166 lines
6.8 KiB
Scheme
166 lines
6.8 KiB
Scheme
(module servlet-helpers mzscheme
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(require (lib "list.ss")
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(lib "etc.ss")
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(lib "xml.ss" "xml")
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(lib "base64.ss" "net")
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(lib "url.ss" "net"))
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(require "util.ss"
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"response.ss"
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"request-parsing.ss")
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(provide get-host
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extract-binding/single
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extract-bindings
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exists-binding?
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extract-user-pass
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build-suspender
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make-html-response/incremental
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report-errors-to-browser
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redirect-to
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permanently
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temporarily
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see-other
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(all-from "request-parsing.ss")
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(rename get-parsed-bindings request-bindings)
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translate-escapes)
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;; get-host : Url (listof (cons Symbol String)) -> Symbol
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;; host names are case insesitive---Internet RFC 1034
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(define DEFAULT-HOST-NAME '<none>)
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(define (get-host uri headers)
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(cond
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[(url-host uri) => string->symbol]
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[(assq 'host headers)
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=>
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(lambda (h) (string->symbol (bytes->string/utf-8 (cdr h))))]
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[else DEFAULT-HOST-NAME]))
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;; get-parsed-bindings : request -> (listof (cons sym str))
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(define (get-parsed-bindings r)
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(let ([x (request-bindings/raw r)])
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(if (list? x)
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x
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(parse-bindings x))))
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;; parse-bindings : (U #f String) -> (listof (cons Symbol String))
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(define (parse-bindings raw)
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(if (string? raw)
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(let ([len (string-length raw)])
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(let loop ([start 0])
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(let find= ([key-end start])
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(if (>= key-end len)
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null
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(if (eq? (string-ref raw key-end) #\=)
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(let find-amp ([amp-end (add1 key-end)])
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(if (or (= amp-end len) (eq? (string-ref raw amp-end) #\&))
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(cons (cons (string->symbol (substring raw start key-end))
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(translate-escapes
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(substring raw (add1 key-end) amp-end)))
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(loop (add1 amp-end)))
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(find-amp (add1 amp-end))))
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(find= (add1 key-end)))))))
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null))
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; extract-binding/single : sym (listof (cons str str)) -> str
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(define (extract-binding/single name bindings)
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(let ([lst (extract-bindings name bindings)])
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(cond
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[(null? lst)
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(error 'extract-binding/single "~e not found in ~e" name bindings)]
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[(null? (cdr lst)) (car lst)]
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[else (error 'extract-binding/single "~e occurs multiple times in ~e" name bindings)])))
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; extract-bindings : sym (listof (cons str str)) -> (listof str)
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(define (extract-bindings name bindings)
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(map cdr (filter (lambda (x) (equal? name (car x))) bindings)))
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; exists-binding? : sym (listof (cons sym str)) -> bool
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; for checkboxes
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(define (exists-binding? name bindings)
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(if (assq name bindings)
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#t
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#f))
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; build-suspender : (listof html) (listof html) [(listof (cons sym str))] [(listof (cons sym str))] -> str -> response
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(define build-suspender
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(opt-lambda (title content [body-attributes '([bgcolor "white"])] [head-attributes null])
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(lambda (k-url)
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`(html (head ,head-attributes
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(meta ([http-equiv "Pragma"] [content "no-cache"])) ; don't cache in netscape
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(meta ([http-equiv "expires"] [content "-1"])) ; don't cache in IE
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; one site said to use -1, another said to use 0.
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(title . ,title))
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(body ,body-attributes
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(form ([action ,k-url] [method "post"])
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,@content))))))
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; redirection-status = (make-redirection-status nat str)
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(define-struct redirection-status (code message))
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(define permanently (make-redirection-status 301 "Moved Permanently"))
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(define temporarily (make-redirection-status 302 "Moved Temporarily"))
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(define see-other (make-redirection-status 303 "See Other"))
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; : str [redirection-status] -> response
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(define redirect-to
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(opt-lambda (uri [perm/temp permanently])
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(make-response/full (redirection-status-code perm/temp)
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(redirection-status-message perm/temp)
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(current-seconds) #"text/html"
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`((location . ,uri)) (list (redirect-page uri)))))
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; : str -> str
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(define (redirect-page url)
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(xexpr->string `(html (head (meta ((http-equiv "refresh") (url ,url)))
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"Redirect to " ,url)
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(body (p "Redirecting to " (a ([href ,url]) ,url))))))
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; make-html-response/incremental : ((string -> void) -> void) -> response/incremental
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(define (make-html-response/incremental chunk-maker)
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(make-response/incremental
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200 "Okay" (current-seconds) #"text/html" '()
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chunk-maker))
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; : (response -> doesn't) -> void
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; to report exceptions that occur later to the browser
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; this must be called at the begining of a servlet
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(define (report-errors-to-browser send/finish-or-back)
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(current-exception-handler
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(lambda (exn)
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(send/finish-or-back
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`(html (head (title "Servlet Error"))
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(body ([bgcolor "white"])
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(p "The following error occured: "
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(pre ,(exn->string exn)))))))))
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; Authentication
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(define AUTHENTICATION-REGEXP (regexp "([^:]*):(.*)"))
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(define (match-authentication x) (regexp-match AUTHENTICATION-REGEXP x))
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;:(define match-authentication (type: (str -> (or/c false (list str str str)))))
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; extract-user-pass : (listof (cons sym bytes)) -> (or/c #f (cons str str))
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;; Notes (GregP)
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;; 1. This is Basic Authentication (RFC 1945 SECTION 11.1)
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;; e.g. an authorization header will look like this:
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;; Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
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;; 2. Headers should be read as bytes and then translated to unicode as appropriate.
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;; 3. The Authorization header should have bytes (i.e. (cdr pass-pair) is bytes
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(define (extract-user-pass headers)
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(let ([pass-pair (assq 'authorization headers)])
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(and pass-pair
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(let ([basic-credentials (cdr pass-pair)])
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(cond
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[(and (basic? basic-credentials)
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(match-authentication
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(base64-decode (subbytes basic-credentials 6 (bytes-length basic-credentials))))
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)
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=> (lambda (user-pass)
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(cons (cadr user-pass) (caddr user-pass)))]
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[else #f])))))
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;; basic?: bytes -> (or/c (listof bytes) #f)
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;; does the second part of the authorization header start with #"Basic "
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(define basic?
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(let ([basic-regexp (byte-regexp #"^Basic .*")])
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(lambda (some-bytes)
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(regexp-match basic-regexp some-bytes))))) |