Crate serde_bencoded

Yet another encoding/decoding library for bencode.

I believe deserializer don't allocate memory. Serializer allocates only when sort_dictionary feature enabled. Must be fast enough.

Examples

For .torrent parsing example see examples directory

Caveats

serde treats [u8; N], Vec<u8>, &[u8] like any other sequence, that is it will be encoded as list of bytes(not a byte string).

Sollution - use serde_bytes.

Behaviour

This crate does sort dictionary by keys if sort_dictionary feature is enabled (enabled by default). Otherwise order of elements can vary (depends on Serialize trait implementation).

Mapping of rust types to bencode

• bool is integer either i1e or i0e.

• all primiteve integer types is integer.

• char is byte string with length at most 4 bytes.

• String is byte string.

• [u8] is list see Caveats.

• Option is bencode value if Some otherwise nothing will be written.

• () (unit) is 0:, empty byte string.

• struct UnitStruct; is 10:UnitStruct, byte string containing name of the unit struct.

• enum E { A, B }

  • E::A is d1:E1:Ae, dictionary with one entry. Key is name of the enum and value is the variant.

• struct Wrapper(u8) (newtype struct) is bencode of the containing type.

• tuples and arrays is lists, tuples can be heterogeneous.

• struct Rgb(u8, u8, u8) (tuple struct) is list of tuple values.

• HashMap is dictionary.

• structs is dictionary. Keys are field names, values are field values.

• f32, f64 is not supported.

Alternatives

Arbitrary order. Search more on crates.io or lib.rs.

• bendy
• bencode
• serde_bencode
• bt_bencode
• bip_bencode

Bencoding

Supported data types

• Byte Strings
• Integers
• Lists
• Dictionaries

Byte Strings

<base ten ASCII>:<string bytes>

Examples:

• 4:abcd
• 0:

Integers

i<base ten ASCII, optional minus sign>e

The maximum number is not specified. This crate handles integers as u64 or i64.

Examples:

• i123456e
• i-5e

Malformed:

• i03e, anything that starts with 0, except i0e
• i-0e

Lists

l<bencode type values>e

Examples:

• li0ei1ei2ee == [1,2,3]
• le == []

Dictionaries

d<bencoded string><bencoded element>e

Keys must be sorted as raw strings. string's should be compared using a binary comparison.

Examples:

• de == {}
• d4:rustl2:is7:awesomeee == {"rust" => ["is", "awesome"]}

Crate features

sort_dictionary

Enables sort by keys when serializing to bencode dictionary.

Structs

Deserializer
Serializer

Enums

DeError
SerError

Functions

from_bytes	Deserializes bencoded bytes to rust's value.
from_str	Deserializes bencoded &str to rust's value.
to_string	Serializes rust's type to bencode string
to_vec	Convenient function to get encoded value as bytes
to_writer	Serializes rust's type to bencode using Write trait

Type Definitions

DeResult
SerResult