Networking

Example 5-1. TCP port checker
#!/usr/bin/env python
import socket
import re
import sys
def check_server(address, port):
    #create a TCP socket
    s = socket.socket()
    print "Attempting to connect to %s on port %s" % (address, port)
    try:
        s.connect((address, port))
        print "Connected to %s on port %s" % (address, port)
        return True
    except socket.error, e:
        print "Connection to %s on port %s failed: %s" % (address, port, e)
    return False
if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option("-a", "--address", dest="address", default='localhost',
        help="ADDRESS for server", metavar="ADDRESS")
    parser.add_option("-p", "--port", dest="port", type="int", default=80,
        help="PORT for server", metavar="PORT")
    (options, args) = parser.parse_args()
    print 'options: %s, args: %s' % (options, args)
    check = check_server(options.address, options.port)
    print 'check_server returned %s' % check
    sys.exit(not check)


Example 5-2. Socket-based web server checker
#!/usr/bin/env python
import socket
import re
import sys
def check_webserver(address, port, resource):
    #build up HTTP request string
    if not resource.startswith('/'):
        resource = '/' + resource
    request_string = "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n" % (resource, address)
    print 'HTTP request:'
    print '|||%s|||' % request_string
    #create a TCP socket
    s = socket.socket()
    print "Attempting to connect to %s on port %s" % (address, port)
    try:
        s.connect((address, port))
        print "Connected to %s on port %s" % (address, port)
        s.send(request_string)
        #we should only need the first 100 bytes or so
        rsp = s.recv(100)
        print 'Received 100 bytes of HTTP response'
        print '|||%s|||' % rsp
    except socket.error, e:
        print "Connection to %s on port %s failed: %s" % (address, port, e)
        return False
    finally:
        #be a good citizen and close your connection
        print "Closing the connection"
        s.close()
    lines = rsp.splitlines()
    print 'First line of HTTP response: %s' % lines[0]
    try:
        version, status, message = re.split(r'\s+', lines[0], 2)
        print 'Version: %s, Status: %s, Message: %s' % (version, status, message)
    except ValueError:
        print 'Failed to split status line'
        return False
    if status in ['200', '301']:
        print 'Success - status was %s' % status
        return True
    else:
        print 'Status was %s' % status
        return False
if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option("-a", "--address", dest="address", default='localhost',
        help="ADDRESS for webserver", metavar="ADDRESS")
    parser.add_option("-p", "--port", dest="port", type="int", default=80,
        help="PORT for webserver", metavar="PORT")
    parser.add_option("-r", "--resource", dest="resource", default='index.html',
        help="RESOURCE to check", metavar="RESOURCE")
    (options, args) = parser.parse_args()
    print 'options: %s, args: %s' % (options, args)
    check = check_webserver(options.address, options.port, options.resource)
    print 'check_webserver returned %s' % check
    sys.exit(not check)

Example 5-3. httplib-based web server checker
#!/usr/bin/env python
import httplib
import sys
def check_webserver(address, port, resource):
    #create connection
    if not resource.startswith('/'):
        resource = '/' + resource
    try:
        conn = httplib.HTTPConnection(address, port)
        print 'HTTP connection created successfully'
        #make request
        req = conn.request('GET', resource)
        print 'request for %s successful' % resource
        #get response
        response = conn.getresponse()
        print 'response status: %s' % response.status
    except sock.error, e:
        print 'HTTP connection failed: %s' % e
        return False
    finally:
        conn.close()
        print 'HTTP connection closed successfully'
    if response.status in [200, 301]:
        return True
    else:
        return False
if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option("-a", "--address", dest="address", default='localhost',
        help="ADDRESS for webserver", metavar="ADDRESS")
    parser.add_option("-p", "--port", dest="port", type="int", default=80,
        help="PORT for webserver", metavar="PORT")
    parser.add_option("-r", "--resource", dest="resource", default='index.html',
        help="RESOURCE to check", metavar="RESOURCE")
    (options, args) = parser.parse_args()
    print 'options: %s, args: %s' % (options, args)
    check = check_webserver(options.address, options.port, options.resource)
    print 'check_webserver returned %s' % check
    sys.exit(not check)


Example 5-4. FTP URL retriever using ftplib
#!/usr/bin/env python
from ftplib import FTP
import ftplib
import sys
from optparse import OptionParser
parser = OptionParser()
parser.add_option("-a", "--remote_host_address", dest="remote_host_address",
    help="REMOTE FTP HOST.",
    metavar="REMOTE FTP HOST")
parser.add_option("-r", "--remote_file", dest="remote_file",
    help="REMOTE FILE NAME to download.",
    metavar="REMOTE FILE NAME")
parser.add_option("-l", "--local_file", dest="local_file",
    help="LOCAL FILE NAME to save remote file to", metavar="LOCAL FILE NAME")
parser.add_option("-u", "--username", dest="username",
    help="USERNAME for ftp server", metavar="USERNAME")
parser.add_option("-p", "--password", dest="password",
    help="PASSWORD for ftp server", metavar="PASSWORD")
(options, args) = parser.parse_args()
if not (options.remote_file and
        options.local_file and
        options.remote_host_address):
    parser.error('REMOTE HOST, LOCAL FILE NAME, ' \
    'and REMOTE FILE NAME are mandatory')
if options.username and not options.password:
    parser.error('PASSWORD is mandatory if USERNAME is present')
ftp = FTP(options.remote_host_address)
if options.username:
    try:
        ftp.login(options.username, options.password)
    except ftplib.error_perm, e:
        print "Login failed: %s" % e
        sys.exit(1)
else:
    try:
        ftp.login()
    except ftplib.error_perm, e:
        print "Anonymous login failed: %s" % e
    sys.exit(1)
try:
    local_file = open(options.local_file, 'wb')
    ftp.retrbinary('RETR %s' % options.remote_file, local_file.write)
finally:
    local_file.close()
    ftp.close()


Example 5-5. FTP URL retriever using urllib
#!/usr/bin/env python
"""
url retriever
Usage:
url_retrieve_urllib.py URL FILENAME
URL:
If the URL is an FTP URL the format should be:
ftp://[username[:password]@]hostname/filename
If you want to use absolute paths to the file to download,
you should make the URL look something like this:
ftp://user:password@host/%2Fpath/to/myfile.txt
Notice the '%2F' at the beginning of the path to the file.
FILENAME:
absolute or relative path to the filename to save downloaded file as
"""
import urllib
import sys
if '-h' in sys.argv or '--help' in sys.argv:
    print __doc__
    sys.exit(1)
if not len(sys.argv) == 3:
    print 'URL and FILENAME are mandatory'
    print __doc__
    sys.exit(1)
url = sys.argv[1]
filename = sys.argv[2]
urllib.urlretrieve(url, filename)


Example 5-6. Simple XML-RPC server
#!/usr/bin/env python
import SimpleXMLRPCServer
import os
def ls(directory):
    try:
        return os.listdir(directory)
    except OSError:
        return []
def ls_boom(directory):
    return os.listdir(directory)
def cb(obj):
    print "OBJECT::", obj
    print "OBJECT.__class__::", obj.__class__
    return obj.cb()
if __name__ == '__main__':
    s = SimpleXMLRPCServer.SimpleXMLRPCServer(('127.0.0.1', 8765))
    s.register_function(ls)
    s.register_function(ls_boom)
    s.register_function(cb)
    s.serve_forever()


Example 5-7. Simple Pyro server
#!/usr/bin/env python
import Pyro.core
import os
from xmlrpc_pyro_diff import PSACB
class PSAExample(Pyro.core.ObjBase):
    def ls(self, directory):
        try:
            return os.listdir(directory)
    except OSError:
        return []
    def ls_boom(self, directory):
        return os.listdir(directory)
    def cb(self, obj):
        print "OBJECT:", obj
        print "OBJECT.__class__:", obj.__class__
        return obj.cb()
if __name__ == '__main__':
    Pyro.core.initServer()
    daemon=Pyro.core.Daemon()
    uri=daemon.connect(PSAExample(),"psaexample")
    print "The daemon runs on port:",daemon.port
    print "The object's uri is:",uri
    daemon.requestLoop()


Example 5-8. Differences between XML-RPC and Pyro
import Pyro.core
import xmlrpclib
class PSACB:
    def __init__(self):
        self.some_attribute = 1
    def cb(self):
        return "PSA callback"
if __name__ == '__main__':
    cb = PSACB()
    print "PYRO SECTION"
    print "*" * 20
    psapyro = Pyro.core.getProxyForURI("PYROLOC://localhost:7766/psaexample")
    print "-->>", psapyro.cb(cb)
    print "*" * 20
    print "XML-RPC SECTION"
    print "*" * 20
    psaxmlrpc = xmlrpclib.ServerProxy('http://localhost:8765')
    print "-->>", psaxmlrpc.cb(cb)
    print "*" * 20


Example 5-9. Connecting to an SSH server and remotely executing a command
#!/usr/bin/env python
import paramiko
hostname = '192.168.1.15'
port = 22
username = 'jmjones'
password = 'xxxYYYxxx'
if __name__ == "__main__":
    paramiko.util.log_to_file('paramiko.log')
    s = paramiko.SSHClient()
    s.load_system_host_keys()
    s.connect(hostname, port, username, password)
    stdin, stdout, stderr = s.exec_command('ifconfig')
    print stdout.read()
    s.close()


Example 5-10. Retrieving files from an SSH server
#!/usr/bin/env python
import paramiko
import os
hostname = '192.168.1.15'
port = 22
username = 'jmjones'
password = 'xxxYYYxxx'
dir_path = '/home/jmjones/logs'
if __name__ == "__main__":
    t = paramiko.Transport((hostname, port))
    t.connect(username=username, password=password)
    sftp = paramiko.SFTPClient.from_transport(t)
    files = sftp.listdir(dir_path)
    for f in files:
        print 'Retrieving', f
        sftp.get(os.path.join(dir_path, f), f)
    t.close()


Example 5-11. Connecting to an SSH server and remotely executing a command—private keys
enabled
#!/usr/bin/env python
import paramiko
hostname = '192.168.1.15'
port = 22
username = 'jmjones'
pkey_file = '/home/jmjones/.ssh/id_rsa'
if __name__ == "__main__":
    key = paramiko.RSAKey.from_private_key_file(pkey_file)
    s = paramiko.SSHClient()
    s.load_system_host_keys()
    s.connect(hostname, port, pkey=key)
    stdin, stdout, stderr = s.exec_command('ifconfig')
    print stdout.read()
    s.close()


Example 5-12. Retrieving files from an SSH server
#!/usr/bin/env python
import paramiko
import os
hostname = '192.168.1.15'
port = 22
username = 'jmjones'
dir_path = '/home/jmjones/logs'
pkey_file = '/home/jmjones/.ssh/id_rsa'
if __name__ == "__main__":
    key = paramiko.RSAKey.from_private_key_file(pkey_file)
    t = paramiko.Transport((hostname, port))
    t.connect(username=username, pkey=key)
    sftp = paramiko.SFTPClient.from_transport(t)
    files = sftp.listdir(dir_path)
    for f in files:
        print 'Retrieving', f
        sftp.get(os.path.join(dir_path, f), f)
    t.close()


Example 5-13. Port checker implemented in Twisted
#!/usr/bin/env python
from twisted.internet import reactor, protocol
import sys
class PortCheckerProtocol(protocol.Protocol):
    def __init__(self):
        print "Created a new protocol"
    def connectionMade(self):
        print "Connection made"
        reactor.stop()
class PortCheckerClientFactory(protocol.ClientFactory):
    protocol = PortCheckerProtocol
    def clientConnectionFailed(self, connector, reason):
        print "Connection failed because", reason
        reactor.stop()
if __name__ == '__main__':
    host, port = sys.argv[1].split(':')
    factory = PortCheckerClientFactory()
    print "Testing %s" % sys.argv[1]
    reactor.connectTCP(host, int(port), factory)
    reactor.run()


Example 5-14. Twisted Perspective Broker server
import os
from twisted.spread import pb
from twisted.internet import reactor
class PBDirLister(pb.Root):
    def remote_ls(self, directory):
        try:
            return os.listdir(directory)
        except OSError:
            return []
    def remote_ls_boom(self, directory):
        return os.listdir(directory)
if __name__ == '__main__':
    reactor.listenTCP(9876, pb.PBServerFactory(PBDirLister()))
    reactor.run()


Example 5-15. Twisted Perspective Broker client
#!/usr/bin/python
from twisted.spread import pb
from twisted.internet import reactor
def handle_err(reason):
    print "an error occurred", reason
    reactor.stop()
def call_ls(def_call_obj):
    return def_call_obj.callRemote('ls', '/home/jmjones/logs')
def print_ls(print_result):
    print print_result
    reactor.stop()
if __name__ == '__main__':
    factory = pb.PBClientFactory()
    reactor.connectTCP("localhost", 9876, factory)
    d = factory.getRootObject()
    d.addCallback(call_ls)
    d.addCallback(print_ls)
    d.addErrback(handle_err)
    reactor.run()


Example 5-16. Twisted Perspective Broker client—error
#!/usr/bin/python
from twisted.spread import pb
from twisted.internet import reactor
def handle_err(reason):
print "an error occurred", reason
reactor.stop()
def call_ls(def_call_obj):
    return def_call_obj.callRemote('ls_boom', '/foo')
def print_ls(print_result):
    print print_result
    reactor.stop()
if __name__ == '__main__':
    factory = pb.PBClientFactory()
    reactor.connectTCP("localhost", 9876, factory)
    d = factory.getRootObject()
    d.addCallback(call_ls)
    d.addCallback(print_ls)
    d.addErrback(handle_err)
    reactor.run()