sys: Add stdio_coap

makefiles/cargo-targets.inc.mk

@@ -16,6 +16,9 @@ endif
 ifneq (,$(filter shell_democommands,$(USEMODULE)))
   CARGO_OPTIONS += --features rust_riotmodules/riot-module-shell-democommands
 endif
+ifneq (,$(filter stdio_coap,$(USEMODULE)))
+  CARGO_OPTIONS += --features rust_riotmodules/riot-module-stdio-coap
+endif
 
 # This is duplicating the compile-commands rule because unlike in the use case
 # when a $(RIOTBASE)/compile_commands.json is built, we *want* this to be

makefiles/stdio.inc.mk

@@ -1,6 +1,7 @@
 STDIO_MODULES = \
   slipdev_stdio \
   stdio_cdc_acm \
+  stdio_coap \
   stdio_ethos \
   stdio_native \
   stdio_nimble \
@@ -25,6 +26,23 @@ ifneq (,$(filter stdio_cdc_acm,$(USEMODULE)))
   USEMODULE += stdio_available
 endif
 
+ifneq (,$(filter stdio_coap,$(USEMODULE)))
+  # FIXME: Does this obsolete the stdio_coap Makefile.{dep,include}?
+  USEMODULE += rust_riotmodules
+  PSEUDOMODULES += stdio_coap
+
+  # FIXME: Whose responsibility is it to include these?
+
+  # either
+  USEMODULE += netdev_default
+  #USEMODULE += usbus_cdc_ecm
+
+  USEMODULE += gnrc_sock_udp
+  USEMODULE += gcoap
+  USEMODULE += gnrc_ipv6_default
+  USEMODULE += auto_init_gnrc_netif
+endif
+
 ifneq (,$(filter stdio_tinyusb_cdc_acm,$(USEMODULE)))
   USEPKG += tinyusb
 endif

pkg/tinydtls/Kconfig

@@ -38,6 +38,7 @@ config DTLS_CONTEXT_MAX
 
 config DTLS_PEER_MAX
     int "Max number of peers"
+    default 2 if KCONFIG_USEMODULE_GCOAP_DTLS
     default 1
     help
         The maximum number of DTLS peers.

pkg/tinydtls/Makefile.include

@@ -63,9 +63,34 @@ endif
 PEER_MAX := $(or $(CONFIG_DTLS_PEER_MAX),$(patsubst -DCONFIG_DTLS_PEER_MAX=%,%,$(filter -DCONFIG_DTLS_PEER_MAX=%,$(CFLAGS))))
 ifneq (,$(PEER_MAX))
     CFLAGS += -DDTLS_PEER_MAX=$(PEER_MAX)
+else ifneq (,$(filter gcoap_dtls,$(USEMODULE)))
+    # The default value in sys/include/net/dtls.h for CONFIG_DTLS_PEER_MAX is 2
+    # when gcoap_dtls is active, otherwise 1. As the default in tinydtls is 1,
+    # we need to set it explicitly if the dtls.h default value deviates from
+    # the tinydtls default.
+    CFLAGS += -DDTLS_PEER_MAX=2
 endif
 
 HANDSHAKE_MAX := $(or $(CONFIG_DTLS_HANDSHAKE_MAX),$(patsubst -DCONFIG_DTLS_HANDSHAKE_MAX=%,%,$(filter -DCONFIG_DTLS_HANDSHAKE_MAX=%,$(CFLAGS))))
 ifneq (,$(HANDSHAKE_MAX))
     CFLAGS += -DDTLS_HANDSHAKE_MAX=$(HANDSHAKE_MAX)
 endif
+
+ifneq (,$(filter gcoap,$(USEMODULE)))
+    # Configuring the buffer large enough that a full Gcoap packet can be
+    # encrypted or decrypted.
+
+    # This is the default in gcoap.h, which we don't have access to, so it is copied over.
+    CONFIG_GCOAP_PDU_BUF_SIZE := $(or $(CONFIG_GCOAP_PDU_BUF_SIZE),128)
+
+    # If there were another way to set up DTLS_MAX_BUF, we'd need to set the
+    # maximum of these here.
+    #
+    # 29 bytes are the overhead measured with Wireshark on packets exchanged in
+    # default configuration; adding some to be safe against variable size fields.
+    CFLAGS += "-DDTLS_MAX_BUF=($(CONFIG_GCOAP_PDU_BUF_SIZE) + 36)"
+endif
+
+# TinyDTLS emits several messages during connection establishment at the info
+# level; this is way more verbose than common in RIOT.
+CFLAGS += -DLOG_LEVEL=LOG_WARNING

sys/include/net/dtls.h

@@ -36,6 +36,8 @@
 #ifndef NET_DTLS_H
 #define NET_DTLS_H
 
+#include "modules.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -44,8 +46,12 @@ extern "C" {
  * @brief The maximum number DTLS peers (i.e. sessions)
  */
 #ifndef CONFIG_DTLS_PEER_MAX
+#if IS_USED(MODULE_GCOAP_DTLS)
+#define CONFIG_DTLS_PEER_MAX       (2)
+#else
 #define CONFIG_DTLS_PEER_MAX       (1)
 #endif
+#endif
 
 #ifdef __cplusplus
 }

sys/rust_riotmodules/Cargo.toml

@@ -12,3 +12,4 @@ publish = false
 
 riot-module-lsm303agr = { path = "../../drivers/lsm303agr", optional = true }
 riot-module-shell-democommands = { path = "../../sys/shell/democommands", optional = true }
+riot-module-stdio-coap = { path = "../../sys/stdio_coap", optional = true }

sys/rust_riotmodules/src/lib.rs

@@ -12,3 +12,6 @@ pub use riot_module_lsm303agr as lsm303agr;
 
 #[cfg(feature = "riot-module-shell-democommands")]
 pub use riot_module_shell_democommands as democommands;
+
+#[cfg(feature = "riot-module-stdio-coap")]
+pub use riot_module_stdio_coap as stdio_coap;

sys/stdio_coap/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "riot-module-stdio-coap"
+version = "0.1.0"
+edition = "2021"
+
+authors = ["Christian Amsüss <chrysn@fsfe.org>"]
+license = "LGPL-2.1-only"
+
+# Shipped with RIOT-OS; this has no external API that would make
+# sense to consume in any context than from within RIOT
+publish = false
+
+[dependencies]
+coap-scroll-ring-server = "0.1"
+riot-wrappers = { version = "^0.8", features = [ "with_coap_handler" ] } # esp. the git version: fixes mutex bug
+riot-sys = "0.7"
+scroll-ring = "0.1.1"
+static_cell = "1"
+# for stdin
+coap-handler = "0.1"
+coap-message = "0.2"
+coap-numbers = "0.2"
+ringbuf = { version = "0.3.2", default-features = false }
+coap-handler-implementations = { git = "https://gitlab.com/chrysn/coap-handler-implementations", features = [ "leaky_names" ] }