| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-util-0.7.8/src/codec/length_delimited.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>length_delimited.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../tokio_util/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../tokio_util/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| <span id="1038">1038</span> |
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| <span id="1043">1043</span> |
| </pre><pre class="rust"><code><span class="doccomment">//! Frame a stream of bytes based on a length prefix |
| //! |
| //! Many protocols delimit their frames by prefacing frame data with a |
| //! frame head that specifies the length of the frame. The |
| //! `length_delimited` module provides utilities for handling the length |
| //! based framing. This allows the consumer to work with entire frames |
| //! without having to worry about buffering or other framing logic. |
| //! |
| //! # Getting started |
| //! |
| //! If implementing a protocol from scratch, using length delimited framing |
| //! is an easy way to get started. [`LengthDelimitedCodec::new()`] will |
| //! return a length delimited codec using default configuration values. |
| //! This can then be used to construct a framer to adapt a full-duplex |
| //! byte stream into a stream of frames. |
| //! |
| //! ``` |
| //! use tokio::io::{AsyncRead, AsyncWrite}; |
| //! use tokio_util::codec::{Framed, LengthDelimitedCodec}; |
| //! |
| //! fn bind_transport<T: AsyncRead + AsyncWrite>(io: T) |
| //! -> Framed<T, LengthDelimitedCodec> |
| //! { |
| //! Framed::new(io, LengthDelimitedCodec::new()) |
| //! } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The returned transport implements `Sink + Stream` for `BytesMut`. It |
| //! encodes the frame with a big-endian `u32` header denoting the frame |
| //! payload length: |
| //! |
| //! ```text |
| //! +----------+--------------------------------+ |
| //! | len: u32 | frame payload | |
| //! +----------+--------------------------------+ |
| //! ``` |
| //! |
| //! Specifically, given the following: |
| //! |
| //! ``` |
| //! use tokio::io::{AsyncRead, AsyncWrite}; |
| //! use tokio_util::codec::{Framed, LengthDelimitedCodec}; |
| //! |
| //! use futures::SinkExt; |
| //! use bytes::Bytes; |
| //! |
| //! async fn write_frame<T>(io: T) -> Result<(), Box<dyn std::error::Error>> |
| //! where |
| //! T: AsyncRead + AsyncWrite + Unpin, |
| //! { |
| //! let mut transport = Framed::new(io, LengthDelimitedCodec::new()); |
| //! let frame = Bytes::from("hello world"); |
| //! |
| //! transport.send(frame).await?; |
| //! Ok(()) |
| //! } |
| //! ``` |
| //! |
| //! The encoded frame will look like this: |
| //! |
| //! ```text |
| //! +---- len: u32 ----+---- data ----+ |
| //! | \x00\x00\x00\x0b | hello world | |
| //! +------------------+--------------+ |
| //! ``` |
| //! |
| //! # Decoding |
| //! |
| //! [`FramedRead`] adapts an [`AsyncRead`] into a `Stream` of [`BytesMut`], |
| //! such that each yielded [`BytesMut`] value contains the contents of an |
| //! entire frame. There are many configuration parameters enabling |
| //! [`FramedRead`] to handle a wide range of protocols. Here are some |
| //! examples that will cover the various options at a high level. |
| //! |
| //! ## Example 1 |
| //! |
| //! The following will parse a `u16` length field at offset 0, including the |
| //! frame head in the yielded `BytesMut`. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(0) // default value |
| //! .length_field_type::<u16>() |
| //! .length_adjustment(0) // default value |
| //! .num_skip(0) // Do not strip frame header |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT DECODED |
| //! +-- len ---+--- Payload ---+ +-- len ---+--- Payload ---+ |
| //! | \x00\x0B | Hello world | --> | \x00\x0B | Hello world | |
| //! +----------+---------------+ +----------+---------------+ |
| //! ``` |
| //! |
| //! The value of the length field is 11 (`\x0B`) which represents the length |
| //! of the payload, `hello world`. By default, [`FramedRead`] assumes that |
| //! the length field represents the number of bytes that **follows** the |
| //! length field. Thus, the entire frame has a length of 13: 2 bytes for the |
| //! frame head + 11 bytes for the payload. |
| //! |
| //! ## Example 2 |
| //! |
| //! The following will parse a `u16` length field at offset 0, omitting the |
| //! frame head in the yielded `BytesMut`. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(0) // default value |
| //! .length_field_type::<u16>() |
| //! .length_adjustment(0) // default value |
| //! // `num_skip` is not needed, the default is to skip |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT DECODED |
| //! +-- len ---+--- Payload ---+ +--- Payload ---+ |
| //! | \x00\x0B | Hello world | --> | Hello world | |
| //! +----------+---------------+ +---------------+ |
| //! ``` |
| //! |
| //! This is similar to the first example, the only difference is that the |
| //! frame head is **not** included in the yielded `BytesMut` value. |
| //! |
| //! ## Example 3 |
| //! |
| //! The following will parse a `u16` length field at offset 0, including the |
| //! frame head in the yielded `BytesMut`. In this case, the length field |
| //! **includes** the frame head length. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(0) // default value |
| //! .length_field_type::<u16>() |
| //! .length_adjustment(-2) // size of head |
| //! .num_skip(0) |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT DECODED |
| //! +-- len ---+--- Payload ---+ +-- len ---+--- Payload ---+ |
| //! | \x00\x0D | Hello world | --> | \x00\x0D | Hello world | |
| //! +----------+---------------+ +----------+---------------+ |
| //! ``` |
| //! |
| //! In most cases, the length field represents the length of the payload |
| //! only, as shown in the previous examples. However, in some protocols the |
| //! length field represents the length of the whole frame, including the |
| //! head. In such cases, we specify a negative `length_adjustment` to adjust |
| //! the value provided in the frame head to represent the payload length. |
| //! |
| //! ## Example 4 |
| //! |
| //! The following will parse a 3 byte length field at offset 0 in a 5 byte |
| //! frame head, including the frame head in the yielded `BytesMut`. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(0) // default value |
| //! .length_field_length(3) |
| //! .length_adjustment(2) // remaining head |
| //! .num_skip(0) |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT |
| //! +---- len -----+- head -+--- Payload ---+ |
| //! | \x00\x00\x0B | \xCAFE | Hello world | |
| //! +--------------+--------+---------------+ |
| //! |
| //! DECODED |
| //! +---- len -----+- head -+--- Payload ---+ |
| //! | \x00\x00\x0B | \xCAFE | Hello world | |
| //! +--------------+--------+---------------+ |
| //! ``` |
| //! |
| //! A more advanced example that shows a case where there is extra frame |
| //! head data between the length field and the payload. In such cases, it is |
| //! usually desirable to include the frame head as part of the yielded |
| //! `BytesMut`. This lets consumers of the length delimited framer to |
| //! process the frame head as needed. |
| //! |
| //! The positive `length_adjustment` value lets `FramedRead` factor in the |
| //! additional head into the frame length calculation. |
| //! |
| //! ## Example 5 |
| //! |
| //! The following will parse a `u16` length field at offset 1 of a 4 byte |
| //! frame head. The first byte and the length field will be omitted from the |
| //! yielded `BytesMut`, but the trailing 2 bytes of the frame head will be |
| //! included. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(1) // length of hdr1 |
| //! .length_field_type::<u16>() |
| //! .length_adjustment(1) // length of hdr2 |
| //! .num_skip(3) // length of hdr1 + LEN |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT |
| //! +- hdr1 -+-- len ---+- hdr2 -+--- Payload ---+ |
| //! | \xCA | \x00\x0B | \xFE | Hello world | |
| //! +--------+----------+--------+---------------+ |
| //! |
| //! DECODED |
| //! +- hdr2 -+--- Payload ---+ |
| //! | \xFE | Hello world | |
| //! +--------+---------------+ |
| //! ``` |
| //! |
| //! The length field is situated in the middle of the frame head. In this |
| //! case, the first byte in the frame head could be a version or some other |
| //! identifier that is not needed for processing. On the other hand, the |
| //! second half of the head is needed. |
| //! |
| //! `length_field_offset` indicates how many bytes to skip before starting |
| //! to read the length field. `length_adjustment` is the number of bytes to |
| //! skip starting at the end of the length field. In this case, it is the |
| //! second half of the head. |
| //! |
| //! ## Example 6 |
| //! |
| //! The following will parse a `u16` length field at offset 1 of a 4 byte |
| //! frame head. The first byte and the length field will be omitted from the |
| //! yielded `BytesMut`, but the trailing 2 bytes of the frame head will be |
| //! included. In this case, the length field **includes** the frame head |
| //! length. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(1) // length of hdr1 |
| //! .length_field_type::<u16>() |
| //! .length_adjustment(-3) // length of hdr1 + LEN, negative |
| //! .num_skip(3) |
| //! .new_read(io); |
| //! # } |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT |
| //! +- hdr1 -+-- len ---+- hdr2 -+--- Payload ---+ |
| //! | \xCA | \x00\x0F | \xFE | Hello world | |
| //! +--------+----------+--------+---------------+ |
| //! |
| //! DECODED |
| //! +- hdr2 -+--- Payload ---+ |
| //! | \xFE | Hello world | |
| //! +--------+---------------+ |
| //! ``` |
| //! |
| //! Similar to the example above, the difference is that the length field |
| //! represents the length of the entire frame instead of just the payload. |
| //! The length of `hdr1` and `len` must be counted in `length_adjustment`. |
| //! Note that the length of `hdr2` does **not** need to be explicitly set |
| //! anywhere because it already is factored into the total frame length that |
| //! is read from the byte stream. |
| //! |
| //! ## Example 7 |
| //! |
| //! The following will parse a 3 byte length field at offset 0 in a 4 byte |
| //! frame head, excluding the 4th byte from the yielded `BytesMut`. |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncRead; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn bind_read<T: AsyncRead>(io: T) { |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_offset(0) // default value |
| //! .length_field_length(3) |
| //! .length_adjustment(0) // default value |
| //! .num_skip(4) // skip the first 4 bytes |
| //! .new_read(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! The following frame will be decoded as such: |
| //! |
| //! ```text |
| //! INPUT DECODED |
| //! +------- len ------+--- Payload ---+ +--- Payload ---+ |
| //! | \x00\x00\x0B\xFF | Hello world | => | Hello world | |
| //! +------------------+---------------+ +---------------+ |
| //! ``` |
| //! |
| //! A simple example where there are unused bytes between the length field |
| //! and the payload. |
| //! |
| //! # Encoding |
| //! |
| //! [`FramedWrite`] adapts an [`AsyncWrite`] into a `Sink` of [`BytesMut`], |
| //! such that each submitted [`BytesMut`] is prefaced by a length field. |
| //! There are fewer configuration options than [`FramedRead`]. Given |
| //! protocols that have more complex frame heads, an encoder should probably |
| //! be written by hand using [`Encoder`]. |
| //! |
| //! Here is a simple example, given a `FramedWrite` with the following |
| //! configuration: |
| //! |
| //! ``` |
| //! # use tokio::io::AsyncWrite; |
| //! # use tokio_util::codec::LengthDelimitedCodec; |
| //! # fn write_frame<T: AsyncWrite>(io: T) { |
| //! # let _ = |
| //! LengthDelimitedCodec::builder() |
| //! .length_field_type::<u16>() |
| //! .new_write(io); |
| //! # } |
| //! # pub fn main() {} |
| //! ``` |
| //! |
| //! A payload of `hello world` will be encoded as: |
| //! |
| //! ```text |
| //! +- len: u16 -+---- data ----+ |
| //! | \x00\x0b | hello world | |
| //! +------------+--------------+ |
| //! ``` |
| //! |
| //! [`LengthDelimitedCodec::new()`]: method@LengthDelimitedCodec::new |
| //! [`FramedRead`]: struct@FramedRead |
| //! [`FramedWrite`]: struct@FramedWrite |
| //! [`AsyncRead`]: trait@tokio::io::AsyncRead |
| //! [`AsyncWrite`]: trait@tokio::io::AsyncWrite |
| //! [`Encoder`]: trait@Encoder |
| //! [`BytesMut`]: bytes::BytesMut |
| |
| </span><span class="kw">use </span><span class="kw">crate</span>::codec::{Decoder, Encoder, Framed, FramedRead, FramedWrite}; |
| |
| <span class="kw">use </span>tokio::io::{AsyncRead, AsyncWrite}; |
| |
| <span class="kw">use </span>bytes::{Buf, BufMut, Bytes, BytesMut}; |
| <span class="kw">use </span>std::error::Error <span class="kw">as </span>StdError; |
| <span class="kw">use </span>std::io::{<span class="self">self</span>, Cursor}; |
| <span class="kw">use </span>std::{cmp, fmt, mem}; |
| |
| <span class="doccomment">/// Configure length delimited `LengthDelimitedCodec`s. |
| /// |
| /// `Builder` enables constructing configured length delimited codecs. Note |
| /// that not all configuration settings apply to both encoding and decoding. See |
| /// the documentation for specific methods for more detail. |
| </span><span class="attribute">#[derive(Debug, Clone, Copy)] |
| </span><span class="kw">pub struct </span>Builder { |
| <span class="comment">// Maximum frame length |
| </span>max_frame_len: usize, |
| |
| <span class="comment">// Number of bytes representing the field length |
| </span>length_field_len: usize, |
| |
| <span class="comment">// Number of bytes in the header before the length field |
| </span>length_field_offset: usize, |
| |
| <span class="comment">// Adjust the length specified in the header field by this amount |
| </span>length_adjustment: isize, |
| |
| <span class="comment">// Total number of bytes to skip before reading the payload, if not set, |
| // `length_field_len + length_field_offset` |
| </span>num_skip: <span class="prelude-ty">Option</span><usize>, |
| |
| <span class="comment">// Length field byte order (little or big endian) |
| </span>length_field_is_big_endian: bool, |
| } |
| |
| <span class="doccomment">/// An error when the number of bytes read is more than max frame length. |
| </span><span class="kw">pub struct </span>LengthDelimitedCodecError { |
| _priv: (), |
| } |
| |
| <span class="doccomment">/// A codec for frames delimited by a frame head specifying their lengths. |
| /// |
| /// This allows the consumer to work with entire frames without having to worry |
| /// about buffering or other framing logic. |
| /// |
| /// See [module level] documentation for more detail. |
| /// |
| /// [module level]: index.html |
| </span><span class="attribute">#[derive(Debug, Clone)] |
| </span><span class="kw">pub struct </span>LengthDelimitedCodec { |
| <span class="comment">// Configuration values |
| </span>builder: Builder, |
| |
| <span class="comment">// Read state |
| </span>state: DecodeState, |
| } |
| |
| <span class="attribute">#[derive(Debug, Clone, Copy)] |
| </span><span class="kw">enum </span>DecodeState { |
| Head, |
| Data(usize), |
| } |
| |
| <span class="comment">// ===== impl LengthDelimitedCodec ====== |
| |
| </span><span class="kw">impl </span>LengthDelimitedCodec { |
| <span class="doccomment">/// Creates a new `LengthDelimitedCodec` with the default configuration values. |
| </span><span class="kw">pub fn </span>new() -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| builder: Builder::new(), |
| state: DecodeState::Head, |
| } |
| } |
| |
| <span class="doccomment">/// Creates a new length delimited codec builder with default configuration |
| /// values. |
| </span><span class="kw">pub fn </span>builder() -> Builder { |
| Builder::new() |
| } |
| |
| <span class="doccomment">/// Returns the current max frame setting |
| /// |
| /// This is the largest size this codec will accept from the wire. Larger |
| /// frames will be rejected. |
| </span><span class="kw">pub fn </span>max_frame_length(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.builder.max_frame_len |
| } |
| |
| <span class="doccomment">/// Updates the max frame setting. |
| /// |
| /// The change takes effect the next time a frame is decoded. In other |
| /// words, if a frame is currently in process of being decoded with a frame |
| /// size greater than `val` but less than the max frame length in effect |
| /// before calling this function, then the frame will be allowed. |
| </span><span class="kw">pub fn </span>set_max_frame_length(<span class="kw-2">&mut </span><span class="self">self</span>, val: usize) { |
| <span class="self">self</span>.builder.max_frame_length(val); |
| } |
| |
| <span class="kw">fn </span>decode_head(<span class="kw-2">&mut </span><span class="self">self</span>, src: <span class="kw-2">&mut </span>BytesMut) -> io::Result<<span class="prelude-ty">Option</span><usize>> { |
| <span class="kw">let </span>head_len = <span class="self">self</span>.builder.num_head_bytes(); |
| <span class="kw">let </span>field_len = <span class="self">self</span>.builder.length_field_len; |
| |
| <span class="kw">if </span>src.len() < head_len { |
| <span class="comment">// Not enough data |
| </span><span class="kw">return </span><span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>); |
| } |
| |
| <span class="kw">let </span>n = { |
| <span class="kw">let </span><span class="kw-2">mut </span>src = Cursor::new(<span class="kw-2">&mut *</span>src); |
| |
| <span class="comment">// Skip the required bytes |
| </span>src.advance(<span class="self">self</span>.builder.length_field_offset); |
| |
| <span class="comment">// match endianness |
| </span><span class="kw">let </span>n = <span class="kw">if </span><span class="self">self</span>.builder.length_field_is_big_endian { |
| src.get_uint(field_len) |
| } <span class="kw">else </span>{ |
| src.get_uint_le(field_len) |
| }; |
| |
| <span class="kw">if </span>n > <span class="self">self</span>.builder.max_frame_len <span class="kw">as </span>u64 { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidData, |
| LengthDelimitedCodecError { _priv: () }, |
| )); |
| } |
| |
| <span class="comment">// The check above ensures there is no overflow |
| </span><span class="kw">let </span>n = n <span class="kw">as </span>usize; |
| |
| <span class="comment">// Adjust `n` with bounds checking |
| </span><span class="kw">let </span>n = <span class="kw">if </span><span class="self">self</span>.builder.length_adjustment < <span class="number">0 </span>{ |
| n.checked_sub(-<span class="self">self</span>.builder.length_adjustment <span class="kw">as </span>usize) |
| } <span class="kw">else </span>{ |
| n.checked_add(<span class="self">self</span>.builder.length_adjustment <span class="kw">as </span>usize) |
| }; |
| |
| <span class="comment">// Error handling |
| </span><span class="kw">match </span>n { |
| <span class="prelude-val">Some</span>(n) => n, |
| <span class="prelude-val">None </span>=> { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidInput, |
| <span class="string">"provided length would overflow after adjustment"</span>, |
| )); |
| } |
| } |
| }; |
| |
| src.advance(<span class="self">self</span>.builder.get_num_skip()); |
| |
| <span class="comment">// Ensure that the buffer has enough space to read the incoming |
| // payload |
| </span>src.reserve(n.saturating_sub(src.len())); |
| |
| <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(n)) |
| } |
| |
| <span class="kw">fn </span>decode_data(<span class="kw-2">&</span><span class="self">self</span>, n: usize, src: <span class="kw-2">&mut </span>BytesMut) -> <span class="prelude-ty">Option</span><BytesMut> { |
| <span class="comment">// At this point, the buffer has already had the required capacity |
| // reserved. All there is to do is read. |
| </span><span class="kw">if </span>src.len() < n { |
| <span class="kw">return </span><span class="prelude-val">None</span>; |
| } |
| |
| <span class="prelude-val">Some</span>(src.split_to(n)) |
| } |
| } |
| |
| <span class="kw">impl </span>Decoder <span class="kw">for </span>LengthDelimitedCodec { |
| <span class="kw">type </span>Item = BytesMut; |
| <span class="kw">type </span>Error = io::Error; |
| |
| <span class="kw">fn </span>decode(<span class="kw-2">&mut </span><span class="self">self</span>, src: <span class="kw-2">&mut </span>BytesMut) -> io::Result<<span class="prelude-ty">Option</span><BytesMut>> { |
| <span class="kw">let </span>n = <span class="kw">match </span><span class="self">self</span>.state { |
| DecodeState::Head => <span class="kw">match </span><span class="self">self</span>.decode_head(src)<span class="question-mark">? </span>{ |
| <span class="prelude-val">Some</span>(n) => { |
| <span class="self">self</span>.state = DecodeState::Data(n); |
| n |
| } |
| <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>), |
| }, |
| DecodeState::Data(n) => n, |
| }; |
| |
| <span class="kw">match </span><span class="self">self</span>.decode_data(n, src) { |
| <span class="prelude-val">Some</span>(data) => { |
| <span class="comment">// Update the decode state |
| </span><span class="self">self</span>.state = DecodeState::Head; |
| |
| <span class="comment">// Make sure the buffer has enough space to read the next head |
| </span>src.reserve(<span class="self">self</span>.builder.num_head_bytes().saturating_sub(src.len())); |
| |
| <span class="prelude-val">Ok</span>(<span class="prelude-val">Some</span>(data)) |
| } |
| <span class="prelude-val">None </span>=> <span class="prelude-val">Ok</span>(<span class="prelude-val">None</span>), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Encoder<Bytes> <span class="kw">for </span>LengthDelimitedCodec { |
| <span class="kw">type </span>Error = io::Error; |
| |
| <span class="kw">fn </span>encode(<span class="kw-2">&mut </span><span class="self">self</span>, data: Bytes, dst: <span class="kw-2">&mut </span>BytesMut) -> <span class="prelude-ty">Result</span><(), io::Error> { |
| <span class="kw">let </span>n = data.len(); |
| |
| <span class="kw">if </span>n > <span class="self">self</span>.builder.max_frame_len { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidInput, |
| LengthDelimitedCodecError { _priv: () }, |
| )); |
| } |
| |
| <span class="comment">// Adjust `n` with bounds checking |
| </span><span class="kw">let </span>n = <span class="kw">if </span><span class="self">self</span>.builder.length_adjustment < <span class="number">0 </span>{ |
| n.checked_add(-<span class="self">self</span>.builder.length_adjustment <span class="kw">as </span>usize) |
| } <span class="kw">else </span>{ |
| n.checked_sub(<span class="self">self</span>.builder.length_adjustment <span class="kw">as </span>usize) |
| }; |
| |
| <span class="kw">let </span>n = n.ok_or_else(|| { |
| io::Error::new( |
| io::ErrorKind::InvalidInput, |
| <span class="string">"provided length would overflow after adjustment"</span>, |
| ) |
| })<span class="question-mark">?</span>; |
| |
| <span class="comment">// Reserve capacity in the destination buffer to fit the frame and |
| // length field (plus adjustment). |
| </span>dst.reserve(<span class="self">self</span>.builder.length_field_len + n); |
| |
| <span class="kw">if </span><span class="self">self</span>.builder.length_field_is_big_endian { |
| dst.put_uint(n <span class="kw">as </span>u64, <span class="self">self</span>.builder.length_field_len); |
| } <span class="kw">else </span>{ |
| dst.put_uint_le(n <span class="kw">as </span>u64, <span class="self">self</span>.builder.length_field_len); |
| } |
| |
| <span class="comment">// Write the frame to the buffer |
| </span>dst.extend_from_slice(<span class="kw-2">&</span>data[..]); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| } |
| |
| <span class="kw">impl </span>Default <span class="kw">for </span>LengthDelimitedCodec { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new() |
| } |
| } |
| |
| <span class="comment">// ===== impl Builder ===== |
| |
| </span><span class="kw">mod </span>builder { |
| <span class="doccomment">/// Types that can be used with `Builder::length_field_type`. |
| </span><span class="kw">pub trait </span>LengthFieldType {} |
| |
| <span class="kw">impl </span>LengthFieldType <span class="kw">for </span>u8 {} |
| <span class="kw">impl </span>LengthFieldType <span class="kw">for </span>u16 {} |
| <span class="kw">impl </span>LengthFieldType <span class="kw">for </span>u32 {} |
| <span class="kw">impl </span>LengthFieldType <span class="kw">for </span>u64 {} |
| |
| <span class="attribute">#[cfg(any( |
| target_pointer_width = <span class="string">"8"</span>, |
| target_pointer_width = <span class="string">"16"</span>, |
| target_pointer_width = <span class="string">"32"</span>, |
| target_pointer_width = <span class="string">"64"</span>, |
| ))] |
| </span><span class="kw">impl </span>LengthFieldType <span class="kw">for </span>usize {} |
| } |
| |
| <span class="kw">impl </span>Builder { |
| <span class="doccomment">/// Creates a new length delimited codec builder with default configuration |
| /// values. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_offset(0) |
| /// .length_field_type::<u16>() |
| /// .length_adjustment(0) |
| /// .num_skip(0) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>new() -> Builder { |
| Builder { |
| <span class="comment">// Default max frame length of 8MB |
| </span>max_frame_len: <span class="number">8 </span>* <span class="number">1_024 </span>* <span class="number">1_024</span>, |
| |
| <span class="comment">// Default byte length of 4 |
| </span>length_field_len: <span class="number">4</span>, |
| |
| <span class="comment">// Default to the header field being at the start of the header. |
| </span>length_field_offset: <span class="number">0</span>, |
| |
| length_adjustment: <span class="number">0</span>, |
| |
| <span class="comment">// Total number of bytes to skip before reading the payload, if not set, |
| // `length_field_len + length_field_offset` |
| </span>num_skip: <span class="prelude-val">None</span>, |
| |
| <span class="comment">// Default to reading the length field in network (big) endian. |
| </span>length_field_is_big_endian: <span class="bool-val">true</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Read the length field as a big endian integer |
| /// |
| /// This is the default setting. |
| /// |
| /// This configuration option applies to both encoding and decoding. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .big_endian() |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>big_endian(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.length_field_is_big_endian = <span class="bool-val">true</span>; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Read the length field as a little endian integer |
| /// |
| /// The default setting is big endian. |
| /// |
| /// This configuration option applies to both encoding and decoding. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .little_endian() |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>little_endian(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.length_field_is_big_endian = <span class="bool-val">false</span>; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Read the length field as a native endian integer |
| /// |
| /// The default setting is big endian. |
| /// |
| /// This configuration option applies to both encoding and decoding. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .native_endian() |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>native_endian(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="kw">if </span><span class="macro">cfg!</span>(target_endian = <span class="string">"big"</span>) { |
| <span class="self">self</span>.big_endian() |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.little_endian() |
| } |
| } |
| |
| <span class="doccomment">/// Sets the max frame length in bytes |
| /// |
| /// This configuration option applies to both encoding and decoding. The |
| /// default value is 8MB. |
| /// |
| /// When decoding, the length field read from the byte stream is checked |
| /// against this setting **before** any adjustments are applied. When |
| /// encoding, the length of the submitted payload is checked against this |
| /// setting. |
| /// |
| /// When frames exceed the max length, an `io::Error` with the custom value |
| /// of the `LengthDelimitedCodecError` type will be returned. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .max_frame_length(8 * 1024 * 1024) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>max_frame_length(<span class="kw-2">&mut </span><span class="self">self</span>, val: usize) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.max_frame_len = val; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Sets the unsigned integer type used to represent the length field. |
| /// |
| /// The default type is [`u32`]. The max type is [`u64`] (or [`usize`] on |
| /// 64-bit targets). |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_type::<u32>() |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| /// |
| /// Unlike [`Builder::length_field_length`], this does not fail at runtime |
| /// and instead produces a compile error: |
| /// |
| /// ```compile_fail |
| /// # use tokio::io::AsyncRead; |
| /// # use tokio_util::codec::LengthDelimitedCodec; |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_type::<u128>() |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>length_field_type<T: builder::LengthFieldType>(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.length_field_length(mem::size_of::<T>()) |
| } |
| |
| <span class="doccomment">/// Sets the number of bytes used to represent the length field |
| /// |
| /// The default value is `4`. The max value is `8`. |
| /// |
| /// This configuration option applies to both encoding and decoding. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_length(4) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>length_field_length(<span class="kw-2">&mut </span><span class="self">self</span>, val: usize) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="macro">assert!</span>(val > <span class="number">0 </span>&& val <= <span class="number">8</span>, <span class="string">"invalid length field length"</span>); |
| <span class="self">self</span>.length_field_len = val; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Sets the number of bytes in the header before the length field |
| /// |
| /// This configuration option only applies to decoding. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_offset(1) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>length_field_offset(<span class="kw-2">&mut </span><span class="self">self</span>, val: usize) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.length_field_offset = val; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Delta between the payload length specified in the header and the real |
| /// payload length |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_adjustment(-2) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>length_adjustment(<span class="kw-2">&mut </span><span class="self">self</span>, val: isize) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.length_adjustment = val; |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Sets the number of bytes to skip before reading the payload |
| /// |
| /// Default value is `length_field_len + length_field_offset` |
| /// |
| /// This configuration option only applies to decoding |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .num_skip(4) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>num_skip(<span class="kw-2">&mut </span><span class="self">self</span>, val: usize) -> <span class="kw-2">&mut </span><span class="self">Self </span>{ |
| <span class="self">self</span>.num_skip = <span class="prelude-val">Some</span>(val); |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Create a configured length delimited `LengthDelimitedCodec` |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// # pub fn main() { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_offset(0) |
| /// .length_field_type::<u16>() |
| /// .length_adjustment(0) |
| /// .num_skip(0) |
| /// .new_codec(); |
| /// # } |
| /// ``` |
| </span><span class="kw">pub fn </span>new_codec(<span class="kw-2">&</span><span class="self">self</span>) -> LengthDelimitedCodec { |
| LengthDelimitedCodec { |
| builder: <span class="kw-2">*</span><span class="self">self</span>, |
| state: DecodeState::Head, |
| } |
| } |
| |
| <span class="doccomment">/// Create a configured length delimited `FramedRead` |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncRead; |
| /// use tokio_util::codec::LengthDelimitedCodec; |
| /// |
| /// # fn bind_read<T: AsyncRead>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_offset(0) |
| /// .length_field_type::<u16>() |
| /// .length_adjustment(0) |
| /// .num_skip(0) |
| /// .new_read(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>new_read<T>(<span class="kw-2">&</span><span class="self">self</span>, upstream: T) -> FramedRead<T, LengthDelimitedCodec> |
| <span class="kw">where |
| </span>T: AsyncRead, |
| { |
| FramedRead::new(upstream, <span class="self">self</span>.new_codec()) |
| } |
| |
| <span class="doccomment">/// Create a configured length delimited `FramedWrite` |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::AsyncWrite; |
| /// # use tokio_util::codec::LengthDelimitedCodec; |
| /// # fn write_frame<T: AsyncWrite>(io: T) { |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_type::<u16>() |
| /// .new_write(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>new_write<T>(<span class="kw-2">&</span><span class="self">self</span>, inner: T) -> FramedWrite<T, LengthDelimitedCodec> |
| <span class="kw">where |
| </span>T: AsyncWrite, |
| { |
| FramedWrite::new(inner, <span class="self">self</span>.new_codec()) |
| } |
| |
| <span class="doccomment">/// Create a configured length delimited `Framed` |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use tokio::io::{AsyncRead, AsyncWrite}; |
| /// # use tokio_util::codec::LengthDelimitedCodec; |
| /// # fn write_frame<T: AsyncRead + AsyncWrite>(io: T) { |
| /// # let _ = |
| /// LengthDelimitedCodec::builder() |
| /// .length_field_type::<u16>() |
| /// .new_framed(io); |
| /// # } |
| /// # pub fn main() {} |
| /// ``` |
| </span><span class="kw">pub fn </span>new_framed<T>(<span class="kw-2">&</span><span class="self">self</span>, inner: T) -> Framed<T, LengthDelimitedCodec> |
| <span class="kw">where |
| </span>T: AsyncRead + AsyncWrite, |
| { |
| Framed::new(inner, <span class="self">self</span>.new_codec()) |
| } |
| |
| <span class="kw">fn </span>num_head_bytes(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="kw">let </span>num = <span class="self">self</span>.length_field_offset + <span class="self">self</span>.length_field_len; |
| cmp::max(num, <span class="self">self</span>.num_skip.unwrap_or(<span class="number">0</span>)) |
| } |
| |
| <span class="kw">fn </span>get_num_skip(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.num_skip |
| .unwrap_or(<span class="self">self</span>.length_field_offset + <span class="self">self</span>.length_field_len) |
| } |
| } |
| |
| <span class="kw">impl </span>Default <span class="kw">for </span>Builder { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new() |
| } |
| } |
| |
| <span class="comment">// ===== impl LengthDelimitedCodecError ===== |
| |
| </span><span class="kw">impl </span>fmt::Debug <span class="kw">for </span>LengthDelimitedCodecError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"LengthDelimitedCodecError"</span>).finish() |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>LengthDelimitedCodecError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.write_str(<span class="string">"frame size too big"</span>) |
| } |
| } |
| |
| <span class="kw">impl </span>StdError <span class="kw">for </span>LengthDelimitedCodecError {} |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tokio_util" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
