Bug 153162 – CSP: Deduplicate violation reports before sending

• Component: WebCore Misc.
• Status: NEW

[Daniel Bates]

We should merge <https://src.chromium.org/viewvc/blink?view=rev&revision=155708>.

CSP: Deduplicate violation reports before sending.

Violation reports should be sent once and only once per page load. If a
single line of code generates the same report over and over again, we
should attempt to avoid spamming the report server with not-particularly
valuable duplicates.

For example, if a report-only policy blocks 'eval()', then the following
loop would make a sysadmin somewhere quite unhappy:

    for (i=0;i<Number.MAX_VALUE;i++)
      eval(...);

This patch adds a HashSet<unsigned> to ContentSecurityPolicy, and stores
the hash of the stringified violation report. We check that set just
before handing things off to PingLoader for delivery. If there's a
match, we've already sent the report, and can safely discard it. If not
we send the report, then add it to the list.

Discussed on [e-mail]: http://lists.w3.org/Archives/Public/public-webappsec/2013Aug/0000.html

[Radar WebKit Bug Importer]

<rdar://problem/24383316>