+# development process:
+DEVELHELP ?= 1
+
+# Change this to 0 show compiler invocation lines by default:
+QUIET ?= 1
+
+# Modules to include:
+USEMODULE += shell
+USEMODULE += shell_commands
+
+# enable the fileserver module
+USEMODULE += gcoap_fileserver
+
+# select network modules
+USEMODULE += gnrc_ipv6_default
+USEMODULE += auto_init_gnrc_netif
+USEMODULE += netdev_default
+USEMODULE += gnrc_icmpv6_echo
+
+# enable default file system mount points
+USEMODULE += vfs_default
+# USEMODULE += vfs_auto_format
+
+include $(RIOTBASE)/Makefile.include

examples/gcoap_fileserver/Makefile.ci

@@ -0,0 +1,44 @@
+BOARD_INSUFFICIENT_MEMORY := \
+    arduino-duemilanove \
+    arduino-leonardo \
+    arduino-mega2560 \
+    arduino-nano \
+    arduino-uno \
+    atmega1284p \
+    atmega328p \
+    atmega328p-xplained-mini \
+    atxmega-a3bu-xplained \
+    blackpill \
+    bluepill \
+    bluepill-stm32f030c8 \
+    derfmega128 \
+    i-nucleo-lrwan1 \
+    mega-xplained \
+    microduino-corerf \
+    msb-430 \
+    msb-430h \
+    nucleo-f030r8 \
+    nucleo-f031k6 \
+    nucleo-f042k6 \
+    nucleo-f302r8 \
+    nucleo-f303k8 \
+    nucleo-f334r8 \
+    nucleo-l011k4 \
+    nucleo-l031k6 \
+    nucleo-l053r8 \
+    samd10-xmini \
+    saml10-xpro \
+    saml11-xpro \
+    slstk3400a \
+    stk3200 \
+    stm32f030f4-demo \
+    stm32f0discovery \
+    stm32f7508-dk \
+    stm32g0316-disco \
+    stm32l0538-disco \
+    stm32mp157c-dk2 \
+    telosb \
+    waspmote-pro \
+    z1 \
+    zigduino \
+    #

examples/gcoap_fileserver/main.c

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+/**
+ * @ingroup     examples
+ * @{
+ *
+ * @file
+ * @brief       Example application for demonstrating the GCoAP file server
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ * @}
+ */
+
+#include "net/gcoap.h"
+#include "net/gcoap/fileserver.h"
+#include "shell.h"
+#include "vfs_default.h"
+
+#define MAIN_QUEUE_SIZE (4)
+static msg_t _main_msg_queue[MAIN_QUEUE_SIZE];
+
+static const gcoap_fileserver_entry_t _vfs_entry = {
+    .root = VFS_DEFAULT_DATA,
+    .resource = "/vfs",
+};
+
+/* CoAP resources. Must be sorted by path (ASCII order). */
+static const coap_resource_t _resources[] = {
+    { "/vfs", COAP_GET | COAP_MATCH_SUBTREE, gcoap_fileserver_handler, (void *)&_vfs_entry },
+};
+
+static gcoap_listener_t _listener = {
+    .resources = _resources,
+    .resources_len = ARRAY_SIZE(_resources),
+};
+
+int main(void)
+{
+    msg_init_queue(_main_msg_queue, MAIN_QUEUE_SIZE);
+    gcoap_register_listener(&_listener);
+
+    char line_buf[SHELL_DEFAULT_BUFSIZE];
+    shell_run(NULL, line_buf, SHELL_DEFAULT_BUFSIZE);
+
+    return 0;
+}

makefiles/pseudomodules.inc.mk

@@ -65,6 +65,7 @@ PSEUDOMODULES += evtimer_on_ztimer
 PSEUDOMODULES += fatfs_vfs_format
 PSEUDOMODULES += fmt_%
 PSEUDOMODULES += gcoap_forward_proxy
+PSEUDOMODULES += gcoap_fileserver
 PSEUDOMODULES += gcoap_dtls
 PSEUDOMODULES += fido2_tests
 PSEUDOMODULES += gnrc_dhcpv6_%

sys/Makefile.dep

@@ -623,6 +623,12 @@ ifneq (,$(filter l2filter_%,$(USEMODULE)))
   USEMODULE += l2filter
 endif
 
+ifneq (,$(filter gcoap_fileserver,$(USEMODULE)))
+  USEMODULE += gcoap
+  USEMODULE += checksum
+  USEMODULE += vfs
+endif
+
 ifneq (,$(filter gcoap_forward_proxy,$(USEMODULE)))
   USEMODULE += gcoap
   USEMODULE += uri_parser

sys/include/net/gcoap.h

@@ -627,8 +627,19 @@ extern "C" {
 #define GCOAP_DTLS_EXTRA_STACKSIZE  (0)
 #endif
 
+/**
+ * @brief Extra stack for VFS operations
+ */
+#if IS_USED(MODULE_GCOAP_FILESERVER)
+#include "vfs.h"
+#define GCOAP_VFS_EXTRA_STACKSIZE   (VFS_DIR_BUFFER_SIZE + VFS_FILE_BUFFER_SIZE)
+#else
+#define GCOAP_VFS_EXTRA_STACKSIZE   (0)
+#endif
+
 #define GCOAP_STACK_SIZE (THREAD_STACKSIZE_DEFAULT + DEBUG_EXTRA_STACKSIZE \
-                          + sizeof(coap_pkt_t) + GCOAP_DTLS_EXTRA_STACKSIZE)
+                          + sizeof(coap_pkt_t) + GCOAP_DTLS_EXTRA_STACKSIZE \
+                          + GCOAP_VFS_EXTRA_STACKSIZE)
 #endif
 /** @} */
 

sys/include/net/gcoap/fileserver.h

@@ -0,0 +1,122 @@
+/*
+ * 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.
+ */
+
+/**
+ * @defgroup    net_gcoap_fileserver GCoAP file server
+ * @ingroup     net_gcoap
+ * @brief       Library for serving files from the VFS to CoAP clients
+ *
+ * # About
+ *
+ * This maps files in the local file system onto a resources in CoAP. In that,
+ * it is what is called a static web server in the unconstrained web.
+ *
+ * As usual, GET operations are used to read files<!-- WRITESUPPORT, and PUT writes to files.
+ * In the current implementation, PUTs are expressed as random-access, meaning
+ * that files are not updated atomically -->.
+ *
+ * Directories are expressed to URIs with trailing slashes<!-- WRITESUPPORT, and are always
+ * created implicitly when files are PUT under them; they can be DELETEd when
+ * empty -->.
+ *
+ * @note The file server uses ETag for cache validation. The ETags are built
+ * from the file system stat values. As clients rely on the ETag to differ when
+ * the file changes, it is important that file modification times are set. The
+ * precise time values do not matter, but if a file is changed in place and
+ * neither its length nor its modification time is varied, then clients will
+ * not become aware of the change or may even mix up the versions half way
+ * through if they have a part of the old version cached.
+ *
+ * # Usage
+ *
+ * * ``USEMODULE += gcoap_fileserver``
+ *
+ * * Have a @ref gcoap_fileserver_entry_t populated with the path you want to serve,
+ *   and the number of path components to strip from incoming requests:
+ *
+ *   ```
+ *   static const gcoap_fileserver_entry_t files_sd = {
+ *       .root = "/sd0",
+ *       .resource = "/files/sd"
+ *   };
+ *   ```
+ *
+ * * Enter a @ref gcoap_fileserver_handler handler into your CoAP server's
+ *   resource list like this:
+ *
+ *   ```
+ *   static const coap_resource_t _resources[] = {
+ *       ...
+ *       { "/files/sd", COAP_GET | COAP_MATCH_SUBTREE, gcoap_fileserver_handler, (void*)&files_sd },
+ *       ...
+ *   }
+ *   ```
+ *
+ *   The allowed methods dictate whether it's read-only (``COAP_GET``) or (in the
+ *   future<!-- WRITESUPPORT -->) read-write (``COAP_GET | COAP_PUT | COAP_DELETE``).
+ *
+ * @{
+ *
+ * @file
+ * @brief       Resource handler for the CoAP file system server
+ *
+ * @author      chrysn <chrysn@fsfe.org>
+ */
+
+#ifndef NET_GCOAP_FILESERVER_H
+#define NET_GCOAP_FILESERVER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "net/nanocoap.h"
+
+/**
+ * @brief File server starting point
+ *
+ * This struct needs to be present at the ctx of a gcoap_fileserver_handler entry
+ * in a resource list.
+ *
+ */
+typedef struct {
+    /**
+     * @brief Path in the VFS that should be served.
+     *
+     * This does not need a trailing slash.
+     */
+    const char *root;
+    /**
+     * @brief The associated CoAP resource path
+     */
+    const char *resource;
+} gcoap_fileserver_entry_t;
+
+/**
+ * @brief File server handler
+ *
+ * Serve a directory from the VFS as a CoAP resource tree.
+ * @see net_gcoap_fileserver
+ *
+ * @param[in] pdu   CoAP request package
+ * @param[out] buf  Buffer for the response
+ * @param[in] len   Response buffer length
+ * @param[in] ctx   pointer to a @ref gcoap_fileserver_entry_t
+ *
+ * @return size of the response on success
+ *         negative error
+ */
+ssize_t gcoap_fileserver_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len, void *ctx);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_GCOAP_FILESERVER_H */
+
+/** @} */