Inferred port number in --resolve from request URL.

Error message

Inferred port number in --resolve from request URL.

What it means

When translating to curl, --resolve entries need host:port:addr, but the user supplied only domain and address. xh infers the port from the request URL via port_or_known_default(); if the URL's scheme has no known default port (e.g. a custom or unsupported scheme), the port cannot be determined and the translation fails with this context error.

Solutions

Use an http:// or https:// URL, which have known default ports
Add the port explicitly to the request URL (e.g. https://example.org:8443/...)
Drop --resolve if it is not needed for this request
Check the URL scheme for typos before running

Example fix

# before
xh --curl --resolve=example.org:1.2.3.4 foo://example.org/

# after (explicit port so --resolve can be built)
xh --curl --resolve=example.org:1.2.3.4 https://example.org:8443/

Defensive patterns

Strategy: validation

Validate before calling

// Ensure the URL can yield a port before using --resolve
let url = reqwest::Url::parse(target)?;
let ok = url.port_or_known_default().is_some();
if !ok {
    return Err(format!("cannot build --resolve: no default port for scheme '{}'", url.scheme()));
}

Type guard

fn resolve_supported(url: &reqwest::Url) -> bool {
    url.port_or_known_default().is_some()
}

Prevention

Always use http/https URLs when passing --resolve
Include an explicit port in the URL when targeting a non-default port
Check the scheme for typos (https vs ftp vs custom schemes)
Only pass --resolve when you actually need DNS pinning

When it happens

Trigger: Calling translate() with a non-empty args.resolve on a request whose URL has no explicit port and whose scheme is not http/https (no known default port), e.g. `xh --resolve=example.org:1.2.3.4 ftp://example.org/file`.

Common situations: Typing a URL with a typo'd or unusual scheme; forgetting to include the port in the URL when using --resolve with a non-http(s) scheme; testing exotic protocols through xh.

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

AI-assisted analysis of ducaale/xh@2404aceecc (2026-09-13). Data as JSON: /api/errors/f8de2221cccca17b. Report an issue: GitHub.

Appendix: source

Thrown at src/to_curl.rs:323

        _ => (),
    };

    if let Some(interface) = args.interface {
        cmd.arg("--interface");
        cmd.arg(interface);
    };

    if let Some(unix_socket) = args.unix_socket {
        cmd.arg("--unix-socket");
        cmd.arg(unix_socket);
    }

    if !args.resolve.is_empty() {
        let port = url
            .port_or_known_default()
            .with_context(|| format!("Unsupported URL scheme: '{}'", url.scheme()))?;

        cmd.warn("Inferred port number in --resolve from request URL.");
        for resolve in args.resolve {
            cmd.arg("--resolve");
            cmd.arg(format!("{}:{}:{}", resolve.domain, port, resolve.addr));
        }
    }

    // Payload
    for (header, value) in headers.iter() {
        cmd.opt("-H", "--header");
        if value.is_empty() {
            cmd.arg(format!("{header};"));
        } else {
            cmd.arg(format!("{}: {}", header, value.to_utf8_str()?));
        }
    }
    for header in headers_to_unset {
        cmd.opt("-H", "--header");
        cmd.arg(format!("{header}:"));

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