114 lines
4.4 KiB
Common Lisp
114 lines
4.4 KiB
Common Lisp
;;; Copyright 2023, Jaidyn Ann <jadedctrl@posteo.at>
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;;;
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;;; This program is free software: you can redistribute it and/or
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;;; modify it under the terms of the GNU Affero General Public License
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;;; as published by the Free Software Foundation, either version 3 of
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;;; the License, or (at your option) any later version.
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;;;
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;;; This program is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU Affero General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU Affero General Public License
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;;; along with this program. If not, see <https://www.gnu.org/licenses/>.
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(defpackage #:kaptchapelo
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(:use #:cl)
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(:export :start-server))
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(in-package #:kaptchapelo)
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(defun byte-array-to-hex-string (simple-array)
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"Given an array of bytes (integers), return an equivalent string in hex."
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(string-downcase
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(reduce #'str:concat
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(loop for byte across simple-array
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collect (format nil "~2,'0X" byte)))))
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(defun random-file (directory &key (file-ext ""))
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"Select a random file from the given DIRECTORY of a specific FILE-EXTension."
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(alexandria:random-elt
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(directory (str:concat (format nil "~A" directory)
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"/*"
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(if (not (str:emptyp file-ext))
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(str:concat "." file-ext)
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"")))))
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(defun new-captcha-json (captcha-image-uri captcha-text-file)
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"Create a Kocaptcha-compatibile captcha challenge in JSON-format."
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(yason:with-output-to-string* ()
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(yason:encode-plist
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(list "md5" (byte-array-to-hex-string captcha-text-file)
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"url" captcha-image-uri
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;; I don’t know what Kocaptcha’s token does! :P
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"token" "This_isnt_actually_used_lol"))))
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(defun new-captcha-response (captcha-dir)
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"Create a Clack HTTP response with a new captcha."
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(let* ((captcha-txt-file (random-file captcha-dir :file-ext "txt"))
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(captcha-img-file (str:concat (pathname-name captcha-txt-file) ".png"))
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(captcha-md5-str (byte-array-to-hex-string
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(md5:md5sum-file captcha-txt-file))))
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(list 201 '(:content-type "application/json")
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(list (new-captcha-json (str:concat "/captcha/" captcha-img-file)
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captcha-md5-str)))))
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(defun image-response (request-uri captcha-dir)
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"Given a /captcha/… REQUEST-URI and the CAPTCHA-DIR where images can be found,
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make a Clack HTTP response that serves the appropriate image."
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(let ((image-path (str:replace-first "/captcha/" (format nil "~A" captcha-dir) request-uri)))
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(list 201 '(:content-type "image/png")
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(pathname image-path))))
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(defun index-response ()
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"Return a friendly “salutations” Clack-response for those visting the root-page."
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'(201 (:content-type "text/plain")
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("You’ve installed Kaptĉapelo; good work! If you’d like a captcha challenge, visit /new !")))
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(defun 404-response ()
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"Create a 404-comlpaining HTTP Clack-response."
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'(404 (:content-type "text/plain") ("No such page.")))
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(defun server (env captcha-dir)
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"The heart of the server; returns requests for Clack."
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(let* ((uri (quri:uri (getf env :request-uri)))
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(uri-path (quri:uri-path uri)))
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(format *error-output* "~A" uri-path)
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(cond
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;; Create a new captcha at /new
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((string= uri-path "/new")
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(new-captcha-response captcha-dir))
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;; For lost souls visiting /[index.html], say “hi.”
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((or (string= uri-path "/")
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(string= uri-path "/index.html"))
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(index-response))
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;; At /captcha/*.png, server the given image.
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((and (str:starts-with? "/captcha/" uri-path)
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(str:ends-with? ".png" uri-path))
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(image-response uri-path captcha-dir))
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;; Otherwise… IDK, 404! ¯\_(ツ)_/¯
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('t
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(404-response)))))
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(defun start-server (&key (address "0.0.0.0") (port 5001) (captcha-directory #p"captcha/"))
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"Start the Kaptchapelo server, which takes captcha challenges from the given
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CAPTCHA-DIRECTORY. Challenges are made up of two files:
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* A challenge PNG file (ex. bird.png)
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* An answer TXT file (ex. bird.txt)
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Note that the The answer text-file should not contain a trailing newline."
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(clack:clackup
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(lambda (env)
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(funcall #'server env captcha-directory))
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:address address
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:port port))
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