Implement usage of custom protocol handlers by TimvdLippe · Pull Request #40803 · servo/servo

TimvdLippe · 2025-11-21T19:20:46Z

This implements a dummy mailto: protocol handler in
Servoshell. It registers a new custom handler that
fetches content by substituting the registered url
for the protocol handler.

This does not pass any WPT tests, as that requires
using the document.protocol_handler_automation_mode
which will be part of a follow-up PR.

Part of #40615

codecov-commenter · 2025-11-22T12:16:27Z

⚠️ JUnit XML file not found

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github-actions · 2025-11-22T12:27:53Z

🔨 Triggering try run (#19595453061) for Linux (WPT)

github-actions · 2025-11-22T12:59:11Z

Test results for linux-wpt from try job (#19595453061):

Flaky unexpected result (41)

OK /IndexedDB/idbfactory_open.any.html
- FAIL [expected PASS] subtest: Calling open() with version argument 1.5 should not throw.
```
assert_equals: version expected 1 but got 9007199254740991
```
OK /_mozilla/mozilla/getBoundingClientRect.html (#39668)
- FAIL [expected PASS] subtest: getBoundingClientRect 1
```
assert_equals: expected 62 but got 60.35
```
OK /_mozilla/webxr/create_session.https.html
- FAIL [expected PASS] subtest: create_session
```
can't access property "simulateDeviceConnection", navigator.xr.test is undefined
```

OK /_mozilla/webxr/obtain_frame.https.html

FAIL [expected PASS] subtest: obtain_frame

promise_test: Unhandled rejection with value: object "TypeError: can't access property "simulateDeviceConnection", navigator.xr.test is undefined"

ERROR [expected TIMEOUT] /_mozilla/webxr/sessionavailable.https.html
CRASH [expected OK] /_webgl/conformance2/wasm/readpixels-2gb-in-4gb-wasm-memory.html
OK /content-security-policy/frame-ancestors/frame-ancestors-path-ignored.window.html (#36468)
- FAIL [expected PASS] subtest: A 'frame-ancestors' CSP directive with a URL that includes a path should be ignored.
```
assert_unreached: The IFrame should have been blocked (or cross-origin). It wasn't. Reached unreachable code
```
TIMEOUT /content-security-policy/inheritance/location-reload.html (#38983)
- PASS [expected FAIL] subtest: location.reload() of empty iframe.
FAIL [expected PASS] /css/css-backgrounds/background-size-042.html
CRASH [expected PASS] /css/css-text-decor/text-decoration-line-011.xht
OK /custom-elements/form-associated/ElementInternals-setFormValue.html (#29174)
- PASS [expected FAIL] subtest: Single value - empty name exists
- PASS [expected FAIL] subtest: Multiple values - name content attribute is ignored
CRASH [expected ERROR] /fetch/api/basic/stream-safe-creation.any.serviceworker.html
CRASH [expected ERROR] /fetch/api/credentials/authentication-basic.any.serviceworker.html
CRASH [expected OK] /fetch/api/policies/referrer-unsafe-url-service-worker.https.html
CRASH [expected OK] /fetch/compression-dictionary/dictionary-fetch-with-link-header.tentative.https.html
CRASH [expected TIMEOUT] /fetch/metadata/generated/css-images.https.sub.tentative.html
CRASH [expected OK] /fetch/metadata/generated/window-location.sub.html
TIMEOUT [expected CRASH] /fetch/metadata/window-open.https.sub.html (#40339)
OK /html/browsers/browsing-the-web/navigating-across-documents/initial-empty-document/load-pageshow-events-iframe-contentWindow.html (#28681)
- FAIL [expected PASS] subtest: load & pageshow events do not fire on contentWindow of <iframe> element created with src='about:blank'
```
assert_unreached: load should not be fired Reached unreachable code
```
OK /html/browsers/browsing-the-web/navigating-across-documents/navigation-unload-same-origin-fragment.html (#20768)
- FAIL [expected PASS] subtest: Tests that a fragment navigation in the unload handler will not block the initial navigation
```
assert_equals: expected "" but got "#fragment"
```

OK /html/browsers/browsing-the-web/navigating-across-documents/refresh/same-document-refresh.html (#34597)

FAIL [expected PASS] subtest: Same-Document Referrer from Refresh

assert_equals: original page loads expected "http://web-platform.test:8000/html/browsers/browsing-the-web/navigating-across-documents/refresh/resources/refresh-with-section.sub.html?url=%23section" but got "http://web-platform.test:8000/html/browsers/browsing-the-web/navigating-across-documents/refresh/resources/refresh-with-section.sub.html?url=%23section#section"

CRASH [expected OK] /html/browsers/sandboxing/sandbox-initial-empty-document-toward-same-origin.html (#35948)
CRASH [expected OK] /html/browsers/the-window-object/open-close/open-features-tokenization-width-height.html
CRASH [expected OK] /html/browsers/windows/browsing-context-window.html
OK /html/semantics/embedded-content/the-iframe-element/iframe-loading-lazy-nav-location-replace-set-src.html (#32697)
- PASS [expected FAIL] subtest: Navigating iframe loading='lazy' and then setting src: location.replace
OK /html/semantics/forms/form-submission-0/jsurl-form-submit.tentative.html (#36489)
- PASS [expected FAIL] subtest: Verifies that form submissions scheduled inside javascript: urls take precedence over the javascript: url's return value.
OK /html/semantics/forms/form-submission-0/multipart-formdata.window.html (#28725)
- PASS [expected FAIL] subtest: multipart/form-data: 0x00 in name (normal form)
- PASS [expected FAIL] subtest: multipart/form-data: 0x00 in value (formdata event)
OK /html/semantics/forms/form-submission-0/text-plain.window.html (#28687)
- FAIL [expected PASS] subtest: text/plain: Basic test (formdata event)
```
assert_equals: expected "basic=test\r\n" but got ""
```
- FAIL [expected PASS] subtest: text/plain: Basic File test (normal form)
```
assert_equals: expected "basic=file-test.txt\r\n" but got ""
```
- PASS [expected FAIL] subtest: text/plain: backslash in name (formdata event)
OK [expected CRASH] /html/semantics/forms/the-fieldset-element/disabled-003.html (#31730, #39631)
OK [expected ERROR] /html/semantics/forms/the-input-element/click-user-gesture.html (#40512)
TIMEOUT /resource-timing/test_resource_timing.html (#25720)
- PASS [expected FAIL] subtest: PerformanceEntry has correct name, initiatorType, startTime, and duration (img)
CRASH [expected OK] /trusted-types/eval-csp-no-tt.html
CRASH [expected OK] /trusted-types/get-trusted-types-compliant-attribute-value.html
TIMEOUT /trusted-types/trusted-types-navigation.html?06-10 (#37920)
- TIMEOUT [expected FAIL] subtest: Navigate a frame via anchor with javascript:-urls in report-only mode.
```
Test timed out
```
- NOTRUN [expected TIMEOUT] subtest: Navigate a frame via anchor with javascript:-urls w/ default policy in report-only mode.
TIMEOUT /trusted-types/trusted-types-navigation.html?31-35 (#38034)
- TIMEOUT [expected PASS] subtest: Navigate a frame via form-submission with javascript:-urls in report-only mode.
```
Test timed out
```
- NOTRUN [expected TIMEOUT] subtest: Navigate a frame via form-submission with javascript:-urls w/ default policy in report-only mode.
CRASH [expected OK] /uievents/idlharness.window.html
CRASH [expected ERROR] /wasm/webapi/empty-body.any.serviceworker.html
OK [expected TIMEOUT] /webstorage/localstorage-about-blank-3P-iframe-opens-3P-window.partitioned.html (#29053)
- PASS [expected TIMEOUT] subtest: StorageKey: test 3P about:blank window opened from a 3P iframe
OK [expected ERROR] /webxr/render_state_update.https.html (#27535)
OK /webxr/xrSession_features_deviceSupport.https.html (#24357)
- FAIL [expected PASS] subtest: Immersive XRSession requests with no supported device should reject
```
assert_unreached: Should have rejected: undefined Reached unreachable code
```
ERROR [expected OK] /workers/baseurl/alpha/sharedworker-in-worker.html (#21315)

Stable unexpected results that are known to be intermittent (25)

OK /IndexedDB/idbobjectstore_getAll.any.html (#39276)
- PASS [expected FAIL] subtest: Get all values with transaction.commit()
OK /IndexedDB/idbobjectstore_getAll.any.worker.html (#39400)
- PASS [expected FAIL] subtest: Get all values with transaction.commit()
FAIL [expected PASS] /_mozilla/mozilla/sslfail.html (#10760)
TIMEOUT [expected OK] /_mozilla/mozilla/window_resize_event.html (#36741)
- TIMEOUT [expected PASS] subtest: Popup onresize event fires after resizeTo
```
Test timed out
```
CRASH [expected PASS] /_mozilla/shadow-dom/move-element-with-ua-shadow-tree-crash.html (#39473)
OK /css/css-cascade/layer-font-face-override.html (#35935)
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 1
- PASS [expected FAIL] subtest: @font-face override update with appended sheet 2
OK /css/css-fonts/generic-family-keywords-001.html (#37467)
- FAIL [expected PASS] subtest: @font-face matching for quoted and unquoted generic(khmer-mul)
```
assert_equals: quoted generic(khmer-mul) matches  @font-face rule expected 50 but got 30
```
OK /css/css-fonts/generic-family-keywords-003.html (#38994)
- PASS [expected FAIL] subtest: @font-face matching for quoted and unquoted generic(fangsong) (drawing text in a canvas)
OK /fetch/fetch-later/send-on-discard/not-send-after-abort.https.window.html (#40696)
- FAIL [expected PASS] subtest: A discarded document does not send an already aborted fetchLater request.
```
assert_equals: Number of sent beacons does not match expected count: expected 1 but got 0
```
OK /fetch/metadata/generated/css-font-face.sub.tentative.html (#34624)
- FAIL [expected PASS] subtest: sec-fetch-storage-access - Not sent to non-trustworthy cross-site destination
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
OK /fetch/metadata/generated/element-img-environment-change.https.sub.html (#30111)
- FAIL [expected PASS] subtest: sec-fetch-site - Same site, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
- PASS [expected FAIL] subtest: sec-fetch-site - Same-Origin -> Cross-Site -> Same-Origin redirect, no attributes
- FAIL [expected PASS] subtest: sec-fetch-site - Same-Origin -> Same-Site -> Same-Origin redirect, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
- PASS [expected FAIL] subtest: sec-fetch-site - Cross-Site -> Same Origin, no attributes
- FAIL [expected PASS] subtest: sec-fetch-site - Cross-Site -> Same-Site, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
- PASS [expected FAIL] subtest: sec-fetch-site - Cross-Site -> Cross-Site, no attributes
- FAIL [expected PASS] subtest: sec-fetch-site - Same-Origin -> Same Origin, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
- PASS [expected FAIL] subtest: sec-fetch-site - Same-Origin -> Same-Site, no attributes
- FAIL [expected PASS] subtest: sec-fetch-site - Same-Origin -> Cross-Site, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
- PASS [expected FAIL] subtest: sec-fetch-site - Same-Site -> Same Origin, no attributes
- And 3 more unexpected results...
OK /fetch/metadata/generated/element-img-environment-change.sub.html (#30111)
- PASS [expected FAIL] subtest: sec-fetch-mode - Not sent to non-trustworthy same-origin destination, no attributes
- PASS [expected FAIL] subtest: sec-fetch-dest - Not sent to non-trustworthy cross-site destination, no attributes
- PASS [expected FAIL] subtest: sec-fetch-user - Not sent to non-trustworthy cross-site destination, no attributes
- PASS [expected FAIL] subtest: sec-fetch-storage-access - Not sent to non-trustworthy same-origin destination, no attributes
- FAIL [expected PASS] subtest: sec-fetch-site - HTTPS downgrade-upgrade, no attributes
```
promise_test: Unhandled rejection with value: object "Error: Failed to query for recorded headers."
```
OK [expected ERROR] /focus/focus-event-after-switching-iframes.sub.html (#40368)
CRASH [expected OK] /html/browsers/browsing-the-web/navigating-across-documents/005.html (#27062)
OK /html/browsers/browsing-the-web/navigating-across-documents/replace-before-load/a-click.html (#28697)
- PASS [expected FAIL] subtest: aElement.click() before the load event must NOT replace
ERROR [expected OK] /html/infrastructure/common-dom-interfaces/collections/domstringlist.html (#40665)
OK [expected TIMEOUT] /html/interaction/focus/the-autofocus-attribute/autofocus-dialog.html (#29087)
- FAIL [expected TIMEOUT] subtest: <dialog>-contained autofocus element gets focused when the dialog is shown
```
assert_equals: expected "DIV" but got "BODY"
```

OK [expected TIMEOUT] /html/interaction/focus/the-autofocus-attribute/supported-elements.html (#24145)

FAIL [expected TIMEOUT] subtest: Element with tabindex should support autofocus
```
assert_equals: expected "SPAN" but got "BODY"
```
PASS [expected NOTRUN] subtest: Non-HTMLElement should not support autofocus

FAIL [expected NOTRUN] subtest: Host element with delegatesFocus should support autofocus

assert_equals: expected Element node &lt;div autofocus=""&gt;&lt;/div&gt; but got Element node &lt;body&gt;&lt;div autofocus=""&gt;&lt;/div&gt;&lt;/body&gt;

FAIL [expected NOTRUN] subtest: Host element with delegatesFocus including no focusable descendants should be skipped

assert_equals: expected Element node &lt;input autofocus=""&gt;&lt;/input&gt; but got Element node &lt;body&gt;&lt;div autofocus=""&gt;&lt;/div&gt;&lt;input autofocus=""&gt;&lt;/body&gt;

FAIL [expected NOTRUN] subtest: Area element should support autofocus

promise_test: Unhandled rejection with value: object "TypeError: can't access property "appendChild", w.document.querySelector(...) is null"

TIMEOUT [expected OK] /html/interaction/focus/the-autofocus-attribute/update-the-rendering.html (#24145)
- TIMEOUT [expected FAIL] subtest: "Flush autofocus candidates" should be happen before a scroll event and animation frame callbacks
```
Test timed out
```
OK /navigation-timing/test-navigation-type-reload.html (#33334)
- PASS [expected FAIL] subtest: Reload domComplete > Original domComplete
- PASS [expected FAIL] subtest: Reload loadEventEnd > Original loadEventEnd
- PASS [expected FAIL] subtest: Reload loadEventStart > Original loadEventStart
CRASH [expected OK] /pointerevents/compat/pointerevent_touch-action_two-finger_interaction.html (#40418)
OK /preload/preload-error.sub.html (#37177)
- PASS [expected FAIL] subtest: CORS (fetch): main
OK /trusted-types/trusted-types-navigation.html?26-30 (#38807)
- PASS [expected FAIL] subtest: Navigate a window via form-submission with javascript:-urls in report-only mode.
- PASS [expected FAIL] subtest: Navigate a frame via form-submission with javascript:-urls in enforcing mode.
OK /wasm/webapi/abort.any.html (#39966)
- FAIL [expected PASS] subtest: instantiateStreaming() asynchronously racing with abort should succeed or reject with AbortError
```
assert_equals: expected "AbortError" but got "CompileError"
```
ERROR [expected OK] /workers/baseurl/alpha/import-in-moduleworker.html (#21315)

github-actions · 2025-11-22T12:59:21Z

✨ Try run (#19595453061) succeeded.

mrobinson

I'll let folks more familiar with the fetch implementation review the meet of this, but I have a comment about the servoshell chage:

ports/servoshell/desktop/app.rs

components/net/protocols/mod.rs

nicoburns · 2025-11-25T12:55:59Z

This seems useful for something like a servo:// protocol that loads things like webpages built in to the binary. But for mailto: I would expect an interface that allows for things like opening an external mail client on the user's computer.

Presumably this would be implemented by returning some kind of "cancel navigation" (where this is differentiated from an error state, but the result is that Servo does nothing), with the action actually triggered by the custom handler as a side effect.

webbeef · 2025-11-25T16:42:31Z

registerProtocolHandler is a standard API - if a user is happy with some webapp taking care of all mailto: links this is their choice. Redirecting to an external helper app is a different topic (and should also cover content types that are not supported internally).

TimvdLippe · 2025-11-28T14:29:48Z

This is indeed the standard API that dictates how to navigate these URLs.

If an embedder wants do implement custom logic for a particular scheme, they can already do so with the existing ProtocolRegistry implementation: https://doc.servo.org/net/protocols/struct.ProtocolRegistry.html#method.register Currently we already have a couple of examples in Servoshell (https://github.com/servo/servo/tree/main/ports/servoshell/desktop/protocols) and I can imagine an embedder writing one for a mailto: external client as well. In that case, the embedder can also deny any webpage content to register another mailto: handler.

TimvdLippe · 2025-11-28T14:32:40Z

Added @jdm as reviewer for the Fetch parts

mrobinson

Looks good from my perspective. Thanks for reverting the servoshell bits.

TimvdLippe · 2025-11-30T16:05:39Z

Rebased and also replaced the .unwrap() with an .unwrap_or_else() which was quite straightforward. One less papercut 🎉

components/net/protocols/mod.rs

components/net/fetch/methods.rs

components/net/protocols/mod.rs

This implements a dummy `mailto:` protocol handler in Servoshell. It registers a new custom handler that fetches content by substituting the registered url for the protocol handler. This does not pass any WPT tests, as that requires using the `document.protocol_handler_automation_mode` which will be part of a follow-up PR. Part of servo#40615 Signed-off-by: Tim van der Lippe <[email protected]>

TimvdLippe mentioned this pull request Nov 21, 2025

Implement protocol handlers #40615

Open

TimvdLippe force-pushed the use-protocol-handler branch from a3cec27 to defdd0c Compare November 22, 2025 12:12

TimvdLippe marked this pull request as ready for review November 22, 2025 12:13

TimvdLippe requested a review from atbrakhi as a code owner November 22, 2025 12:13

servo-highfive added the S-awaiting-review There is new code that needs to be reviewed. label Nov 22, 2025

TimvdLippe changed the title ~~Implement using page content protocol handlers~~ Implement usage of custom protocol handlers Nov 22, 2025

TimvdLippe force-pushed the use-protocol-handler branch from defdd0c to 08a2bca Compare November 22, 2025 12:16

TimvdLippe force-pushed the use-protocol-handler branch from 08a2bca to 18efe04 Compare November 22, 2025 12:22

servo-highfive added the S-needs-rebase There are merge conflict errors. label Nov 22, 2025

TimvdLippe force-pushed the use-protocol-handler branch from 18efe04 to 5610402 Compare November 22, 2025 12:27

servo-highfive removed the S-needs-rebase There are merge conflict errors. label Nov 22, 2025

TimvdLippe added the T-linux-wpt Do a try run of the WPT label Nov 22, 2025

github-actions bot removed the T-linux-wpt Do a try run of the WPT label Nov 22, 2025

TimvdLippe force-pushed the use-protocol-handler branch from 5610402 to 4e1270a Compare November 23, 2025 08:47

TimvdLippe mentioned this pull request Nov 23, 2025

Allow webdriver to automatically accept custom protocol handlers #40838

Closed

mrobinson requested changes Nov 24, 2025

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servo-highfive added S-needs-code-changes Changes have not yet been made that were requested by a reviewer. and removed S-awaiting-review There is new code that needs to be reviewed. labels Nov 24, 2025

TimvdLippe force-pushed the use-protocol-handler branch from 4e1270a to dc1c964 Compare November 28, 2025 14:32

servo-highfive added S-awaiting-review There is new code that needs to be reviewed. and removed S-needs-code-changes Changes have not yet been made that were requested by a reviewer. labels Nov 28, 2025

TimvdLippe requested review from jdm and mrobinson November 28, 2025 14:32

TimvdLippe force-pushed the use-protocol-handler branch from dc1c964 to d7fd5c0 Compare November 28, 2025 14:42

mrobinson approved these changes Nov 29, 2025

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servo-highfive removed the S-awaiting-review There is new code that needs to be reviewed. label Nov 29, 2025

TimvdLippe force-pushed the use-protocol-handler branch from d7fd5c0 to 2b73712 Compare November 30, 2025 16:05

servo-highfive added the S-awaiting-review There is new code that needs to be reviewed. label Nov 30, 2025

jdm reviewed Dec 1, 2025

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TimvdLippe force-pushed the use-protocol-handler branch from 2b73712 to f84ed36 Compare December 2, 2025 19:08

TimvdLippe requested a review from jdm December 2, 2025 19:09

TimvdLippe force-pushed the use-protocol-handler branch from f84ed36 to dafb772 Compare December 2, 2025 19:15

jdm approved these changes Dec 2, 2025

View reviewed changes

servo-highfive removed the S-awaiting-review There is new code that needs to be reviewed. label Dec 2, 2025

TimvdLippe added this pull request to the merge queue Dec 2, 2025

servo-highfive added the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Dec 2, 2025

Merged via the queue into servo:main with commit c4db781 Dec 2, 2025
29 checks passed

TimvdLippe deleted the use-protocol-handler branch December 2, 2025 20:36

servo-highfive removed the S-awaiting-merge The PR is in the process of compiling and running tests on the automated CI. label Dec 2, 2025

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