I see that Firefox does NOT encode an URL like http://www.mysite.com/foo?bar=10/12/2010 when it sends a GET request. I know that URLs must be encoded, so I expected to see Firefox requesting http://www.mysite.com/foo?bar=10%2F12%2F2010 (/ = %2F). I inspected the GET requests using Wireshark.
Should the query string in the url be escaped?
I use WebHarvest and I see that when I ask it to download a page with the http directive, an URL like the one above is encoded like I expected (%2F instead of "/").
The / is allowed in plain in the query of a URI:
query = *( pchar / "/" / "?" )
Anything else must be encoded using the percent-encoding.
If, by escaped, you mean URL-encoded, the short answer is yes.
There are a number of characters that are normally encoded during URL encoding but could normally appear in the URL without problem.
But sometimes the potential problems are not always obvious. I would recommend URL encoding query arguments, and decoding them from your site. After all, if you decode too many times, that should not cause any problem.
Can't reproduce your problem.
<form>
<input type="hidden" name="bar" value="10/12/2010">
<input type="submit">
</form>
This displays the proper escape in address bar. Aren't you supplying this URL in an <a> element? Then you need to escape it in the HTML page yourself by either hardcoding it or utilizing the functions provided by the server side language.
Related
Trying to understand why pasting the first link works but not the second one.
Breakdown of the URL, for a clearer view:
Encoded version: [works]
http%3A%2F%2FsomeSite.com
%2FDownload.ashx
%3Frequest
%3DIL7zxW6ETqiYU6cThSNKL8MpY
%252bCRIVFZAVhd8DYPG85C1Uhdd
%252f2hqqmoObeNmuS3dg4bDgGBb0kUUxGZhej89kTaLBHBXS
%252bq3tlaEk2uMEcbWlUZzZQs00sirwZ2IvAvoSpU7HC3N1FaYSNciQ4iHNNmTU
%252f6uMypNlPOJ6enlbZ1OrrYODkaMRdRfGKEba
%252brusdryM4gp
%252bopi1a0gNuMQVCtj
%252bAvDcgXGOcZPNhPAnE
%253d&version=Ma88r6Z6t2JQcnVhVXgp0A%3D%3D
Decoded version: [doesn't work]
http://someSite.com
/Download.ashx
?request=
IL7zxW6ETqiYU6cThSNKL8MpY
+CRIVFZAVhd8DYPG85C1Uhdd
/2hqqmoObeNmuS3dg4bDgGBb0kUUxGZhej89kTaLBHBXS
+q3tlaEk2uMEcbWlUZzZQs00sirwZ2IvAvoSpU7HC3N1FaYSNciQ4iHNNmTU
/6uMypNlPOJ6enlbZ1OrrYODkaMRdRfGKEba
+rusdryM4gp
+opi1a0gNuMQVCtj
+AvDcgXGOcZPNhPAnE
=&version=Ma88r6Z6t2JQcnVhVXgp0A==
If I paste the first link in the browser - it works. A file download automatically starts.
If I paste the second link in the browser - page says Bad request.
Can anyone clarify it for me why the second one doesn't work?
Quoting the URLencodetag:
To “URL encode” or “percent encode” text means to encode it for use in a URL. Some characters are not valid when used as-is in URLs, and so much be URL-encoded (percent-encoded) when appearing in URLs.
The encoding was used for a reason, here because the base64 values for the request and version parameters contains +, / and = which have their own meaning in URLs and therefore need to be URL-encoded.
My server logs show a many attempts to access non existing sides. These are the "usual" bots scanning for known vulnerabilities. Many of the URLs contain =3D, e.g.
/?q=3Duser%2Fpassword&name%5B%23p=
/user/register/?element_parents=3Daccou=
/wp-admin/admin-post.php?swp_debug=3Dlo=
%3D is the url encoded value of = so I would expect to find %3D within the URL but not =3D. However, =3D can be found all over the logs. What is the meaning of this?
=3D is an example of a Quoted-Printable encoding for ASCII 0x3D, or the equals sign character (=).
You don't usually see this in URLs. It's not the normal encoding to use. It's a standard MIME type, an alternative to using base64. It looks like the request is expecting the app to decode the query string using Quoted-Printable, and then use the resulting path in some further redirect.
Failing to escape an "&" character in HTML markup creates an entity. It is often done inadvertently when linking URLs in a document, and W3C's Markup Validation Service will consider this an error.
I'm wondering, does ASP.NET's Response.Redirect method expect ampersands to be escaped in its url parameter? From reading its MSDN description, I honestly can't tell.
Pass the URL exactly as it should appear in the address bar in the web browser. For example, if you're trying to redirect to http://example.com/?foo=bar&baz=quux, then pass that exact string as-is to Response.Redirect.
try UrlEncode The UrlEncode(String) method can be used to encode the entire URL, including query-string values. If characters such as blanks and punctuation are passed in an HTTP stream without encoding, they might be misinterpreted at the receiving end. URL encoding converts characters that are not allowed in a URL into character-entity equivalents; URL decoding reverses the encoding. For example, when the characters < and > are embedded in a block of text to be transmitted in a URL, they are encoded as %3c and %3e. URLEncode
System.Web.HttpUtility.UrlEncode(string url)
I have an encrypted query string passed from another page, it reads something like "/se73j+sef" but after receiving it, the '+' sign got omitted and became "/se73j sef". Is this normal? Please kindly advice. Thanks.
Is this normal?
Yes, perfectly normal. + is a special character in an url. It means space (0x20 ASCII character). If you want to represent the + sign you will have to url encode it:
/se73j%2Bsef
To url encode a string in .NET you could use the UrlEncode method. Or depending on how you are building the url there are certainly better ways.
In some javascript, I have:
var url = "find.aspx?" + "location=" + encodeURIComponent( address );
alert( url );
location.href = url;
where the value of address is the string "Seattle, WA".
In the alert I see
find.aspx?Seattle%2C%20WA
as I expect.
But on the server side, when I look at Request.Url, the relevant substring I see is
find.aspx?Seattle, WA
And in the Firefox url window I see
find.aspx?location=Seattle%2C WA
So I'm getting three different representations whereas I would expect that in all three places I should see what I see in the alert. My expectation is that the url I assign to location.href should show up as-is in the browser url window, and should be passed as-is to the server in Request.Url (and I would need to decode the values on the server before using them). What's happening?
Firefox converts certain encoded characters into their literal forms as a way to be friendly to users. It will also convert spaces typed into the address bar into %20 for the server.
Update: The reason Firefox doesn't display the comma unencoded is because commas are allowed in URLs, but spaces are not, so it knows that a space is going to be unambiguously interpreted, whereas the pre-encoded comma is different from a non-encoded comma to some servers. see: Can I use commas in a URL?
ASP is probably trying to help you out by auto-un-encoding the string for you.
Update: It looks like ASP.NET unencodes Request.Url for you by default, as mentioned here: QueryString malformed after URLDecode They also mention that you can use HttpRequest.Url.Query to access the un-decoded version.
The alert is the only thing not doing any "magic" for you.
For the alert, you are doing the encoding yourself. Perhaps it looks the same as on the server-side if you removed encodeURIComponent.
On the server side, ASP.NET will always show you the unencoded form. This is to make it easier to directly map to files that also have text that needed to be (un)encoded.
Note that you can replace every letter for its UTF8 representation in URL Encoding. It will still be the same URL. I.e., type the following in the browser window and it will still work: %66%59%6E%64.aspx?location=Seattle%2C%20WA. To only encode the necessary chars, use UrlEncode on the server side if you create a link yourself.
URL encoding can become fairly tricky. You ask to explain it. To know the correct escape of a certain character, you need to know how that character looks in UTF8. The hexadecimal value of the UTF-8 bytes then become the %XX%YY value of your letter. Sometimes it's one %XX, but it can be up to six byte sequences in total (some Chinese characters for instance).
URL Encoding works one way only. Never double-encode or double-unencode. This is prohibited by the specification. Also, because you can encode any character, it is not always possible (as you found out) to do roundtrip encoding/unencoding. If you unencode and re-encode again, it is well possible that the resulting string is different, but syntactically the same.
In HTML, URL Encoding is sometimes interspersed with HTML Encoding. I.e., the ampersand is valid in HTML, but not in HTML. find.aspx?city=A&name=B becomes find.aspx?city=A&name=B in and HTML URL. However, browsers are lenient and will accept wrongly HTML-encoded strings.
Finally, a not on the browser: if you type in a space in a link, even inside an <a> tag, it will escape the space (or other character) for you. Likewise, it will nowadays show the odd characters (é, ï etc) in the address bar, but when it sends it over HTTP, the browser will correctly do the encoding for you.
Update: about anwering your question of needing a "definitive" reference or proof.
While I couldn't find any on the internet, I decided to look for it myself using Reflector. Going through the methods that set, for instance, the HttpRequest.QueryString, you quickly encounter the private method HttpRequest.FillInQueryStringCollection which then calls HttpValueCollection.FillfromEncodedBytes. Somewhat near the end of that method, HttpUtility.UrlDecode is called for the values. Conclusion: do not call it yourself, to prevent double decoding.
You can see this for yourself when you download Reflector and disassemble the .NET libs of System.Web.
For your example you can change this line
var url = "find.aspx?" + "location=" + encodeURIComponent( address );
to
var url = "find.aspx?" + "location=" + address;
and see the address as it is. Bu if address variable contains any '&' character your variable will be corrupt. So you are using encodeURIComponent to encode these things url.
On the Server side all these encoded strings are decoded back. It means encodeURIComponent is just for sending the address variable (whether it contains & character or not) to server side correctly.