Is it possible to link/connect/ send a signal from JavaScript code into Solidity/Ethereum?
You can use web3.
There is a different syntax for interfacing with contracts. Depending on if the contract is already deployed or you need to do that yourself.
When you have the contract instance you can then call contract methods.
const ChessGame = web3.eth.contract(abiArray);
const contractInstance = ChessGame.at(address);
contractInstance.declareWinner(winner, function (err, res) {
// do something
});
I personally think web3 is a little cumbersome. I recommend checking out Truffle and following some of their tutorials to get up to speed.
You could install the official Go implementation of the Ethereum protocol, geth.
Geth is a tool for running a local node/miner and also allows you to connect to a running blockchain via the console (which then becomes a Javascript console) and input RPC calls natively via the provided web3 package.
Geth also supports connecting to test nets (such as Ropsten or Rinkeby) or even a private blockchain on localhost.
Additionally to a user interacting directly with the console via the command line, geth can be configured from a shell script/batch file to both run or preload javascript files containing scripted commands for testing!
yes just create an ABI of your smart contract and then interact with your smart contracts however you see fit via web3.
Related
I need to execute a realm-cli command (disable or delete a user) from a mobile application that uses RealmDB, i didn't find any part of the docs that was related to do it.
I thought that i can use mongoClient but i didn't find any methods that allows me to execute raw cli commands.
I need to execute commands like:
realm-cli users disable --app=<Your App ID> --user=<User ID>
Font:
https://docs.mongodb.com/realm/users/delete-or-revoke/
Is there any other way ?
You may need to host the realm-cli and write a HTTP interface middleware to make these call.
I don't believe you can run the application on a mobile application as you would need access to spawning libraries. realm-cli is available open source so it would be possible to port the application to something like C++ (from golang) to make it executable for something like Android or iOS - but it may be cheaper to just buy a VPS somewhere (or even host it locally for a spell) and just pass the arguments to a web route.
I'm attempting to fork Safemoon (or really NotSafeMoon), and use it as a vehicle to learn smart contract development. (I've got a substantial amount of what you might call "Web 2.0" dev experience).
So say I have something like so in my constructor:
constructor () {
_rOwned[_msgSender()] = _rTotal;
IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x10ED43C718714eb63d5aA57B78B54704E256024E); // binance PANCAKE V2
uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());
When I run my tests with npx hardhat test I get the following failure:
Compilation finished successfully
TestToken contract
Deployment
1) "before each" hook for "Has the right name"
0 passing (807ms)
1 failing
1) TestToken contract
"before each" hook for "Has the right name":
Error: Transaction reverted: function call to a non-contract account
Now, this does make perfect sense, after all I am attempting to call the Pancakeswap v2 router contract. How do I get around this limitation? Is there a way to inject the contract address for the router as an environment variable perhaps? Is there a mock constructor for the UniswapRouter I can be using? Generally, how is this sort of thing done in a way that remains testable (and how is it therefore tested) with smart contract development?
A hardhat test deploys the contracts to the hardhat local network (by default). This local network only has few pre-funded and unlocked accounts, but there are no smart contracts deployed. Including the PancakeSwap v2 Router (0x10ED43...).
Instead of deploying and configuring local copy of the router contract, as well as all of its dependencies, you can create a new hardhat network forked from the production BSC.
https://hardhat.org/guides/mainnet-forking.html
This will run a local network with the Router contract available, but your actions will only effect the local network (not the mainnet).
What would be the best way to debug Parse Cloud Code? Currently it's a mess of logging to the console and checking logs. Does anyone have a good workable solution?
During development, you should begin by testing against a local hosted server. I.e., I use VS Code. You can set breakpoints and watch variables for their values. You can set up a tool like ngrok to get a remote URL for your local endpoint so you can test with non-local hosted clients if you'd like.
We also use Slack extensively. We've created our own slack bot, and it has several channels it reports relevant information too, triggered from our parse-server. One of these is a dev error channel. Instead of console.logs, which are hard to sift through and find what you're looking for, we push important information to Slack. We don't switch every single console.log to a slack message, just the important "Hey something went wrong here's the information" messages. This brings them to our attention so we can identify and resolve them way faster. Slack is awesome. I recommend using slack, even on a solo project.
at the moment you can access your Logs using a console.log() or console.error() for functions and all general logs of everything that happens with your app, at Back4App you can access using: Server Settings -> Logs -> Settings -> Server System Log.
Or functions and all logs generated by Parse server, they're: request.log.info() and request.log.error(), at Back4App you can access using: Dashboard -> Logs.
I am wondering how I can test an application that's written with fasthttp using the httptest package in the base library of Go.
I found this guide which explains the testing pretty well, but the issue is that httptest does not satisfy the http.Handler interface so I have no idea how to do the http.HandlerFunc since fasthttp uses it's own fasthttp.ListenAndServe that's incompatible.
Any ideas on how to create a wrapper, or how to otherwise test a fasthttp written library end to end?
There are two possible approaches. Unit testing a handler isn't really viable as you would need to create a RequestCtx and stub/mock all necessary fields.
Instead, I would unit test the code that your fasthttp handlers call out
to. I would do e2e testing of the actual handlers themselves.
There is an in memory listener implementation that you could use to avoid actually listening on a TCP port or Unix socket. You would initialise the server but serve on this listener instead of on a network connection.
You would then create a HTTP client and call the relevant methods as normal but use this listener as the transport.
If you stub/fake anything that your handlers interact with then you could make this in-memory only with no external dependencies, i.e. like a unit test but it will actually doing a full system test.
I'm trying to run a process with elevated privileges - specifically OpenVPN, which requires root privileges to add routes to the system.
Looking around for existing examples around leads me to AuthorizationExecuteWithPrivileges, which seems to be now deprecated.
I tried the new SMJobBless method but I have a few questions regarding its viability for this purpose. As I understand it, I can create a separate privileged tool and communicate with it via sockets to ask the tool to perform privileged commands. However, I can't seem to figure out how I can start the OpenVPN process and capture its standard output in real time doing it this way as the main application would not be starting the process itself.
Another option is to use setuid on the OpenVPN executable. Could I possibly use the helper installed by SMJobBless to set the file permissions and setuid on the executable, then run it normally via NSTask?
Edit:
Lastly is there some way to just run one single command with privileges without having to install anything permanently? Although this new method is more secure, it seems very heavy handed.
I managed to go the SMJobBless method by using a helper and communicating it with XPC (the method shown on Nathan de Vries's Blog). Using this helper I set the permissions on the external process to 04555 (setuid, rx). Then the SMJob is removed as it is no longer required. Essentially emulating an "one-off" privileged job.
Following that I was able to use NSTask to start the process and capture its output in my main application.
Additionally I have a check at the start to see if the permissions are set right on the executable, if not the SMJob helper is re-blessed and permissions set.
If anyone has a cleaner solution, feel free to share. Thanks!
I had the same problem as you, needed it for a OpenVPN Manager App for MacOs X. Your solution is far from optimum because you open the openvpn binary for everyone setting setuid root.
This is a security hole and should be avoided, as it is totally unnecessary when you are using smjobbless helper. This helper runs as root and could do everything you want for you and with administrative privileges, so you can launch openvpn via this helper without setting setuid root on openvpn binary.
Apple designed this process as only your App, the Main App, can communicate with this helper as your Main App and your helper are signed with your developer certificates.
Any malicious App can't use this helper.
When you look at Nathans code you see, that he managed it to send messages to this helper and to get answers from this helper.
In his example there is sth like "Hey there Helper App" and the answer is "Hey there Host App".
So to get sth useful out of this you only have to send commands to the helper app, extract these commands on helper side and launch them with elevated privileges as the helper App runs with elevated privileges.
Look at Nathans code, there is sty like (in smjobblessappcontroller.m):
xpc_object_t message = xpc_dictionary_create(NULL, NULL, 0);
const char* request = "openvpn --config OpenvpnConnection.ovpn";
xpc_dictionary_set_string(message, "request", request);
[self appendLog:[NSString stringWithFormat:#"Sending request: %s", request]];
xpc_connection_send_message_with_reply(connection, message, dispatch_get_main_queue(), ^(xpc_object_t event) {
const char* response = xpc_dictionary_get_string(event, "reply");
[self appendLog:[NSString stringWithFormat:#"Received response: %s.", response]];
});
With this you send the openvpn command to your helper App. You only have to extract this command on helper side to launch the process with elevated privileges.
Look at smjobblesshelper.c and do sth like (in __XPC_Peer_Event_Handler else branch):
const char *response = xpc_dictionary_get_string(event, "request");
In string response you have your openvpn command, now simple launch it:
system(response);
Thats all, this goes with elevated privileges. Now you can use this in your App perhaps in an IBAction push button in your main app, to start openvpn connections as you want every time a user clicks this button.