Add fetch monkeypatches to subresource-loading spec #708

subresource-loading.bs

@@ -1,5 +1,5 @@
 <pre class="metadata">
-Title: Subresource Loading with WebBundles
+Title: Subresource Loading with Web Bundles
 Shortname: web-package-subresource-loading
 Level: none
 Status: CG-DRAFT
@@ -8,18 +8,31 @@ Repository: WICG/webpackage
 URL: https://wicg.github.io/webpackage/subresource-loading.html
 Editor: Hayato Ito, Google Inc. https://google.com/, [email protected]
 Abstract: How UAs load subresources from Web Bundles.
-
 Complain About: accidental-2119 yes, missing-example-ids yes
+Indent: 2
 Markup Shorthands: markdown yes, css no
 Assume Explicit For: yes
 </pre>
+<pre class='biblio'>
+{
+  "draft-ietf-wpack-bundled-responses-latest": {
+    "href": "https://wpack-wg.github.io/bundled-responses/draft-ietf-wpack-bundled-responses.html",
+    "title": "Web Bundles"
+  }
+}
+</pre>
+<pre class='anchors'>
+spec: fetch; urlPrefix: https://fetch.spec.whatwg.org/#
+  type: dfn
+    text: fetch params; url: fetch-params
+</pre>
 <pre class="link-defaults">
+spec:fetch; type:dfn; for:/; text:request
 spec:fetch; type:dfn; for:/; text:response
 spec:html; type:element; text:link
+spec:url; type:dfn; for:/; text:url
 </pre>
 
-<section class="non-normative">
-
 # Introduction # {#intro}
 
 <em>This section is non-normative.</em>
@@ -31,7 +44,159 @@ specification describes how web browsers load those resources. It is expressed
 as several monkeypatches to the [[HTML]] and [[FETCH]] specification which call
 algorithms defined here.
 
-<p class="note">
-  This specification is under construct. See
-  <a href="https://github.com/WICG/webpackage/issues/708">#708</a>.
-</p>
+Note: This specification is under construction. See
+<a href="https://github.com/WICG/webpackage/issues/708">#708</a>.
+
+# Structures # {#structures}
+
+A <dfn>fetched web bundle</dfn> is a representation of a web bundle format
+defined in [[draft-ietf-wpack-bundled-responses-latest]].
+
+A <dfn>bundle rule</dfn> is a [=struct=] with the following [=struct/items=]:
+
+- <dfn for="bundle rule">source</dfn>, a [=URL=].
+- <dfn for="bundle rule">credentials</dfn>, a [=request/mode=].
+- <dfn for="bundle rule">resources</dfn>, a list of [=URLs=].
+- <dfn for="bundle rule">scopes</dfn>, a list of [=URLs=].
+
+A <dfn>web bundle</dfn> is a [=struct=] with the following [=struct/items=]:
+
+- <dfn for="web bundle">fetched bundle</dfn>, a [=fetched web bundle=] or null.
+- <dfn for="web bundle">rule</dfn>, a [=bundle rule=].
+- <dfn for="web bundle">state</dfn>, an internal state which is "fetching",
+  "fetched", or "failed". Initially "fetching".
+
+A {{Document}} has a <dfn for=document>web bundle list</dfn>, which is a list of
+[=web bundles=].
+
+# HTML monkeypatches # {#html-monkeypatches}
+
+Note: TODO. This section uses [=fetch web bundle=].
+
+# Fetch monkeypatches # {#fetch-monkeypatches}
+
+## Monkeypatch HTTP-network-or-cache fetch ## {#monkeypatch-http-network-or-cache-fetch}
+
+In <a spec="fetch">HTTP-network-or-cache fetch</a>, before
+
+> 8.22. Set httpCache to the result of determining the HTTP cache partition,
+> given |httpRequest|.
+
+add the following steps:
+
+22. Set the |response| to the result of [=fetch from web bundle=], given
+    |httpRequest|.
+
+    1. If |response| is [=network error=], return [=network error=].
+
+    2. If |response| is non-null, skip the steps 8.22-8.24 and goto the step 9.
+
+       Note: That means a subresource from a webbundle never interacts with
+       HttpCache. We plan to support HttpCache as a feature enhancement in the
+       future.
+
+# Algorithms # {#algorithms}
+
+## Fetch web bundle ## {#fetch-web-bundle}
+
+To <dfn id="concept-fetch-web-bundle">fetch web bundle</dfn> given [=web
+bundle=] |web bundle| and [=fetch params=] |fetch params|:
+
+1. Assert: |web bundle|'s [=web bundle/state=] is "fetching".
+
+1. Let |request| be |fetch params|'s [=request=].
+
+1. Set |request|'s [=request/url=] to |web bundle|'s [=web bundle/rule=]'s
+   [=bundle rule/source=].
+
+   Note: Source URL is resolved on document's base URL.
+
+1. Set |request|'s [=request/destination=] to "webbundle",
+
+1. Set |request|'s [=request/mode=] to "cors",
+
+1. Set |request|'s [=request/credentials mode=] to |web bundle|'s [=web
+   bundle/rule=]'s [=bundle rule/credentials=].
+
+1. Append a [=header=], a tuple of ("Accept", "application/webbundle;v=b2"), to
+   |request|'s [=request/header list=].
+
+   Note: The final [[draft-yasskin-http-origin-signed-responses]] will use a
+   version of `1`, but this specification tracks what’s actually implemented in
+   browsers, which still uses draft versions.
+
+1. Let |response| be the result of running <a spec="fetch">HTTP-network-or-cache
+   fetch</a> given |fetch params|.
+
+   Note: Chromium's current implementation doesn't allow a *nested bundle*. A
+   Web bundle is never fetched from other web bundles.
+
+1. If |response|'s [=response/status=] is 200,
+
+   1. Set |web bundle|'s [=web bundle/fetched bundle=] to the result of parsing
+      |response|'s body ([[draft-ietf-wpack-bundled-responses-latest]]) and |web
+      bundle|'s [=web bundle/state=] be "fetched". If parsing fails, or any
+      other conformance is violated, set [=web bundle/fetched bundle=] to null
+      and [=web bundle/state=] to "failed".
+
+      Note: In parsing, Chromium's experimental implementation only accepts "b2"
+      as a web bundle format version number
+      ([[draft-ietf-wpack-bundled-responses-latest]]).
+
+1. Otherwise, set |web bundle|'s [=web bundle/state=] to "failed".
+
+## Fetch from web bundle ## {#fetch-from-web-bundle}
+
+To <dfn id="concept-fetch-from-web-bundle">fetch from web bundle</dfn> given
+[=request=] |httpRequest|:
+
+1. For each |web bundle| of [=document=]'s [=document/web bundle list=]:
+
+   1. If the result of running [=match url with web bundle=] given
+      |httpRequest|'s [=request/url=] and |web bundle| is true:
+
+      1. Let |response| be the result of [=get response from web bundle=] given
+         |httpRequest|'s [=request/url=] and |web bundle|.
+
+      2. If |response| is null, return a [=network error=].
+
+         Note: This means a browser does not fallback to fetch a subresource
+         from network.
+
+      3. Otherwise, return |response|.
+
+2. Return null.
+
+## Match url with web bundle ## {#match-url-with-web-bundle}
+
+To <dfn id="concept-match-url-with-web-bundle">match url with web bundle</dfn>
+given [=url=] |url| and [=web bundle=] |web bundle|:
+
+1. If |url| doesn't meet a path restriction rule, given |web bundle|'s [=web
+   bundle/rule=]'s [=bundle rule/source=], then return false.
+
+   Issue: Clarify path restriction rule in algorithm.
+
+2. If |url| matches any of |web bundle|'s [=web bundle/rule=]'s [=bundle
+   rule/resources=], then return true.
+
+3. If |url|'s prefix matches any of |web bundle|'s [=web bundle/rule=]'s
+   [=bundle rule/scopes=], then return true.
+
+4. Otherwise, return false.
+
+## Get response from web bundle ## {#get-response-from-web-bundle}
+
+To <dfn id="concept-get-response-from-web-bundle">get response from web
+bundle</dfn> given [=url=] |url| and [=web bundle=] |web bundle|:
+
+1. If |web bundle|'s [=web bundle/state=] is "fetching", await until [=web
+   bundle/state=] becomes "fetched" or "failed" asynchronously.
+
+2. If |web bundle|'s [=web bundle/state=] is "failed", return null.
+
+3. Assert: |web bundle|'s [=web bundle/fetched bundle=] is non-null.
+
+4. Returns [=response=] from |web bundle|'s [=web bundle/fetched bundle=] given
+   |url| ([[draft-ietf-wpack-bundled-responses-latest]]). If a representation of
+   |url| is not found in [=web bundle/fetched bundle=], return null.