119 lines
4.2 KiB
Markdown
119 lines
4.2 KiB
Markdown
# Native Inserter
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Fork of the Clipboard Inserter whose purpose it is to automatically insert the
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data received by a native application into a broswer page.
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It is useful for use with text extraction tools like Textractor for looking up
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words in the browser.
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This repository contains the browser plugin, native application, native
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messaging manifest and an example client. Textractor plugin is not included.
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Currently this addon is not available on any of the browsers addon stores, nor
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are releases past the fork signed by our benevolent overlords at
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Mozilla/Google.
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Only tested on GNU/Linux with Firefox 91 ESR.
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## Install
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You will need:
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- This code
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- A go compiler
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- A browser supporting native extensions (eg modern Firefox, Chrome)
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1) Compile and install the native application
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2) Edit `native_inserter.json` to find the native application
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3) Put `native_inserter.json` into your browsers native messaging manifest directory
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4) Build and install the addon in your browser
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For this to be useful you will also need a sender, for example a [Textractor
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plugin](https://github.com/45Tatami/Textractor-TCPSender) and a HTML page ([for
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example](https://pastebin.com/raw/DRDE075L)) that the can be inserted into.
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### Firefox
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This addon is not signed. From the [official Firefox
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documentation](https://extensionworkshop.com/documentation/publish/signing-and-distribution-overview/):
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> Unsigned extensions can be installed in Developer Edition, Nightly, and ESR
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> versions of Firefox, after toggling the xpinstall.signatures.required
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> preference in about:config.
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You can download the unsigned build from the releases or follow the official
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instruction for building addons, for example via `web-ext`:
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```
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$ npm install -g web-ext
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$ web-ext build
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```
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You can then install the resulting zip via the `Install Add-On From File`
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dialog under `about:addons`.
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The native messaging manifest directory under linux is
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`~/.mozilla/native-messaging-hosts`.
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## How does it work
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The browser plugin starts a native application which creates a raw TCP listen
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socket currently on all interfaces on port 30501 for incoming connections.
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One or more applications (eg Textractor plugin) will connect to this socket and
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send messages. Messages consist of a 4 Byte little-endian length header and
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UTF-8 payload.
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The native application will forward the UTF-8 data to the browser plugin which
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in turn will insert the text into a webpage similar to the original clipboard
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version.
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## Troubleshooting
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The native application is writing to stderr. Browsers usually forward this to
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their default log.
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The browser addon itself will log to the console. Problems with the native
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messaging manifest might not necessarily be logged.
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If the native application does not run in the background after loading the
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add-on, double-check if the native messaging manifest is in the correct
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directory and has the binary path set correctly.
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## (Not so) FAQ
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#### Why not the clipboard
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Abusing the clipboard functionality to transfer data to the browser is ugly. It
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does also not work under Wayland which does not allow unfocused applications to
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access the clipboard.
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(No opinion here whether the native application/messaging setup is more or less
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ugly than the clipboard approach)
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It also has the bonus of working with VMs without setting up clipboard
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forwarding between host and guest.
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#### Why a native application
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The APIs including TCP listen sockets are no longer supported by modern
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Browsers. The only alternative would be connecting to a WebSocket server, but
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this has two drawbacks:
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1) The API only supports the client side protocol and does not implement a
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server. This would mean the sending side would need to be the server and the
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native application the client, which would not work with multiple senders.
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2) The sending side (eg C++ Textractor plugin) would need to implement a
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Websocket server which is a lot more work than raw tcp.
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## Bugs
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- Native messaging expects the length prefix in native byte order. Go does
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neither have a non-unsafe way to convert an integer to a byte stream in
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native order for writing nor a way to detect endianness. The native
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application will write in little-endian, which will break the protocol on
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big-endian machines
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- Messages over the native-messaging 1MB limit will be discarded instead of
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split up
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