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tinmop/src/gemini/client.lisp

245 lines
8.7 KiB
Common Lisp

;; tinmop: an humble mastodon client
;; Copyright (C) 2020 cage
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program.
;; If not, see [[http://www.gnu.org/licenses/][http://www.gnu.org/licenses/]].
(in-package :gemini-client)
(eval-when (:compile-toplevel :load-toplevel :execute)
(defclass response-status-code ()
((code
:initform nil
:initarg :code
:accessor code)
(description
:initform nil
:initarg :description
:accessor description)))
(defun response= (a b)
(= (code a)
(code b))))
(defmacro gen-status-constant (value description)
`(define-constant ,(format-fn-symbol t "+~a+" value)
(make-instance 'response-status-code
:code ,value
:description ,description)
:test #'response=))
(gen-status-constant 10 "Input")
(gen-status-constant 11 "Sensitive input")
(gen-status-constant 20 "success")
(gen-status-constant 30 "redirect - temporary")
(gen-status-constant 31 "redirect - permanent")
(gen-status-constant 40 "temporary failure")
(gen-status-constant 41 "server unavailable")
(gen-status-constant 42 "cgi error")
(gen-status-constant 43 "proxy error")
(gen-status-constant 44 "slow down")
(gen-status-constant 50 "permanent failure")
(gen-status-constant 51 "not found")
(gen-status-constant 52 "gone")
(gen-status-constant 53 "proxy request refused")
(gen-status-constant 59 "bad request")
(gen-status-constant 60 "client certificate required")
(gen-status-constant 61 "certificate not authorised")
(gen-status-constant 62 "certificate not valid")
(defparameter *all-codes* (list +10+ +11+
+20+
+30+ +31+
+40+ +41+ +42+ +43+ +44+
+50+ +51+ +52+ +53+ +59+
+60+ +61+ +62+))
(defun code= (code code-class)
(= code
(code code-class)))
(defun find-code-class (code)
(find-if (lambda (a) (code= code a)) *all-codes*))
(defun read-all (stream)
(let ((raw (loop
for c = (read-byte stream nil nil)
while c
collect c)))
(coerce raw '(vector (unsigned-byte 8)))))
(defun mime-gemini-p (header-meta)
(string-starts-with-p "text/gemini" header-meta))
(defun header-code= (header code-class)
(code= (status-code header)
code-class))
(defun header-input-request-p (header)
(or (header-code= header +10+)
(header-code= header +11+)))
(defun header-success-p (header)
(header-code= header +20+))
(defun header-redirect-p (header)
(or (header-code= header +30+)
(header-code= header +31+)))
(defun header-temporary-failure-p (header)
(or (header-code= header +40+)
(header-code= header +41+)
(header-code= header +42+)
(header-code= header +43+)
(header-code= header +44+)))
(defun header-permanent-failure-p (header)
(or (header-code= header +50+)
(header-code= header +51+)
(header-code= header +52+)
(header-code= header +53+)
(header-code= header +59+)))
(defun header-not-implemented-p (header)
(or (header-code= header +60+)
(header-code= header +61+)
(header-code= header +62+)))
(defun response-input-p (code)
(code= code +10+))
(defun response-sensitive-input-p (code)
(code= code +11+))
(defun response-redirect-p (code)
(or (code= code +30+)
(code= code +31+)))
(define-condition gemini-protocol-error (error)
((error-code
:initarg :error-code
:reader error-code)
(error-description
:initarg :error-description
:reader error-description))
(:report (lambda (condition stream)
(format stream
(_ "The server responded with the error ~a: ~a")
(error-code condition)
(error-description condition))))
(:documentation "The condition signalled for error codes (i.e. 4x and 5x)"))
(define-condition gemini-tofu-error (error)
((host
:initarg :host
:reader host))
(:report (lambda (condition stream)
(format stream
(_ "The certificate of host ~a has changed from your latest visit.")
(host condition))))
(:documentation "The condition signalled when tofu failed"))
(defun parse-response (stream host port path)
(let* ((header (read-line stream))
(parsed-header (parse-gemini-response-header (format nil "~a~a" header #\Newline))))
(with-accessors ((meta meta)
(status-code status-code)) parsed-header
(flet ((results (code-class body)
(values status-code
(description code-class)
meta
body)))
(cond
((header-success-p parsed-header)
(let ((body (read-all stream)))
(if (mime-gemini-p meta)
(let ((parsed (parse-gemini-file (babel:octets-to-string body
:errorp nil))))
(values status-code
(description +20+)
meta
parsed
(format nil
"-> ~a://~a:~a~a~2%~a"
+gemini-scheme+
host port path
(sexp->text parsed))
(sexp->links parsed host port path)))
(results +20+ body))))
((or (header-input-request-p parsed-header)
(header-redirect-p parsed-header))
(results (find-code-class status-code) nil))
((or (header-permanent-failure-p parsed-header)
(header-temporary-failure-p parsed-header))
(let ((response-code (find-code-class status-code)))
(error 'gemini-protocol-error
:error-code (code response-code)
:error-description (description response-code))))
((header-not-implemented-p parsed-header)
(error 'conditions:not-implemented-error
:text (_ "The server requested a certificate but client validation is not implemented by this program")))
(t
parsed-header))))))
(defun absolute-url-p (url)
(text-utils:string-starts-with-p +gemini-scheme+ url))
(defun request (host path &key
(query nil)
(port +gemini-default-port+))
(let* ((uri (make-gemini-uri host path query port))
(ctx (cl+ssl:make-context :verify-mode cl+ssl:+ssl-verify-none+)))
(when query
(setf uri (strcat uri "?" (percent-encode query))))
(cl+ssl:with-global-context (ctx :auto-free-p t)
(let ((socket (usocket:socket-connect host port :element-type '(unsigned-byte 8))))
(unwind-protect
(when socket
(let ((stream (usocket:socket-stream socket)))
(let* ((ssl-stream (cl+ssl:make-ssl-client-stream stream
:external-format '(:ascii)
:unwrap-stream-p t
:verify nil
:hostname host))
(request (format nil "~a~a~a" uri #\return #\newline))
(cert-hash (crypto-shortcuts:sha512 (x509:dump-certificate ssl-stream))))
(if (not (db:tofu-passes-p host cert-hash))
(error 'gemini-tofu-error :host host)
(progn
(write-string request ssl-stream)
(force-output ssl-stream)
(multiple-value-bind (status description meta body gemini-text gemini-links)
(parse-response ssl-stream host port path)
(values status description meta body gemini-text
gemini-links)))))))
(when socket
(usocket:socket-close socket)))))))