depot/third_party/tvl/lisp/dns/client.lisp

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;; Implementation of a DoH-client, see RFC 8484 (DNS Queries over
;; HTTPS (DoH))
(in-package #:dns)
(defvar *doh-base-url* "https://dns.google/resolve"
"Base URL of the service providing DNS-over-HTTP(S). Defaults to the
Google-hosted API.")
(define-condition doh-error (error)
((query-name :initarg :query-name
:reader doh-error-query-name
:type string)
(query-type :initarg :query-type
:reader doh-error-query-type
:type string)
(doh-url :initarg :doh-url
:reader doh-error-doh-url
:type string)
(status-code :initarg :status-code
:reader doh-error-status-code
:type integer)
(response-body :initarg :response-body
:reader doh-error-response-body
:type (or nil (vector (unsigned-byte 8)) string)))
(:report (lambda (condition stream)
(let ((url (doh-error-doh-url condition))
(status (doh-error-status-code condition))
(body (doh-error-response-body condition)))
(format stream "DoH service at '~A' responded with non-success (~A): ~%~%~A"
url status body)))))
(defun lookup-generic (name type doh-url)
(multiple-value-bind (body status)
(drakma:http-request doh-url
:decode-content t
;; TODO(tazjin): Figure out why 'want-stream' doesn't work
:parameters `(("type" . ,type)
("name" . ,name)
("ct" . "application/dns-message")))
(if (= 200 status)
(dns-message-answer
(read-binary 'dns-message (flexi-streams:make-in-memory-input-stream body)))
(restart-case (error 'doh-error
:query-name name
:query-type type
:doh-url doh-url
:status-code status
:response-body body)
(call-with-other-name (new-name)
:interactive (lambda () (list (the string (read))))
:test (lambda (c) (typep c 'doh-error))
(lookup-generic new-name type doh-url))
(call-with-other-type (new-type)
:interactive (lambda () (list (the string (read))))
:test (lambda (c) (typep c 'doh-error))
(lookup-generic name new-type doh-url))
(call-with-other-url (new-url)
:interactive (lambda () (list (the string (read))))
:test (lambda (c) (typep c 'doh-error))
(lookup-generic name type new-url))))))
(defun lookup-a (name &key (doh-url *doh-base-url*))
"Look up the A records at NAME."
(lookup-generic name "A" doh-url))
(defun lookup-txt (name &key (doh-url *doh-base-url*))
"Look up the TXT records at NAME."
(lookup-generic name "TXT" doh-url))
(defun lookup-mx (name &key (doh-url *doh-base-url*))
"Look up the MX records at NAME."
(lookup-generic name "MX" doh-url))
(defun lookup-cname (name &key (doh-url *doh-base-url*))
"Look up the CNAME records at NAME."
(lookup-generic name "CNAME" doh-url))
(defun lookup-ns (name &key (doh-url *doh-base-url*))
"Look up the NS records at NAME."
(lookup-generic name "NS" doh-url))