dos batch iterate through a delimited string

Question

I have a delimited list of IPs I'd like to process individually. The list length is unknown ahead of time. How do I split and process each item in the list?

@echo off
set servers=127.0.0.1,192.168.0.1,10.100.0.1

FOR /f "tokens=* delims=," %%a IN ("%servers%") DO call :sub %%a

:sub
    echo In subroutine
    echo %1
exit /b

Outputs:

In subroutine
127.0.0.1
In subroutine
ECHO is off.

Update: Using Franci's answer as reference, here's the solution:

@echo off
set servers=127.0.0.1,192.168.0.1,10.100.0.1

call :parse "%servers%"
goto :end


:parse
setlocal
set list=%1
set list=%list:"=%
FOR /f "tokens=1* delims=," %%a IN ("%list%") DO (
  if not "%%a" == "" call :sub %%a
  if not "%%b" == "" call :parse "%%b"
)
endlocal
exit /b

:sub
setlocal
echo In subroutine
echo %1
endlocal
exit /b

:end

Outputs:

In subroutine
127.0.0.1
In subroutine
192.168.0.1
In subroutine
10.100.0.1

Answer 1

Update: If the number of items in the list is not known, it is still possible to parse all items with simple recursion on the head of the list. (I've changed the IPs to simple numbers for simplicity of the list)

Finally that Lisp class I took 18 years ago paid off...

@echo off
setlocal

set servers=1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24

echo %servers%

call :parse "%servers%"

goto :eos

:parse

set list=%1
set list=%list:"=%

FOR /f "tokens=1* delims=," %%a IN ("%list%") DO (
  if not "%%a" == "" call :sub %%a
  if not "%%b" == "" call :parse "%%b"
)

goto :eos

:sub

echo %1

goto :eos

:eos
endlocal