fix(FEC-14578): [DRM] playkit-js changes needed to support uDRM CPIX multikey solution for HLS FPS

[chanakabr]

Description of the Changes

Baseline Fairplay Implementation: Following the legacy Key System (com.apple.fps.1_0).
Background: We have a new feature in the uDRM and in the CPIX 2.3 encrypters/packagers to support multikeys/key rotation, which uses kid per track per crypto period.
The Packager is signalling the kid as keyUri in the playlist:
Format:
EXT-X-KEY:METHOD=SAMPLE-AES,URI="skd://kid",KEYFORMAT="com.apple.streamingkeydelivery",KEYFORMATVERSIONS="1"
Sample:

#EXT-X-KEY:KEYFORMATVERSIONS="1",METHOD=SAMPLE-AES,URI="skd://86bb0abb-a6af-3819-8d6d-98ac161c595e",KEYFORMAT="com.apple.streamingkeydelivery"

During the license flow the uDRM needs to locate the kid from the request.
It can be in 2 places.
a. SPC's AssetID TLLVS (this works with modern media key system how in the legacy the AssetID can't be parsed)
b. X-InitData-Kaltura (skd in base64 - explained in this PR).

The PR Change:

1. Set the X-InitData-Kaltura on the license request of FPS.

CheckLists

• [ Y] changes have been done against master branch, and PR does not conflict
• [ Y] new unit / functional tests have been added (whenever applicable)
• [Y ] test are passing in local environment
• Travis tests are passing (or test results are not worse than on master branch :))
• Docs have been updated

[Copilot]

Pull Request Overview

This PR implements CPIX 2.3 support for FairPlay DRM by adding multi-key/key rotation functionality. The changes enable the uDRM to locate key IDs (KIDs) from license requests to support the new CPIX 2.3 encrypters/packagers that use KID per track per crypto period.

• Adds X-Kaltura-InitData header to license requests containing base64-encoded KID
• Updates content ID extraction to properly parse skd:// format URLs
• Enhances WebKit key message handling to extract KID from session content

Comments suppressed due to low confidence (2)

src/engines/html5/media-source/adapters/fairplay-drm-handler.ts:133

• The header name 'X-Kaltura-InitData' is inconsistent with the description which mentions 'X-InitData-Kaltura'. Please verify the correct header name format.

      headers: {'X-Kaltura-InitData': kidBase64} // pass the kid to uDRM

src/engines/html5/media-source/adapters/fairplay-drm-handler.ts:274

• The variable name 'hostname' is misleading since it's now extracting a key ID rather than a hostname. Consider renaming to 'keyId' or 'contentId' for clarity.

    const hostname = url.slice(url.lastIndexOf("skd://")+6,url.length); // handle the skd://mykeyid format

[Copilot]

The btoa() function expects a string input, but 'kid' could be undefined or null if session?.contentId is falsy. This will throw an error. Add validation: const kidBase64 = kid ? btoa(kid) : '';

Suggested change

	const kidBase64 = btoa(kid);
	const kidBase64 = kid ? btoa(kid) : '';

[Copilot]

If the URL doesn't contain 'skd://', lastIndexOf() returns -1, causing slice(-1+6, length) which would return the last 5 characters. Add validation: if (url.includes('skd://')) { return url.slice(url.lastIndexOf('skd://') + 6); } else { /* fallback logic */ }

Suggested change

	const hostname = url.slice(url.lastIndexOf("skd://")+6,url.length); // handle the skd://mykeyid format
	return hostname;
	if (url.includes("skd://")) {
	const hostname = url.slice(url.lastIndexOf("skd://") + 6); // handle the skd://mykeyid format
	return hostname;
	} else {
	throw new Error("Invalid URL format: 'skd://' not found");
	}