1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
//! A collection of serialization and deserialization functions //! that use the `rustc_serialize` crate for the encodable and decodable //! implementation. use rustc_serialize_crate::{Encodable, Decodable}; use std::io::{Write, Read}; use ::SizeLimit; pub use self::writer::{SizeChecker, EncoderWriter, EncodingResult, EncodingError}; pub use self::reader::{DecoderReader, DecodingResult, DecodingError}; mod reader; mod writer; /// Encodes an encodable object into a `Vec` of bytes. /// /// If the encoding would take more bytes than allowed by `size_limit`, /// an error is returned. pub fn encode<T: Encodable>(t: &T, size_limit: SizeLimit) -> EncodingResult<Vec<u8>> { // Since we are putting values directly into a vector, we can do size // computation out here and pre-allocate a buffer of *exactly* // the right size. let mut w = if let SizeLimit::Bounded(l) = size_limit { let actual_size = encoded_size_bounded(t, l); let actual_size = try!(actual_size.ok_or(EncodingError::SizeLimit)); Vec::with_capacity(actual_size as usize) } else { vec![] }; match encode_into(t, &mut w, SizeLimit::Infinite) { Ok(()) => Ok(w), Err(e) => Err(e) } } /// Decodes a slice of bytes into an object. /// /// This method does not have a size-limit because if you already have the bytes /// in memory, then you don't gain anything by having a limiter. pub fn decode<T: Decodable>(b: &[u8]) -> DecodingResult<T> { let mut b = b; decode_from(&mut b, SizeLimit::Infinite) } /// Encodes an object directly into a `Writer`. /// /// If the encoding would take more bytes than allowed by `size_limit`, an error /// is returned and *no bytes* will be written into the `Writer`. /// /// If this returns an `EncodingError` (other than SizeLimit), assume that the /// writer is in an invalid state, as writing could bail out in the middle of /// encoding. pub fn encode_into<T: Encodable, W: Write>(t: &T, w: &mut W, size_limit: SizeLimit) -> EncodingResult<()> { try!(match size_limit { SizeLimit::Infinite => Ok(()), SizeLimit::Bounded(x) => { let mut size_checker = SizeChecker::new(x); t.encode(&mut size_checker) } }); t.encode(&mut writer::EncoderWriter::new(w)) } /// Decoes an object directly from a `Buffer`ed Reader. /// /// If the provided `SizeLimit` is reached, the decode will bail immediately. /// A SizeLimit can help prevent an attacker from flooding your server with /// a neverending stream of values that runs your server out of memory. /// /// If this returns an `DecodingError`, assume that the buffer that you passed /// in is in an invalid state, as the error could be returned during any point /// in the reading. pub fn decode_from<R: Read, T: Decodable>(r: &mut R, size_limit: SizeLimit) -> DecodingResult<T> { Decodable::decode(&mut reader::DecoderReader::new(r, size_limit)) } /// Returns the size that an object would be if encoded using bincode. /// /// This is used internally as part of the check for encode_into, but it can /// be useful for preallocating buffers if thats your style. pub fn encoded_size<T: Encodable>(t: &T) -> u64 { use std::u64::MAX; let mut size_checker = SizeChecker::new(MAX); t.encode(&mut size_checker).ok(); size_checker.written } /// Given a maximum size limit, check how large an object would be if it /// were to be encoded. /// /// If it can be encoded in `max` or fewer bytes, that number will be returned /// inside `Some`. If it goes over bounds, then None is returned. pub fn encoded_size_bounded<T: Encodable>(t: &T, max: u64) -> Option<u64> { let mut size_checker = SizeChecker::new(max); t.encode(&mut size_checker).ok().map(|_| size_checker.written) }