@echo off
setlocal enableextensions disabledelayedexpansion
if "%~1"=="" goto :eof
call :isOnline "%~1"
if not errorlevel 1 ( echo ONLINE ) else ( echo OFFLINE )
endlocal
exit /b
:isOnline address pingCount
setlocal enableextensions disabledelayedexpansion
:: send only one ping packed unless it is indicated to send more than one
set /a "pingCount=0", "pingCount+=%~2" >nul 2>nul
if %pingCount% lss 1 set "pingCount=1"
:: a temporary file is needed to capture ping output for later processing
set "tempFile=%temp%\%~nx0.%random%.tmp"
:: ping the indicated address getting command output and errorlevel
ping -w 1000 -n %pingCount% "%~1" > "%tempFile%" && set "pingError=" || set "pingError=1"
::
:: When pinging, the behaviours of ipv4 and ipv6 are different
::
:: we get errorlevel = 1 when
:: ipv4 - when at least one packet is lost. When sending more than one packet
:: the easiest way to check for reply is search the string "TTL=" in
:: the output of the command.
:: ipv6 - when all packet are lost.
::
:: we get errorlevel = 0 when
:: ipv4 - all packets are received. BUT pinging a inactive host on the same
:: subnet result in no packet lost. It is necessary to check for "TTL="
:: string in the output of the ping command
:: ipv6 - at least one packet reaches the host
::
:: We can try to determine if the input address (or host name) will result in
:: ipv4 or ipv6 pinging, but it is easier to check the result of the command
::
:: +--------------+-------------+
:: | TTL= present | No TTL |
:: +-----------------------+--------------+-------------+
:: | ipv4 errorlevel 0 | OK | ERROR |
:: | errorlevel 1 | OK | ERROR |
:: +-----------------------+--------------+-------------+
:: | ipv6 errorlevel 0 | | OK |
:: | errorlevel 1 | | ERROR |
:: +-----------------------+----------------------------+
::
:: So, if TTL= is present in output, host is online. If TTL= is not present,
:: errorlevel is 0 and the address is ipv6 then host is online. In the rest
:: of the cases host is offline.
::
:: To determine the ip version, a regular expresion to match a ipv6 address is
:: used with findstr. As it will be only tested in the case of no errorlevel,
:: the ip address will be present in ping command output.
set "exitCode=1"
>nul 2>nul (
find "TTL=" "%tempFile%" && ( set "exitCode=0" ) || (
if not defined pingError (
findstr /r /c:" [a-f0-9:][a-f0-9]*:[a-f0-9:%%]*[a-f0-9]: " "%tempFile%" && set "exitCode=0"
)
)
del /q "%tempFile%"
)
:: cleanup and return errorlevel: 0=online , 1=offline
endlocal & exit /b %exitCode%