Fix/fairplay different key per asset

[facugu1998]

Summary

As described in #3227, when a content has mutliple asset and each asset has different key, for example, skd://{key}/AUDIO for audio playlist, skd://{key}/HD and skd://{key}/SD for video playlist, the content is not being played.

Problem found

In ios/Video/Features/RCTResourceLoaderDelegate.swift, for every contentId the function handleDrm() is called. For every call, the _loadingRequest object was set to the current call, so the reference to the previous _loadingRequest is lost. Also, when the license is retrieved from the getLicense function, the setLicenseResult is called, and sets the current _loadingRequest to finished, event though it was already finished.

Solution description

We replaced the _loadingRequest object to a dictionary of AVAssetResourceLoadingRequest with key the contentId of the request. So, when the license is resolved, it looks for the request in the dictionary and finishes it with the corresponding value. Then, it removes it from the dictionary.

In order to get that working, we had to add the parameter contentId to the native functions setLicenseResult and setLicenseResultError. Also, we had to pass the contentId as loadingRequest.request.url?.absoluteString, in _onGetLicense inside handleDRM, so, the getLicense function now receives the full request url and not only the request's host.

Video Sample

You can test the problem and solution with the following content:

URL: https://cdnw1-stg.zetatv.com.uy/testzapp/bigbuckbunny/playlist.m3u8
licenseServer: https://pm-stg.zetatv.com.uy:8443/api/fairplay/get_license/fbdd541b-0036-4b4c-afef-351b7627ba81/
certificateUrl: https://pm-stg.zetatv.com.uy:8443/fairplay/cert.crt

Requirements for testing

The onGetLicense function defined on the video component should be the following:

import { Base64 } from "js-base64";
getLicense: async (spc, skd) => {
          return fetch(licenseServer, {
            method: "POST",
            headers: {
              "Content-Type": "application/octet-stream",
              keyId: skd,
            },
            body: Base64.toUint8Array(spc),
          })
            .then((response) => response.blob())
            .then(async (response) => {
              const base_64 = await blobToBase64(response);
              return base_64.split(",")[1];
            })
            .catch((error) => {
              console.error("Error", error);
            });
        },
      },

[freeboub]

Do this change impact client app ?

[facugu1998]

It should not affect the client app because setLicenseResult and setLicenseError are not called by the client.

[freeboub]

Thank you for this great enhancement !
I just have doubt on api changes done (as you see in my comments).
As you change api, can you also update documentation to explicite changes you made.

I think you update https://github.com/react-native-video/react-native-video/blob/master/docs/DRM.md#getlicense function
and I am not sure, but the setLicence result changes also need application update ? will / can it be backward compatible with previous version ?

Thank you

[facugu1998]

Hello @freeboub, thanks for your comments. We decided to take in account your comment #2881 (comment) and kept contentId as is, and use the licenseServer instead, to forward the skd url to the client.

The getLicense function passed on the drm object receives the same parameters as before, the difference is that if the client does not specify the licenseServer, the getLicense function receives the skd://{key} url.

[freeboub]

@facugu1998 Thank you for the changes, can you please complete DRM.md file, at least to add the new prop: licenseUrl
Thank you

[facugu1998]

@freeboub Actually, the parameters were available before the PR. The docs were not updated, how can we describe the function? We thought something like this:

getLicense

licenseServer and headers will be ignored. You will obtain as argument the SPC (as ASCII string, you will probably need to convert it to base 64) obtained from your contentId + the provided certificate via [loadingRequest streamingContentKeyRequestDataForApp:certificateData contentIdentifier:contentIdData options:nil error:&spcError];.

Also, you will receive the contentId and a licenseUrl URL defined as loadingRequest.request.URL.absoluteString or as the licenseServer prop if it's passed.

You should return on this method a CKC in Base64, either by just returning it or returning a Promise that resolves with the CKC.

With this prop you can override the license acquisition flow, as an example:

getLicense: (spcString, contentId, licenseUrl) => {
  const base64spc = Base64.encode(spcString);
  const formData = new FormData();
  formData.append('spc', base64spc);
  return fetch(`https://license.pallycon.com/ri/licenseManager.do`, {
      method: 'POST',
      headers: {
          'pallycon-customdata-v2': 'd2VpcmRiYXNlNjRzdHJpbmcgOlAgRGFuaWVsIE1hcmnxbyB3YXMgaGVyZQ==',
          'Content-Type': 'application/x-www-form-urlencoded',
      },
      body: formData
  }).then(response => response.text()).then((response) => {
      return response;
  }).catch((error) => {
      console.error('Error', error);
  });
}

[freeboub]

@facugu1998 Yes that's Ok for me, thank you. (I agree DRM doc is not really clear in general ;) )

[facugu1998]

Hello @freeboub, we updated the DRM documentation. Should we change something else?

[freeboub]

@facugu1998 can you please chack following PR please ? #3578 I changed the api as it is causing some regressions on existing implementation, do you agree with that ?

[facugu1998]

@freeboub hello, I think it's perfect. But in order to make it work I had to do the changes I detailed here #3417 (comment).