EBADF The socket descriptor is invalid. ECONNRESET A connection was forcibly closed by a peer. EFAULT A valid message buffer was not specified. Nonexistent or protected address space is specified for the message buffer. EINTR A signal interrupted the recvfrom() function before any data was available. EINVAL The MSG_OOB flag is set, and no out-of-band data is available. ENOBUFS The system has insufficient resources to complete the call. ENOMEM The system did not have sufficient memory to fulfill the request. ENOTCONN A receive is attempted on a connection- oriented socket that is not connected. ENOTSOCK The socket descriptor is invalid. EOPNOTSUPP The specified flags are not supported for this socket type. ETIMEDOUT The connection timed out when trying to establish a connection or when a transmission timed out on an active connection. EWOULDBLOCK The NBIO (nonblocking) flag is set for the socket descriptor and the process delayed during the write operation.