Crate micro_http

An asynchronous micro HTTP server implementation

This crate provides a lightweight, efficient, and modular HTTP/1.1 server implementation built on top of tokio. It focuses on providing a clean API while maintaining high performance through careful memory management and asynchronous processing.

Features

• Full HTTP/1.1 protocol support
• Asynchronous I/O using tokio
• Streaming request and response bodies
• Chunked transfer encoding
• Keep-alive connections
• Expect-continue mechanism
• Efficient memory usage through zero-copy parsing
• Clean error handling

Example

use http::{Request, Response, StatusCode};
use http_body_util::BodyExt;
use std::error::Error;
use std::sync::Arc;
use tokio::net::TcpListener;
use tracing::{error, info, warn, Level};
use tracing_subscriber::FmtSubscriber;
use micro_http::connection::HttpConnection;
use micro_http::handler::make_handler;
use micro_http::protocol::body::ReqBody;

#[tokio::main]
async fn main() {
    // Initialize logging
    let subscriber = FmtSubscriber::builder()
        .with_max_level(Level::INFO)
        .finish();
    tracing::subscriber::set_global_default(subscriber)
        .expect("setting default subscriber failed");
     
    info!(port = 8080, "start listening");
    let tcp_listener = match TcpListener::bind("127.0.0.1:8080").await {
        Ok(tcp_listener) => tcp_listener,
        Err(e) => {
            error!(cause = %e, "bind server error");
            return;
        }
    };
     
    let handler = Arc::new(make_handler(hello_world));
     
    loop {
        let (tcp_stream, _remote_addr) = match tcp_listener.accept().await {
            Ok(stream_and_addr) => stream_and_addr,
            Err(e) => {
                warn!(cause = %e, "failed to accept");
                continue;
            }
        };
         
        let handler = handler.clone();
         
        tokio::spawn(async move {
            let (reader, writer) = tcp_stream.into_split();
            let connection = HttpConnection::new(reader, writer);
            match connection.process(handler).await {
                Ok(_) => {
                    info!("finished process, connection shutdown");
                }
                Err(e) => {
                    error!("service has error, cause {}, connection shutdown", e);
                }
            }
        });
    }
}

async fn hello_world(request: Request<ReqBody>) -> Result<Response<String>, Box<dyn Error + Send + Sync>> {
    let path = request.uri().path().to_string();
    info!("request path {}", path);
     
    let (_header, body) = request.into_parts();
     
    let body_bytes = body.collect().await?.to_bytes();
    info!(body = std::str::from_utf8(&body_bytes[..]).unwrap(), "receiving request body");
     
    let response_body = "Hello World!\r\n";
    let response = Response::builder()
        .status(StatusCode::OK)
        .header(http::header::CONTENT_LENGTH, response_body.len())
        .body(response_body.to_string())
        .unwrap();
     
    Ok(response)
}

Architecture

The crate is organized into several key modules:

• connection: Core connection handling and lifecycle management
• protocol: Protocol types and abstractions
• codec: Protocol encoding/decoding implementation
• handler: Request handler traits and utilities

Core Components

Connection Handling

The connection::HttpConnection type is the main entry point for processing HTTP connections. It manages the full lifecycle of connections including:

• Request parsing
• Body streaming
• Response generation
• Keep-alive handling

Request Processing

Requests are processed through handler functions that implement the handler::Handler trait. The crate provides utilities for creating handlers from async functions through handler::make_handler.

Body Streaming

Request and response bodies are handled through streaming interfaces that implement the http_body::Body trait. This enables efficient processing of large payloads without buffering entire bodies in memory.

Error Handling

The crate uses custom error types that implement std::error::Error:

• protocol::HttpError: Top-level error type
• protocol::ParseError: Request parsing errors
• protocol::SendError: Response sending errors

Performance Considerations

The implementation focuses on performance through:

• Zero-copy parsing where possible
• Efficient buffer management
• Streaming processing of bodies
• Concurrent request/response handling
• Connection keep-alive

Limitations

• HTTP/1.1 only (currently HTTP/2 or HTTP/3 is not supported)
• No TLS support (use a reverse proxy for HTTPS)
• Maximum header size: 8KB
• Maximum number of headers: 64

Safety

The crate uses unsafe code in a few well-documented places for performance optimization, particularly in header parsing. All unsafe usage is carefully reviewed and tested.

Modules

codec

HTTP codec module for encoding and decoding HTTP messages

connection

HTTP connection handling module

handler

HTTP request handler module

protocol

Core HTTP protocol abstractions and implementations.