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URL
The contents of this page, URL, and all edits made to this page in its history, are hereby released under the CC0 Public Domain Dedication, as described in WHATWG Wiki:Copyrights.
This documents research and notes around URLs for the URL standard.
Implementations
- http://trac.webkit.org/browser/trunk/Source/WebCore/platform/KURL.cpp
- http://trac.webkit.org/browser/trunk/Source/WebCore/platform/KURLWTFURL.cpp
- http://trac.webkit.org/browser/trunk/Source/WebCore/platform/KURLGoogle.cpp
- http://trac.webkit.org/browser/trunk/Source/WebCore/platform/network/DataURL.cpp (data URLs)
- http://mxr.mozilla.org/mozilla-central/source/netwerk/base/src/nsStandardURL.cpp
- http://mxr.mozilla.org/mozilla-central/source/dom/src/jsurl/nsJSProtocolHandler.cpp (javascript URLs)
- http://mxr.mozilla.org/mozilla-central/source/nsprpub/pr/src/misc/prnetdb.c#1544 (IPv6)
Tests
Variants of the following code (runs in Live DOM Viewer) are useful to test which code points are URL escaped in browsers:
<!DOCTYPE html> <script> var a = document.createElement("a") i = 0 cp = 0x100 while ( i < cp ) { a.href = "http://x" + String.fromCharCode(i) + "@x/" if(a.href.length != "http://x)@x/".length) { w(a.href) } i++ } </script>
Parsing
- https://github.com/annevk/url/blob/master/url.js
- http://lists.w3.org/Archives/Public/public-whatwg-archive/2012Sep/0305.html has notes on file URLs in Gecko.
JavaScript libraries
For improving the API we might want to take inspiration from:
- http://medialize.github.com/URI.js/
- https://github.com/joyent/node/blob/master/doc/api/url.markdown
- https://github.com/bestiejs/punycode.js (just Punycode)
Schemes
Apart from the scheme-types listed below, the URL Standard identifies "relative schemes", used for parsing a URL into a parsed URL.
Purpose-specific schemes
URL schemes are purpose-specific schemes if they only work in one context. These only work for WebSocket:
- ws
- wss
Fetch schemes
URL schemes are resource schemes if fetching the URL results in either a network error or a resource with associated MIME type (potentially sniffed).
- ftp
- http
- https
- These all can be used by the corresponding protocol directly.
- file
- Needs platform-specific interpretation and mapping to a resource on a the local file system.
- data
- Needs its resource and MIME type information retrieved from its scheme data/query.
- blob
- about
- The resource is effectively the result of passing scheme data to a hash table (not sure if case-sensitive or not; definitely no percent decoding). Query and fragment can be used by the resource.
(The same-origin definition should maybe account for about/blob/data.)
- The "fetch schemes" -> use "fetch"
- javascript
- Not the "purpose-specific schemes" -> error
- All other schemes (including "external schemes")
External schemes
Depending on the context, schemes not listed above will either launch an external application or result in a network error. Examples:
- mailto
- skype
IDNA
Definitions
- IDNA2003+: IDNA2003 with Unicode updated to the latest version. (So not NFKC from Unicode 3.2., although Python might do that... ) Restrictions on display might be in place.
- IDNA2008+: IDNA2008 with RFC 5895 section 2 mapping and IDNA2003 domain label separators. Display is restricted to IDNA2008, lookup is unrestricted (everything gets Punycoded).
Implementations
- IDNA2003+: Safari, Chrome, Firefox, Internet Explorer
- Changing, see e.g. https://codereview.chromium.org/23642003#msg4
- IDNA2008+: Opera
Tests
- http://mathias.html5.org/tests/url/idna2003-separators/ IDNA2003 domain label separators are supported everywhere
Algorithms
- ToLabels(domain string) -> ASCII-label list (empty label at the end signifies trailing dot) or failure.
- ToASCII(Unicode-label) -> ASCII-label.
- ToUnicode(ASCII-label) -> Unicode label.
(For convenience maybe ToASCII and ToUnicode should accept lists too.)
UI
Note that this has potential security implications too, but does not matter for interoperability.
- http://www.chromium.org/developers/design-documents/idn-in-google-chrome (also includes summary for other browsers)
- https://wiki.mozilla.org/IDN_Display_Algorithm
- http://www.alvestrand.no/pipermail/idna-update/2011-December/date.html (has lots of background discussion)
Notes
- Input to DNS is a byte array. (This means that "_" and byte 0x03 can be valid input. Not sure whether "." works within a label. Higher than 0x7F cannot happen if IDNA is used.)
- DNS is of course not the only system in place, but browsers do not seem to care as far as mapping is concerned.
- http://www.unicode.org/mail-arch/unicode-ml/y2011-m07/0036.html http://www.unicode.org/mail-arch/unicode-ml/y2011-m07/0057.html
- http://tools.ietf.org/html/rfc6055 has historical deliberations