90 lines
3.3 KiB
Scheme
90 lines
3.3 KiB
Scheme
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;; Copyright 2002, 2003 Andreas Bernauer
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;; Bindings of POST requests can be read only once, since they are
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;; read from an input port. So we have to cache them, for the case of
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;; a later GET-BINDINGS call on the same POST request. The requests
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;; are referenced by a weak pointer. Thread-safe as all threads use
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;; the same lock.
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(define *POST-bindings-cache* '())
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(define *cache-lock* (make-lock))
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(define (get-bindings surflet-request)
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(let ((request-method (surflet-request-method surflet-request)))
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(cond
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((string=? request-method "GET")
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(form-query-list (http-url-search
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(surflet-request-url surflet-request))))
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((string=? request-method "POST")
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(or (cached-bindings surflet-request)
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(let* ((content-length (get-content-length
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(surflet-request-headers surflet-request)))
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(input-port (surflet-request-input-port surflet-request))
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(form-data (read-string content-length input-port)))
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(let ((form-bindings (form-query-list form-data)))
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(obtain-lock *cache-lock*)
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(set! *POST-bindings-cache* (cons (cons (make-weak-pointer surflet-request)
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form-bindings)
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*POST-bindings-cache*))
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(release-lock *cache-lock*)
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form-bindings))))
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(else
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(error "unsupported request type")))))
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;; Looking up, if we have cached this request. While going through the
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;; list, we remove entries to request objects, that are no longer
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;; valid. Expecting a call for an uncached request every now and then,
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;; it is guaranteed, that the list is cleaned up every now and
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;; then. The cache is a list of pairs
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;;; (surflet-request . computed-binding)
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(define (cached-bindings surflet-request)
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(obtain-lock *cache-lock*)
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(let ((result
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(let loop ((cache *POST-bindings-cache*))
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(if (null? cache)
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#f ; no such request cached
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(let* ((head (car cache))
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(s-req (weak-pointer-ref (car head))))
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(if s-req
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(if (eq? s-req surflet-request)
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(cdar cache) ; request is cached
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(loop (cdr cache))) ; request isn't cached
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(begin
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;; request object is gone ==> remove it from list
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(set! cache (cdr cache))
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(loop cache))))))))
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(release-lock *cache-lock*)
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result))
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;; Will be needed when we handle POST requests.
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(define (get-content-length headers)
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(cond ((get-header headers 'content-length) =>
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;; adopted from httpd/cgi-server.scm
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(lambda (content-length) ; Skip initial whitespace (& other non-digits).
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(let ((first-digit (string-index content-length char-set:digit))
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(content-length-len (string-length content-length)))
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(if first-digit
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(string->number (substring content-length first-digit
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content-length-len))
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;; (status-code bad-request) req
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(error "Illegal `Content-length:' header.")))))
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(else
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(error "No Content-length specified for POST data."))))
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(define (extract-bindings key bindings)
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(let ((key (if (symbol? key) (symbol->string key) key)))
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(map cdr
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(filter (lambda (binding)
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(equal? (car binding) key))
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bindings))))
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(define (extract-single-binding key bindings)
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(let ((key-bindings (extract-bindings key bindings)))
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(if (= 1 (length key-bindings))
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(car key-bindings)
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(error "extract-one-binding: more than one or zero bindings found"
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(length key-bindings)
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key bindings))))
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