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285 lines
7.1 KiB
Rust
285 lines
7.1 KiB
Rust
#![allow(dead_code)]
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use bytes::Bytes;
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use std::collections::HashMap;
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use std::error::Error;
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use std::fmt::{Display, Formatter};
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use std::num::ParseIntError;
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use std::str::FromStr;
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use std::string::FromUtf8Error;
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#[derive(Debug, Clone)]
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pub enum BencodeValue {
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Int(i64),
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Bytes(Bytes),
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Dict(BencodeDict),
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List(BencodeList),
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}
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#[derive(Debug)]
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pub enum BencodeError {
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InputTooShort,
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UnknownType,
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FailedToParseNumber(ParseIntError),
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Expected(char),
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}
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impl Display for BencodeError {
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fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
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write!(f, "{:?}", self)
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}
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}
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impl Error for BencodeError {}
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impl BencodeValue {
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pub fn bytes(&self) -> Option<Bytes> {
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if let BencodeValue::Bytes(bytes) = self {
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Some(bytes.clone())
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} else {
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None
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}
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}
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pub fn string(&self) -> Option<Result<String, FromUtf8Error>> {
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if let Some(bytes) = self.bytes() {
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Some(String::from_utf8(bytes.to_vec()))
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} else {
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None
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}
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}
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pub fn int(&self) -> Option<i64> {
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if let BencodeValue::Int(num) = self {
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Some(*num)
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} else {
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None
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}
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}
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pub fn dict(&self) -> Option<&BencodeDict> {
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if let BencodeValue::Dict(dict) = self {
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Some(dict)
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} else {
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None
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}
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}
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pub fn list(&self) -> Option<&BencodeList> {
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if let BencodeValue::List(list) = self {
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Some(list)
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} else {
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None
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}
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}
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pub fn decode<T: Into<Bytes>>(bytes: T) -> Result<Self, BencodeError> {
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let bytes = bytes.into();
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Ok(Self::consume(bytes)?.1)
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}
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fn consume(bytes: Bytes) -> Result<(usize, Self), BencodeError> {
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if bytes.len() < 2 {
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return Err(BencodeError::InputTooShort);
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}
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match bytes[0] {
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b'd' => {
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let (consumed, item) = BencodeDict::consume(bytes)?;
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Ok((consumed, BencodeValue::Dict(item)))
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}
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b'0'..=b'9' => {
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let (consumed, item) = BencodeValue::consume_bytes(bytes)?;
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Ok((consumed, BencodeValue::Bytes(item)))
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}
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b'i' => {
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let (consumed, item) = BencodeValue::consume_int(bytes)?;
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Ok((consumed, BencodeValue::Int(item)))
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}
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b'l' => {
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let (consumed, list) = BencodeList::consume(bytes)?;
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Ok((consumed, BencodeValue::List(list)))
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}
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_ => Err(BencodeError::UnknownType),
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}
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}
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fn consume_int(bytes: Bytes) -> Result<(usize, i64), BencodeError> {
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let mut offset = 1;
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while bytes.len() > offset && bytes[offset] != b'e' {
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offset += 1;
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}
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if bytes.len() <= offset {
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return Err(BencodeError::Expected('e'));
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}
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let length = String::from_utf8_lossy(&bytes[1..offset]);
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offset += 1;
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let nr = i64::from_str(&length)
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.map_err(|parse_error| BencodeError::FailedToParseNumber(parse_error))?;
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Ok((offset, nr))
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}
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fn consume_bytes(bytes: Bytes) -> Result<(usize, Bytes), BencodeError> {
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let mut offset = 1;
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while bytes.len() > offset && bytes[offset] != b':' {
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offset += 1;
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}
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if bytes.len() <= offset {
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return Err(BencodeError::Expected(':'));
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}
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let length = String::from_utf8_lossy(&bytes[0..offset]);
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offset += 1;
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let length = usize::from_str(&length)
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.map_err(|parse_error| BencodeError::FailedToParseNumber(parse_error))?;
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let result = bytes.slice(offset..offset + length);
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Ok((offset + length, result))
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}
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}
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#[derive(Debug, Clone)]
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pub struct BencodeDict {
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bytes: Bytes,
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map: HashMap<Bytes, BencodeValue>,
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}
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impl BencodeDict {
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pub fn buffer(&self) -> Bytes {
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self.bytes.clone()
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}
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fn consume(bytes: Bytes) -> Result<(usize, Self), BencodeError> {
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let mut offset = 1;
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let mut map = HashMap::new();
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while bytes[offset] != b'e' {
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// consume key
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let (len, str) = BencodeValue::consume_bytes(bytes.slice(offset..))?;
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offset += len;
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let (len, value) = BencodeValue::consume(bytes.slice(offset..))?;
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offset += len;
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map.insert(str, value);
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}
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offset += 1;
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Ok((
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offset,
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BencodeDict {
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bytes: bytes.slice(0..offset),
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map,
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},
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))
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}
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pub fn contains_key(&self, key: &[u8]) -> bool {
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self.map.contains_key(key)
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}
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pub fn get(&self, key: &[u8]) -> Option<&BencodeValue> {
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self.map.get(key)
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}
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}
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#[derive(Debug, Clone)]
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pub struct BencodeList {
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bytes: Bytes,
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list: Vec<BencodeValue>,
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}
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impl BencodeList {
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pub fn buffer(&self) -> Bytes {
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self.bytes.clone()
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}
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fn consume(bytes: Bytes) -> Result<(usize, Self), BencodeError> {
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let mut offset = 1;
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let mut list = vec![];
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while bytes.len() > offset && bytes[offset] != b'e' {
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let (consumed, item) = BencodeValue::consume(bytes.slice(offset..))?;
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offset += consumed;
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list.push(item);
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}
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offset += 1;
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Ok((
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offset,
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BencodeList {
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bytes: bytes.slice(0..offset),
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list,
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},
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))
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}
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pub fn len(&self) -> usize {
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self.list.len()
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}
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pub fn iter(&self) -> impl Iterator<Item = &BencodeValue> {
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self.list.iter()
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}
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pub fn get(&self, index: usize) -> Option<&BencodeValue> {
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self.list.get(index)
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::BencodeValue;
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#[test]
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fn test_string() {
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let input = b"4:spam";
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let value = BencodeValue::decode(input.as_ref()).unwrap();
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if let BencodeValue::Bytes(bytes) = value {
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assert_eq!(bytes.as_ref(), b"spam");
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} else {
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panic!(":(")
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}
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}
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#[test]
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fn test_integer() {
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let input = b"i42e";
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let value = BencodeValue::decode(input.as_ref()).unwrap();
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if let BencodeValue::Int(nr) = value {
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assert_eq!(nr, 42);
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} else {
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panic!(":(")
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}
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}
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#[test]
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fn test_dict() {
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let input = b"d4:spam3:egg3:eggdee";
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let value = BencodeValue::decode(input.as_ref()).unwrap();
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if let BencodeValue::Dict(dict) = value {
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assert!(dict.contains_key(b"spam"));
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assert_eq!(dict.get(b"spam").unwrap().bytes().unwrap().as_ref(), b"egg");
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} else {
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panic!(":(")
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}
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}
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#[test]
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fn test_list() {
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let input = b"l4:spam3:egge";
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let value = BencodeValue::decode(input.as_ref()).unwrap();
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if let BencodeValue::List(list) = value {
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assert_eq!(list.get(0).unwrap().bytes().unwrap().as_ref(), b"spam");
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assert_eq!(list.get(1).unwrap().bytes().unwrap().as_ref(), b"egg");
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} else {
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panic!(":(")
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}
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}
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}
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