WebTransport是一种新的协议，用于实现客户端和服务器之间通过web进行低延迟、双向通信。它旨在通过提供更高效、更灵活的传输层来解决WebSocket协议的局限性。
WebTransport的优点：
下面我们来看一下使用WebTransport的例子。
首先，创建一个新的Rust项目：
cargo new webtransport-example然后，在Cargo.toml文件中加入依赖项：
[dependencies]
tokio = { version = "1.28.1", default-features = false, features = ["macros", "rt-multi-thread"] }
wtransport = {version = "0.1.8", features = ["dangerous-configuration"]}
tracing = "0.1.37"
tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
anyhow = "1.0.71"
wtransport-proto = "0.1.8"
base64 = "0.21.0"
rcgen = "0.11.1"
ring = "0.17.0"
time = "0.3.21"接下来，在项目根目录下创建一个bin目录，在bin目录下创建两个文件：server.rs和client.rs。
server.rs的代码如下：
use std::time::Duration;
use anyhow::Result;
use tracing::error;
use tracing::info;
use tracing::info_span;
use tracing::Instrument;
use tracing_subscriber::filter::LevelFilter;
use tracing_subscriber::EnvFilter;
use wtransport::endpoint::IncomingSession;
use wtransport::tls::Certificate;
use wtransport::Endpoint;
use wtransport::ServerConfig;
#[tokio::main]
async fn main() -> Result<()> {
init_logging();
// 配置Server端
let config = ServerConfig::builder()
// 设置监听端口为 4433
.with_bind_default(4433)
// 设置证书和密钥
.with_certificate(Certificate::load("cert.pem", "key.pem").await?)
.keep_alive_interval(Some(Duration::from_secs(3)))
.build();
let server = Endpoint::server(config)?;
info!("Server ready!");
for id in 0.. {
let incoming_session = server.accept().await;
tokio::spawn(handle_connection(incoming_session).instrument(info_span!("Connection", id)));
}
Ok(())
}
async fn handle_connection(incoming_session: IncomingSession) {
let result = handle_connection_impl(incoming_session).await;
error!("{:?}", result);
}
async fn handle_connection_impl(incoming_session: IncomingSession) -> Result<()> {
let mut buffer = vec![0; 65536].into_boxed_slice();
info!("Waiting for session request...");
// 等待会话请求
let session_request = incoming_session.await?;
info!(
"New session: Authority: '{}', Path: '{}'",
session_request.authority(),
session_request.path()
);
let connection = session_request.accept().await?;
info!("Waiting for data from client...");
// 等待来自客户端的数据
// 多路复用
loop {
tokio::select! {
// 接收双向通信流消息
stream = connection.accept_bi() => {
let mut stream = stream?;
info!("Accepted BI stream");
let bytes_read = match stream.1.read(&mut buffer).await? {
Some(bytes_read) => bytes_read,
None => continue,
};
let str_data = std::str::from_utf8(&buffer[..bytes_read])?;
info!("Received (bi) '{str_data}' from client");
stream.0.write_all(b"ACK").await?;
}
// 接收单向通信流消息
stream = connection.accept_uni() => {
let mut stream = stream?;
info!("Accepted UNI stream");
let bytes_read = match stream.read(&mut buffer).await? {
Some(bytes_read) => bytes_read,
None => continue,
};
let str_data = std::str::from_utf8(&buffer[..bytes_read])?;
info!("Received (uni) '{str_data}' from client");
let mut stream = connection.open_uni().await?.await?;
stream.write_all(b"ACK").await?;
}
// 接收数据报消息
dgram = connection.receive_datagram() => {
let dgram = dgram?;
let str_data = std::str::from_utf8(&dgram)?;
info!("Received (dgram) '{str_data}' from client");
connection.send_datagram(b"ACK")?;
}
}
}
}
fn init_logging() {
let env_filter = EnvFilter::builder()
.with_default_directive(LevelFilter::INFO.into())
.from_env_lossy();
tracing_subscriber::fmt()
.with_target(true)
.with_level(true)
.with_env_filter(env_filter)
.init();
}client.rs的代码如下：
use wtransport::ClientConfig;
use wtransport::Endpoint;
#[tokio::main]
async fn main() {
// 配置 client 端
let config = ClientConfig::builder()
.with_bind_default()
.with_no_cert_validation()
.build();
// 连接服务器的4433端口
let connection = Endpoint::client(config)
.unwrap()
.connect("https://[::1]:4433")
.await
.unwrap();
// 使用双向通信流发送消息
let mut stream = connection.open_bi().await.unwrap().await.unwrap();
stream.0.write_all(b"HELLO").await.unwrap();
stream.0.finish().await.unwrap();
// 使用单向通信流发消息
let mut stream = connection.open_uni().await.unwrap().await.unwrap();
stream.write_all(b"WORLD").await.unwrap();
stream.finish().await.unwrap();
// 发送数据报消息
connection.send_datagram(b"Hello, world!").unwrap();
tokio::time::sleep(Duration::from_secs(3)).await;
}在bin目录下创建gencert.rs文件，用于生成证书。代码如下：
use base64::engine::general_purpose::STANDARD as Base64Engine;
use base64::Engine;
use rcgen::CertificateParams;
use rcgen::DistinguishedName;
use rcgen::DnType;
use rcgen::KeyPair;
use rcgen::PKCS_ECDSA_P256_SHA256;
use ring::digest::digest;
use ring::digest::SHA256;
use std::fs;
use std::io::Write;
use time::Duration;
use time::OffsetDateTime;
fn main() {
const COMMON_NAME: &str = "localhost";
let mut dname = DistinguishedName::new();
dname.push(DnType::CommonName, COMMON_NAME);
let keypair = KeyPair::generate(&PKCS_ECDSA_P256_SHA256).unwrap();
let digest = digest(&SHA256, &keypair.public_key_der());
let mut cert_params = CertificateParams::new(vec![COMMON_NAME.to_string()]);
cert_params.distinguished_name = dname;
cert_params.alg = &PKCS_ECDSA_P256_SHA256;
cert_params.key_pair = Some(keypair);
cert_params.not_before = OffsetDateTime::now_utc()
.checked_sub(Duration::days(2))
.unwrap();
cert_params.not_after = OffsetDateTime::now_utc()
.checked_add(Duration::days(2))
.unwrap();
let certificate = rcgen::Certificate::from_params(cert_params).unwrap();
fs::File::create("cert.pem")
.unwrap()
.write_all(certificate.serialize_pem().unwrap().as_bytes())
.unwrap();
fs::File::create("key.pem")
.unwrap()
.write_all(certificate.serialize_private_key_pem().as_bytes())
.unwrap();
println!("Certificate generated");
println!("Fingerprint: {}", Base64Engine.encode(digest));
}执行如下命令生成证书：
cargo run --bin gencert在项目根目录下生成cert.pem和key.pem两个文件。
执行如下命令启动server：
cargo run --bin server然后打开一个新的终端，执行如下命令运行client：
cargo run --bin client这时，服务器端的输出信息如下：
INFO server: Server ready!
INFO Connection{id=0}: server: Waiting for session request...
INFO Connection{id=0}: server: New session: Authority: '[::1]:4433', Path: '/'
INFO Connection{id=0}: server: Waiting for data from client...
INFO Connection{id=0}: server: Accepted BI stream
INFO Connection{id=0}: server: Received (bi) 'HELLO' from client
INFO Connection{id=0}: server: Accepted UNI stream
INFO Connection{id=0}: server: Received (uni) 'WORLD' from client
INFO Connection{id=0}: server: Received (dgram) 'Hello, world!' from clientCopyright© 2013-2020
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