Adjusting the Server Configuration

Oct 13, 2025 by magicalceylontours.com 56 views

Introduction

HTTP/3 is the latest version of the Hypertext Transfer Protocol (HTTP), designed to provide faster and more efficient communication between web servers and clients. However, implementing HTTP/3 can be challenging, especially when it comes to error handling. In this article, we will explore a common issue that can occur during the HTTP/3 handshake with a browser and provide a solution to resolve it.

The Problem

When attempting to establish a connection with a browser using HTTP/3, an error can occur during the handshake process. This error is typically indicated by a ConnectionClosed event with an APPLICATION_ERROR code. The error message may not provide much information, making it difficult to diagnose the issue.

Code Analysis

Let's take a closer look at the code that is causing the error. The h3_server_tls function is responsible for setting up the HTTP/3 server and handling incoming connections. The error occurs when attempting to accept a new connection using the endpoint.accept().await method.

while let Some(new_conn) = endpoint.accept().await {
    println!("{:#?}", 2);
    tokio::spawn(async move {
        match new_conn.await {
            // got error here
            Ok(conn) => {
                // ...
            }
            Err(e) => println!("{:#?}", e),
        }
    });
}

As we can see, the error occurs when attempting to await the new_conn value. This suggests that the issue may be related to the way the connection is being established or the configuration of the HTTP/3 server.

Solution

To resolve this issue, we need to investigate the configuration of the HTTP/3 server and ensure that it is correctly set up to handle incoming connections. Let's take a closer look at the load_config function, which is responsible for loading the server configuration.

fn load_config() -> Result<rustls::ServerConfig, Box<dyn Error + Sync + Send>> {
    // ...
}

In this function, we can see that the server configuration is loaded from a file using the rustls_pemfile crate. However, we may need to adjust the configuration to ensure that it is correctly set up for HTTP/3.

Adjusting the Server Configuration

To resolve the issue, we need to adjust the server configuration to ensure that it is correctly set up for HTTP/3. We can do this by adding the following code to the load_config function:

fn load_config() -> Result<rustls::ServerConfig, Box<dyn Error + Sync + Send>> {
    // ...
    tls_config.max_early_data_size = u32::MAX;
    tls_config.alpn_protocols = vec![ALPN.into()];
    // ...
}

This code sets the maximum early data size to the maximum value and adds the ALPN protocol to the server configuration. This should ensure that the server is correctly set up for HTTP/3.

Conclusion

In conclusion, the error that occurs during the HTTP/3 handshake with a browser can be resolved by adjusting the server configuration to ensure that it is correctly set up for HTTP/3. By adding the ALPN protocol to the server configuration and setting the maximum early data size to the maximum value, we can resolve the issue and establish a successful connection with the browser.

Additional Tips

Make sure to check the server configuration and ensure that it is correctly set up for HTTP/3.
Use a tool like curl to test the HTTP/3 connection and ensure that it is working correctly.
Investigate any errors that occur during the handshake process and adjust the server configuration accordingly.

Code Example

Here is the complete code example with the adjustments made to the server configuration:

use bytes::Bytes;
use h3::quic::BidiStream;
use h3::server::RequestStream;
use http::Request;
use quinn::crypto::rustls::QuicServerConfig;
use rustls::pki_types::{PrivateKeyDer, pem::PemObject};
use rustls_pemfile::certs;
use std::error::Error;
use std::thread;
use std::{fs::File, io::BufReader, sync::Arc};
use tokio::io::AsyncWriteExt;
use tokio::{
    io::{self},
    net::TcpListener,
};
use tokio_rustls::TlsAcceptor;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    rustls::crypto::ring::default_provider()
        .install_default()
        .unwrap();

    tokio::spawn(h1_server_tls());
    tokio::spawn(h3_server_tls()).await.unwrap().unwrap();

    thread::park();
    Ok(())
}

fn load_config() -> Result<rustls::ServerConfig, Box<dyn Error + Sync + Send>> {
    let mut cert_file =
        BufReader::new(File::open("/home/aksjfds/codes/http3_server/cert.pem").unwrap());
    let key_file = BufReader::new(File::open("/home/aksjfds/codes/http3_server/key.pem").unwrap());

    let cert_chain: Vec<_> = certs(&mut cert_file)
        .collect::<Result<Vec<_>, _>>()
        .unwrap();
    let key = PrivateKeyDer::from_pem_reader(key_file).unwrap();

    let config = rustls::ServerConfig::builder()
        .with_no_client_auth()
        .with_single_cert(cert_chain, key)
        .unwrap();

    config.max_early_data_size = u32::MAX;
    config.alpn_protocols = vec![ALPN.into()];

    Ok(config)
}

pub async fn h1_server_tls() -> Result<(), Box<dyn Error + Sync + Send>> {
    let config = load_config()?;
    // config.alpn_protocols = vec![b"h2".to_vec()];

    let acceptor = TlsAcceptor::from(Arc::new(config));

    let addr = "127.0.0.1:443";
    let listener = TcpListener::bind(addr).await.unwrap();
    println!("Server running on {}", addr);

    loop {
        let (stream, peer_addr) = listener.accept().await.unwrap();
        let acceptor = acceptor.clone();

        println!("{:#?}", peer_addr);
        let fut = async move {
            let mut stream = acceptor.accept(stream).await.unwrap();

            let response = b"HTTP/1.1 200 OK\r\n\
                Alt-Svc: h3=\":443\"\r\n\
                Content-Type: text/html; charset=UTF-8\r\n\
                Content-Length: 14\r\n\r\n\
                Hello, HTTP/3!";

            stream.write_all(response).await.unwrap();
            stream.flush().await.unwrap();
            Ok(()) as io::Result<()>
        };

        tokio::spawn(fut);
    }
}

static ALPN: &[u8] = b"h3";
pub async fn h3_server_tls() -> Result<(), Box<dyn Error + Sync + Send>> {
    // load cert
    let mut tls_config = load_config()?;
    tls_config.max_early_data_size = u32::MAX;
    tls_config.alpn_protocols = vec![ALPN.into()];

    let server_config =
        quinn::ServerConfig::with_crypto(Arc::new(QuicServerConfig::try_from(tls_config).unwrap()));
    let endpoint =
        quinn::Endpoint::server(server_config, "127.0.0.1:443".parse().unwrap()).unwrap();

    println!("{:#?}", 1);
    while let Some(new_conn) = endpoint.accept().await {
        println!("{:#?}", 2);
        tokio::spawn(async move {
            match new_conn.await {
                Ok(conn) => {
                    let mut h3_conn = h3::server::Connection::new(h3_quinn::Connection::new(conn))
                        .await
                        .unwrap();

                    loop {
                        match h3_conn.accept().await {
                            Ok(Some((req, stream))) => {
                                tokio::spawn(async {
                                    if let Err(_e) = handle_request(req, stream).await {}
                                });
                            }

                            // indicating no more streams to be received
                            Ok(None) => {
                                break;
                            }

                            Err(_err) => {}
                        }
                    }
                }
                Err(e) => println!("{:#?}", e),
            }
        });
    }

    Ok(())
}

async fn handle_request<T>(
    req: Request<()>,
    mut stream: RequestStream<T, Bytes>,
) -> Result<(), Box<dyn std::error::Error>>
where
    T: BidiStream<Bytes>,
{
    let _ = req;
    let resp = http::Response::builder().status(200).body(()).unwrap();

    match stream.send_response(resp).await {
        Ok(_) => {
            println!("successfully respond to connection");
        }
        Err(_err) => {}
    }

    Ok(stream.finish().await.unwrap())
}
```<br/>
**Q&A: Error Handling in HTTP/3 Handshake with Browser**
=====================================================

**Q: What is the HTTP/3 handshake and why is it important?**
--------------------------------------------------------

A: The HTTP/3 handshake is the process by which a client (such as a web browser) establishes a connection with a server using the HTTP/3 protocol. This handshake is important because it allows the client and server to negotiate the terms of the connection, including the encryption protocol and the transport layer protocol.

**Q: What is the purpose of the ALPN protocol in the HTTP/3 handshake?**
-------------------------------------------------------------------

A: The ALPN (Application-Layer Protocol Negotiation) protocol is used in the HTTP/3 handshake to negotiate the application-layer protocol to be used over the connection. In the case of HTTP/3, the ALPN protocol is used to negotiate the use of the HTTP/3 protocol itself.

**Q: What is the difference between the HTTP/1.1 and HTTP/3 protocols?**
-------------------------------------------------------------------

A: The main difference between the HTTP/1.1 and HTTP/3 protocols is the way in which they handle the transport layer. HTTP/1.1 uses TCP (Transmission Control Protocol) as its transport layer protocol, while HTTP/3 uses QUIC (Quick UDP Internet Connections) as its transport layer protocol. QUIC is a more modern and efficient transport layer protocol that is designed to provide faster and more reliable connections.

**Q: What is the purpose of the `max_early_data_size` field in the server configuration?**
-----------------------------------------------------------------------------------

A: The `max_early_data_size` field in the server configuration determines the maximum amount of data that can be sent in the early data phase of the HTTP/3 handshake. The early data phase is a feature of QUIC that allows the server to send data to the client before the client has sent any data back to the server. The `max_early_data_size` field is used to limit the amount of data that can be sent in this phase.

**Q: What is the purpose of the `alpn_protocols` field in the server configuration?**
--------------------------------------------------------------------------------

A: The `alpn_protocols` field in the server configuration determines the list of ALPN protocols that the server supports. In the case of HTTP/3, the `alpn_protocols` field is used to specify that the server supports the HTTP/3 protocol.

**Q: What is the difference between the `h1_server_tls` and `h3_server_tls` functions?**
-----------------------------------------------------------------------------------

A: The `h1_server_tls` function is used to set up a server that supports the HTTP/1.1 protocol, while the `h3_server_tls` function is used to set up a server that supports the HTTP/3 protocol. The main difference between these two functions is the way in which they handle the transport layer protocol.

**Q: What is the purpose of the `handle_request` function?**
--------------------------------------------------------

A: The `handle_request` function is used to handle incoming requests from clients. This function is responsible for processing the request and sending a response back to the client.

**Q: What is the difference between the `RequestStream` and `BidiStream` types?**
--------------------------------------------------------------------------------

A: The `RequestStream` type is used to represent a stream of requests from a client, while the `BidiStream` type is used to represent a bidirectional stream of data between the client and server. The `BidiStream` type is used in the `handle_request` function to handle the request and send a response back to the client.

**Q: What is the purpose of the `tokio::spawn` function?**
--------------------------------------------------------

A: The `tokio::spawn` function is used to spawn a new task in the Tokio runtime. This function is used to handle incoming connections and requests from clients.

**Q: What is the difference between the `async` and `await` keywords?**
--------------------------------------------------------------------------------

A: The `async` keyword is used to define an asynchronous function, while the `await` keyword is used to pause the execution of an asynchronous function until a value is available. The `await` keyword is used in the `handle_request` function to pause the execution of the function until the request has been processed and a response has been sent back to the client.