336 lines
8.4 KiB
Rust
336 lines
8.4 KiB
Rust
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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use std::borrow::Borrow;
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use byteorder::{ByteOrder, BigEndian};
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use elastic_array::{ElasticArray16, ElasticArray1024};
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use traits::Encodable;
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#[derive(Debug, Copy, Clone)]
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struct ListInfo {
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position: usize,
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current: usize,
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max: usize,
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}
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impl ListInfo {
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fn new(position: usize, max: usize) -> ListInfo {
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ListInfo {
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position: position,
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current: 0,
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max: max,
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}
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}
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}
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/// Appendable rlp encoder.
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pub struct RlpStream {
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unfinished_lists: ElasticArray16<ListInfo>,
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buffer: ElasticArray1024<u8>,
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finished_list: bool,
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}
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impl Default for RlpStream {
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fn default() -> Self {
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RlpStream::new()
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}
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}
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impl RlpStream {
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/// Initializes instance of empty `Stream`.
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pub fn new() -> Self {
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RlpStream {
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unfinished_lists: ElasticArray16::new(),
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buffer: ElasticArray1024::new(),
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finished_list: false,
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}
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}
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/// Initializes the `Stream` as a list.
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pub fn new_list(len: usize) -> Self {
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let mut stream = RlpStream::new();
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stream.begin_list(len);
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stream
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}
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/// Appends value to the end of stream, chainable.
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///
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/// ```rust
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/// extern crate rlp;
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/// use rlp::*;
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///
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/// fn main () {
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/// let mut stream = RlpStream::new_list(2);
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/// stream.append(&"cat").append(&"dog");
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/// let out = stream.out();
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/// assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
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/// }
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/// ```
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pub fn append<'a, E>(&'a mut self, value: &E) -> &'a mut Self where E: Encodable {
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self.finished_list = false;
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value.rlp_append(self);
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if !self.finished_list {
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self.note_appended(1);
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}
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self
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}
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/// Appends list of values to the end of stream, chainable.
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pub fn append_list<'a, E, K>(&'a mut self, values: &[K]) -> &'a mut Self where E: Encodable, K: Borrow<E> {
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self.begin_list(values.len());
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for value in values {
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self.append(value.borrow());
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}
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self
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}
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/// Appends value to the end of stream, but do not count it as an appended item.
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/// It's useful for wrapper types
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pub fn append_internal<'a, E>(&'a mut self, value: &E) -> &'a mut Self where E: Encodable {
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value.rlp_append(self);
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self
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}
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/// Declare appending the list of given size, chainable.
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///
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/// ```rust
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/// extern crate rlp;
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/// use rlp::*;
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///
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/// fn main () {
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/// let mut stream = RlpStream::new_list(2);
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/// stream.begin_list(2).append(&"cat").append(&"dog");
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/// stream.append(&"");
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/// let out = stream.out();
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/// assert_eq!(out, vec![0xca, 0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g', 0x80]);
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/// }
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/// ```
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pub fn begin_list(&mut self, len: usize) -> &mut RlpStream {
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self.finished_list = false;
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match len {
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0 => {
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// we may finish, if the appended list len is equal 0
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self.buffer.push(0xc0u8);
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self.note_appended(1);
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self.finished_list = true;
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},
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_ => {
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// payload is longer than 1 byte only for lists > 55 bytes
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// by pushing always this 1 byte we may avoid unnecessary shift of data
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self.buffer.push(0);
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let position = self.buffer.len();
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self.unfinished_lists.push(ListInfo::new(position, len));
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},
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}
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// return chainable self
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self
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}
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/// Apends null to the end of stream, chainable.
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///
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/// ```rust
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/// extern crate rlp;
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/// use rlp::*;
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///
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/// fn main () {
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/// let mut stream = RlpStream::new_list(2);
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/// stream.append_empty_data().append_empty_data();
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/// let out = stream.out();
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/// assert_eq!(out, vec![0xc2, 0x80, 0x80]);
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/// }
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/// ```
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pub fn append_empty_data(&mut self) -> &mut RlpStream {
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// self push raw item
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self.buffer.push(0x80);
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// try to finish and prepend the length
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self.note_appended(1);
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// return chainable self
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self
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}
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/// Appends raw (pre-serialised) RLP data. Use with caution. Chainable.
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pub fn append_raw<'a>(&'a mut self, bytes: &[u8], item_count: usize) -> &'a mut RlpStream {
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// push raw items
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self.buffer.append_slice(bytes);
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// try to finish and prepend the length
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self.note_appended(item_count);
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// return chainable self
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self
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}
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/// Clear the output stream so far.
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///
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/// ```rust
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/// extern crate rlp;
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/// use rlp::*;
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///
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/// fn main () {
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/// let mut stream = RlpStream::new_list(3);
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/// stream.append(&"cat");
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/// stream.clear();
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/// stream.append(&"dog");
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/// let out = stream.out();
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/// assert_eq!(out, vec![0x83, b'd', b'o', b'g']);
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/// }
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pub fn clear(&mut self) {
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// clear bytes
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self.buffer.clear();
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// clear lists
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self.unfinished_lists.clear();
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}
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/// Returns true if stream doesnt expect any more items.
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///
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/// ```rust
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/// extern crate rlp;
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/// use rlp::*;
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///
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/// fn main () {
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/// let mut stream = RlpStream::new_list(2);
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/// stream.append(&"cat");
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/// assert_eq!(stream.is_finished(), false);
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/// stream.append(&"dog");
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/// assert_eq!(stream.is_finished(), true);
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/// let out = stream.out();
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/// assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
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/// }
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pub fn is_finished(&self) -> bool {
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self.unfinished_lists.len() == 0
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}
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/// Get raw encoded bytes
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pub fn as_raw(&self) -> &[u8] {
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//&self.encoder.bytes
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&self.buffer
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}
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/// Streams out encoded bytes.
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///
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/// panic! if stream is not finished.
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pub fn out(self) -> Vec<u8> {
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match self.is_finished() {
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//true => self.encoder.out().to_vec(),
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true => self.buffer.to_vec(),
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false => panic!()
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}
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}
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/// Try to finish lists
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fn note_appended(&mut self, inserted_items: usize) -> () {
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if self.unfinished_lists.len() == 0 {
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return;
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}
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let back = self.unfinished_lists.len() - 1;
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let should_finish = match self.unfinished_lists.get_mut(back) {
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None => false,
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Some(ref mut x) => {
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x.current += inserted_items;
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if x.current > x.max {
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panic!("You cannot append more items then you expect!");
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}
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x.current == x.max
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}
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};
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if should_finish {
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let x = self.unfinished_lists.pop().unwrap();
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let len = self.buffer.len() - x.position;
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self.encoder().insert_list_payload(len, x.position);
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self.note_appended(1);
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}
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self.finished_list = should_finish;
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}
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pub fn encoder(&mut self) -> BasicEncoder {
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BasicEncoder::new(self)
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}
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/// Drain the object and return the underlying ElasticArray.
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pub fn drain(self) -> ElasticArray1024<u8> {
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match self.is_finished() {
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true => self.buffer,
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false => panic!()
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}
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}
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}
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pub struct BasicEncoder<'a> {
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buffer: &'a mut ElasticArray1024<u8>,
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}
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impl<'a> BasicEncoder<'a> {
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fn new(stream: &'a mut RlpStream) -> Self {
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BasicEncoder {
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buffer: &mut stream.buffer
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}
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}
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fn insert_size(&mut self, size: usize, position: usize) -> u8 {
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let size = size as u32;
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let leading_empty_bytes = size.leading_zeros() as usize / 8;
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let size_bytes = 4 - leading_empty_bytes as u8;
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let mut buffer = [0u8; 4];
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BigEndian::write_u32(&mut buffer, size);
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self.buffer.insert_slice(position, &buffer[leading_empty_bytes..]);
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size_bytes as u8
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}
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/// Inserts list prefix at given position
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fn insert_list_payload(&mut self, len: usize, pos: usize) {
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// 1 byte was already reserved for payload earlier
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match len {
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0...55 => {
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self.buffer[pos - 1] = 0xc0u8 + len as u8;
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},
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_ => {
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let inserted_bytes = self.insert_size(len, pos);
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self.buffer[pos - 1] = 0xf7u8 + inserted_bytes;
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}
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};
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}
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/// Pushes encoded value to the end of buffer
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pub fn encode_value(&mut self, value: &[u8]) {
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match value.len() {
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// just 0
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0 => self.buffer.push(0x80u8),
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// byte is its own encoding if < 0x80
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1 if value[0] < 0x80 => self.buffer.push(value[0]),
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// (prefix + length), followed by the string
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len @ 1 ... 55 => {
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self.buffer.push(0x80u8 + len as u8);
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self.buffer.append_slice(value);
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}
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// (prefix + length of length), followed by the length, followd by the string
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len => {
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self.buffer.push(0);
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let position = self.buffer.len();
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let inserted_bytes = self.insert_size(len, position);
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self.buffer[position - 1] = 0xb7 + inserted_bytes;
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self.buffer.append_slice(value);
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}
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}
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}
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}
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