ASP grab two parameters from referral url - asp-classic

Question

Hi I am using a code to get the referral URL as you can see below:
sRef = encode(Request.ServerVariables("HTTP_REFERER"))
The code above is getting the following URL:
http://www.rzammit.com/pages/linux-form.asp?adv=101&loc=349&websync=233344-4555665-454&ptu=454545
From that url I want to grab ONLY the ADV and LOC (Request.querystring doesnt work because this is a script which is run when the form is submitted)
So to cut the story short, by using the referral URL, i want to get out the values for the adv and loc parameters.
Any help please on how I can do this?
Below is the code I am currently using but I have a problem. The parameters which are after the loc, is showing as well. I want something dynamic. Also the values of the adv and loc can be longer.
<%
sRef = Request.ServerVariables("HTTP_REFERER")
a=instr(sRef, "adv")+4
b=instr(sRef, "&loc")
response.write(mid(sRef ,a,b-a))
response.write("<br>")
response.write(mid(sRef ,b+5))
%>

Answer 1

Here is something to get you started; it uses regular expressions to get all URL variables for you. You can use the split() function to split them on the "=" sign and get a simple array, or put them in a dictionary or whatever.
Dim fieldcontent : fieldcontent = "http://www.rzammit.com/pages/linux-form.asp?adv=101&loc=349&websync=233344-4555665-454&ptu=454545"
Dim regEx, Matches, Item
Set regEx = New RegExp
regEx.IgnoreCase = True
regEx.Global = True
regEx.MultiLine = False
regEx.Pattern = "(\?|&)([a-zA-Z0-9]+)=([^&])"
Set Matches = regEx.Execute(fieldcontent)
For Each Item in Matches
response.write(Item.Value & "<br/>")
Next
Set regEx = Nothing

Answer 2

substring everything after the ?.
Split on "&"
Iterate the array to find "adv=" and "loc="
Below is the code:
Dim fieldcontent
fieldcontent = "http://www.rzammit.com/pages/linux-form.asp?adv=101&loc=349&websync=233344-4555665-454&ptu=454545"
fieldcontent = mid(fieldcontent,instr(fieldcontent,"?")+1)
Dim params
params = Split(fieldcontent,"&")
for i = 0 to ubound(params) + 1
if instr(params(i),"adv=")>0 then
advvalue = mid(params(i),len("adv=")+1)
end if
if instr(params(i),"loc=")>0 then
locvalue = mid(params(i),5)
end if
next

Answer 3

You can use the following generic function:
function getQueryStringValueFromUrl(url, key)
dim queryString, queryArray, i, value
' check if a querystring is present
if not inStr(url, "?") > 0 then
getQueryStringValueFromUrl = empty
end if
' extract the querystring part from the url
queryString = mid(url, inStr(url, "?") + 1)
' split the querystring into key/value pairs
queryArray = split(queryString, "&")
' see if the key is present in the pairs
for i = 0 to uBound(queryArray)
if inStr(queryArray(i), key) = 1 then
value = mid(queryArray(i), len(key) + 2)
end if
next
' return the value or empty if not found
getQueryStringValueFromUrl = value
end function
In your case:
dim url
url = "http://www.rzammit.com/pages/linux-form.asp?adv=101&loc=349&websync=233344-4555665-454&ptu=454545"
response.write "ADV = " & getQueryStringValueFromUrl(url, "adv") & "<br />"
response.write "LOC = " & getQueryStringValueFromUrl(url, "loc")