BigPizzaV3/CodexPlusPlus · error · anyhow::Error

CDP WebSocket URL has no host

Error message

CDP WebSocket URL has no host

What it means

validate_cdp_websocket_url (crates/codex-plus-core/src/cdp.rs:218) requires the parsed URL to have a host component; host_str() returns None when the authority is empty or the URL is not hierarchical (e.g. 'ws:///devtools/browser/id'). This is the earliest structural check after the ws/wss scheme check, so it fires before the loopback/port validation can run.

Source

Thrown at crates/codex-plus-core/src/cdp.rs:218

        .context("failed to deserialize CDP targets")?;
    for target in &targets {
        if let Some(websocket_url) = target.web_socket_debugger_url.as_deref() {
            validate_cdp_websocket_url(websocket_url, debug_port).with_context(|| {
                format!("unsafe CDP target WebSocket URL for target {}", target.id)
            })?;
        }
    }
    Ok(targets)
}

pub fn validate_cdp_websocket_url(url: &str, expected_port: u16) -> anyhow::Result<()> {
    let parsed = reqwest::Url::parse(url).context("invalid CDP WebSocket URL")?;
    if !matches!(parsed.scheme(), "ws" | "wss") {
        bail!("CDP WebSocket URL must use ws or wss");
    }
    let host = parsed
        .host_str()
        .ok_or_else(|| anyhow::anyhow!("CDP WebSocket URL has no host"))?;
    let address = host
        .trim_start_matches('[')
        .trim_end_matches(']')
        .parse::<IpAddr>()
        .with_context(|| "CDP WebSocket host must be a loopback IP address")?;
    if !address.is_loopback() {
        bail!("CDP WebSocket host must be loopback");
    }
    let port = parsed
        .port()
        .ok_or_else(|| anyhow::anyhow!("CDP WebSocket URL must include an explicit port"))?;
    if port != expected_port {
        bail!("CDP WebSocket port {port} does not match debug port {expected_port}");
    }
    Ok(())
}

pub fn pick_page_target(targets: &[CdpTarget]) -> anyhow::Result<CdpTarget> {

View on GitHub (pinned to 1f431ae49b)

Solutions

1. Fill in the host: ws://127.0.0.1:9222/devtools/browser/<id> (must be a loopback IP to pass the next check)
2. Trace where the URL string is assembled and guard the empty-host case before calling the validator
3. Prefer taking the URL from /json/version of the running browser instead of assembling it yourself

Example fix

# before: empty authority
ws:///devtools/browser/4f8a...

# after: explicit loopback host (and port)
ws://127.0.0.1:9222/devtools/browser/4f8a...

// Check host presence (and loopback-ness) before validation/connect
let u = reqwest::Url::parse(ws_url)?;
let host = u.host_str().context("CDP WebSocket URL has no host")?;
ensure!(host.trim_start_matches('[').trim_end_matches(']').parse::<std::net::IpAddr>().is_ok_and(|a| a.is_loopback()), "host must be loopback IP");
validate_cdp_websocket_url(ws_url, expected_port)?;

fn ws_url_has_host(url: &str) -> bool {
    reqwest::Url::parse(url).ok().and_then(|u| u.host_str().map(|_| true)).unwrap_or(false)
}

match validate_cdp_websocket_url(ws_url, port) {
    Ok(()) => Ok(()),
    Err(e) if e.to_string().contains("no host") => {
        // template bug: rebuild URL from known loopback host + port and retry once
        let repaired = format!("ws://127.0.0.1:{port}/devtools/browser/{id}");
        validate_cdp_websocket_url(&repaired, port)
    }
    Err(e) => Err(e),
}

When it happens

Trigger: Validating a URL string like ws:///devtools/browser/<id> (empty host) or an opaque 'ws:...' string; passing a URL whose host was lost during templating/formatting (e.g. format!("ws://{}/devtools/...", host) with an empty host variable).

Common situations: Config templating that concatenates an unset/empty host variable; copy-paste that drops '127.0.0.1:9222' from the URL; environment-driven host configuration that is empty in CI.

Related errors

• CDP WebSocket URL must include an explicit port
• CDP WebSocket URL must include an explicit port
• Page.captureScreenshot returned no image data
• browser WebSocket URL has no path
• selected CDP target has no websocket URL

AI-assisted analysis of BigPizzaV3/CodexPlusPlus@1f431ae49b (2026-08-16). Data as JSON: /api/errors/254afc97b6c8ab95. Report an issue: GitHub.