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;; disfluid, implementation of the Solid specification
;; Copyright (C) 2020, 2021 Vivien Kraus
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU Affero General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU Affero General Public License for more details.
;; You should have received a copy of the GNU Affero General Public License
;; along with this program. If not, see <https://www.gnu.org/licenses/>.
(define-module (webid-oidc authorization-code)
#:use-module (webid-oidc errors)
#:use-module ((webid-oidc stubs) #:prefix stubs:)
#:use-module (webid-oidc jws)
#:use-module (webid-oidc jwk)
#:use-module (webid-oidc jti)
#:use-module ((webid-oidc parameters) #:prefix p:)
#:use-module (web uri)
#:use-module (srfi srfi-19)
#:use-module (webid-oidc web-i18n)
#:use-module (ice-9 match)
#:use-module (ice-9 exceptions)
#:declarative? #t
#:export
(
&invalid-authorization-code
make-invalid-authorization-code
invalid-authorization-code?
the-authorization-code
authorization-code?
authorization-code-alg
authorization-code-webid
authorization-code-client-id
authorization-code-jti
authorization-code-exp
authorization-code-decode
issue-authorization-code
))
(define-exception-type
&invalid-authorization-code
&external-error
make-invalid-authorization-code
invalid-authorization-code?)
(define (the-authorization-code x)
(with-exception-handler
(lambda (error)
(let ((final-message
(cond
((invalid-jws? error)
(if (exception-with-message? error)
(format #f (G_ "this is not an authorization code, because it is not even a JWS: ~a")
(exception-message error))
(format #f (G_ "this is not an authorization code, because it is not even a JWS"))))
(else
(if (exception-with-message? error)
(format #f (G_ "this is not an authorization code: ~a")
(exception-message error))
(format #f (G_ "this is not an authorization code")))))))
(raise-exception
(make-exception
(make-invalid-authorization-code)
(make-exception-with-message final-message)
error))))
(lambda ()
(match (the-jws x)
((header . payload)
(let examine-payload ((payload payload)
(webid #f)
(client-id #f)
(jti #f)
(exp #f)
(other-fields '()))
(match payload
(()
(unless (and webid client-id jti exp)
(fail (format #f (G_ "the payload is missing ~s")
`(,@(if webid '() '("webid"))
,@(if client-id '() '("client_id"))
,@(if jti '() '("jti"))
,@(if exp '() '("exp"))))))
`(,header
. ((webid . ,(uri->string webid))
(client_id . ,(uri->string client-id))
(jti . ,jti)
(exp . ,(time-second (date->time-utc exp)))
,@(reverse other-fields))))
((('webid . (? string? (= string->uri (? uri? webid-given)))) payload ...)
(examine-payload payload
(or webid webid-given)
client-id jti exp other-fields))
((('webid . infringing) payload ...)
(fail (format #f (G_ "the \"webid\" field should be an URI, ~s is given")
infringing)))
((('client_id . (? string? (= string->uri (? uri? client-id-given)))) payload ...)
(examine-payload payload webid
(or client-id client-id-given)
jti exp other-fields))
((('client_id . infringing) payload ...)
(fail (format #f (G_ "the \"client_id\" field should be an URI, ~s is given")
infringing)))
((('jti . (? string? jti-given)) payload ...)
(examine-payload payload webid client-id
(or jti jti-given)
exp other-fields))
((('jti . invalid) payload ...)
(fail (format #f (G_ "the \"jti\" field should be a string, ~s is given")
invalid)))
((('exp . (? (lambda (x) (and (integer? x) (>= x 0))) exp-given)) payload ...)
(examine-payload payload webid client-id jti
(or exp (time-utc->date (make-time time-utc 0 exp-given)))
other-fields))
((('exp . infringing) payload ...)
(fail (format #f (G_ "the \"exp\" field should be a timestamp, ~s is given")
infringing)))
((field payload ...)
(examine-payload payload webid client-id jti exp `(,field ,@other-fields))))))
(else
(scm-error 'wrong-type-arg "the-authorization-code"
"expected a pair of lists"
'()
(list x)))))))
(define (authorization-code? x)
(false-if-exception (the-authorization-code x)))
(define (authorization-code-alg x)
(match (the-authorization-code x)
((header . _)
(string->symbol (assq-ref header 'alg)))))
(define (authorization-code-webid x)
(match (the-authorization-code x)
((_ . payload)
(string->uri (assq-ref payload 'webid)))))
(define (authorization-code-client-id x)
(match (the-authorization-code x)
((_ . payload)
(string->uri (assq-ref payload 'client_id)))))
(define (authorization-code-jti x)
(match (the-authorization-code x)
((_ . payload)
(assq-ref payload 'jti))))
(define (authorization-code-exp x)
(match (the-authorization-code x)
((_ . payload)
(time-utc->date (make-time time-utc 0 (assq-ref payload 'exp))))))
(define (authorization-code-decode str jwk)
(parameterize ((p:current-date
(time-second (date->time-utc ((p:current-date))))))
(with-exception-handler
(lambda (error)
(let ((final-message
(if (exception-with-message? error)
(format #f (G_ "the authorization code is invalid: ~a")
(exception-message error))
(format #f (G_ "the authorization code is invalid")))))
(raise-exception
(make-exception
(make-invalid-authorization-code)
(make-exception-with-message final-message)
error))))
(lambda ()
(let ((code (the-authorization-code (jws-decode str (lambda (x) jwk)))))
(let ((exp (authorization-code-exp code))
(current-date ((p:current-date))))
(let ((exp-s (time-second (date->time-utc exp)))
(current-s (time-second (date->time-utc current-date))))
(when (>= current-s exp-s)
(let ((final-message
(format #f (G_ "the authorization expired ~a, which is in the past (from ~a)")
(date->string exp)
(date->string current-date))))
(raise-exception
(make-exception
(make-expired exp current-date)
(make-exception-with-message final-message)))))
(jti-check (authorization-code-jti code)
(- exp-s current-s))
code)))))))
(define (authorization-code-encode authorization-code key)
(with-exception-handler
(lambda (error)
(let ((final-message
(if (exception-with-message? error)
(format #f (G_ "cannot encode the authorization code: ~a")
(exception-message error))
(format #f (G_ "cannot encode the authorization code")))))
(raise-exception
(make-exception-with-message final-message))))
(lambda ()
(jws-encode authorization-code key))))
(define* (issue-authorization-code issuer-key
#:key
(validity 120)
webid
client-id)
(let* ((iat (time-second (date->time-utc ((p:current-date)))))
(exp (+ iat validity)))
(authorization-code-encode
`(((alg . ,(symbol->string (alg issuer-key))))
. ((webid . ,(uri->string webid))
(client_id . ,(uri->string client-id))
(exp . ,exp)
(jti . ,(stubs:random 12))))
issuer-key)))
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