Check the Internet Connection

internet-check.rkt

#!/usr/bin/env racket
#lang racket

(require racket/date)
(require net/http-client)

(define (print-status now online [reason #f])
  (if reason
      (printf "date=~a online=~s reason=~s\n"
              now
              online
              reason)
      (printf "date=~a online=~s\n"
              now
              online)))

(define (check-internet)
  (define now-seconds (current-seconds))
  (define this-thread (current-thread))

  (define status
    (begin
      (sync/timeout/enable-break
       5
       (thread
        (lambda ()
          (with-handlers ([exn:fail?
                           (lambda (e)
                             (thread-send this-thread
                                          '#:connection-fail))])
            (define conn (http-conn-open "google.com"
                                         #:ssl? #t
                                         #:port 443))
            (http-conn-send! conn "/")
            (define-values (http-status headers port)
              (http-conn-recv! conn
                               #:close? #t))
            (thread-send this-thread http-status)))))
      (let ((result (or (thread-try-receive)
                        '#:timeout)))
        (cond
          ((keyword? result)
           result)

          ((not (equal? #"HTTP/1.1 301 Moved Permanently" result))
           '#:wrong-status)

          (else
           #t)))))

  (define now (date->string (seconds->date now-seconds) #t))
  (if (equal? #t status)
      (print-status now #t)
      (print-status now #f status))

  (with-output-to-file "/Users/sulami/internet"
    (lambda ()
      (if (equal? #t status)
          (print-status now #t)
          (print-status now #f status)))
    #:exists 'append)

  (sleep 60)
  (check-internet))

(date-display-format 'iso-8601)
(check-internet)

internet-check.ros

#!/bin/sh
#|-*- mode:lisp -*-|#
#|
exec ros -Q -- $0 "$@"
|#
(progn ;;init forms
  (ros:ensure-asdf)
  #+quicklisp(ql:quickload '(dexador trivial-timeout) :silent t)
  )

(defpackage :ros.script.internetcheck.3799674981
  (:use :cl))
(in-package :ros.script.internetcheck.3799674981)

(defconstant PING-HOST "https://google.com")

(defun online-status ()
  (handler-case
      (trivial-timeout:with-timeout (5)
        (dex:get PING-HOST)
        :ok)
    (dex:http-request-failed (e)
      (print e)
      (terpri)
      :request-failed)
    (trivial-timeout:timeout-error (e)
      (print e)
      (terpri)
      :timeout)
    (error (e)
      (print e)
      (terpri)
      :error)))

(defun format-log-line (time status)
  (if (equal :ok status)
      (format nil "date=~a online=true~%"
              time)
      (format nil "date=~a online=false reason=~a~%"
              time
              status)))

(defun write-log-entry (entry)
  (with-open-file (stream "~/internet2"
                          :direction :output
                          :if-exists :append)
    (format stream entry)))

(defun now-timestamp ()
  (local-time:format-timestring nil (local-time:now)))

(defun check-internet ()
  (let ((log-entry (format-log-line
                    (now-timestamp)
                    (online-status))))
    (format t log-entry)
    (write-log-entry log-entry)))

(defun main (&rest argv)
  (declare (ignorable argv))
  (handler-case
      (loop do (check-internet)
               (sleep 5))
    (sb-sys:interactive-interrupt () nil)))
;;; vim: set ft=lisp lisp: