BigPizzaV3/CodexPlusPlus · error

CDP WebSocket URL has no host

Error message

CDP WebSocket URL has no host

What it means

`validate_cdp_websocket_url` enforces that CDP WebSocket URLs use ws/wss, point at a loopback IP, and match the expected debug port. This error is raised when `Url::host_str()` returns None, i.e. the parsed URL has no host component. It prevents connecting to CDP endpoints that aren't a concrete loopback address.

Solutions

1. Pass a full absolute URL including host, e.g. ws://127.0.0.1:9222/devtools/browser/<id>
2. Ensure the host is a literal loopback IP (127.0.0.1 or ::1) — hostnames like localhost are also rejected later
3. Check config for empty host placeholders and fill them from the detected debug port
4. Pre-parse with Url::parse yourself and log the components to catch truncation early

Example fix

// before
let url = format!("ws:///devtools/browser/{id}"); // missing host
// after
let url = format!("ws://127.0.0.1:{debug_port}/devtools/browser/{id}");

let u = reqwest::Url::parse(&url)?;
if u.scheme() != "ws" && u.scheme() != "wss" { bail!("must be ws/wss"); }
if u.host_str().is_none() { bail!("CDP URL needs a host: {url}"); }

if let Err(e) = validate_cdp_websocket_url(&url, port) {
    log::warn!("rejecting CDP URL {url}: {e:#}");
    return Ok(None); // treat as no CDP target rather than propagating
}

When it happens

Trigger: Calling `validate_cdp_websocket_url` (directly or via `browser_identity`, `query_targets_url`, `response_contains_codex_target`, or bridge connect) with a URL whose host is absent — e.g. relative path input, `ws:///devtools/...`, or a non-URL string that still parses oddly.

Common situations: Template string left with an empty host placeholder, URL truncated during config serialization, or passing a path like `/devtools/browser/id` instead of a full ws:// URL.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• CDP WebSocket URL must include an explicit port
• CDP WebSocket URL must include an explicit port
• CDP websocket closed before response for
• CDP WebSocket host must be loopback
• selected CDP target has no websocket URL

AI-assisted analysis of BigPizzaV3/CodexPlusPlus@b1ed92e5e4 (2026-09-19). Data as JSON: /api/errors/254afc97b6c8ab95. Report an issue: GitHub.

Appendix: 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> {

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