datagram | Event-driven UDP client and server sockets for ReactPHP | Socket library
kandi X-RAY | datagram Summary
kandi X-RAY | datagram Summary
Event-driven UDP datagram socket client and server for ReactPHP.
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Top functions reviewed by kandi - BETA
- Resolve an address .
- Resolve host .
- Listen for write events .
- Close the socket .
- Receive data from the socket
- Send data to the socket .
- Create a server socket .
- Receive received data
- Create client socket .
- Sanitize an IPv6 address .
datagram Key Features
datagram Examples and Code Snippets
@Override
public DatagramPacket read(SelectionKey key) throws IOException {
var buffer = ByteBuffer.allocate(1024);
var sender = ((DatagramChannel) key.channel()).receive(buffer);
/*
* It is required to create a DatagramPacket bec
public static String receiveMessage(DatagramChannel server) throws IOException {
ByteBuffer buffer = ByteBuffer.allocate(1024);
SocketAddress remoteAdd = server.receive(buffer);
String message = extractMessage(buffer);
private AbstractNioChannel udpChannel(int port, ChannelHandler handler) throws IOException {
var channel = new NioDatagramChannel(port, handler);
channel.bind();
channels.add(channel);
return channel;
}
Community Discussions
Trending Discussions on datagram
QUESTION
I have simple client/server application. I am receiving message on the server side from client but I want to send that response to the channel from server to other file and I am receiving error "borrowed value does not live long enough".
I have searched in the stack overflow for similar previous questions but not getting enough understanding of lifetime. Is there a good documentation or if simple example available on this topic?
For now if someone can help me to fix this code (may be edit the portion of code which needs to fix) that would be helpful.
Thanks in advance.
Server side: ...ANSWER
Answered 2021-Jun-09 at 05:45There's a hint in the compiler message, that values in a scope are dropped in the opposite order they are defined in, and in the example, buf
is defined after tx
, which means it will be dropped before tx
. Since a reference to buf
(in the form of received_message
) is passed to tx.send()
, then buf
should live longer that tx, and therefore switching the definition order will fix this particular error (ie. switch lines 19 and 20).
QUESTION
I have four modules. The client is sending messages and the server is receiving messages. Once the server receives the message, it tries to send the message to the MPSC channel. I put the receiver in the other .rs file where I intend to receive the message.
I am not getting any message on the receiver side.
Maybe an infinite loop on the server side creates a problem, but is there a way to make this channel communication working?
client.rs
...ANSWER
Answered 2021-Jun-10 at 01:23Maybe an infinite loop on the server side creates a problem
Yes, quite literally, your server code does an infinite loop
to handle continuously messages from the client(s). So the call to tcp_datagram_server
never returns.
but is there a way to make this channel communication working?
Of course, it seems you are simply missing a second thread for your message_receiver
. Wrapping your tcp_datagram_server(tx)
in std::thread::spawn
should do it. You could also add a loop
to keep processing requests to match the one in tcp_datagram_server
:
QUESTION
I am creating simple client server communication with unix datagram socket in Rust. I am receiving message to server from client with bytes length but not able to converting back to the original string I sent from client. I have tried https://doc.rust-lang.org/std/str/fn.from_utf8.html and from_utf8_lossy but had no success. Here is the code.
How to get original string on the server?
Server side: ...ANSWER
Answered 2021-Jun-04 at 19:03std::str::from_utf8(buf.as_slice()).unwrap()
should give you a &str of the data, which you can convert to a String if need be:
QUESTION
I'm currently trying to scan over all available channels while in monitor mode to find IP traffic on open networks around me. I noticed that IP in sniffed_packet
was never true, and after some debugging, found that frames aren't being parsed properly.
I'm sniffing using this:
...ANSWER
Answered 2021-May-30 at 23:16This was a bug in Scapy. I reported it, and it was just fixed.
If you're having this issue, make sure to run the following to get the most recent version of Scapy:
QUESTION
My DLL gets injected into a program and then hooks to connect
, send
, recv
and closesocket
functions using Detours. The point is to stop the program from connecting to some server and instead communicate with my DLL directly.
My recv
function uses an infinite loop, just waiting for any data to send to the program. When closesocket
is called that loop is broken and everything works fine.
But there's one program written in C# that just hangs when I close it. Its error log says:
SocketException: A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied.
at System.Net.Sockets.Socket.Disconnect (Boolean reuseSocket) [0x00000] in :0
The exception is expected since the socket never connects to anything. But is there any workaround for this? What does System.Net.Sockets.Socket.Disconnect
call under the hood? What other function do I need to hook to detect that?
I've tried hooking to shutdown
, setsockopt
, WSACancelBlockingCall
, WSACleanup
, WSASend
, WSASendDisconnect
, WSASendMsg
, WSASendTo
, WSARecv
, WSARecvDisconnect
and WSARecvFrom
. None of them get called.
ANSWER
Answered 2021-May-29 at 07:58System.Net.Sockets.Socket.Disconnect
calls DisconnectEx
. And as the remarks say:
Note The function pointer for the DisconnectEx function must be obtained at run time by making a call to the WSAIoctl function with the SIO_GET_EXTENSION_FUNCTION_POINTER opcode specified. The input buffer passed to the WSAIoctl function must contain WSAID_DISCONNECTEX, a globally unique identifier (GUID) whose value identifies the DisconnectEx extension function. On success, the output returned by the WSAIoctl function contains a pointer to the DisconnectEx function. The WSAID_DISCONNECTEX GUID is defined in the Mswsock.h header file.
So if you want to do what I did you have to:
- hook to
WSAIoctl
- check if
dwIoControlCode
isSIO_GET_EXTENSION_FUNCTION_POINTER
- check if
lpvInBuffer
isWSAID_DISCONNECTEX
:
QUESTION
I'm trying to make a console chat app in python using socket library.
Whenever I send a message to the server, the server code crashes with the following message:
OSError: [WinError 10057] A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied
Server code
...ANSWER
Answered 2021-May-28 at 16:25You're attempting to send data to your own server socket. You instead want to send to the client that you accepted.
QUESTION
I have the following data from a datagram message received by UDP socket:
...ANSWER
Answered 2021-May-19 at 19:55each float is 4 bytes of data (typically... not always... again you need to consult the docs for whatever p[ayload you need)
but assuming that /13/raw
is easy enough for you and the rest is what you need to decode
if we assume that \x00
is some sort of delimiter we are left with the bytestring as follows
QUESTION
I had a problem with UDP Datagrams in that I could not receive UDP packets from a server but I could send them. I looked through many examples but could not figure out what was wrong with my code. I finally found hints to what was going wrong from different sites.
I have thus updated the question here in case it might help someone in the future. The code below is working over a WiFi network on a LG phone and was built on Android Studio 4.2 (29/4/2021); SDK Platform 30; Kotlin 1.5.0
At the end of the code section below I have written some comments as to what was causing my code not to work.
This is my MainActivity code
...ANSWER
Answered 2021-May-15 at 08:23I have found the solution. There was actually no issue with the code. I have updated the original question with comments on what caused the problem... Please see the question above for a full explanation.
In short the problem was with Android's emulator having a different IP to the PC IP and secondly the phone stopped listening to broadcasted messages once it goes to sleep.
QUESTION
I'm new to c++ and need help. I use an UDP server to receive structure however i have problem to read it , the client send a structure I call : ChannAccessReq so the structure is send and the server receive it with RECVFROM and I use a general structure by reading the header (H1) of the struct only and then i do a read when a condition is fullfill with a more precise structure (temp2) for the buffer. However the client need to send the message twice , the first time it goes until recvfrom and the second it reach read() (i think) I tried all the day and wonder if its the size of the buffer ?
I think the most sensitive part is in the server with the recvfrom() who have a struct different from the read() just after..
I hope it's clear!
here is the server :
...ANSWER
Answered 2021-Apr-07 at 07:06In C++ you have to define the type of the parameters. As I deduced from the calling place, it should be int and bool.
QUESTION
I would like experts' advice on the usage of the socket option IP_MULTICAST_IF ("set multicast interface") combined with static multicast routes.
On a LAN, a multicast IP datagram is commonly sent in a multicast Ethernet frame (IP/MAC multicast destination address mapping). On a multi-homed Linux system (kernel 5.11), I have noticed that the socket option IP_MULTICAST_IF
modifies the behavior as follow:
- Without static route, the multicast IP datagram is always sent in a multicast Ethernet frame, with or without
IP_MULTICAST_IF
. - With a static route, without
IP_MULTICAST_IF
, the multicast IP datagram is sent in a multicast Ethernet frame. - With a static route, with
IP_MULTICAST_IF
, the multicast IP datagram is sent in a unicast Ethernet frame to the gateway.
First question: With a static route for the multicast packet, should the multicast IP datagram be sent in a multicast Ethernet frame or in a unicast Ethernet frame to the gateway?
Second question: Whatever is the answer to the first question, why does the socket option IP_MULTICAST_IF switch from multicast to unicast MAC addressing?
The Linux man page ("man 7 ip") is not very explicit:
...ANSWER
Answered 2021-Apr-28 at 03:45Linux doesn't normally handle multicast routing without special software such as mrouted or pimd. I tried this on a CentOS 7 VM (3.10 kernel) and saw unicast MAC addresses with the static route whether or not I used IP_MULTICAST_IF
.
The following post on ServerFault goes into this in more detail:
TL;DR -- Don't use static multicast routes. Stick with setting IP_MULTICAST_IF
.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
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