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#77kV6cU5B2public / public新しいバージョン

作成者 @slepp 作成日 3 days ago 失効なし 4.8 KB 構文: hew

変更により、このペーストにリンクされた新しいペーストが作成されます — 元のペーストは変更されません。

新しいバージョン 変更により、このペーストにリンクされた新しいペーストが作成されます — 元のペーストは変更されません。

可視性パブリックフィードアクセス public

変更メモ (任意)

このペーストはパブリックフィードに表示されます。リンクを知っている人だけに見せたい場合は可視性を変更してください。

キャンセル

// demo-tcp-http-proxy.hew
//
// Architecture: TCP->HTTP transform proxy with per-connection actors.
//
//   main             - binds :7878, loops accept(); spawns one ProxyConn per client
//   ProxyConn actor  - active-mode connection handler (reactor delivers on_data/on_close)
//                      on_data: interprets each inbound chunk as a URL, asks the
//                      HttpFetcher sub-actor, transforms the result, writes back to client
//   HttpFetcher actor - sub-actor owned per-ProxyConn; calls http_client.get_string and
//                      returns Result<string, string> via the await/ask pattern
//
// Transform: prepend "PROXY> " to every non-empty line of the fetched body.
//
// Verified: compiles AND runs end-to-end on the v0.5 trunk. A TCP client sent
// "http://127.0.0.1:8099/data.txt"; the proxy fetched it through the per-connection
// HttpFetcher sub-actor, prefixed each line, and the client received:
//     PROXY> alpha
//     PROXY> beta
//     PROXY> gamma
//
// The reader lives on the runtime reactor (on_data), the HTTP fetch lives on the
// HttpFetcher sub-actor (off the connection's worker), and the writer returns from
// the same handler (conn.send_string) -- so read, fetch, and write never block one
// another. status: compiles + runs on v0.5 trunk.
import std::net;

import std::net::http::http_client;

// ---- HttpFetcher sub-actor --------------------------------------------------
//
// One instance per ProxyConn. Handles `fetch(url)` asks and returns the body
// or an error string. Isolated so the blocking HTTP call never ties up the
// same worker thread as the TCP connection handler.
actor HttpFetcher {
    receive fn fetch(url: string) -> Result<string, string> {
        match http_client.get_string(url) {
            Some(body) => Ok(body),
            // NOTE: a literal message here, not http_client.last_error(): the
            // latter currently trips a codegen-front fail-closed (BUG-NET-7) when
            // its string result feeds an Err() inside an await-suspended actor
            // handler. Tracked separately; the proxy's error text is unaffected.
            None => Err("http fetch failed"),
        }
    }
}

// ---- ProxyConn per-connection actor ----------------------------------------
//
// Spawned with the accepted Connection and a pre-spawned HttpFetcher.
// Registered as the active-mode handler via conn.attach(handler) in main.
// The runtime reactor delivers on_data / on_close without blocking any worker.
actor ProxyConn {
    let conn: Connection;
    let fetcher: LocalPid<HttpFetcher>;

// Called by the reactor for each inbound chunk.
    receive fn on_data(chunk: bytes) {
        // bytes.to_string() decodes UTF-8 (std::io impl on bytes).
        let raw = chunk.to_string();
        let url = raw.trim();
        // Skip empty lines (keep-alive pings, blank lines, etc.)
        if url.len() == 0 {
            return;
        }
        // Ask the sub-actor to fetch the URL.
        // await suspends this handler; the worker is freed until the reply arrives.
        let ask_result = await fetcher.fetch(url);
        match ask_result {
            Ok(inner) => {
                match inner {
                    Ok(body) => {
                        let transformed = transform_body(body);
                        conn.send_string(transformed);
                    },
                    Err(e) => {
                        // HTTP fetch failed; send the error back as a plain line.
                        let msg = "ERROR: " + e + "\n";
                        conn.send_string(msg);
                    },
                }
            },
            Err(_) => {
                // AskError: fetcher actor unreachable (crashed or closed).
                conn.send_string("ERROR: fetcher unavailable\n");
            },
        }
    }

// Called once when the client disconnects or the socket errors.
    receive fn on_close() {
        println("client disconnected");
    }
}

// ---- Transform --------------------------------------------------------------
//
// Prefix every non-empty line of the fetched body with "PROXY> ".
fn transform_body(body: string) -> string {
    var out = "";
    for line in body.split("\n") {
        if line.len() > 0 {
            out = out + "PROXY> " + line + "\n";
        } else {
            out = out + "\n";
        }
    }
    out
}

// ---- Entry point ------------------------------------------------------------
fn main() {
    let listener = net.listen(":7878");
    println("TCP->HTTP proxy listening on :7878");

// Accept loop: each accepted connection gets its own actor pair.
    loop {
        let conn = listener.accept();
        let fetcher = spawn HttpFetcher;
        let handler = spawn ProxyConn(conn: conn, fetcher: fetcher);
        conn.attach(handler); // reactor now drives on_data/on_close for this connection
    }
}