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;; webid-oidc, 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 catalog)
#:use-module (web uri)
#:use-module (web client)
#:use-module (ice-9 match)
#:use-module (web client)
#:use-module (rnrs bytevectors)
#:use-module (sxml simple)
#:use-module (sxml match)
#:use-module (ice-9 optargs)
#:use-module (ice-9 receive)
#:export (resolve-uri))
(define useful-namespaces
'((ct . "urn:oasis:names:tc:entity:xmlns:xml:catalog")
(xml . "http://www.w3.org/XML/1998/namespace")))
(define (run-catalog-entry do-examine-catalog base first-entry rest other-entries
uri
candidate match-length next-catalogs-rev)
;; do-examine-catalog is the recursive function to examine a new catalog.
;; base is the current base.
;; rest is a catalog containing the other entries.
;; This function is there because I can’t nest two sxml pattern
;; matchings.
(sxml-match
first-entry
((ct:group (@ (xml:base ,new-base)) ,group-entries ...)
(let ((new-base (string->uri* base new-base)))
(receive (candidate match-length next-catalogs-rev)
(do-examine-catalog
`(*TOP*
(ct:catalog (@ (xml:base ,(uri->string new-base)))
,@group-entries))
candidate match-length next-catalogs-rev)
(do-examine-catalog rest candidate match-length next-catalogs-rev))))
((ct:group ,group-entries ...)
;; The group does not have a specific base, we can merge the
;; entries with other-entries.
(do-examine-catalog
`(*TOP*
(ct:catalog (@ (xml:base ,(uri->string base)))
,@group-entries
,@other-entries))
candidate match-length next-catalogs-rev))
((ct:uri (@ (name ,exact-pattern)
(uri ,replacement)
(xml:base ,new-base)))
;; exact-pattern is not relative to xml:base
(if (equal? (string->uri exact-pattern) uri)
;; Perfect replacement, stop here
(values
;; but replacement is relative to xml:base
(string->uri* base new-base replacement)
(string-length (uri->string uri))
'())
(do-examine-catalog rest candidate match-length next-catalogs-rev)))
((ct:rewriteUri (@ (name ,pattern)
(uri ,replacement)
(xml:base ,new-base)))
(when (and (string-prefix? pattern (uri->string uri))
(> (string-length pattern) match-length))
;; The match is significant
(set! candidate
(string->uri* base
new-base
(string-append
replacement
(substring (uri->string uri)
(string-length pattern)))))
(set! match-length (string-length pattern)))
;; Maybe the match was perfect, in which case we must stop
;; there.
(if (eqv? match-length (string-length (uri->string uri)))
(values candidate match-length '())
(do-examine-catalog rest candidate match-length next-catalogs-rev)))
((ct:uriSuffix (@ (uriSuffix ,suffix)
(uri ,replacement)
(base ,new-base)))
(when (and (string-suffix? suffix (uri->string uri))
(> (string-length suffix) match-length))
(let* ((length-kept
(- (string-length (uri->string uri))
(string-length suffix)))
(part-kept (substring (uri->string uri) 0 length-kept)))
(set! candidate
(string->uri* base new-base (string-append part-kept suffix)))
(set! match-length (string-length suffix))))
(if (eqv? match-length (string-length (uri->string uri)))
(values candidate match-length '())
(do-examine-catalog rest candidate match-length next-catalogs-rev)))
((ct:delegateURI (@ (uriStartString ,pattern)
(catalog ,next-catalog)
(base ,new-base)))
(if (string-prefix? pattern (uri->string uri))
;; Perfect match
(values #f 0 (list (string->uri* base new-base next-catalog)))
(do-examine-catalog rest candidate match-length next-catalogs-rev)))
((ct:nextCatalog (@ (catalog ,next-catalog)
(base ,new-base)))
(do-examine-catalog rest candidate match-length
(cons (string->uri* base new-base next-catalog)
next-catalogs)))
(,else
(match first-entry
((node-name attributes/children ...)
;; The node is simply missing a base
(do-examine-catalog
`(*TOP*
(ct:catalog (@ (xml:base ,(uri->string base)))
(,node-name (@ (xml:base ,(uri->string base))) ,@attributes/children)
,@other-entries))
candidate match-length next-catalogs-rev))
(else
(do-examine-catalog rest candidate match-length next-catalogs-rev))))))
(define (make-absolute base uri)
(when (string? base)
(set! base (string->uri base)))
(let ((final-scheme (or (uri-scheme uri) (uri-scheme base)))
(uri-with-final-authority
(if (or (uri-scheme uri)
(uri-userinfo uri)
(uri-host uri)
(uri-port uri))
;; we should use that of uri
uri
;; nothing specified, use base
base))
(final-path
(if (or (uri-scheme uri)
(uri-userinfo uri)
(uri-host uri)
(uri-port uri)
(string-prefix? "/" (uri-path uri)))
(uri-path uri)
(let with-absolute-relative-path
((defined '())
(components
(append (split-and-decode-uri-path (uri-path base))
(split-and-decode-uri-path (uri-path uri)))))
(match components
(() (string-append "/" (encode-and-join-uri-path (reverse defined))))
(("" components ...) (with-absolute-relative-path defined components))
(("." components ...) (with-absolute-relative-path defined components))
((".." components ...)
(match defined
(() (error "Invalid relative URI"))
((dropped kept ...)
(with-absolute-relative-path kept components))))
((head components ...)
(with-absolute-relative-path `(,head ,@defined) components))))))
(uri-with-final-query
(if (or (uri-scheme uri)
(uri-userinfo uri)
(uri-host uri)
(uri-port uri)
(not (equal? (uri-path uri) ""))
(uri-query uri))
uri
base)))
(build-uri final-scheme
#:userinfo (uri-userinfo uri-with-final-authority)
#:host (uri-host uri-with-final-authority)
#:port (uri-port uri-with-final-authority)
#:path final-path
#:query (uri-query uri-with-final-query)
#:fragment (uri-fragment uri))))
(define (string->uri** base str)
(make-absolute base (string->uri-reference str)))
(define (string->uri* base str . rest)
(if (null? rest)
(string->uri** base str)
(apply string->uri* (string->uri** base str) rest)))
(define (resolve-uri-in-catalog uri catalog-uri catalog other-catalog-uris)
(let do-examine-catalog ((catalog catalog)
(candidate uri)
(match-length 0)
(next-catalogs-rev (reverse other-catalog-uris)))
(sxml-match
catalog
((*TOP*
(ct:catalog))
;; End of the catalog
(values candidate
match-length
(if (eqv? match-length 0)
(reverse next-catalogs-rev)
'())))
((*TOP*
(ct:catalog (@ (xml:base ,base))
,first-entry
,other-entries ...))
(let* ((base (string->uri* catalog-uri base))
(rest `(*TOP*
(ct:catalog (@ (xml:base ,(uri->string base)))
,@other-entries))))
(run-catalog-entry do-examine-catalog base first-entry rest other-entries
uri
candidate match-length next-catalogs-rev)))
((*TOP*
(ct:catalog ,entries ...))
;; No explicit xml:base
(do-examine-catalog
`(*TOP*
(ct:catalog (@ (xml:base ,(uri->string catalog-uri)))
,@entries))
candidate
match-length
next-catalogs-rev)))))
(define* (get-catalog uri #:key (http-get http-get))
(case (uri-scheme uri)
((http https)
(receive (response response-body) (http-get uri)
(when (bytevector? response-body)
(set! response-body (utf8->string response-body)))
(xml->sxml response-body #:namespaces useful-namespaces)))
((file)
(call-with-input-file (uri-path uri)
(lambda (port)
(xml->sxml port #:namespaces useful-namespaces))))
(else
(error (format #f "Unsupported delegate catalog URI scheme: ~s\n" (uri-scheme uri))))))
(define* (resolve-uri uri #:key (http-get http-get))
(when (string? uri)
(set! uri (string->uri uri)))
(let do-examine ((uris
(let ((var
(getenv "XML_CATALOG_FILES")))
(if var
(map string->uri
(string-split var #\space))
'()))))
(match uris
(() uri)
((catalog-uri uris ...)
(let ((catalog (get-catalog catalog-uri
#:http-get http-get)))
(receive (candidate match-length next-uris)
(resolve-uri-in-catalog uri catalog-uri catalog uris)
(if (null? next-uris)
candidate
(do-examine next-uris))))))))
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