92 lines
3.8 KiB
Scheme
92 lines
3.8 KiB
Scheme
;;; A library of procs for handlers.
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;;; This file is part of the Scheme Untergrund Networking package.
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;;; For copyright information, see the file COPYING which comes with
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;;; the distribution.
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;; interpolate host info from our request's net connection.
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;; return string. Example: "134.2.12.72:7777"
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(define (get-socket-host-string req)
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(let ((addr (socket-local-address (request-socket req))))
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(call-with-values
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(lambda ()(socket-address->internet-address addr))
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(lambda (ipaddr portnum)
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(string-append (format-internet-host-address ipaddr) ":" (number->string portnum))))))
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;; GET-NUMERIC-FIELD-VALUE
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;; generalized function to get a field value of the form 1*DIGIT
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;; req is a request record, field-name a symbol
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;; check wether a header-field with name field-name is contained in req;
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;; if not, return #f,
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;; else, take the first such header field and check wether its field-content conforms to
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;; field-content = *LWS 1*DIGIT *LWS
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;; if so, return digit as a number
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(define (get-numeric-field-value req field-name)
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(let
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;;try to get first "field-name" header
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((field-content (get-header (request-headers req) field-name)))
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(if field-content ;; request contained "field-name" header
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(let ;;see * below
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((field-value (string->number (string-trim-both field-content char-set:blank)))) ;;char-set:blank = Space + Tab = LWS from RFC2616 after folding
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(if (and (integer? field-value) (>= field-value 0)) ;;yes, field value contained only digits, and at least one digit.
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field-value
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(http-error
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(status-code bad-request) req
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(format #f
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"~A header contained only whitespace, or characters other than digits, or whitespace between digits"
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field-name))))
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#f)))
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;;* RFC 2616, 4.2: The field-content does not include any leading or
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;;trailing LWS: linear white space occurring before the first
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;;non-whitespace character of the field-value or after the last
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;;non-whitespace character of the field-value. Such leading or
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;;trailing LWS MAY be removed without changing the semantics of the
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;;field value.
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;;(probably read-rfc822-headers in rfc822.scm should do the job of skipping leading and trailing whitespace?)
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;;get request's message-body length from Content-length: header or
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;;throw http-error if no such header
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(define (get-body-length-from-content-length req)
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(let
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;;try to get field value of first Content-length header (RFC 2616 allows only one Content-length: header)
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((maybe-length (get-numeric-field-value req 'content-length)))
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(or maybe-length
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(http-error (status-code bad-request) req "No Content-Length header in request"))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Decode chunked entity bodies: "chunked transfer-coding"
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;;; See RFC 2616, 3.6.1 and 19.4.6 for the composition of chunked entity bodies.
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;;; See RFC 2616, 4.4 for precedence of Transfer-encoding header over Content-length header.
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;;; Is the request's entity body sent in chunked transfer-encoding?
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;;; (See RFC 2616, 14.41 and 3.6 for syntax and semantics of Transfer-Encoding header.)
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(define (chunked-transfer-coding? req)
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(let ((field-value (get-header (request-headers req) 'transfer-encoding)))
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(if (not field-value)
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#f
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; the field value is a comma-separated list of transfer-codings (3.6),
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; extract the last transfer-coding in the list
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(let* ((reversed-field-value (string-reverse field-value))
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(index ; does the list contain more than one element?
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(string-contains reversed-field-value " ,"))
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(last-transfer-coding
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(if index
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(string-trim (string-reverse (string-take reversed-field-value index)))
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(string-trim field-value))))
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; the first token of the (extracted last) transfer-coding must be "chunked" to indicate chunked transfer coding
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(string-prefix? "chunked" last-transfer-coding)))))
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