getrandom | small cross-platform library | Cryptography library
kandi X-RAY | getrandom Summary
kandi X-RAY | getrandom Summary
A Rust library for retrieving random data from (operating) system source. It is assumed that system always provides high-quality cryptographically secure random data, ideally backed by hardware entropy sources. This crate derives its name from Linux's getrandom function, but is cross platform, roughly supporting the same set of platforms as Rust's std lib. This is a low-level API. Most users should prefer using high-level random-number library like rand.
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Community Discussions
Trending Discussions on getrandom
QUESTION
I have a service that always returns Observable
, and I cannot change the code of this service.
Supposed I have a button, whenever the button is clicked, I call the method in the service, and it returns a new Observable. How can I update the new data to UI?
Source code and playground on StackBlitz
app.component.ts
ANSWER
Answered 2022-Apr-09 at 16:56One easy way is to convert the Observable to a Promise and use await:
QUESTION
I have this function which opens /dev/urand and reads into a pointer of size; however it's very C like and not very C++ like. I want to make the function look more like modern C++.
...ANSWER
Answered 2022-Mar-06 at 17:12You might be looking for something like this:
QUESTION
I'm trying to scrape a YouTube playlists URL using Node / puppeteer. It was working, but now I'm getting ERR_TOO_MANY_REDIRECTS error. I can still access the page using chrome from my desktop.
I've tried using the chromium browser and chrome browsers. I've also tried using the puppeteer-extra stealth plugin and the random-useragent.
This is how my code stand at the moment:
...ANSWER
Answered 2022-Feb-16 at 08:29If all you need is playlist IDs for a given channel, it's possible to query a feed at:
QUESTION
I'm trying to compile my Rust code on my M1 Mac for a x86_64 target with linux. I use Docker to achieve that.
My Dockerfile:
...ANSWER
Answered 2022-Jan-18 at 17:25It looks like the executable is actually named x86_64-linux-gnu-gcc
, see https://packages.debian.org/bullseye/arm64/gcc-x86-64-linux-gnu/filelist.
QUESTION
I am trying to subclass a fabricjs Image for a barcode field.
...ANSWER
Answered 2022-Jan-18 at 14:44I got it positioned correctly (after restoring) by resetting the position attributes in the setSrc callback:
QUESTION
I have a program which uses PF_PACKET
raw sockets to send TCP SYN
packets to a list of web servers. The program reads in a file which has an IPv4 address on each line of a web server. The program is the beginnings of an attempt to connect to multiple servers in a high performance manner. However, currently the program is only sending about 10 packets/second. This despite the program using non blocking socket. It should be running orders of magnitude faster. Any ideas why it could be running so slowly.
I include a full code listing below. Warning - the code is quite long. That's because it takes a surprisingly large amount of code to get the IP and MAC address of the gateway router. The good news is you can skip all the functions before main because they just do the necessary work of getting the IP and MAC address of the router as well as the local IP address. Anyway, here's the code:
...ANSWER
Answered 2022-Jan-11 at 20:59If I follow the code correctly, you're redoing a ton of work for every IP address that doesn't need to be redone. Every time through the main loop you're:
- creating a new packet socket
- binding it
- setting up a tx packet ring buffer
- mmap'ing it
- sending a single packet
- unmapping
- closing the socket
That's a huge amount of work you're causing the system to do for one packet.
You should only create one packet socket at the beginning, set up the tx buffer and mmap once, and leave it open until the program is done. You can send any number of packets through the interface without closing/re-opening.
This is why your top time users are setsockopt
, mmap
, unmap
, etc. All of those operations are heavy in the kernel.
Also, the point of PACKET_TX_RING
is that you can set up a large buffer and create one packet after another within the buffer without making a send
system call for each packet. By using the packet header's tp_status
field you're telling the kernel that this frame is ready to be sent. You then advance your pointer within the ring buffer to the next available slot and build another packet. When you have no more packets to build (or you've filled the available space in the buffer [i.e. wrapped around to your oldest still-in-flight frame]), you can then make one send/sendto
call to tell the kernel to go look at your buffer and (start) sending all those packets.
You can then start building more packets (being careful to ensure they are not still in use by the kernel -- through the tp_status
field).
That said, if this were a project I were doing, I would simplify a lot - at least for the first pass: create a packet socket, bind it to the interface, build packets one at a time, and use send
once per frame (i.e. not bothering with PACKET_TX_RING
). If (and only if) performance requirements are so tight that it needs to send faster would I bother setting up and using the ring buffer. I doubt you'll need that. This should go a ton faster without the excess setsockopt
and mmap
calls.
Finally, a non-blocking socket is only useful if you have something else to do while you're waiting. In this case, if you have the socket set to be non-blocking and the packet can't be sent because the call would block, the send
call will fail and if you don't do something about that (enqueue the packet somewhere, and retry later, say), the packet will be lost. In this program, I can't see any benefit whatsoever to using a non-blocking socket. If the socket blocks, it's because the device transmit queue is full. After that, there's no point in you continuing to produce packets to be sent, you won't be able send those packets either. Much simpler to just block at that point until the queue drains.
QUESTION
I have the following toy code for a library package with a static array:
...ANSWER
Answered 2022-Jan-02 at 13:14If I remember correctly using new
in field initialization is forbidden in Java Card. You either have to perform the new
from within the static install
method (or a method called from install
) or you can mark the field private
, in which case the array is stored in the constant pool. I would strongly recommend the latter. Basically, no static
code execution is allowed.
Using TRUE
and FALSE
as public static fields is not a good idea either, as they would be reference lookups, which is vulnerable to timing oracles. The whole idea of having TRUE
and FALSE
defined this way is to protect against such oracles as well as fault injection; I suggest to make them private
.
QUESTION
I have the following code I am using to try and update angular carbon charts line graph.. but the graph seems to not update even though the data is. What am I doing wrong here?
Pressing the button is supposed to add a segment to the array and load in the graph.. I see in the console the data array updating and yet nothing on the graph..
...ANSWER
Answered 2021-Dec-30 at 17:16I think you are just pushing in the array but this needs to be reminded to angular change detection that there is an update already made in data
try below code instead,
QUESTION
I've made this effect with React and Tailwind:
As you can see, so far, so good. However, this effect just works when:
- I scroll on the browser
- I click on the browser
- I open the Chrome tools inspector
This is what happens when I do not do something of the above:
GIF with the effect but not working as expected
As you can see, that's not the effect I'm looking for.
So, apparently, there is a React render problem ocurring right here, and I'm stucked.
Inside, this works as follows:
...ANSWER
Answered 2021-Dec-07 at 17:32Ok, solved. The problem was with React applying tailwind effects instantly in the element. I just added the onLoad event to the component instead of ussing useEffect and it works perfectly.
QUESTION
I've been working on a command that returns a random string using a dictionary and the random library:
...ANSWER
Answered 2021-Nov-23 at 16:26You need to get the random number in your function so it generates a new number each time it is called:
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