What causes "Missing HTTP request line" in affaan-m/ECC?

Send a well-formed HTTP/1.x request starting with a request line like `GET /path HTTP/1.1` followed by CRLF.

affaan-m/ECC · warning · anyhow::Error

Missing HTTP request line

Error message

Missing HTTP request line

What it means

This error comes from the local HTTP request parser (used by an embedded/dev server in main.rs). After locating the header terminator `\r\n\r\n`, the parser splits the header text into lines and requires the first line to be a non-empty request line. A connection whose first header line is missing or blank yields this error.

Solutions

Send a well-formed HTTP/1.x request starting with a request line like `GET /path HTTP/1.1` followed by CRLF.
Check that you're not connecting with TLS/HTTPS to a plain-HTTP port (or vice versa).
Inspect the client (curl, browser, health checker) to ensure it actually writes a request before closing.
If this is a health probe, switch it to an actual HTTP GET rather than a bare TCP connect.

Example fix

// before (raw TCP probe, no request sent)
$ printf '' | nc localhost 8080
// after
$ curl -v http://localhost:8080/healthz

Defensive patterns

Strategy: try-catch

Try / catch

// Client side: ensure a full request is written before shutdown
conn.write_all(b"GET /healthz HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n")?;
conn.flush()?;

Prevention

Use real HTTP clients (curl, reqwest) against the server instead of raw TCP probes.
Don't point TLS clients at plain-HTTP ports.
Configure health checks to send an actual HTTP GET, not a bare connect.

When it happens

Trigger: A client opens a TCP connection and sends an empty payload or only `\r\n`; the buffer read returns a header_end of 0 with an empty header region; malformed/binary data where no valid first line exists; health-check probes that connect and immediately close.

Common situations: Load balancers or monitoring tools opening raw TCP connections without sending a request; a client speaking the wrong protocol (e.g. TLS bytes to a plain-HTTP port, or HTTP/2 preface not handled); half-written requests due to network truncation.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/dc613917d366d1e6. Report an issue: GitHub.

Appendix: source

Thrown at ecc2/src/main.rs:4215

        if read == 0 {
            anyhow::bail!("Unexpected EOF while reading HTTP request");
        }
        buffer.extend_from_slice(&temp[..read]);
        if let Some(index) = buffer.windows(4).position(|window| window == b"\r\n\r\n") {
            break index + 4;
        }
        if buffer.len() > 64 * 1024 {
            anyhow::bail!("HTTP request headers too large");
        }
    };

    let header_text = String::from_utf8(buffer[..header_end].to_vec())
        .context("HTTP request headers were not valid UTF-8")?;
    let mut lines = header_text.split("\r\n");
    let request_line = lines
        .next()
        .filter(|line| !line.trim().is_empty())
        .ok_or_else(|| anyhow::anyhow!("Missing HTTP request line"))?;
    let mut request_parts = request_line.split_whitespace();
    let method = request_parts
        .next()
        .ok_or_else(|| anyhow::anyhow!("Missing HTTP method"))?
        .to_string();
    let path = request_parts
        .next()
        .ok_or_else(|| anyhow::anyhow!("Missing HTTP path"))?
        .to_string();

    let mut headers = BTreeMap::new();
    for line in lines {
        if line.is_empty() {
            break;
        }
        if let Some((key, value)) = line.split_once(':') {
            headers.insert(key.trim().to_ascii_lowercase(), value.trim().to_string());
        }

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