Client

`KEV::Client`

Fetches the CISA Known Exploited Vulnerabilities feed over HTTPS and parses the result into a Catalog.

Constants

Constant	Description
`Client::DEFAULT_URL`	Canonical feed URL: `https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json`
`Client::DEFAULT_USER_AGENT`	`kev.cr/<VERSION> (+https://github.com/hahwul/kev.cr)`

Construction

KEV::Client.new(
  url: KEV::Client::DEFAULT_URL,
  user_agent: KEV::Client::DEFAULT_USER_AGENT,
  connect_timeout: 10.seconds,
  read_timeout: 30.seconds,
)

Methods

Method	Description
`fetch : Catalog`	Unconditional fetch. Raises `KEV::FetchError` on transport or HTTP failures.
`fetch_if_modified : Catalog?`	Conditional fetch using `If-None-Match` / `If-Modified-Since`. Returns `nil` on `304 Not Modified`.
`Client.fetch(url = DEFAULT_URL) : Catalog`	Class-level convenience for a single fetch.

State

After each successful fetch the client captures the upstream cache validators:

Getter	Description
`last_etag : String?`	Captured from the response `ETag` header.
`last_modified : String?`	Captured from the response `Last-Modified` header.

These are used automatically by fetch_if_modified and can be persisted manually for cross-process caching.

Exception mapping

Failure	Exception
DNS / connect / TLS error	`KEV::FetchError` (wraps `IO::Error`, `Socket::Error`, or `OpenSSL::SSL::Error`)
Non-2xx response (incl. 3xx — see below)	`KEV::FetchError`
Body is not JSON	`JSON::ParseException`
JSON valid but schema-malformed	`KEV::ParseError`

Redirects

KEV::Client does not follow HTTP redirects. A 3xx response surfaces as a FetchError so the caller can update the configured URL deliberately, rather than silently route to a different host.

Non-http(s) URLs

URLs with a scheme other than http or https (e.g. file://) are rejected eagerly with a FetchError — the library will not read from the local filesystem under the guise of a feed fetch.

Example: polling loop

client = KEV::Client.new
loop do
  if catalog = client.fetch_if_modified
    publish(catalog)
  end
  sleep 1.hour
end