Hacks Send to Kindle extension sideloading hack

[endriu]

After inspecting the code of the Send to Kindle extension I discovered that it generates complete EPUB files and uploads them to S3 for further processing.

Therefore, the code can be modified to download the file to disk instead of uploading it to the cloud. This modification may prove useful for individuals who sideload their ebooks but still want to utilize the extension for web articles, etc., particularly considering the unresolved Amazon bug that wipes out sideloaded ebooks upon connecting to the network.

To implement this modification, follow these steps:

1. Locate the extension code on your system. For example, on my system, it resides in:

C:\Users\<Profile>\AppData\Local\Google\Chrome\User Data\Default\Extensions\cgdjpilhipecahhcilnafpblkieebhea

2. Copy the entire folder found at the above location (e.g., 2.1.1.7_0 - the current version of the extension) and paste it into a temporary location.

3. Remove the original extension from your browser.

4. In the copied folder, locate the manifest.json file and remove the "differential_fingerprint" key. Save the file.

5. Next, find the file named s2k-worker.js. Open it and search for the function called "sendWorkflow". Right after the "try {" statement, add the following lines:

const dataURI = `data:application/octet-stream;base64,${documentMetadata.epubString}`;
chrome.downloads.download({ url: dataURI, filename: 'download.epub' });

Optionally, if you don't want your documents to be uploaded to the cloud, add:

throw new Error();

6. In your browser, open the Extensions management page (chrome://extensions/). Toggle developer mode on the right. Then, drag the entire folder (e.g., 2.1.1.7_0 or whichever version you have) to that page. The extension may require you to log in again.

You can now use the extension as before. When you click "Send," you will be prompted to save the EPUB file.

[tomsem]

Why not just use one of the extensions that converts (web articles etc) to ePub directly?

[slm]

That's cool.


It would be nice if there is a way to have Calibre send epubs to Kindle using Send to Kindle, instead of email. Do you think that you've learned enough about the Send to Kindle extension that there is a way to do that?

[tomsem]

Originally Posted by slm

That's cool.


It would be nice if there is a way to have Calibre send epubs to Kindle using Send to Kindle, instead of email. Do you think that you've learned enough about the Send to Kindle extension that there is a way to do that?

The extension is linked to your Amazon account. Calibre cannot do that, so you would need to supply your credentials (including 2nd factor) every time you send a book. Email doesn't require any credentials, just whitelist of the sender address.

OpenAudible has a way of registering with Audible: it uses an in-app web browser to login to Audible and after that it's 'trusted' to download AAX. Maybe some approach like that would work with calibre too. OpenAudible is open source so it's there for borrowing code.

[endriu]

Originally Posted by tomsem

Why not just use one of the extensions that converts (web articles etc) to ePub directly?

I just like the way Amazon does the conversion. I remember trying some other tools in the past and it wasn't that good.

[endriu]

Originally Posted by slm

That's cool.


It would be nice if there is a way to have Calibre send epubs to Kindle using Send to Kindle, instead of email. Do you think that you've learned enough about the Send to Kindle extension that there is a way to do that?

Further down that "sendWorkflow" function there is code that fetches a pre-signed URL for S3 upload and then uploads the file to S3. Then I suppose it gets picked up and put in the conversion and distribution pipeline. To wire it up with Calibre it would require a plugin I guess.