affaan-m/ECC · error · anyhow::Error

Missing HTTP method

Error message

Missing HTTP method

What it means

Thrown by read_http_request when the request line is present and non-empty (it passed the blank-line filter) but split_whitespace yields no first token to use as the HTTP method. The parser needs METHOD PATH VERSION and bails if the method token is absent.

Source

Thrown at ecc2/src/main.rs:4219

        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());
        }
    }

    let content_length = headers
        .get("content-length")

View on GitHub (pinned to 01e15490f0)

Solutions

1. Inspect the raw bytes the client sent (tcpdump/Wireshark or log the buffer) and fix the client to send a well-formed request line like 'GET / HTTP/1.1'.
2. Treat this as a 400 Bad Request at the accept site instead of crashing the listener.
3. If you control the client, validate the request line before writing it to the socket.

Example fix

// caller: classify parse failures as client errors
match read_http_request(&mut stream) {
    Ok(req) => dispatch(req),
    Err(e) if e.to_string().contains("Missing HTTP method") => {
        let _ = write_http_response(&mut stream, 400, "text/plain", "bad request line");
    }
    Err(e) => return Err(e),
}

fn has_method_token(request_line: &str) -> bool {
    request_line.trim().split_whitespace().next().is_some()
}

match read_http_request(&mut stream) {
    Ok(req) => dispatch(req),
    Err(e) if e.to_string().contains("Missing HTTP method") => {
        let _ = write_http_response(&mut stream, 400, "text/plain", "bad request line");
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Effectively a defensive guard: because the prior filter rejects lines that trim to empty, split_whitespace would normally yield at least one token. It can still fire if the request line is composed solely of whitespace-like characters that pass the empty check in some edge form, or if a future refactor weakens the filter. Nominal trigger is a first line with no recognizable method token.

Common situations: Malformed hand-crafted requests, buggy custom HTTP clients that emit a request line with only delimiters, or protocol probes that send non-HTTP bytes whose first line happens to be non-empty but contains no method.

Related errors

• Missing HTTP request line
• Missing HTTP path
• Unexpected EOF while reading HTTP request body
• HTTP ${res.status}
• open failed (HTTP ${res.statusCode})

AI-assisted analysis of affaan-m/ECC@01e15490f0 (2026-08-13). Data as JSON: /api/errors/06f41e564de95beb. Report an issue: GitHub.