Tag Archives: Chromium

Detecting When the User is Offline

Can you hear me now? In the web platform, simple tasks are often anything but. Properly detecting whether the user is online/offline has been one of the “Surprisingly hard problems in computing” since, well, forever. Web developers often ask one question (“Is this browser online?”) but when you dig into it, they’re really trying toContinue reading “Detecting When the User is Offline”

Improving Native Message Host Reliability on Windows

Last Update: Nov 28, 2023 Update: This change was checked into Chromium 113 before being backed out. The plan is to eventually turn it on-by-default, so extension authors really should read this post and update their extensions if needed. The feature was relanded inside Chrome Canary version 115.0.5789.0. It’s off-by-default, behind a flag on theContinue reading “Improving Native Message Host Reliability on Windows”

TLS Certificate Verification Changes in Edge

Last Updated August 21 2023: When establishing a secure HTTPS connection with a server, a browser must validate that the certificate sent by the server is valid — that is to say, that: In the past, Chromium running on Windows delegated this validation task to APIs in the operating system, layering a minimal set ofContinue reading “TLS Certificate Verification Changes in Edge”

Understanding Browser Channels

Microsoft Edge (and upstream Chrome) is available in four different Channels: Stable, Beta, Dev, and Canary. The vast majority of Edge users run on the Stable Channel, but the three pre-Stable channels can be downloaded easily from microsoftedgeinsider.com. You can keep them around for testing if you like, or join the cool kids and setContinue reading “Understanding Browser Channels”

Certificate Revocation in Microsoft Edge

When you visit a HTTPS site, the server must present a certificate, signed by a trusted third-party (a Certificate Authority, aka CA), vouching for the identity of the bearer. The certificate contains an expiration date, and is considered valid until that date arrives. But what if the CA later realizes that it issued the certificateContinue reading “Certificate Revocation in Microsoft Edge”

Chromium Internals: PAK Files

Web browsers are made up of much more than the native code (mostly compiled C++) that makes up their .exe and .dll files. A significant portion of the browser’s functionality (and bulk) is what we’d call “resources”, which include things like: Images (at two resolutions, regular and “high-DPI”) Localized UI Strings HTML, JavaScript, and CSSContinue reading “Chromium Internals: PAK Files”

Chromium’s DNS Cache

From the mailbag: Q: How long does Chromium cache hostnames? I know a user can clear the hostname cache using the Clear host cache button on about://net-internals/#dns, but how long it will take for the cache to be removed if no manual action is taken? After changing DNS records on my server, nslookup from aContinue reading “Chromium’s DNS Cache”

Smarter Defaults by Paying Attention

As a part of every page load, browsers have to make dozens, hundreds, or even thousands of decisions of varying levels of importance: should a particular API be available? Should a resource load be permitted? Should script be allowed to run? Should video be allowed to start playing automatically? Should cookies or credentials be sentContinue reading “Smarter Defaults by Paying Attention”

MHTML in Chromium

The MHTML file format (aka “Webpage, single file”) allows a single file to contain the multiple resources that are used to load a webpage (script, css, images, etc). Edge (Chromium) has an option to use the format when saving the current page via Ctrl+S or the Save page as… menu command: … but the browser’sContinue reading “MHTML in Chromium”