[ENH] Use socket keepalived instead of original

[leungigi]

Scenarios:

Sometimes, enduser need to run longterm traffic (more than 2 hours), and ixia client socket will idle after send out traffic, some network gateway or linux server maybe close ixia client socket due to no any response during that time, then script will crash due to socket closed.

Solution:

Use "setsockopt" to set socket as keepalived, detail pls refer Python socket.TCP_KEEPINTVL() Examples

Code change as below:

def connect(self):
        log.debug('Opening connection to %s:%d', self.host, self.port)
        fd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        fd.connect((self.host, self.port))
        self.fd = fd
        self.set_socket_keepalive 
        self.call('package req IxTclHal')

def set_socket_keepalive(self):
        self.fd.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
        self.fd.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 1)
        self.fd.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 60)
        self.fd.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 5)