Implement stub for inspect hostcall

[ulyssa]

This adds a small stub for the inspect hostcall that makes sure its input looks okay and then always returns an allow response. I've put the "allow" value into the Session so that in the future it should be possible to make it configurable, so that folks can change it to block when testing denied requests.

[elliottt]

This looks great! There's only one change I'd recommend for the adapter, which is to rebuild the flags and config values for the wit-generated types.

[elliottt]

I think that info will need to be rebuilt as a fastly::api::http_req::InspectConfig. There's an example of the same over here:

Viceroy/crates/adapter/src/fastly/core.rs

Lines 1460 to 1488 in a945b34

	macro_rules! make_vec {
	($ptr_field:ident, $len_field:ident) => {
	unsafe {
	let len = usize::try_from((*config).$len_field).trapping_unwrap();
	Vec::from_raw_parts((*config).$ptr_field as *mut _, len, len)
	}
	};
	}
	let config = http_req::DynamicBackendConfig {
	host_override: make_vec!(host_override, host_override_len),
	connect_timeout: unsafe { (*config).connect_timeout_ms },
	first_byte_timeout: unsafe { (*config).first_byte_timeout_ms },
	between_bytes_timeout: unsafe { (*config).between_bytes_timeout_ms },
	ssl_min_version: unsafe { (*config).ssl_min_version }.try_into().ok(),
	ssl_max_version: unsafe { (*config).ssl_max_version }.try_into().ok(),
	cert_hostname: make_vec!(cert_hostname, cert_hostname_len),
	ca_cert: make_vec!(ca_cert, ca_cert_len),
	ciphers: make_vec!(ciphers, ciphers_len),
	sni_hostname: make_vec!(sni_hostname, sni_hostname_len),
	client_cert: make_vec!(client_certificate, client_certificate_len),
	client_key: unsafe { (*config).client_key },
	};
	let res = http_req::register_dynamic_backend(name_prefix, target, options, &config);
	std::mem::forget(config);
	convert_result(res)

[ulyssa]

Thank you for pointing me to that! I've set up something similar for InspectConfigOptions and InspectConfig in af24988.

[elliottt]

This looks great!