mdebray/tvl-depot
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
tvl-depot/users/Profpatsch/netencode/netencode.rs
Profpatsch ed68ba6751 feat(users/Profpatsch/netencode): ignore earlier record entries 
It turns out that the netencode spec requiring to ignore *later*
entries meant that every parser has to do an extra check for each
element, instead of just overriding the key in the hash map.

This leads to a situation where the simple implementation is the wrong
one, which would lead to very subtle problems in parsers (see also the
infamous “json duplicate record entry” problem which has been used for
various exploits in the past).

To be fair, exploits are still possible, but at least a `Map.fromList`
will be the right implementation (provided it folds from the left) now
instead of the wrong one.

Examples of the trivial implementation being now right:

Python:

    > dict([("foo", 1), ("foo", 2)])
    {'foo': 2}

Rust:

    > println!("{:?}", HashMap::from([
      ("foo", 1),
      ("foo", 2)
    ]));
    {"foo": 2}

Haskell:

    > Data.Map.fromList [ ("foo", 1), ("foo", 2) ]
    fromList [("foo",2)]

Change-Id: Ife9593956f4718e5e720f4f348c227e4f3a71e2d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5108
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: Profpatsch <mail@profpatsch.de>
2022-02-14 14:12:19 +00:00

891 lines
27 KiB
Rust
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

extern crate exec_helpers;
extern crate nom;
use std::collections::HashMap;
use std::fmt::{Debug, Display};
use std::io::{Read, Write};
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum T {
// Unit
Unit,
// Boolean
N1(bool),
// Naturals
N3(u8),
N6(u64),
N7(u128),
// Integers
I3(i8),
I6(i64),
I7(i128),
// Text
// TODO: make into &str
Text(String),
// TODO: rename to Bytes
Binary(Vec<u8>),
// Tags
// TODO: make into &str
// TODO: rename to Tag
Sum(Tag<String, T>),
// TODO: make into &str
Record(HashMap<String, T>),
List(Vec<T>),
}
impl T {
pub fn to_u<'a>(&'a self) -> U<'a> {
match self {
T::Unit => U::Unit,
T::N1(b) => U::N1(*b),
T::N3(u) => U::N3(*u),
T::N6(u) => U::N6(*u),
T::N7(u) => U::N7(*u),
T::I3(i) => U::I3(*i),
T::I6(i) => U::I6(*i),
T::I7(i) => U::I7(*i),
T::Text(t) => U::Text(t.as_str()),
T::Binary(v) => U::Binary(v),
T::Sum(Tag { tag, val }) => U::Sum(Tag {
tag: tag.as_str(),
val: Box::new(val.to_u()),
}),
T::Record(map) => U::Record(map.iter().map(|(k, v)| (k.as_str(), v.to_u())).collect()),
T::List(l) => U::List(l.iter().map(|v| v.to_u()).collect::<Vec<U<'a>>>()),
}
}
pub fn encode<'a>(&'a self) -> Vec<u8> {
match self {
// TODO: don’t go via U, inefficient
o => o.to_u().encode(),
}
}
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum U<'a> {
Unit,
// Boolean
N1(bool),
// Naturals
N3(u8),
N6(u64),
N7(u128),
// Integers
I3(i8),
I6(i64),
I7(i128),
// Text
Text(&'a str),
Binary(&'a [u8]),
// TODO: the U-recursion we do here means we can’t be breadth-lazy anymore
// like we originally planned; maybe we want to go `U<'a>` → `&'a [u8]` again?
// Tags
// TODO: rename to Tag
Sum(Tag<&'a str, U<'a>>),
Record(HashMap<&'a str, U<'a>>),
List(Vec<U<'a>>),
}
impl<'a> U<'a> {
pub fn encode(&self) -> Vec<u8> {
let mut c = std::io::Cursor::new(vec![]);
encode(&mut c, self);
c.into_inner()
}
pub fn to_t(&self) -> T {
match self {
U::Unit => T::Unit,
U::N1(b) => T::N1(*b),
U::N3(u) => T::N3(*u),
U::N6(u) => T::N6(*u),
U::N7(u) => T::N7(*u),
U::I3(i) => T::I3(*i),
U::I6(i) => T::I6(*i),
U::I7(i) => T::I7(*i),
U::Text(t) => T::Text((*t).to_owned()),
U::Binary(v) => T::Binary((*v).to_owned()),
U::Sum(Tag { tag, val }) => T::Sum(Tag {
tag: (*tag).to_owned(),
val: Box::new(val.to_t()),
}),
U::Record(map) => T::Record(
map.iter()
.map(|(k, v)| ((*k).to_owned(), v.to_t()))
.collect::<HashMap<String, T>>(),
),
U::List(l) => T::List(l.iter().map(|v| v.to_t()).collect::<Vec<T>>()),
}
}
}
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Tag<S, A> {
// TODO: make into &str
pub tag: S,
pub val: Box<A>,
}
impl<S, A> Tag<S, A> {
fn map<F, B>(self, f: F) -> Tag<S, B>
where
F: Fn(A) -> B,
{
Tag {
tag: self.tag,
val: Box::new(f(*self.val)),
}
}
}
fn encode_tag<W: Write>(w: &mut W, tag: &str, val: &U) -> std::io::Result<()> {
write!(w, "<{}:{}|", tag.len(), tag)?;
encode(w, val)?;
Ok(())
}
pub fn encode<W: Write>(w: &mut W, u: &U) -> std::io::Result<()> {
match u {
U::Unit => write!(w, "u,"),
U::N1(b) => {
if *b {
write!(w, "n1:1,")
} else {
write!(w, "n1:0,")
}
}
U::N3(n) => write!(w, "n3:{},", n),
U::N6(n) => write!(w, "n6:{},", n),
U::N7(n) => write!(w, "n7:{},", n),
U::I3(i) => write!(w, "i3:{},", i),
U::I6(i) => write!(w, "i6:{},", i),
U::I7(i) => write!(w, "i7:{},", i),
U::Text(s) => {
write!(w, "t{}:", s.len());
w.write_all(s.as_bytes());
write!(w, ",")
}
U::Binary(s) => {
write!(w, "b{}:", s.len());
w.write_all(&s);
write!(w, ",")
}
U::Sum(Tag { tag, val }) => encode_tag(w, tag, val),
U::Record(m) => {
let mut c = std::io::Cursor::new(vec![]);
for (k, v) in m {
encode_tag(&mut c, k, v)?;
}
write!(w, "{{{}:", c.get_ref().len())?;
w.write_all(c.get_ref())?;
write!(w, "}}")
}
U::List(l) => {
let mut c = std::io::Cursor::new(vec![]);
for u in l {
encode(&mut c, u)?;
}
write!(w, "[{}:", c.get_ref().len())?;
w.write_all(c.get_ref())?;
write!(w, "]")
}
}
}
pub fn text(s: String) -> T {
T::Text(s)
}
pub fn u_from_stdin_or_die_user_error<'a>(prog_name: &'_ str, stdin_buf: &'a mut Vec<u8>) -> U<'a> {
std::io::stdin().lock().read_to_end(stdin_buf);
let u = match parse::u_u(stdin_buf) {
Ok((rest, u)) => match rest {
b"" => u,
_ => exec_helpers::die_user_error(
prog_name,
format!(
"stdin contained some soup after netencode value: {:?}",
String::from_utf8_lossy(rest)
),
),
},
Err(err) => exec_helpers::die_user_error(
prog_name,
format!("unable to parse netencode from stdin: {:?}", err),
),
};
u
}
pub mod parse {
use super::{Tag, T, U};
use std::collections::HashMap;
use std::ops::Neg;
use std::str::FromStr;
use nom::branch::alt;
use nom::bytes::streaming::{tag, take};
use nom::character::streaming::{char, digit1};
use nom::combinator::{flat_map, map, map_parser, map_res, opt};
use nom::error::{context, ErrorKind, ParseError};
use nom::sequence::tuple;
use nom::IResult;
fn unit_t(s: &[u8]) -> IResult<&[u8], ()> {
let (s, _) = context("unit", tag("u,"))(s)?;
Ok((s, ()))
}
fn usize_t(s: &[u8]) -> IResult<&[u8], usize> {
context(
"usize",
map_res(map_res(digit1, |n| std::str::from_utf8(n)), |s| {
s.parse::<usize>()
}),
)(s)
}
fn sized(begin: char, end: char) -> impl Fn(&[u8]) -> IResult<&[u8], &[u8]> {
move |s: &[u8]| {
// This is the point where we check the descriminator;
// if the beginning char does not match, we can immediately return.
let (s, _) = char(begin)(s)?;
let (s, (len, _)) = tuple((usize_t, char(':')))(s)?;
let (s, (res, _)) = tuple((take(len), char(end)))(s)?;
Ok((s, res))
}
}
fn uint_t<'a, I: FromStr + 'a>(t: &'static str) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], I> {
move |s: &'a [u8]| {
let (s, (_, _, int, _)) = tuple((
tag(t.as_bytes()),
char(':'),
map_res(map_res(digit1, |n: &[u8]| std::str::from_utf8(n)), |s| {
s.parse::<I>()
}),
char(','),
))(s)?;
Ok((s, int))
}
}
fn bool_t<'a>() -> impl Fn(&'a [u8]) -> IResult<&'a [u8], bool> {
context(
"bool",
alt((map(tag("n1:0,"), |_| false), map(tag("n1:1,"), |_| true))),
)
}
fn int_t<'a, I: FromStr + Neg<Output = I>>(
t: &'static str,
) -> impl Fn(&'a [u8]) -> IResult<&[u8], I> {
context(t, move |s: &'a [u8]| {
let (s, (_, _, neg, int, _)) = tuple((
tag(t.as_bytes()),
char(':'),
opt(char('-')),
map_res(map_res(digit1, |n: &[u8]| std::str::from_utf8(n)), |s| {
s.parse::<I>()
}),
char(','),
))(s)?;
let res = match neg {
Some(_) => -int,
None => int,
};
Ok((s, res))
})
}
fn tag_t(s: &[u8]) -> IResult<&[u8], Tag<String, T>> {
// recurses into the main parser
map(tag_g(t_t), |Tag { tag, val }| Tag {
tag: tag.to_string(),
val,
})(s)
}
fn tag_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], Tag<&'a str, O>>
where
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
move |s: &[u8]| {
let (s, tag) = sized('<', '|')(s)?;
let (s, val) = inner(s)?;
Ok((
s,
Tag {
tag: std::str::from_utf8(tag)
.map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
val: Box::new(val),
},
))
}
}
/// parse text scalar (`t5:hello,`)
fn text(s: &[u8]) -> IResult<&[u8], T> {
let (s, res) = text_g(s)?;
Ok((s, T::Text(res.to_string())))
}
fn text_g(s: &[u8]) -> IResult<&[u8], &str> {
let (s, res) = sized('t', ',')(s)?;
Ok((
s,
std::str::from_utf8(res).map_err(|_| nom::Err::Failure((s, ErrorKind::Char)))?,
))
}
fn binary<'a>() -> impl Fn(&'a [u8]) -> IResult<&'a [u8], T> {
map(binary_g(), |b| T::Binary(b.to_owned()))
}
fn binary_g() -> impl Fn(&[u8]) -> IResult<&[u8], &[u8]> {
sized('b', ',')
}
fn list_t(s: &[u8]) -> IResult<&[u8], Vec<T>> {
list_g(t_t)(s)
}
/// Wrap the inner parser of an `many0`/`fold_many0`, so that the parser
/// is not called when the `s` is empty already, preventing it from
/// returning `Incomplete` on streaming parsing.
fn inner_no_empty_string<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], O>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
move |s: &'a [u8]| {
if s.is_empty() {
// This is a bit hacky, `many0` considers the inside done
// when a parser returns `Err::Error`, ignoring the actual error content
Err(nom::Err::Error((s, nom::error::ErrorKind::Many0)))
} else {
inner(s)
}
}
}
fn list_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], Vec<O>>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
map_parser(
sized('[', ']'),
nom::multi::many0(inner_no_empty_string(inner)),
)
}
fn record_t<'a>(s: &'a [u8]) -> IResult<&'a [u8], HashMap<String, T>> {
let (s, r) = record_g(t_t)(s)?;
Ok((
s,
r.into_iter()
.map(|(k, v)| (k.to_string(), v))
.collect::<HashMap<_, _>>(),
))
}
fn record_g<'a, P, O>(inner: P) -> impl Fn(&'a [u8]) -> IResult<&'a [u8], HashMap<&'a str, O>>
where
O: Clone,
P: Fn(&'a [u8]) -> IResult<&'a [u8], O>,
{
move |s: &'a [u8]| {
let (s, map) = map_parser(
sized('{', '}'),
nom::multi::fold_many0(
inner_no_empty_string(tag_g(&inner)),
HashMap::new(),
|mut acc: HashMap<_, _>, Tag { tag, mut val }| {
// ignore earlier tags with the same name
// according to netencode spec
let _ = acc.insert(tag, *val);
acc
},
),
)(s)?;
if map.is_empty() {
// records must not be empty, according to the spec
Err(nom::Err::Failure((s, nom::error::ErrorKind::Many1)))
} else {
Ok((s, map))
}
}
}
pub fn u_u(s: &[u8]) -> IResult<&[u8], U> {
alt((
map(text_g, U::Text),
map(binary_g(), U::Binary),
map(unit_t, |()| U::Unit),
map(tag_g(u_u), |t| U::Sum(t)),
map(list_g(u_u), U::List),
map(record_g(u_u), U::Record),
map(bool_t(), |u| U::N1(u)),
map(uint_t("n3"), |u| U::N3(u)),
map(uint_t("n6"), |u| U::N6(u)),
map(uint_t("n7"), |u| U::N7(u)),
map(int_t("i3"), |u| U::I3(u)),
map(int_t("i6"), |u| U::I6(u)),
map(int_t("i7"), |u| U::I7(u)),
// less common
map(uint_t("n2"), |u| U::N3(u)),
map(uint_t("n4"), |u| U::N6(u)),
map(uint_t("n5"), |u| U::N6(u)),
map(int_t("i1"), |u| U::I3(u)),
map(int_t("i2"), |u| U::I3(u)),
map(int_t("i4"), |u| U::I6(u)),
map(int_t("i5"), |u| U::I6(u)),
// TODO: 8, 9 not supported
))(s)
}
pub fn t_t(s: &[u8]) -> IResult<&[u8], T> {
alt((
text,
binary(),
map(unit_t, |_| T::Unit),
map(tag_t, |t| T::Sum(t)),
map(list_t, |l| T::List(l)),
map(record_t, |p| T::Record(p)),
map(bool_t(), |u| T::N1(u)),
// 8, 64 and 128 bit
map(uint_t("n3"), |u| T::N3(u)),
map(uint_t("n6"), |u| T::N6(u)),
map(uint_t("n7"), |u| T::N7(u)),
map(int_t("i3"), |u| T::I3(u)),
map(int_t("i6"), |u| T::I6(u)),
map(int_t("i7"), |u| T::I7(u)),
// less common
map(uint_t("n2"), |u| T::N3(u)),
map(uint_t("n4"), |u| T::N6(u)),
map(uint_t("n5"), |u| T::N6(u)),
map(int_t("i1"), |u| T::I3(u)),
map(int_t("i2"), |u| T::I3(u)),
map(int_t("i4"), |u| T::I6(u)),
map(int_t("i5"), |u| T::I6(u)),
// TODO: 8, 9 not supported
))(s)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_parse_unit_t() {
assert_eq!(unit_t("u,".as_bytes()), Ok(("".as_bytes(), ())));
}
#[test]
fn test_parse_bool_t() {
assert_eq!(bool_t()("n1:0,".as_bytes()), Ok(("".as_bytes(), false)));
assert_eq!(bool_t()("n1:1,".as_bytes()), Ok(("".as_bytes(), true)));
}
#[test]
fn test_parse_usize_t() {
assert_eq!(usize_t("32foo".as_bytes()), Ok(("foo".as_bytes(), 32)));
}
#[test]
fn test_parse_int_t() {
assert_eq!(
uint_t::<u8>("n3")("n3:42,abc".as_bytes()),
Ok(("abc".as_bytes(), 42))
);
assert_eq!(
uint_t::<u8>("n3")("n3:1024,abc".as_bytes()),
Err(nom::Err::Error((
"1024,abc".as_bytes(),
nom::error::ErrorKind::MapRes
)))
);
assert_eq!(
int_t::<i64>("i6")("i6:-23,abc".as_bytes()),
Ok(("abc".as_bytes(), -23))
);
assert_eq!(
int_t::<i128>("i3")("i3:0,:abc".as_bytes()),
Ok((":abc".as_bytes(), 0))
);
assert_eq!(
uint_t::<u8>("n7")("n7:09,".as_bytes()),
Ok(("".as_bytes(), 9))
);
// assert_eq!(
// length("c"),
// Err(nom::Err::Error(("c", nom::error::ErrorKind::Digit)))
// );
// assert_eq!(
// length(":"),
// Err(nom::Err::Error((":", nom::error::ErrorKind::Digit)))
// );
}
#[test]
fn test_parse_text() {
assert_eq!(
text("t5:hello,".as_bytes()),
Ok(("".as_bytes(), T::Text("hello".to_owned()))),
"{}",
r"t5:hello,"
);
assert_eq!(
text("t4:fo".as_bytes()),
// The content of the text should be 4 long
Err(nom::Err::Incomplete(nom::Needed::Size(4))),
"{}",
r"t4:fo,"
);
assert_eq!(
text("t9:今日は,".as_bytes()),
Ok(("".as_bytes(), T::Text("今日は".to_owned()))),
"{}",
r"t9:今日は,"
);
}
#[test]
fn test_parse_binary() {
assert_eq!(
binary()("b5:hello,".as_bytes()),
Ok(("".as_bytes(), T::Binary(Vec::from("hello".to_owned())))),
"{}",
r"b5:hello,"
);
assert_eq!(
binary()("b4:fo".as_bytes()),
// The content of the byte should be 4 long
Err(nom::Err::Incomplete(nom::Needed::Size(4))),
"{}",
r"b4:fo,"
);
assert_eq!(
binary()("b4:foob".as_bytes()),
// The content is 4 bytes now, but the finishing , is missing
Err(nom::Err::Incomplete(nom::Needed::Size(1))),
"{}",
r"b4:fo,"
);
assert_eq!(
binary()("b9:今日は,".as_bytes()),
Ok(("".as_bytes(), T::Binary(Vec::from("今日は".as_bytes())))),
"{}",
r"b9:今日は,"
);
}
#[test]
fn test_list() {
assert_eq!(
list_t("[0:]".as_bytes()),
Ok(("".as_bytes(), vec![])),
"{}",
r"[0:]"
);
assert_eq!(
list_t("[6:u,u,u,]".as_bytes()),
Ok(("".as_bytes(), vec![T::Unit, T::Unit, T::Unit,])),
"{}",
r"[6:u,u,u,]"
);
assert_eq!(
list_t("[15:u,[7:t3:foo,]u,]".as_bytes()),
Ok((
"".as_bytes(),
vec![T::Unit, T::List(vec![T::Text("foo".to_owned())]), T::Unit,]
)),
"{}",
r"[15:u,[7:t3:foo,]u,]"
);
}
#[test]
fn test_record() {
assert_eq!(
record_t("{21:<1:a|u,<1:b|u,<1:c|u,}".as_bytes()),
Ok((
"".as_bytes(),
vec![
("a".to_owned(), T::Unit),
("b".to_owned(), T::Unit),
("c".to_owned(), T::Unit),
]
.into_iter()
.collect::<HashMap<String, T>>()
)),
"{}",
r"{21:<1:a|u,<1:b|u,<1:c|u,}"
);
// duplicated keys are ignored (first is taken)
assert_eq!(
record_t("{25:<1:a|u,<1:b|u,<1:a|i1:-1,}".as_bytes()),
Ok((
"".as_bytes(),
vec![("a".to_owned(), T::I3(-1)), ("b".to_owned(), T::Unit),]
.into_iter()
.collect::<HashMap<_, _>>()
)),
"{}",
r"{25:<1:a|u,<1:b|u,<1:a|i1:-1,}"
);
// empty records are not allowed
assert_eq!(
record_t("{0:}".as_bytes()),
Err(nom::Err::Failure((
"".as_bytes(),
nom::error::ErrorKind::Many1
))),
"{}",
r"{0:}"
);
}
#[test]
fn test_parse() {
assert_eq!(
t_t("n3:255,".as_bytes()),
Ok(("".as_bytes(), T::N3(255))),
"{}",
r"n3:255,"
);
assert_eq!(
t_t("t6:halloo,".as_bytes()),
Ok(("".as_bytes(), T::Text("halloo".to_owned()))),
"{}",
r"t6:halloo,"
);
assert_eq!(
t_t("<3:foo|t6:halloo,".as_bytes()),
Ok((
"".as_bytes(),
T::Sum(Tag {
tag: "foo".to_owned(),
val: Box::new(T::Text("halloo".to_owned()))
})
)),
"{}",
r"<3:foo|t6:halloo,"
);
// { a: Unit
// , foo: List <A: Unit | B: List i3> }
assert_eq!(
t_t("{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}".as_bytes()),
Ok((
"".as_bytes(),
T::Record(
vec![
("a".to_owned(), T::Unit),
(
"foo".to_owned(),
T::List(vec![
T::Sum(Tag {
tag: "A".to_owned(),
val: Box::new(T::Unit)
}),
T::Sum(Tag {
tag: "A".to_owned(),
val: Box::new(T::N1(true))
}),
T::Sum(Tag {
tag: "B".to_owned(),
val: Box::new(T::List(vec![T::I3(127)]))
}),
])
)
]
.into_iter()
.collect::<HashMap<String, T>>()
)
)),
"{}",
r"{52:<1:a|u,<3:foo|[33:<1:A|u,<1:A|n1:1,<1:B|[7:i3:127,]]}"
);
}
}
}
pub mod dec {
use super::*;
use std::collections::HashMap;
pub struct DecodeError(pub String);
pub trait Decoder<'a> {
type A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError>;
}
/// Any netencode, as `T`.
#[derive(Clone, Copy)]
pub struct AnyT;
/// Any netencode, as `U`.
#[derive(Clone, Copy)]
pub struct AnyU;
impl<'a> Decoder<'a> for AnyT {
type A = T;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
Ok(u.to_t())
}
}
impl<'a> Decoder<'a> for AnyU {
type A = U<'a>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
Ok(u)
}
}
/// A text
#[derive(Clone, Copy)]
pub struct Text;
/// A bytestring
// TODO: rename to Bytes
#[derive(Clone, Copy)]
pub struct Binary;
impl<'a> Decoder<'a> for Text {
type A = &'a str;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Text(t) => Ok(t),
other => Err(DecodeError(format!("Cannot decode {:?} into Text", other))),
}
}
}
impl<'a> Decoder<'a> for Binary {
type A = &'a [u8];
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Binary(b) => Ok(b),
other => Err(DecodeError(format!(
"Cannot decode {:?} into Binary",
other
))),
}
}
}
/// Any scalar, converted to bytes.
#[derive(Clone, Copy)]
pub struct ScalarAsBytes;
impl<'a> Decoder<'a> for ScalarAsBytes {
type A = Vec<u8>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::N3(u) => Ok(format!("{}", u).into_bytes()),
U::N6(u) => Ok(format!("{}", u).into_bytes()),
U::N7(u) => Ok(format!("{}", u).into_bytes()),
U::I3(i) => Ok(format!("{}", i).into_bytes()),
U::I6(i) => Ok(format!("{}", i).into_bytes()),
U::I7(i) => Ok(format!("{}", i).into_bytes()),
U::Text(t) => Ok(t.as_bytes().to_owned()),
U::Binary(b) => Ok(b.to_owned()),
o => Err(DecodeError(format!("Cannot decode {:?} into scalar", o))),
}
}
}
/// A map of Ts (TODO: rename to map)
#[derive(Clone, Copy)]
pub struct Record<T>(pub T);
impl<'a, Inner> Decoder<'a> for Record<Inner>
where
Inner: Decoder<'a>,
{
type A = HashMap<&'a str, Inner::A>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match u {
U::Record(map) => map
.into_iter()
.map(|(k, v)| self.0.dec(v).map(|v2| (k, v2)))
.collect::<Result<Self::A, _>>(),
o => Err(DecodeError(format!("Cannot decode {:?} into record", o))),
}
}
}
/// Assume a record and project out the field with the given name and type.
#[derive(Clone, Copy)]
pub struct RecordDot<'a, T> {
pub field: &'a str,
pub inner: T,
}
impl<'a, Inner> Decoder<'a> for RecordDot<'_, Inner>
where
Inner: Decoder<'a> + Clone,
{
type A = Inner::A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match Record(self.inner.clone()).dec(u) {
Ok(mut map) => match map.remove(self.field) {
Some(inner) => Ok(inner),
None => Err(DecodeError(format!(
"Cannot find `{}` in record map",
self.field
))),
},
Err(err) => Err(err),
}
}
}
/// Equals one of the listed `A`s exactly, after decoding.
#[derive(Clone)]
pub struct OneOf<T, A> {
pub inner: T,
pub list: Vec<A>,
}
impl<'a, Inner> Decoder<'a> for OneOf<Inner, Inner::A>
where
Inner: Decoder<'a>,
Inner::A: Display + Debug + PartialEq,
{
type A = Inner::A;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match self.inner.dec(u) {
Ok(inner) => match self.list.iter().any(|x| x.eq(&inner)) {
true => Ok(inner),
false => Err(DecodeError(format!(
"{} is not one of {:?}",
inner, self.list
))),
},
Err(err) => Err(err),
}
}
}
/// Try decoding as `T`.
#[derive(Clone)]
pub struct Try<T>(pub T);
impl<'a, Inner> Decoder<'a> for Try<Inner>
where
Inner: Decoder<'a>,
{
type A = Option<Inner::A>;
fn dec(&self, u: U<'a>) -> Result<Self::A, DecodeError> {
match self.0.dec(u) {
Ok(inner) => Ok(Some(inner)),
Err(err) => Ok(None),
}
}
}
}
Reference in a new issue View git blame Copy permalink