Test if string is URL encoded in PHP

Question

How can I test if a string is URL encoded   Which of the following approaches is better    Search the string for characters which would be encoded  which aren t  and if any exist then its not encoded  or  Use something like this which I ve made     function is urlEncoded  string     test string    string   while urldecode  test string      test string      test string   urldecode  test string       return  urlencode  test string      string  True False       t    Hello World   how are you    if is urlEncoded  sreq     print  Was Encoded  n    else   print  Not Encoded  n    print  Should be   urlencode  sreq    n       The above code works  but not in instances where the string has been doubly encoded  as in these examples     t    Hello 2BWorld 2B 253E 2Bhow 2Bare 2Byou 253F    t    Hello World 2B 253E 2Bhow 2Bare 2Byou 253F

User · Answer

well  the term  url encoded  is a bit vague  perhaps simple regex check will do the trick   is encoded   preg match     0-9A-F  2  i    string

User · Answer

send a variable that flags the decode when you already getting data from an url    path folder new 20file txt amp decode 1

User · Answer

I am using the following test to see if strings have been urlencoded   if urlencode  str     str replace               25    2B     str     If a string has already been urlencoded  the only characters that will changed by double encoding are    which starts all encoded character strings  and    which replaces spaces    Change them back and you should have the original string   Let me know if this works for you

User · Answer

private static boolean isEncodedText String val  String    encoding  throws UnsupportedEncodingException               String decodedText    URLDecoder decode val  TransformFetchConstants DEFAULT CHARSET        if encoding    null  amp  amp  encoding length  gt  0           decodedText   URLDecoder decode val  encoding 0               String encodedText    URLEncoder encode decodedText        return encodedText equalsIgnoreCase val      decodedText equalsIgnoreCase val

User · Answer

You ll never know for sure if a string is URL-encoded or if it was supposed to have the sequence  2B in it   Instead  it probably depends on where the string came from  i e  if it was hand-crafted or from some application      Is it better to search the string for characters which would be encoded  which aren t  and if any exist then its not encoded    I think this is a better approach  since it would take care of things that have been done programmatically  assuming the application would not have left a non-encoded character behind    One thing that will be confusing here     Technically  the    should be  encoded if it will be present in the final value  since it is a special character   You might have to combine your approaches to look for should-be-encoded characters as well as validating that the string decodes successfully if none are found

User · Answer

Here is something i just put together   if   urlencode urldecode  data        data       echo  string urlencoded     else       echo  string is NOT urlencoded

User · Answer

What about   if  urldecode trim  url      trim  url      url form    decoded       else    url form    encoded       Will not work with double encoding but this is out of scope anyway I suppose

User · Answer

user187291 code works and only fails when   is not encoded    I know this is very old post  But this worked to me    is encoded   preg match     0-9A-F  2  i    string   if  is encoded      string    urlencode urldecode str replace               2B    3D     string       else      string   urlencode  string

User · Answer

I found  The url is For Exapmle  https   example com xD foo bar amp uri https 3A 2F 2Fexample com 2FxD You need Found   GET  uri   is encoded or not   preg match     uri      amp          SERVER  REQUEST URI     r   if  isset   GET  uri     amp  amp  urldecode  r  1         r  1           Code Here if url is not encoded

User · Answer

i have one trick    you can do this to prevent doubly encode  Every time first decode then again encode    string   urldecode  string     Then do again    string   urlencode  string     Performing this way we can avoid double encode

User · Answer

I think there s no foolproof way to do it  For example  consider the following    t    A B     Is that an URL encoded  A B  or does it need to be encoded to  A 2BB

User · Answer

In my case I wanted to check if a complete URL is encoded  so I already knew that the URL must contain the string https     and what I did was to check if the string had the encoded version of https    in it  https 3A 2F 2F  and if it didn t  then I knew it was not encoded    make sure  completeUrl is encoded if  strpos  completeUrl  urlencode  https           false           not encoded  need to encode it      completeUrl   urlencode  completeUrl      in theory this solution can be used with any string other than complete URLs  as long as you know part of the string  https    in this example  will always exists in what you are trying to check

User · Answer

There s no reliable way to do this  as there are strings which stay the same through the encoding process  i e  is  abc  encoded or not  There s no clear answer  Also  as you ve encountered  some characters have multiple encodings    But     Your decode-check-encode-check scheme fails due to the fact that some characters may be encoded in more than one way  However  a slight modification to your function should be fairly reliable  just check if the decode modifies the string  if it does  it was encoded   It won t be fool proof of course  as  10 20 30  will return true    gets converted to space   but we re actually just doing arithmetic  I suppose this is what you re scheme is attempting to counter  I m sorry to say that I don t think there s a perfect solution   HTH   Edit  As I entioned in my own comment  just reiterating here for clarity   a good compromise would probably be to check for invalid characters in your url  e g  space   and if there are some it s not encoded  If there are none  try to decode and see if the string changes  This still won t handle the arithmetic above  which is impossible   but it ll hopefully be sufficient

[php] Test if string is URL encoded in PHP

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