Checking for valid IP addresses

[Adrian C Aitken]

Hi everyone, does anyone have an alternative to the following code. Basically I'm after the fastest way to check for a valid IP address in a string (retreived via DDT). My version is simple but seems to go and check the internet which is not always going to be appropriate.

Regards

Adrian Aitken

FUNCTION CheckIPAddress(strIP AS STRING ) AS LONG

LOCAL b AS BYTE PTR, ip AS LONG
HOST ADDR strIP TO ip
b = VARPTR(ip)
IF strIP <> FORMAT$(@b[0]) + "." + FORMAT$(@b[1]) + "." + FORMAT$(@b[2]) + "." + FORMAT$(@b[3]) THEN
FUNCTION = 1
ELSE
FUNCTION = 0
END IF

END FUNCTION


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[Lance Edmonds]

DDT only offers GUI functionality, not IP (Winsock) functionality!

A long time ago (circa 1998/99), Dave Navarro posted some information in the Internet Programming forum about ways to stop the dialer from appearing in Win95 - that may offer some assistance for you.

Other than that, you could drop down and use the the Winsock API directly, but it is unlikely to be any faster since the overhead is within Winsock and what it has to deal with, and HOST ADDR has to go through the same process.

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Lance
PowerBASIC Support
mailto:[email protected]com[email protected]</A>

[Adrian C Aitken]

Hi Lance,
All I really wanted was a quick and reliable method of checking for a valid IP address (to do with the COMM problem as well!).
I have resorted to using instr(x,"."), putting the value in a byte AND 255 (just incase) and then building the 4 bytes into a dot seperated string.

Regards

Adrian

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[Sven Blumenstein]

You can use the TALLY function to determine that there are 3 dot's in the IP.

i.e. if TALLY(IPstring, ".") <> 3 then msgbox "Incorrect IP!"

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e-mail: [email protected]
e-mail (work): [email protected]

[Adrian C Aitken]

Hi Sven, nice idea but the people who'll be using the program will be engineers (not computer engineers) who might have finger trouble ie 2555 instead of 255 etc so I need to check the individual numbers as well.

Thanks

Adrian

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[Sven Blumenstein]

ipString$ = trim$(ipString$)
If tally(ipString$, ".") <> 3 then msgbox "no!"
if len(ipString$) > 15 then msgbox "no!" 
tempIP$ = ipString$
tempIP$ = remove$(tempIP$, any ". ")
if verify(tempIP$, "0123456789") <> 0 then msgbox "no!"

Try this!



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e-mail: [email protected]
e-mail (work): [email protected]

[Adrian C Aitken]

Hi Sven, nice but it doesn't stop things like 192..168.0.1 or 25555.255.255.0

Regards

Adrian Aitken


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[Lance Edmonds]

Your original question used HOST ADDR to validate the address, so it appears you wanted a "real" IP address validated, not just that the dotted-IP address string "fits" into the 255.255.255.255 format.

You should be able to validate the string format quite easily using VERIFY, INSTR, PARSECOUNT and PARSE$. Something like this (off the top of my head, untested code)

a$ = "168.0.0.1"
...
FUNCTION Valid&(BYVAL a$)
  LOCAL x&
  IF ISTRUE VERIFY(a$, ANY "0123456789.") THEN EXIT FUNCTION ' invalid chars
  IF INSTR(a$, "..") THEN EXIT FUNCTION                      ' Stop invalid format of "0..0.0"
  IF PARSECOUNT(a$, ".") <> 4 THEN EXIT FUNCTION             ' Ensure 4 values in string
  FOR x& = 1 TO 4                                            ' Test all elements for 0-255 range
    IF VAL(PARSE$(a$, ".", x&)) > 255 THEN EXIT FUNCTION     ' Outside the range?
  NEXT x&
  Valid& = -1
END FUNCTION

I hope this helps!


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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Adrian C Aitken]

Lance , parsecount - thats the function I was looking for ! Thanks

Regards

Adrian Aitken

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[Peter Lameijn]

You can also use inet_addr function. (still needs parsecount, because Winsock sees
1, 1.1, 1.1.1, and 1.1.1.1 all as valid IP addresses....

#Include "wsock32.inc"
Function ValidIPAddress(IPAddress As Asciiz) As Long
  Function = (Inet_Addr(IPAddress) <> -1) And (ParseCount(IPAddress,".")=4)
End Function

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Peter.
mailto[email protected][email protected]</A>

[Scott Wolfington]

Doesn't a valid IP address also depend on the subnet mask of
the network? For instance, 204.31.85.20 is a valid IP address
on a Class C network, but on a Class A network it might be
invalid.

Scott


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Scott Wolfington
http://www.boogietools.com



[This message has been edited by Scott Wolfington (edited March 05, 2003).]

[Lance Edmonds]

Seems Adrian is more concerned with string validation than the actual validity of the IP address itself... at least, that is what I gleaned from the discussion thus far.

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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Adrian C Aitken]

Lance, you're right (again!) ,
the IP address could be anything legal (0-255, 4 sets of digits seperated by dots), either internet valid or private (192.168.x.x etc). The routine also needs to be subnet mask enabled ie 255.255.255.0 is not a valid ip address but is a valid subnet mask.
I initially used HOST ADDR because it was built into PB and when I first used it I was connected to the internet so didn't realise HOST ADDR would try to connect (to a DNS server ?).

Regards

Adrian Aitken

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[Peter Manders]

adrian,

you can use this trick to disable the dialup window temporarily:
http://www.powerbasic.com/support/pb...ead.php?t=1813

i'm using it for almost a year now on all 32 bit windows platforms and it's working great.

here's a function demonstrating this:

function filladdr(psin as sockaddr_in, socknum as long, bclient as long, nhost as string) as long
local phe as long
local he_list as long
local he as hostentstru
local sz as asciiz * 200
local zkey1 as asciiz * 200
local zkey2 as asciiz * 200
local autodial as string
local dtype as long

  psin.sin_family = %af_inet
  ' if we are setting up for a listen() call (bclient = false), fill servent with our address.
  if bclient <> 0 then
    gethostname sz, sizeof(sz)
  else
    sz = nhost
  end if
  zkey1 = "software\microsoft\windows\currentversion\internet settings"
  zkey2 = "enableautodial"
  'binary value: "enableautodial"
  dtype = %reg_binary
  autodial = getregistryvalue(%hkey_current_user, dtype, zkey1, zkey2, ")
  dtype = %reg_binary
  if len(autodial) then
    setregistryvalue %hkey_current_user, dtype, zkey1, zkey2, mkl$(0)
  end if
  phe = gethostbyname(sz)
  if len(autodial) then
    if asc(autodial) <> 0 then
      setregistryvalue %hkey_current_user, dtype, zkey1, zkey2, mkl$(1)
    end if
  end if
  if phe <> %null then
    copymemory byval varptr(he), byval phe, byval len(he)
    he_list = he.h_list
    he_list = cvl(peek$(he_list,4))
    psin.sin_addr.s_addr = cvl(peek$(he_list,4))
  end if
  'set the port number
  psin.sin_port = htons(socknum)        ' convert to network ordering
  function = %true
end function

peter.


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