Why would RECV fail?
If the socket is connection oriented and the remote side has shut down the connection gracefully, and all data has been received, a recv will complete immediately with zero bytes received. If the connection has been reset, a recv will fail with the error WSAECONNRESET.
What does RECV return in Python?
If no error occurs, recv() returns the bytes received. If the connection has been gracefully closed, the return value is an empty byte string. The recv() is a blocking method that blocks until it is done, or a timeout is reached or another exception occurs.
What is the difference between RECV and Recvfrom?
The recv() function is normally used only on a connected socket (see connect) and is identical to recvfrom() with a null pointer passed as its from argument. As it is redundant, it may not be supported in future releases. All three routines return the length of the message on successful completion.
Does recv wait for data?
Now in the last call to recv, it would block till it gets CHUNK_SIZE amount of data or a default timeout occurs which can be from 30 seconds to 1 minute. This can be too much of waiting for an application.
What does RECV return when there is still data in the OS buffer but the other side has closed the socket?
recv() will return whatever it can read, or an empty string signalling that the other side has shut down (the official docs don’t even mention what it returns when the connection is shut down… great!).
Why do we use Recvfrom?
Similarly, you would normally use recvfrom() to know where the UDP data was received from. However, you can actually use connect() on UDP socket as an option. In that case, you can use send()/recv() on the UDP socket to send data to the address specified with the connect() and to receive data only from the address.
Can we use Recvfrom in TCP?
The recvfrom() function receives data on a socket named by descriptor socket and stores it in a buffer. The recvfrom() function applies to any datagram socket, whether connected or unconnected. It is valid for TCP sockets only. Other normal receive requests are also completed.
What does RECV return in C?
The recv() function shall return the length of the message written to the buffer pointed to by the buffer argument. For message-based sockets, such as SOCK_DGRAM and SOCK_SEQPACKET, the entire message shall be read in a single operation.
Is recv blocking in C?
In short: yes, it is blocking.
What does Recvfrom return?
Return value If no error occurs, recvfrom returns the number of bytes received. If the connection has been gracefully closed, the return value is zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.