socket.recvfrom(maxlen, flags) => [mesg, sender_addrinfo]
Receives up to maxlen bytes from socket
.
flags is zero or more of the MSG_
options. The first
element of the results, mesg, is the data received. The second
element, sender_addrinfo, contains protocol-specific address
information of the sender.
Parameters
-
maxlen
- the maximum number of bytes to receive from the socket -
flags
- zero or more of theMSG_
options
Example
# In one file, start this first require 'socket' include Socket::Constants socket = Socket.new( AF_INET, SOCK_STREAM, 0 ) sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' ) socket.bind( sockaddr ) socket.listen( 5 ) client, client_addrinfo = socket.accept data = client.recvfrom( 20 )[0].chomp puts "I only received 20 bytes '#{data}'" sleep 1 socket.close # In another file, start this second require 'socket' include Socket::Constants socket = Socket.new( AF_INET, SOCK_STREAM, 0 ) sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' ) socket.connect( sockaddr ) socket.puts "Watch this get cut short!" socket.close
Unix-based Exceptions
On unix-based based systems the following system exceptions may be raised if the call to recvfrom fails:
-
Errno::EAGAIN - the
socket
file descriptor is marked as O_NONBLOCK and no data is waiting to be received; or MSG_OOB is set and no out-of-band data is available and either thesocket
file descriptor is marked as O_NONBLOCK or thesocket
does not support blocking to wait for out-of-band-data -
Errno::EWOULDBLOCK - see Errno::EAGAIN
-
Errno::EBADF - the
socket
is not a valid file descriptor -
Errno::ECONNRESET - a connection was forcibly closed by a peer
-
Errno::EFAULT - the socket's internal buffer, address or address length cannot be accessed or written
-
Errno::EINTR - a signal interrupted recvfrom before any data was available
-
Errno::EINVAL - the MSG_OOB flag is set and no out-of-band data is available
-
Errno::EIO - an i/o error occurred while reading from or writing to the filesystem
-
Errno::ENOBUFS - insufficient resources were available in the system to perform the operation
-
Errno::ENOMEM - insufficient memory was available to fulfill the request
-
Errno::ENOSR - there were insufficient STREAMS resources available to complete the operation
-
Errno::ENOTCONN - a receive is attempted on a connection-mode socket that is not connected
-
Errno::ENOTSOCK - the
socket
does not refer to a socket -
Errno::EOPNOTSUPP - the specified flags are not supported for this socket type
-
Errno::ETIMEDOUT - the connection timed out during connection establishment or due to a transmission timeout on an active connection
Windows Exceptions
On Windows systems the following system exceptions may be raised if the call to recvfrom fails:
-
Errno::ENETDOWN - the network is down
-
Errno::EFAULT - the internal buffer and from parameters on
socket
are not part of the user address space, or the internal fromlen parameter is too small to accommodate the peer address -
Errno::EINTR - the (blocking) call was cancelled by an internal call to the WinSock function WSACancelBlockingCall
-
Errno::EINPROGRESS - a blocking Windows Sockets 1.1 call is in progress or the service provider is still processing a callback function
-
Errno::EINVAL -
socket
has not been bound with a call to bind, or an unknown flag was specified, or MSG_OOB was specified for a socket with SO_OOBINLINE enabled, or (for byte stream-style sockets only) the internal len parameter onsocket
was zero or negative -
Errno::EISCONN -
socket
is already connected. The call to recvfrom is not permitted with a connected socket on a socket that is connection oriented or connectionless. -
Errno::ENETRESET - the connection has been broken due to the keep-alive activity detecting a failure while the operation was in progress.
-
Errno::EOPNOTSUPP - MSG_OOB was specified, but
socket
is not stream-style such as type SOCK_STREAM. OOB data is not supported in the communication domain associated withsocket
, orsocket
is unidirectional and supports only send operations -
Errno::ESHUTDOWN -
socket
has been shutdown. It is not possible to call recvfrom on a socket after shutdown has been invoked. -
Errno::EWOULDBLOCK -
socket
is marked as nonblocking and a call to recvfrom would block. -
Errno::EMSGSIZE - the message was too large to fit into the specified buffer and was truncated.
-
Errno::ETIMEDOUT - the connection has been dropped, because of a network failure or because the system on the other end went down without notice
-
Errno::ECONNRESET - the virtual circuit was reset by the remote side executing a hard or abortive close. The application should close the socket; it is no longer usable. On a UDP-datagram socket this error indicates a previous send operation resulted in an ICMP Port Unreachable message.
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