UDP Socket: recvfrom() returns -1 (SOCKET_ERROR)

UDP Socket: recvfrom() returns -1 (SOCKET_ERROR)

By : aszac
Date : November 14 2020, 04:51 PM
seems to work fine Your datagram is too big, or your buffer is too small.
The datagram is larger than your buffer, so it gets trucated, you get an error return from recvfrom and GetLastError() returns 10040, ('WSAEMSGSIZE').
code :

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why bind() returns SOCKET_ERROR

why bind() returns SOCKET_ERROR

By : Hikaru
Date : March 29 2020, 07:55 AM
it helps some times If that's your real code, you've got the brackets in the wrong place in the bind call. One of the two at the end should be moved to immediately after the "sizeof(sin)".
In other words, change it from:
code :
if(bind(server, (sockaddr *)&sin, sizeof(sin) == SOCKET_ERROR))
if(bind(server, (sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
socket.recvfrom(1024) throws socket.error invalid argument supplied

socket.recvfrom(1024) throws socket.error invalid argument supplied

By : guy lancaster
Date : March 29 2020, 07:55 AM
it fixes the issue UDP datagram communications take place between source and destination ports. You can assign a port with a bind call or let the network stack choose one for you by simply calling one of the send/recv methods. If you call sendto (and you have no bound a port), the stack will assign a number in the dynamic port range. If you call recvfrom, the stack will typically assign port 0. But there is no port 0. What happens next is platform dependent. Windows will attempt to bind you as a promiscuous listener. But that is a privileged call and you will likely get an invalid argument error. But it may work if you are administrator - i'm not sure.
To start a conversation, the first entity to send something needs to know what destination port to use. That means that the entity that receives the first communication needs to bind to a port number that the other side knows about in advance. This could be a well-known port number, a port hardwired into your code, something in a config file or even something advertised with a name service protocol such as LDAP.
code :
import socket

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.bind(('', 9999))
while 1:
    data, addr = s.recvfrom(8096)
    s.sendto(data, addr)
import socket

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
for i in range(10):
    s.sendto(str(i), ('', 9999))
recvfrom() returns -1 for RAW socket when used in a thread?

recvfrom() returns -1 for RAW socket when used in a thread?

By : JInhan Yoo
Date : March 29 2020, 07:55 AM
help you fix your problem i want to use multithreading for capturing and processing the IP packets.one thread will only capture and store the packets for say 2 seconds and after that send(using pipe) this chunk to another thread where necessary informations will be extracted. to capture ip packets, am using RAW sockets and recvfrom() but recvfrom() returns -1 for each loop iteration. I think socket is not capturing the packets but i could not find out the reason...any help?? here is the Code... , Your two last arguments here is wrong,
code :
rbytes = recvfrom (Rsock , buffer , 65536 , 0 , &saddr ,(socklen_t *)sizeof saddr);
struct sockaddr_storage saddr; //Or sockaddr_in if you are certain you
                               // only deal with IPv4...
socklen_t slen = sizeof saddr;

rbytes = recvfrom (Rsock , buffer , 65536 , 0 , (struct sockaddr*)&saddr ,&slen);
accept() returns SOCKET_ERROR without connection request

accept() returns SOCKET_ERROR without connection request

By : user2295219
Date : March 29 2020, 07:55 AM
To fix this issue The function accept third parameter addrlen is a pointer. It must point to a valid memory location. Additionally it's an in/out pointer, i.e. a variable. So you must create a variable with a value the is the size of your adrIncomming variable. After return from accept the variable will have the actual length of the address.
This code is more appropriate.
code :
int adrLength = sizeof(adrIncomming);
wsocket = accept(wserver, (struct sockaddr*)&adrIncomming, &adrLength);
Socket.io cdn won't connect and returns a socket.io folder with socket.io.js script that returns an html file in console

Socket.io cdn won't connect and returns a socket.io folder with socket.io.js script that returns an html file in console

By : user3729177
Date : March 29 2020, 07:55 AM
wish of those help Your analysis is correct. The link to script is wrong.
Here's Socket.io's link: https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.3.0/socket.io.js
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