Move everything to workspaces

crates/bencode/src/serde_bencode_de.rs

@@ -0,0 +1,567 @@
+use buffers::ByteBuf;
+use serde::de::Error as DeError;
+use sha1w::{ISha1, Sha1};
+
+pub struct BencodeDeserializer<'de> {
+    buf: &'de [u8],
+    field_context: Vec<ByteBuf<'de>>,
+    parsing_key: bool,
+
+    // This is a f**ing hack
+    pub is_torrent_info: bool,
+    pub torrent_info_digest: Option<[u8; 20]>,
+}
+
+impl<'de> BencodeDeserializer<'de> {
+    pub fn new_from_buf(buf: &'de [u8]) -> BencodeDeserializer<'de> {
+        Self {
+            buf,
+            field_context: Default::default(),
+            parsing_key: false,
+            is_torrent_info: false,
+            torrent_info_digest: None,
+        }
+    }
+    pub fn into_remaining(self) -> &'de [u8] {
+        self.buf
+    }
+    fn parse_integer(&mut self) -> Result<i64, Error> {
+        match self.buf.iter().copied().position(|e| e == b'e') {
+            Some(end) => {
+                let intbytes = &self.buf[1..end];
+                let value: i64 = std::str::from_utf8(intbytes)
+                    .map_err(|e| Error::new_from_err(e).set_context(self))?
+                    .parse()
+                    .map_err(|e| Error::new_from_err(e).set_context(self))?;
+                let rem = self.buf.get(end + 1..).unwrap_or_default();
+                self.buf = rem;
+                Ok(value)
+            }
+            None => Err(Error::custom("cannot parse integer, unexpected EOF").set_context(self)),
+        }
+    }
+
+    fn parse_bytes(&mut self) -> Result<&'de [u8], Error> {
+        match self.buf.iter().copied().position(|e| e == b':') {
+            Some(length_delim) => {
+                let lenbytes = &self.buf[..length_delim];
+                let length: usize = std::str::from_utf8(lenbytes)
+                    .map_err(|e| Error::new_from_err(e).set_context(self))?
+                    .parse()
+                    .map_err(|e| Error::new_from_err(e).set_context(self))?;
+                let bytes_start = length_delim + 1;
+                let bytes_end = bytes_start + length;
+                let bytes = &self.buf.get(bytes_start..bytes_end).ok_or_else(|| {
+                    Error::custom(format!(
+                        "could not get byte range {}..{}, data in the buffer: {:?}",
+                        bytes_start, bytes_end, &self.buf
+                    ))
+                    .set_context(self)
+                })?;
+                let rem = self.buf.get(bytes_end..).unwrap_or_default();
+                self.buf = rem;
+                Ok(bytes)
+            }
+            None => Err(Error::custom("cannot parse bytes, unexpected EOF").set_context(self)),
+        }
+    }
+
+    fn parse_bytes_checked(&mut self) -> Result<&'de [u8], Error> {
+        let first = match self.buf.first().copied() {
+            Some(first) => first,
+            None => return Err(Error::custom("expected bencode bytes, got EOF").set_context(self)),
+        };
+        match first {
+            b'0'..=b'9' => {}
+            _ => return Err(Error::custom("expected bencode bytes").set_context(self)),
+        }
+        let b = self.parse_bytes()?;
+        if self.parsing_key {
+            self.field_context.push(ByteBuf(b));
+        }
+        Ok(b)
+    }
+}
+
+pub fn from_bytes<'a, T>(buf: &'a [u8]) -> anyhow::Result<T>
+where
+    T: serde::de::Deserialize<'a>,
+{
+    let mut de = BencodeDeserializer::new_from_buf(buf);
+    let v = T::deserialize(&mut de)?;
+    if !de.buf.is_empty() {
+        anyhow::bail!(
+            "deserialized successfully, but {} bytes remaining",
+            de.buf.len()
+        )
+    }
+    Ok(v)
+}
+
+#[derive(Debug)]
+enum ErrorKind {
+    Other(anyhow::Error),
+    NotSupported(&'static str),
+}
+
+#[derive(Debug, Default)]
+pub struct ErrorContext {
+    field_stack: Vec<String>,
+}
+
+impl std::fmt::Display for ErrorContext {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut it = self.field_stack.iter();
+        if let Some(field) = it.next() {
+            write!(f, "\"{}\"", field)?;
+        } else {
+            return Ok(());
+        }
+        for field in self.field_stack.iter().skip(1) {
+            write!(f, " -> \"{}\"", field)?;
+        }
+        f.write_str(": ")
+    }
+}
+
+#[derive(Debug)]
+pub struct Error {
+    kind: ErrorKind,
+    context: ErrorContext,
+}
+
+impl std::fmt::Display for ErrorKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ErrorKind::Other(err) => err.fmt(f),
+            ErrorKind::NotSupported(s) => write!(f, "{} is not supported by bencode", s),
+        }
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}{}", self.context, self.kind)
+    }
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match &self.kind {
+            ErrorKind::Other(err) => err.source(),
+            _ => None,
+        }
+    }
+}
+
+impl Error {
+    fn new_from_err<E>(e: E) -> Self
+    where
+        E: std::error::Error + Send + Sync + 'static,
+    {
+        Error {
+            kind: ErrorKind::Other(anyhow::Error::new(e)),
+            context: Default::default(),
+        }
+    }
+
+    fn new_from_kind(kind: ErrorKind) -> Self {
+        Self {
+            kind,
+            context: Default::default(),
+        }
+    }
+
+    fn new_from_anyhow(e: anyhow::Error) -> Self {
+        Error {
+            kind: ErrorKind::Other(e),
+            context: Default::default(),
+        }
+    }
+    fn custom_with_de<M: std::fmt::Display>(msg: M, de: &BencodeDeserializer<'_>) -> Self {
+        Self::custom(msg).set_context(de)
+    }
+    fn set_context(mut self, de: &BencodeDeserializer<'_>) -> Self {
+        self.context = ErrorContext {
+            field_stack: de.field_context.iter().map(|s| format!("{}", s)).collect(),
+        };
+        self
+    }
+}
+
+impl serde::de::Error for Error {
+    fn custom<T>(msg: T) -> Self
+    where
+        T: std::fmt::Display,
+    {
+        Self {
+            kind: ErrorKind::Other(anyhow::anyhow!("{}", msg)),
+            context: Default::default(),
+        }
+    }
+}
+
+impl<'de, 'a> serde::de::Deserializer<'de> for &'a mut BencodeDeserializer<'de> {
+    type Error = Error;
+
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        match self.buf.first().copied() {
+            Some(b'd') => self.deserialize_map(visitor),
+            Some(b'i') => self.deserialize_u64(visitor),
+            Some(b'l') => self.deserialize_seq(visitor),
+            Some(_) => self.deserialize_bytes(visitor),
+            None => Err(Error::custom_with_de("empty input", self)),
+        }
+    }
+
+    fn deserialize_bool<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("bencode doesn't support booleans"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_i8<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_i16<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_i32<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_i64<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        if !self.buf.starts_with(b"i") {
+            return Err(Error::custom_with_de("expected bencode int", self));
+        }
+        visitor
+            .visit_i64(self.parse_integer()?)
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_u16<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_u32<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_u64<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_i64(visitor)
+    }
+
+    fn deserialize_f32<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("bencode doesn't support floats"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_f64<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("bencode doesn't support floats"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_char<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("bencode doesn't support chars"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        let first = match self.buf.first().copied() {
+            Some(first) => first,
+            None => {
+                return Err(Error::custom_with_de(
+                    "expected bencode string, got EOF",
+                    self,
+                ))
+            }
+        };
+        match first {
+            b'0'..=b'9' => {}
+            _ => return Err(Error::custom_with_de("expected bencode string", self)),
+        }
+        let b = self.parse_bytes()?;
+        let s = std::str::from_utf8(b).map_err(|e| {
+            Error::new_from_anyhow(anyhow::anyhow!("error reading utf-8: {}", e)).set_context(self)
+        })?;
+        visitor
+            .visit_borrowed_str(s)
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_string<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_str(visitor)
+    }
+
+    fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        let b = self.parse_bytes_checked()?;
+        visitor
+            .visit_borrowed_bytes(b)
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_bytes(visitor)
+    }
+
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        visitor
+            .visit_some(&mut *self)
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_unit<V>(self, _visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(Error::new_from_kind(ErrorKind::NotSupported(
+            "bencode doesn't support unit types",
+        ))
+        .set_context(self))
+    }
+
+    fn deserialize_unit_struct<V>(
+        self,
+        _name: &'static str,
+        _visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(Error::new_from_kind(ErrorKind::NotSupported(
+            "bencode doesn't support unit structs",
+        ))
+        .set_context(self))
+    }
+
+    fn deserialize_newtype_struct<V>(
+        self,
+        _name: &'static str,
+        _visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("bencode doesn't newtype structs"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_seq<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        if !self.buf.starts_with(b"l") {
+            return Err(Error::custom(format!(
+                "expected bencode list, but got {}",
+                self.buf[0] as char,
+            )));
+        }
+        self.buf = self.buf.get(1..).unwrap_or_default();
+        visitor
+            .visit_seq(SeqAccess { de: &mut self })
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_seq(visitor)
+    }
+
+    fn deserialize_tuple_struct<V>(
+        self,
+        _name: &'static str,
+        _len: usize,
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_seq(visitor)
+    }
+
+    fn deserialize_map<V>(mut self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        if !self.buf.starts_with(b"d") {
+            return Err(Error::custom("expected bencode dict"));
+        }
+        self.buf = self.buf.get(1..).unwrap_or_default();
+        visitor
+            .visit_map(MapAccess { de: &mut self })
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_struct<V>(
+        self,
+        _name: &'static str,
+        _fields: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_map(visitor)
+    }
+
+    fn deserialize_enum<V>(
+        self,
+        _name: &'static str,
+        _variants: &'static [&'static str],
+        _visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        Err(
+            Error::new_from_kind(ErrorKind::NotSupported("deserializing enums not supported"))
+                .set_context(self),
+        )
+    }
+
+    fn deserialize_identifier<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        let name = self.parse_bytes_checked()?;
+        visitor
+            .visit_borrowed_bytes(name)
+            .map_err(|e: Self::Error| e.set_context(self))
+    }
+
+    fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::Visitor<'de>,
+    {
+        self.deserialize_any(visitor)
+    }
+}
+
+struct MapAccess<'a, 'de> {
+    de: &'a mut BencodeDeserializer<'de>,
+}
+
+struct SeqAccess<'a, 'de> {
+    de: &'a mut BencodeDeserializer<'de>,
+}
+
+impl<'a, 'de> serde::de::MapAccess<'de> for MapAccess<'a, 'de> {
+    type Error = Error;
+
+    fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>, Self::Error>
+    where
+        K: serde::de::DeserializeSeed<'de>,
+    {
+        if self.de.buf.starts_with(b"e") {
+            self.de.buf = self.de.buf.get(1..).unwrap_or_default();
+            return Ok(None);
+        }
+        self.de.parsing_key = true;
+        let retval = seed.deserialize(&mut *self.de)?;
+        self.de.parsing_key = false;
+        Ok(Some(retval))
+    }
+
+    fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error>
+    where
+        V: serde::de::DeserializeSeed<'de>,
+    {
+        let buf_before = self.de.buf;
+        let value = seed.deserialize(&mut *self.de)?;
+        if self.de.is_torrent_info && self.de.field_context.as_slice() == [ByteBuf(b"info")] {
+            let len = self.de.buf.as_ptr() as usize - buf_before.as_ptr() as usize;
+            let mut hash = Sha1::new();
+            hash.update(&buf_before[..len]);
+            let digest = hash.finish();
+            self.de.torrent_info_digest = Some(digest)
+        }
+        self.de.field_context.pop();
+        Ok(value)
+    }
+}
+
+impl<'a, 'de> serde::de::SeqAccess<'de> for SeqAccess<'a, 'de> {
+    type Error = Error;
+
+    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>, Self::Error>
+    where
+        T: serde::de::DeserializeSeed<'de>,
+    {
+        if self.de.buf.starts_with(b"e") {
+            self.de.buf = self.de.buf.get(1..).unwrap_or_default();
+            return Ok(None);
+        }
+        Ok(Some(seed.deserialize(&mut *self.de)?))
+    }
+}