riot_coap_handler_demos/saul.rs
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//! This is a CoAP server application that exposes SAUL entries.
//!
//! For discovery, this exposes all entries as
//! rt="tag:chrysn@fsfe.org,2020-10-02:saul";saul=ACT_LED_RGB or similar.
//!
//! For GETs, the supported formats are:
//! * text/plain;encoding=utf-8 -- renders through the phydat's Display implementation, or uses the
//! command-line listing on the index
//! * application/cbor (individuals only) -- renders CBOR equivalent to RIOT's phydat_to_json
//! output
//!
//! The implementation of the CBOR serialization doubles as a playground for comparing individual
//! embedded CBOR libraries (serde_cbor, minicbor, ciborium-ll); all are implemented, but all but
//! minicbor are commented out in the renderer.
//! * application/link-format (index only) -- gives the index as produced by the `saul.rs` command
//! line output
//!
//! For actor PUTs, the supported formats are:
//! * text/plain;charset=utf-8 -- only single integer values and no units are supported.
//! * application/cbor -- like in GETs (but with limited units support). Numerics are accepted as
//! integers or decimal fractions; unlike fractions are processed to the GCD.
//! * 65362 (experimental) -- RGB hex color codes in '#rrggbb' format as used with CSS (but
//! without the named colors or alternative forms); those are fed in without units.
use coap_handler_implementations::{helpers::block2_write, wkc};
use coap_message::{
error::RenderableOnMinimal, Code, MessageOption, MinimalWritableMessage,
MutableWritableMessage, ReadableMessage,
};
use coap_message_utils::{option_value::Block2RequestData, OptionsExt};
use coap_numbers::{code, option};
use core::fmt::Write;
use riot_wrappers::error::NumericError;
use riot_wrappers::saul::{Phydat, RegistryEntry, Unit};
use serde::Serialize;
/// An extended phydat that almost behaves like phydat_to_json but with CBOR
///
/// It produces a map containing a "u" entry with the text form of the unit, and a "d" entry with
/// either a single numeric of a vector of 2 or 3 numeric entries. Numeric entries are integers or
/// decimal fractions (thus easily expressing the phydat's scale value without actually
/// calculating)
///
/// It can be serialized using serde, minicbor or ciborium_ll. (ciborium would use serde, but is
/// not an option here as it uses alloc).
struct JsonStylePhydat(Phydat);
impl Serialize for JsonStylePhydat {
fn serialize<S: serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
use serde::ser::{Error, SerializeStruct};
if self.0.scale() != 0 {
// The simple workaround of expressing it as a tag-unwrapped(?) array would be
// ambiguous against the possibly elided outer array
return Err(S::Error::custom("has scale"));
}
let unit = self.0.unit().and_then(|u| u.name_owned::<16>());
let length = 1 + unit.is_some() as usize;
// dont-serialize: For the desired CBOR outcome the struct's name won't be serialized
// anyway (it also has none)
let mut map = s.serialize_struct("dont-serialize", length)?;
if let Some(u) = unit {
map.serialize_field("u", u.as_str())?;
}
match self.0.value() {
// Single values are mapped without an outer array
&[v] => map.serialize_field("d", &v)?,
v => map.serialize_field("d", v)?,
};
map.end()
}
}
impl<C> minicbor::Encode<C> for JsonStylePhydat {
fn encode<W: minicbor::encode::Write>(
&self,
e: &mut minicbor::Encoder<W>,
_ctx: &mut C,
) -> Result<(), minicbor::encode::Error<W::Error>> {
let unit = self.0.unit().and_then(|u| u.name_owned::<16>());
let length = 1 + unit.is_some() as usize;
let map = e.map(length as _)?;
if let Some(u) = unit {
map.encode("u")?;
map.encode(u.as_str())?;
}
map.encode("d")?;
// minicbor is incredibly lax when it comes to what items are actually written to, but then
// again, that makes work very easy in this case
let item_encoder = match self.0.value().len() {
1 => map,
n => map.array(n as _)?,
};
for v in self.0.value() {
if self.0.scale() != 0 {
let tagged = item_encoder.tag(minicbor::data::IanaTag::Decimal)?;
let list = tagged.array(2)?;
list.encode(self.0.scale())?;
list.encode(v)?;
} else {
item_encoder.encode(v)?;
}
}
Ok(())
}
}
impl<'a, C> minicbor::Decode<'a, C> for JsonStylePhydat {
/// Decode a JsonStylePhydat item from CBOR
///
/// This decoder is generally strict, it currently accepts one oddity: It lets unrecognized
/// units slip silently; consequently it also doesn't complain if the unit is given multiple
/// times if it's nonsensical.
// Yikes, that's a lot of code for "matching that CDDL, give me..."
fn decode(
d: &mut minicbor::Decoder<'_>,
_ctx: &mut C,
) -> Result<Self, minicbor::decode::Error> {
#[derive(Default)]
struct NumericState {
values: heapless::Vec<i16, 3>,
minscale: Option<i8>,
}
impl NumericState {
fn push(&mut self, val: ScaledI16) -> Result<(), minicbor::decode::Error> {
let ScaledI16(mut value, mut scale) = val;
if self.values.len() == 0 {
self.values.push(value).unwrap();
self.minscale = Some(scale);
return Ok(());
}
while scale > self.minscale.unwrap() {
scale -= 1;
value = value
.checked_mul(10)
.ok_or(minicbor::decode::Error::message(
"Phydat can't express that range",
))?;
}
while scale < self.minscale.unwrap() {
self.minscale = Some(self.minscale.unwrap() - 1);
for v in self.values.iter_mut() {
*v = v.checked_mul(10).ok_or(minicbor::decode::Error::message(
"Phydat can't express that range",
))?;
}
}
self.values
.push(value)
.map_err(|_| minicbor::decode::Error::message("Exceeding phydat size"))?;
Ok(())
}
}
struct ScaledI16(i16, i8);
impl<'b, C> minicbor::Decode<'b, C> for ScaledI16 {
fn decode(
d: &mut minicbor::Decoder<'_>,
_ctx: &mut C,
) -> Result<Self, minicbor::decode::Error> {
if d.probe().tag().is_err() {
return Ok(ScaledI16(d.decode()?, 0));
}
if d.tag()? != minicbor::data::Tag::from(minicbor::data::IanaTag::Decimal) {
return Err(minicbor::decode::Error::message("Unsupported tag"));
}
if !matches!(d.array(), Ok(Some(2))) {
return Err(minicbor::decode::Error::message("Unsupported array length"));
}
let scale = d.decode()?;
let value = d.decode()?;
Ok(ScaledI16(value, scale))
}
}
let mut unit = None;
let mut state: NumericState = Default::default();
let mut d_seen = false;
let mut items_remaining = d.map()?;
while match items_remaining {
Some(0) => false,
Some(n) => {
items_remaining = Some(n - 1);
true
}
None => matches!(d.probe().simple(), Ok(0x1f)),
} {
match d.str()? {
"u" => {
if unit.is_some() {
return Err(minicbor::decode::Error::message("Duplicate unit"));
}
unit = match d.str()? {
"%" => Some(Unit::Percent),
"none" => Some(Unit::None),
// FIXME: List is incomplete, should use utility function, maybe even in
// RIOT -- as it's incomplete, failing silently
_ => None,
};
}
"d" => {
if d_seen {
return Err(minicbor::decode::Error::message("Duplicate data"));
}
d_seen = true;
if d.probe().array().is_ok() {
for val in d.array_iter()? {
state.push(val?)?;
}
} else {
let val = d.decode()?;
state.push(val)?;
}
}
_ => {
return Err(minicbor::decode::Error::message("Unknown key"));
}
}
}
if items_remaining.is_none() {
// To allow the wrapper to do the assertion on being at EOF
let _ = d.simple();
}
Ok(Self(Phydat::new(
&state.values,
unit,
state.minscale.unwrap_or(0),
)))
}
}
impl JsonStylePhydat {
#[allow(dead_code)] // reason: All are around for comparison, but not active at the same time
fn push_to_ciborium<W: ciborium_io::Write>(
&self,
e: &mut ciborium_ll::Encoder<W>,
) -> Result<(), W::Error> {
use ciborium_ll::Header;
fn numeric(n: impl Into<i64>) -> Header {
let n = n.into();
if n > 0 {
Header::Positive(n as u64)
} else {
Header::Negative((!n) as u64)
}
}
let unit = self.0.unit().and_then(|u| u.name_owned::<16>());
let length = 1 + unit.is_some() as usize;
e.push(Header::Map(Some(length as _)))?;
if let Some(u) = unit {
e.text("u", None)?;
e.text(u.as_str(), None)?;
}
e.text("d", None)?;
match self.0.value().len() {
1 => (),
n => e.push(Header::Array(Some(n)))?,
};
for v in self.0.value() {
if self.0.scale() != 0 {
e.push(Header::Tag(4))?;
e.push(Header::Array(Some(2)))?;
e.push(numeric(self.0.scale()))?;
e.push(numeric(*v))?;
} else {
e.push(numeric(*v))?;
}
}
Ok(())
}
}
#[derive(Copy, Clone, Debug)]
pub enum ContentFormat {
TextPlain,
LinkFormat,
Cbor, // a CBOR-JSON convertible mapping of the Json format
RGB, // An ad-hoc '#RRGGBB' hex format used with code point 65362
}
impl ContentFormat {
fn from_option(opt: &impl MessageOption) -> Result<Self, ()> {
Ok(match opt.value_uint().ok_or(())? {
0u16 => ContentFormat::TextPlain,
40 => ContentFormat::LinkFormat,
60 => ContentFormat::Cbor,
65362 => ContentFormat::RGB,
_ => Err(())?,
})
}
#[allow(dead_code)] // reason: We should be using it, but there are FIXMEs about how we can't
// send a Content-Format with blockwise'd responses.
fn as_number(self) -> u16 {
match self {
ContentFormat::TextPlain => 0,
ContentFormat::LinkFormat => 40,
ContentFormat::Cbor => 60,
ContentFormat::RGB => 65362,
}
}
}
pub enum SaulRequest {
GetIndex {
accept: ContentFormat,
block2: Block2RequestData,
},
Get {
entry: RegistryEntry,
accept: ContentFormat,
block2: Block2RequestData,
},
// No details at all -- the request was already acted on in the extraction part
Put,
}
use SaulRequest::*;
#[derive(Debug)]
pub enum Error {
// some on which we may provide extra text
ReadError(NumericError),
WriteError(NumericError),
UnsupportedContentFormat,
FormatError(ContentFormat),
NotAcceptableForIndex,
NotAcceptableForItem,
UnknownContentFormat,
MethodNotAllowedRoot,
MethodNotAllowedItem,
// some are just "the weird stack can't express simple things"
MissingCoAPStackSupport,
// ... and some straightforward general ones
BadOption,
NotFound,
}
use Error::*;
impl Error {
fn code(&self) -> u8 {
match self {
// maybe say something smarter on unreadable devices?
ReadError(_) => code::INTERNAL_SERVER_ERROR,
WriteError(_) => code::INTERNAL_SERVER_ERROR,
UnsupportedContentFormat => code::UNSUPPORTED_CONTENT_FORMAT,
FormatError(_) => code::BAD_REQUEST,
NotAcceptableForIndex => code::NOT_ACCEPTABLE,
NotAcceptableForItem => code::NOT_ACCEPTABLE,
UnknownContentFormat => code::UNSUPPORTED_CONTENT_FORMAT,
MethodNotAllowedRoot => code::METHOD_NOT_ALLOWED,
MethodNotAllowedItem => code::METHOD_NOT_ALLOWED,
BadOption => code::BAD_OPTION,
NotFound => code::NOT_FOUND,
MissingCoAPStackSupport => code::INTERNAL_SERVER_ERROR,
}
}
fn message(&self) -> &'static str {
match self {
// maybe say something smarter on unreadable devices?
ReadError(_) => "Read error or unsupported",
WriteError(_) => "Write error or unsupported",
UnsupportedContentFormat => "Try text/plain, CBOR or 65362",
FormatError(ContentFormat::RGB) => "Format is hex #RRGGBB",
FormatError(ContentFormat::TextPlain) => "Only single ASCII int supported",
FormatError(ContentFormat::Cbor) => r#"like {"u":"%","d":[0,0,100]}"#,
FormatError(ContentFormat::LinkFormat) => "", // inapplicable, won't happen
NotAcceptableForIndex => "Try text/plain or link-format",
NotAcceptableForItem => "Try text/plain or CBOR",
UnknownContentFormat => "",
MethodNotAllowedRoot => "",
MethodNotAllowedItem => "",
BadOption => "",
NotFound => "",
// and likely it won't be able to send that either, but let's try.
MissingCoAPStackSupport => "CoAP stack can not send message",
}
}
}
impl RenderableOnMinimal for Error {
type Error<IE: RenderableOnMinimal + core::fmt::Debug> = IE;
fn render<M: MinimalWritableMessage>(self, msg: &mut M) -> Result<(), M::UnionError> {
msg.set_code(Code::new(self.code())?);
let _ = msg.set_payload(self.message().as_bytes());
Ok(())
}
}
/// A handler for SAUL requests, using SAUL_MATCH_SUBTREE to manage its resources.
///
/// The path this is registered at must be passed in as the prefix, as link-format responses
/// necessitate knowing one's own path, and the prefix needs to be stripped off when processing the
/// Uri-Path options.
///
/// As the link-format handler is bad, the name must be simple.
pub struct SaulHandler {
prefix: &'static [&'static str],
}
impl SaulHandler {
/// Create a SaulHandler
///
/// The prefix needs to be passed in in order to produce proper link-format responses which can
/// not be path-relative, and should thus be equal to the prefix assigned in the tree.
pub fn new(prefix: &'static [&'static str]) -> Self {
Self { prefix }
}
fn put_value(
&self,
entry: RegistryEntry,
content_format: ContentFormat,
body: &[u8],
) -> Result<(), Error> {
let phydat = match content_format {
ContentFormat::TextPlain => {
let val: i16 = core::str::from_utf8(body)
.ok()
.and_then(|s| s.parse().ok())
.ok_or_else(|| FormatError(ContentFormat::TextPlain))?;
Phydat::new(&[val], None, 0)
}
ContentFormat::Cbor => {
let mut decoder = minicbor::Decoder::new(body);
let jsp: JsonStylePhydat = decoder
.decode()
.map_err(|_| FormatError(ContentFormat::Cbor))?;
if decoder.datatype().map_err(|e| e.is_end_of_input()) != Err(true) {
return Err(FormatError(ContentFormat::Cbor));
}
jsp.0
}
ContentFormat::RGB => {
if body.len() != 7 || body[0] != b'#' {
return Err(FormatError(ContentFormat::RGB));
}
let mut bytes = [0u8; 3];
hex::decode_to_slice(&body[1..], bytes.as_mut())
.map_err(|_| FormatError(ContentFormat::RGB))?;
Phydat::new(
&[bytes[0].into(), bytes[1].into(), bytes[2].into()],
None,
0,
)
}
_ => Err(UnsupportedContentFormat)?,
};
entry
.write(phydat)
// in the rough anticipation that maybe one day this won't return a NumericError but
// something more wrapped that would then still implement Into<NumericError> for
// exactly this kind of compatibility
.map_err(|e| WriteError(e.into()))
}
}
impl coap_handler::Handler for SaulHandler {
type RequestData = SaulRequest;
type ExtractRequestError = Error;
type BuildResponseError<M: MinimalWritableMessage> = Error;
fn extract_request_data<M: ReadableMessage>(
&mut self,
request: &M,
) -> Result<SaulRequest, Error> {
#[derive(PartialEq, Copy, Clone)]
enum Path {
Initial,
Root,
Index(usize),
NotFound,
}
impl Path {
fn crank(&mut self, optval: &str) {
*self = match (*self, optval) {
(Path::Initial, "") => Path::Root,
(Path::Initial, x) => {
if let Ok(i) = x.parse() {
Path::Index(i)
} else {
Path::NotFound
}
}
(_, _) => Path::NotFound,
};
}
}
let mut path = Path::Initial;
let mut block2 = None;
let mut accept = None;
let mut content_format = None;
for opt in request
.options()
.take_uri_path(|p| path.crank(p))
.take_block2(&mut block2)
{
match opt.number() {
option::ACCEPT => {
// Not converting the error here...
accept = Some(ContentFormat::from_option(&opt));
}
option::CONTENT_FORMAT => {
content_format =
Some(ContentFormat::from_option(&opt).map_err(|_| UnknownContentFormat)?);
}
x => match option::get_criticality(x) {
option::Criticality::Critical => return Err(BadOption),
_ => {}
},
}
}
let block2 = block2.unwrap_or_default();
let content_format = content_format.unwrap_or(ContentFormat::TextPlain);
let accept = accept
.unwrap_or(Ok(ContentFormat::TextPlain))
// ... but delaying error conversion until here when we know (well we did before but
// Rust can't know that) the path
.map_err(|_| match path {
Path::Root => NotAcceptableForIndex,
_ => NotAcceptableForItem,
})?;
match path {
Path::Root => {
if request.code().into() == code::GET {
Ok(GetIndex { accept, block2 })
} else {
Err(MethodNotAllowedRoot)
}
}
Path::Index(index) => {
let entry = RegistryEntry::nth(index).ok_or(NotFound)?;
match request.code().into() {
code::GET => Ok(Get {
entry,
accept,
block2,
}),
code::PUT => {
self.put_value(entry, content_format, request.payload())?;
Ok(Put)
}
_ => Err(MethodNotAllowedItem),
}
}
_ => Err(NotFound),
}
}
fn estimate_length(&mut self, _: &<Self as coap_handler::Handler>::RequestData) -> usize {
// Still enough to get a reasonable block in there if it comes to Block2 through countless
// sensors or a read-all
200
}
fn build_response<M: MutableWritableMessage>(
&mut self,
response: &mut M,
request: Self::RequestData,
) -> Result<(), Self::BuildResponseError<M>> {
let code = match request {
GetIndex { accept, block2 } => block2_write(block2, response, |w| {
match accept {
ContentFormat::TextPlain => {
riot_shell_commands::saul(w, ["saul"].iter().map(|x| *x));
}
ContentFormat::LinkFormat => {
wkc::write_link_format(w, self, self.prefix).unwrap();
}
_ => Err(NotAcceptableForItem)?,
};
Ok(code::CONTENT)
})?,
Get {
entry,
accept,
block2,
} => {
// FIXME: Not sending the content format because it goes between ETag and Block2
// and the block2_writer won't let us put data inbetween there
block2_write(block2, response, |w| {
// FIXME: In the error case, block and content-format are still there :-(
// Worse yet, serde errors are not caught.
let phydat = entry.read().map_err(|e| ReadError(e.into()))?;
match accept {
ContentFormat::TextPlain => writeln!(w, "{}", phydat).unwrap(),
ContentFormat::Cbor => {
let phydat = JsonStylePhydat(phydat);
// Enable this to use serde_cbor
// phydat.serialize(&mut serde_cbor::ser::Serializer::new(w));
// Usually, this is serialized using minicbor
minicbor::encode(&phydat, w)
// FIXME: enhance error handling
.unwrap();
// Enable this to try out ciborium
// let mut encoder = ciborium_ll::Encoder::from(w);
// phydat.push_to_ciborium(&mut encoder).unwrap();
// use ciborium_io::Write;
// encoder.flush().unwrap();
}
_ => Err(NotAcceptableForItem)?,
};
Ok(code::CONTENT)
})?
}
Put => code::CHANGED,
};
response.set_code(Code::new(code).map_err(|_| Error::MissingCoAPStackSupport)?);
Ok(())
}
}
pub enum Record {
Root,
Entry(usize, RegistryEntry),
}
impl coap_handler::Record for Record {
type PathElement = heapless::String<4>;
// FIXME: Once TAIT is stable, replace with the simpler forms below
type PathElements = core::iter::Once<heapless::String<4>>;
type Attributes = core::iter::Cloned<core::slice::Iter<'static, coap_handler::Attribute>>;
// type PathElements = impl Iterator<Item = Self::PathElement>;
// type Attributes = impl Iterator<Item = coap_handler::Attribute>;
fn path(&self) -> Self::PathElements {
let mut buf = heapless::String::new();
if let Record::Entry(i, _e) = self {
// Error for i > 9999 checked elsewhere, so this shouldn't happened (but we'll let it
// slide)
let _ = write!(buf, "{}", i);
} // else, Root is just rendered as "" which is already in there
core::iter::once(buf)
}
fn rel(&self) -> core::option::Option<&str> {
None
}
fn attributes(&self) -> Self::Attributes {
match self {
Record::Root => [coap_handler::Attribute::Title("SAUL index")]
.iter()
.cloned(),
// FIXME: produce rt="tag:chrysn@fsfe.org,2020-10-02:saul";saul=ACT_LED_RGB
Record::Entry(_i, _e) => [
coap_handler::Attribute::ResourceType("tag:chrysn@fsfe.org,2020-10-02:saul"),
// Title would be nice but requires more elaborate structure than [] even though
// it's a &'static string because the array itself will need to be passed; might
// work with a heapless::Vec
// coap_handler::Attribute::Title(e.name().unwrap_or("unnamed")),
// ... but still, where do we transport the custom saul attribute?
]
.iter()
.cloned(),
}
}
}
// To be removed with TAIT, see below
fn first_arg_fits_in_4_bytes(data: &(usize, RegistryEntry)) -> bool {
data.0 <= 9999
}
// To be removed with TAIT, see below
fn make_record(data: (usize, RegistryEntry)) -> Record {
Record::Entry(data.0, data.1)
}
/// A SaulHandler lists all its SAUL devices in /.well-known/core. This is especially useful when
/// registering at a Resource Directory using simple registration and lookup clients try to
/// discover sensors.
impl coap_handler::Reporting for SaulHandler {
type Record<'res> = Record;
// FIXME: Once TAIT is stable, this all can become its simple form again, and the filter/map
// workhorses can become (empty) closures.
type Reporter<'res> = core::iter::Chain<
core::iter::Once<Record>,
core::iter::Map<
core::iter::Filter<
core::iter::Enumerate<riot_wrappers::saul::AllRegistryEntries>,
fn(&(usize, RegistryEntry)) -> bool,
>,
fn((usize, RegistryEntry)) -> Record,
>,
>;
// or type Reporter<'res> = impl Iterator<Item=Record>;
fn report(&self) -> Self::Reporter<'_> {
core::iter::once(Record::Root).chain(
RegistryEntry::all()
.enumerate()
// for the String<4>, but whoever has so many sensors will have a hard time
// listing them all in .wk/c anyway
.filter(first_arg_fits_in_4_bytes as _)
// or .filter(|(i, _r)| *i <= 9999)
.map(make_record as _),
// or .map(|(i, r)| Record::Entry(i, r))
)
}
}