submit.scm

#|
LambdaNative - a cross-platform Scheme framework
Copyright (c) 2009-2015, University of British Columbia
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|#

;; Server settings for RFC 3161 compatible trusted timestamping
;; The default server declared here is run by the German National
;; Research and Education Network (DFN), which doesn't allow
;; commercial use. See https://www.pki.dfn.de/zeitstempeldienst/
(define timestamp:host "zeitstempel.dfn.de")
(define (timestamp-host-set! name) (set! timestamp:host name))
(define timestamp:url "/")
(define (timestamp-url-set! url) (set! timestamp:url url))

;; Make query to TTS server
(define (timestamp-tsr-request-raw tsq)
  (let* ((request-str (string-append "POST " timestamp:url " HTTP/1.0\r\n"
           "Host: " timestamp:host "\r\n"
           "User-Agent: " (system-appname) "/" (system-appversion) "\r\n"
           "Content-Type: application/timestamp-query\r\n"
           "Content-Length: " (number->string (u8vector-length tsq)) "\r\n\r\n"))
         (request-u8vec (string->u8vector request-str))
         (request-len (u8vector-length request-u8vec))
         (res (with-exception-catcher (lambda (e) #f)
           (lambda ()
             (let* ((port 80)
                    (p (open-tcp-client (list server-address: timestamp:host port-number: port))))
               (if (port? p) (begin
                 (input-port-timeout-set! p 2. (lambda () #f))
                 (output-port-timeout-set! p 1. (lambda () #f))
                 (write-subu8vector request-u8vec 0 request-len p)
                 (write-subu8vector tsq 0 (u8vector-length tsq) p)
                 (force-output p)
                 (with-exception-catcher (lambda (e) #f)
                   (lambda () (let ((data (read-all p read-char))) (close-port p) data)))
               ))
             )
           ))))
    (if res (list->u8vector (map char->integer res)) #f)))

(define-macro (V= idx match) `(fx= (u8vector-ref u8v ,idx) ,match))

;; seek to 0d-0a-0d-0a and trim
(define (timestamp-tsr-request-parse u8v)
  (if u8v (let ((len (u8vector-length u8v)))
    (if (> len 4) (let loop ((i 3))
      (if (= i len) #f
        (if (and (V= (- i 3) 13) (V= (- i 2) 10) (V= (- i 1) 13) (V= i 10))
          (subu8vector u8v (+ i 1) (u8vector-length u8v))
            (loop (+ i 1))))) #f)) #f))

(define  (timestamp-tsr-request tsq)
  (let ((res (timestamp-tsr-request-raw tsq)))
    (if res (timestamp-tsr-request-parse res))))

;; eof