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Pysnmp Command Responder with GetNext or Walk operation

I am implementing a Pysnmp responder that receives SNMP GET/SET requests currently and would like to extend with Walk, getNext and getBulk operations. All the OID and its values are stored in key-value in a file.
What I have tried is to use readNextVars() method from instrum.AbstractMibInstrumController class where I iterate over OID's list by calling self.readVars() within readNextVars()
Below is a code snippet showing only GET request and SET request is similar but it writes value to its respective OID in oid.json file.
from pysnmp.entity import engine, config
from pysnmp.entity.rfc3413 import cmdrsp, context
from pysnmp.carrier.asynsock.dgram import udp
from pysnmp.smi import instrum, error
from pysnmp.proto.api import v2c
import json
class SnmpData:
def __init__(self, host, port):
self.snmpEngine = engine.SnmpEngine()
config.addSocketTransport(
self.snmpEngine,
udp.domainName,
udp.UdpTransport().openServerMode((host, port))
)
config.addV1System(self.snmpEngine, 'my-area', 'public', contextName='my-context')
config.addVacmUser(self.snmpEngine, 2, 'my-area', 'noAuthNoPriv', (1, 3, 6), (4, 5, 7))
self.snmpContext = context.SnmpContext(self.snmpEngine)
def snmp_run_command(self):
self.snmpContext.registerContextName(
v2c.OctetString('my-context'),
FileInstrumController()
)
cmdrsp.GetCommandResponder(self.snmpEngine, self.snmpContext)
cmdrsp.SetCommandResponder(self.snmpEngine, self.snmpContext)
cmdrsp.NextCommandResponder(self.snmpEngine, self.snmpContext)
cmdrsp.BulkCommandResponder(self.snmpEngine, self.snmpContext)
self.snmpEngine.transportDispatcher.jobStarted(1)
try:
self.snmpEngine.transportDispatcher.runDispatcher()
except:
self.snmpEngine.transportDispatcher.closeDispatcher()
return "yes"
def main(self):
self.snmp_run_command()
class FileInstrumController(instrum.AbstractMibInstrumController):
def readVars(self, vars, acInfo=(None, None)):
try:
data = None
final_data = None
with open('oid.json') as f:
data = json.load(f)
if str(vars[0][0]) in data.keys())):
final_data = data[str(vars[0][0])]
return [(vars[0][0], v2c.OctetString(str(final_data)))]
else:
return [(vars[0][0], v2c.OctetString(str("Not a Valid OID")))]
except IOError:
raise error.SmiError
def readNextVars(self, vars, acInfo=(None, None))
# get oid & split and match if in file than return its value
# else return invalid oid and break but its not breaking
# and sending continuously requests of next oid (OID + 1)
Here is the oid file (oid.json)
{
"1.3.6.1.1.999.1.1.0": 1,
"1.3.6.1.1.999.1.2.0": 2,
"1.3.6.1.1.999.1.3.0": 3,
"1.3.6.1.1.999.1.4.0": 4,
"1.3.6.1.1.999.1.5.0": 5,
"1.3.6.1.1.999.1.6.0": 100,
"1.3.6.1.1.999.1.7.0": 200,
"1.3.6.1.1.999.1.8.0": 300,
"1.3.6.1.1.999.1.9.0": 400,
"1.3.6.1.1.999.1.10.0": 500
}

multipath iSCSI cleanup code

I know only the very basics of python. I have this project for my INFORMATION STORAGE AND MANAGEMENT subject. I have to give an explanation the following code.
I searched every command used in this script but could not find most of them. The code can be found here:
import glob
import json
import os
import re
import string
import sys
from oslo.config import cfg
from nova import context
from nova.db.sqlalchemy import api as db_api
from nova.db.sqlalchemy import models
from nova import utils
CONF = cfg.CONF
def usage():
print("""
Usage:
python %s --config-file /etc/nova/nova.conf
Note: This script intends to clean up the iSCSI multipath faulty devices
hosted by VNX Block Storage.""" % sys.argv[0])
class FaultyDevicesCleaner(object):
def __init__(self):
# Get host name of Nova computer node.
self.host_name = self._get_host_name()
def _get_host_name(self):
(out, err) = utils.execute('hostname')
return out
def _get_ncpu_emc_target_info_list(self):
target_info_list = []
# Find the targets used by VM on the compute node
bdms = db_api.model_query(context.get_admin_context(),
models.BlockDeviceMapping,
session = db_api.get_session())
bdms = bdms.filter(models.BlockDeviceMapping.connection_info != None)
bdms = bdms.join(models.BlockDeviceMapping.instance).filter_by(
host=string.strip(self.host_name))
for bdm in bdms:
conn_info = json.loads(bdm.connection_info)
if 'data' in conn_info:
if 'target_iqns' in conn_info['data']:
target_iqns = conn_info['data']['target_iqns']
target_luns = conn_info['data']['target_luns']
elif 'target_iqn' in conn_info['data']:
target_iqns = [conn_info['data']['target_iqn']]
target_luns = [conn_info['data']['target_lun']]
else:
target_iqns = []
target_luns = []
for target_iqn, target_lun in zip(target_iqns, target_luns):
if 'com.emc' in target_iqn:
target_info = {
'target_iqn': target_iqn,
'target_lun': target_lun,
}
target_info_list.append(target_info)
return target_info_list
def _get_ncpu_emc_target_info_set(self):
target_info_set = set()
for target_info in self._get_ncpu_emc_target_info_list():
target_iqn = target_info['target_iqn']
target_lun = target_info['target_lun']
target_info_key = "%s-%s" % (target_iqn.rsplit('.', 1)[0],
target_lun)
# target_iqn=iqn.1992-04.com.emc:cx.fnm00130200235.a7
# target_lun=203
# target_info_key=iqn.1992-04.com.emc:cx.fnm00130200235-203
target_info_set.add(target_info_key)
return target_info_set
def _get_target_info_key(self, path):
temp_tuple = path.split('-lun-', 1)
target_lun = temp_tuple[1]
target_iqn = temp_tuple[0].split('-iscsi-')[1]
target_info_key = "%s-%s" % (target_iqn.rsplit('.', 1)[0], target_lun)
# path=/dev/disk/by-path/ip-192.168.3.52:3260-iscsi-iqn.1992-
# 04.com.emc:cx.fnm00130200235.a7-lun-203
# target_info_key=iqn.1992-04.com.emc:cx.fnm00130200235-203
return target_info_key
def _get_non_ncpu_target_info_map(self):
# Group the paths by target_info_key
ncpu_target_info_set = self._get_ncpu_emc_target_info_set()
device_paths = self._get_emc_device_paths()
target_info_map = {}
for path in device_paths:
target_info_key = self._get_target_info_key(path)
if target_info_key in ncpu_target_info_set:
continue
if target_info_key not in target_info_map:
target_info_map[target_info_key] = []
target_info_map[target_info_key].append(path)
return target_info_map
def _all_related_paths_faulty(self, paths):
for path in paths:
real_path = os.path.realpath(path)
out, err = self._run_multipath(['-ll', real_path],
run_as_root=True,
check_exit_code=False)
if 'active ready' in out:
# At least one path is still working
return False
return True
def _delete_all_related_paths(self, paths):
for path in paths:
real_path = os.path.realpath(path)
device_name = os.path.basename(real_path)
device_delete = '/sys/block/%s/device/delete' % device_name
if os.path.exists(device_delete):
# Copy '1' from stdin to the device delete control file
utils.execute('cp', '/dev/stdin', device_delete,
process_input='1', run_as_root=True)
else:
print "Unable to delete %s" % real_path
def _cleanup_faulty_paths(self):
non_ncpu_target_info_map = self._get_non_ncpu_target_info_map()
for paths in non_ncpu_target_info_map.itervalues():
if self._all_related_paths_faulty(paths):
self._delete_all_related_paths(paths)
def _cleanup_faulty_dm_devices(self):
out_ll, err_ll = self._run_multipath(['-ll'],
run_as_root=True,
check_exit_code=False)
# Pattern to split the dm device contents as follows
# Each section starts with a WWN and ends with a line with
# " `-" as the prefix
#
# 3600601601bd032007c097518e96ae411 dm-2 ,
# size=1.0G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
# `-+- policy='round-robin 0' prio=0 status=active
# `- #:#:#:# - #:# active faulty running
# 36006016020d03200bb93e048f733e411 dm-0 DGC,VRAID
# size=1.0G features='1 queue_if_no_path' hwhandler='1 alua' wp=rw
# |-+- policy='round-robin 0' prio=130 status=active
# | |- 3:0:0:2 sdd 8:48 active ready running
# | `- 5:0:0:2 sdj 8:144 active ready running
# `-+- policy='round-robin 0' prio=10 status=enabled
# |- 4:0:0:2 sdg 8:96 active ready running
# `- 6:0:0:2 sdm 8:192 active ready running
dm_pat = r'([0-9a-fA-F]{30,})[^\n]+,[^\n]*\n[^,]* `-[^\n]*'
dm_m = re.compile(dm_pat)
path_pat = r'- \d+:\d+:\d+:\d+ '
path_m = re.compile(path_pat)
for m in dm_m.finditer(out_ll):
if not path_m.search(m.group(0)):
# Only #:#:#:# remain in the output, all the paths of the dm
# device should have been deleted. No need to keep the device
out_f, err_f = self._run_multipath(['-f', m.group(1)],
run_as_root=True,
check_exit_code=False)
def cleanup(self):
self._cleanup_faulty_paths()
# Make sure the following configuration is in /etc/multipath.conf
# Otherwise, there may be "map in use" failure when deleting
# dm device
#
# defaults {
# flush_on_last_del yes
# }
#
self._cleanup_faulty_dm_devices()
def _get_emc_device_paths(self):
# Find all the EMC iSCSI devices under /dev/disk/by-path
# except LUNZ and partition reference
pattern = '/dev/disk/by-path/ip-*-iscsi-iqn*com.emc*-lun-*'
device_paths = [path for path in glob.glob(pattern)
if ('lun-0' not in path and '-part' not in path)]
return device_paths
def _run_multipath(self, multipath_command, **kwargs):
check_exit_code = kwargs.pop('check_exit_code', 0)
(out, err) = utils.execute('multipath',
*multipath_command,
run_as_root=True,
check_exit_code=check_exit_code)
print ("multipath %(command)s: stdout=%(out)s stderr=%(err)s"
% {'command': multipath_command, 'out': out, 'err': err})
return out, err
if __name__ == "__main__":
if len(sys.argv) != 3 or sys.argv[1] != '--config-file':
usage()
exit(1)
out, err = utils.execute('which', 'multipath', check_exit_code=False)
if 'multipath' not in out:
print('Info: Multipath tools not installed. No cleanup need be done.')
exit(0)
multipath_flush_on_last_del = False
multipath_conf_path = "/etc/multipath.conf"
if os.path.exists(multipath_conf_path):
flush_on_last_del_yes = re.compile(r'\s*flush_on_last_del.*yes')
for line in open(multipath_conf_path, "r"):
if flush_on_last_del_yes.match(line):
multipath_flush_on_last_del = True
break
if not multipath_flush_on_last_del:
print("Warning: 'flush_on_last_del yes' is not seen in"
" /etc/multipath.conf."
" 'map in use' failure may show up during cleanup.")
CONF(sys.argv[1:])
# connect_volume and disconnect_volume in nova/virt/libvirt/volume.py
# need be adjusted to take the same 'external=True' lock for
# synchronization
#utils.synchronized('connect_volume', external=True)
def do_cleanup():
cleaner = FaultyDevicesCleaner()
cleaner.cleanup()
do_cleanup()

https://wiki.python.org/moin/BeginnersGuide/Programmers
http://www.astro.ufl.edu/~warner/prog/python.html
looks like this python version 3 so. go for the tutorials of version three.
try downloading any IDE. eric5 is good by the way.
try executing this file once.
learn indentations
and dynamic variable declaration
do not jump into the ocean first try swimming pool : )

Also Try to learn method declaration.
Python is a bit different than java.
I will give you a hint looks like system call are also made to execute os commands so try looking at subprocess and how its output is directed to an output stream and error stream.

Return value VarBinds pysnmp

I've made my first Python SNMP agent from a custom MIB .
It is supporting SNMP GET and SET requests, but it returns values ​​pre-determined by me.
How do I make my function's returned varbinds' be the values ​​that users have supplied via their SNMP SETs?
The code:
from pysnmp.entity import engine, config
from pysnmp import debug
from pysnmp.entity.rfc3413 import cmdrsp, context, ntforg
from pysnmp.carrier.asynsock.dgram import udp
from pysnmp.proto.rfc1902 import OctetString
from pysnmp.smi import builder
import threading
import collections
import time
#can be useful
debug.setLogger(debug.Debug('all'))
MibObject = collections.namedtuple('MibObject', ['mibName',
'objectType', 'valueFunc'])
class Mib(object):
"""Stores the data we want to serve.
"""
def __init__(self):
self._lock = threading.RLock()
self._system_channel = 0
self._system_programmed = 0
def getSystemModel(self):
return "Teste 1 Ok"
def getTransportStream(self):
return "Teste 2 Ok"
def getSystemProgrammedPower(self):
with self._lock:
return self._system_programmed
def setSystemProgrammedPower(self, value):
with self._lock:
self._system_programmed = value
def getSystemChannel(self):
with self._lock:
return self._system_channel
def setSystemChannel(self, value):
with self._lock:
self._system_channel = value
def createVariable(SuperClass, getValue, *args):
"""This is going to create a instance variable that we can export.
getValue is a function to call to retreive the value of the scalar
"""
class Var(SuperClass):
def readGet(self, name, *args):
return name, self.syntax.clone(getValue())
return Var(*args)
class SNMPAgent(object):
"""Implements an Agent that serves the custom MIB and
can send a trap.
"""
def __init__(self, mibObjects):
"""
mibObjects - a list of MibObject tuples that this agent
will serve
"""
#each SNMP-based application has an engine
self._snmpEngine = engine.SnmpEngine()
#open a UDP socket to listen for snmp requests
config.addSocketTransport(
self._snmpEngine,
udp.domainName,
udp.UdpTransport().openServerMode(('127.0.0.1', 161))
)
# SNMPv3/USM setup
config.addV1System(self._snmpEngine, 'test-agent', 'public')
# user: usr-sha-none, auth: SHA, priv NONE
config.addV3User(
self._snmpEngine, 'test-user',
config.usmHMACMD5AuthProtocol, 'authkey1',
config.usmDESPrivProtocol, 'privkey1'
)
# Allow full MIB access for each user at VACM
config.addContext(self._snmpEngine, '')
config.addRwUser(self._snmpEngine, 1, 'test-agent', 'noAuthNoPriv', (1,3,6)) # v1
config.addRwUser(self._snmpEngine, 2, 'test-agent', 'noAuthNoPriv', (1,3,6)) # v2c
config.addRwUser(self._snmpEngine, 3, 'test-user', 'authPriv', (1,3,6)) # v3
#each app has one or more contexts
self._snmpContext = context.SnmpContext(self._snmpEngine)
#the builder is used to load mibs. tell it to look in the
#current directory for our new MIB. We'll also use it to
#export our symbols later
mibBuilder = self._snmpContext.getMibInstrum().getMibBuilder()
mibSources = mibBuilder.getMibSources() + (builder.DirMibSource('.'),)
mibBuilder.setMibSources(*mibSources)
#our variables will subclass this since we only have scalar types
#can't load this type directly, need to import it
MibScalarInstance, = mibBuilder.importSymbols('SNMPv2-SMI',
'MibScalarInstance')
#export our custom mib
for mibObject in mibObjects:
nextVar, = mibBuilder.importSymbols(mibObject.mibName,
mibObject.objectType)
instance = createVariable(MibScalarInstance,
mibObject.valueFunc,
nextVar.name, (0,),
nextVar.syntax)
#need to export as <var name>Instance
instanceDict = {str(nextVar.name)+"Instance":instance}
mibBuilder.exportSymbols(mibObject.mibName,
**instanceDict)
# tell pysnmp to respotd to get, set, getnext, and getbulk
cmdrsp.GetCommandResponder(self._snmpEngine, self._snmpContext)
cmdrsp.NextCommandResponder(self._snmpEngine, self._snmpContext)
cmdrsp.BulkCommandResponder(self._snmpEngine, self._snmpContext)
cmdrsp.SetCommandResponder(self._snmpEngine, self._snmpContext)
def setTrapReceiver(self, host, community):
"""Send traps to the host using community string community
"""
config.addV1System(self._snmpEngine, 'nms-area', community)
config.addVacmUser(self._snmpEngine, 2, 'nms-area', 'noAuthNoPriv',
notifySubTree=(1,3,6,1,4,1))
config.addTargetParams(self._snmpEngine,
'nms-creds', 'nms-area', 'noAuthNoPriv', 1)
config.addTargetAddr(self._snmpEngine, 'my-nms', udp.domainName,
(host, 162), 'nms-creds',
tagList='all-my-managers')
#set last parameter to 'notification' to have it send
#informs rather than unacknowledged traps
config.addNotificationTarget(
self._snmpEngine, 'test-notification', 'my-filter',
'all-my-managers', 'trap')
def sendTrap(self):
print "Sending trap"
ntfOrg = ntforg.NotificationOriginator(self._snmpContext)
errorIndication = ntfOrg.sendNotification(
self._snmpEngine,
'test-notification',
('LINEARISDBLQ-MIB', 'systemCurrentAlarmTrap'),
())
def serve_forever(self):
print "Starting agent"
self._snmpEngine.transportDispatcher.jobStarted(1)
try:
self._snmpEngine.transportDispatcher.runDispatcher()
except:
self._snmpEngine.transportDispatcher.closeDispatcher()
raise
class Worker(threading.Thread):
"""Just to demonstrate updating the MIB
and sending traps
"""
def __init__(self, agent, mib):
threading.Thread.__init__(self)
self._agent = agent
self._mib = mib
self.setDaemon(True)
def run(self):
while True:
time.sleep(3)
self._mib.setSystemChannel(mib.getSystemChannel()+1)
self._agent.sendTrap()
if __name__ == '__main__':
mib = Mib()
objects = [MibObject('LINEARISDBLQ-MIB', 'systemModel', mib.getSystemModel),
MibObject('LINEARISDBLQ-MIB', 'systemChannel', mib.getSystemChannel),
MibObject('LINEARISDBLQ-MIB', 'transportStream', mib.getTransportStream),
MibObject('LINEARISDBLQ-MIB', 'systemProgrammedPower', mib.getSystemProgrammedPower)]
agent = SNMPAgent(objects)
agent.setTrapReceiver('127.0.0.1', 'traps')
Worker(agent, mib).start()
try:
agent.serve_forever()
except KeyboardInterrupt:
print "Shutting down"

Looks like you designed your own MIB structures which are not connected to pysnmp engine.
To make your MIB variables available to pysnmp-based Agent, you have to either A) inherit your MIB objects from pysnmp's MibScalarInstance class or B) build your own MIB Controller supporting pysnmp-compatible interfaces.
For more information please refer to the above examples.

Python error Module has no attribute token

I am trying to find the tweets using this code but it is resulting a traceback
Please help me to resolve the problem.
import time
import pycurl
import urllib
import json
import oauth2 as oauth
API_ENDPOINT_URL = 'https://stream.twitter.com/1.1/statuses/filter.json'
USER_AGENT = 'TwitterStream 1.0' # This can be anything really
# You need to replace these with your own values
OAUTH_KEYS = {'consumer_key': 'ABC',
'consumer_secret': 'ABC',
'access_token_key': 'ABC',
'access_token_secret': 'ABC'}
# These values are posted when setting up the connection
POST_PARAMS = {'include_entities': 0,
'stall_warning': 'true',
'track': 'iphone,ipad,ipod'}
# twitter streaming is here
class TwitterStream:
def __init__(self, timeout=False):
self.oauth_token = oauth.Token(key=OAUTH_KEYS['access_token_key'], secret=OAUTH_KEYS['access_token_secret'])
self.oauth_consumer = oauth.Consumer(key=OAUTH_KEYS['consumer_key'], secret=OAUTH_KEYS['consumer_secret'])
self.conn = None
self.buffer = ''
self.timeout = timeout
self.setup_connection()
def setup_connection(self):
""" Create persistant HTTP connection to Streaming API endpoint using cURL.
"""
if self.conn:
self.conn.close()
self.buffer = ''
self.conn = pycurl.Curl()
# Restart connection if less than 1 byte/s is received during "timeout" seconds
if isinstance(self.timeout, int):
self.conn.setopt(pycurl.LOW_SPEED_LIMIT, 1)
self.conn.setopt(pycurl.LOW_SPEED_TIME, self.timeout)
self.conn.setopt(pycurl.URL, API_ENDPOINT_URL)
self.conn.setopt(pycurl.USERAGENT, USER_AGENT)
# Using gzip is optional but saves us bandwidth.
self.conn.setopt(pycurl.ENCODING, 'deflate, gzip')
self.conn.setopt(pycurl.POST, 1)
self.conn.setopt(pycurl.POSTFIELDS, urllib.urlencode(POST_PARAMS))
self.conn.setopt(pycurl.HTTPHEADER, ['Host: stream.twitter.com',
'Authorization: %s' % self.get_oauth_header()])
# self.handle_tweet is the method that are called when new tweets arrive
self.conn.setopt(pycurl.WRITEFUNCTION, self.handle_tweet)
def get_oauth_header(self):
""" Create and return OAuth header.
"""
params = {'oauth_version': '1.0',
'oauth_nonce': oauth.generate_nonce(),
'oauth_timestamp': int(time.time())}
req = oauth.Request(method='POST', parameters=params, url='%s?%s' % (API_ENDPOINT_URL,
urllib.urlencode(POST_PARAMS)))
req.sign_request(oauth.SignatureMethod_HMAC_SHA1(), self.oauth_consumer, self.oauth_token)
return req.to_header()['Authorization'].encode('utf-8')
def start(self):
""" Start listening to Streaming endpoint.
Handle exceptions according to Twitter's recommendations.
"""
backoff_network_error = 0.25
backoff_http_error = 5
backoff_rate_limit = 60
while True:
self.setup_connection()
try:
self.conn.perform()
except:
# Network error, use linear back off up to 16 seconds
print 'Network error: %s' % self.conn.errstr()
print 'Waiting %s seconds before trying again' % backoff_network_error
time.sleep(backoff_network_error)
backoff_network_error = min(backoff_network_error + 1, 16)
continue
# HTTP Error
sc = self.conn.getinfo(pycurl.HTTP_CODE)
if sc == 420:
# Rate limit, use exponential back off starting with 1 minute and double each attempt
print 'Rate limit, waiting %s seconds' % backoff_rate_limit
time.sleep(backoff_rate_limit)
backoff_rate_limit *= 2
else:
# HTTP error, use exponential back off up to 320 seconds
print 'HTTP error %s, %s' % (sc, self.conn.errstr())
print 'Waiting %s seconds' % backoff_http_error
time.sleep(backoff_http_error)
backoff_http_error = min(backoff_http_error * 2, 320)
def handle_tweet(self, data):
""" This method is called when data is received through Streaming endpoint.
"""
self.buffer += data
if data.endswith('\r\n') and self.buffer.strip():
# complete message received
message = json.loads(self.buffer)
self.buffer = ''
msg = ''
if message.get('limit'):
print 'Rate limiting caused us to miss %s tweets' % (message['limit'].get('track'))
elif message.get('disconnect'):
raise Exception('Got disconnect: %s' % message['disconnect'].get('reason'))
elif message.get('warning'):
print 'Got warning: %s' % message['warning'].get('message')
else:
print 'Got tweet with text: %s' % message.get('text')
if __name__ == '__main__':
ts = TwitterStream()
ts.setup_connection()
ts.start()
Traceback call:
Traceback (most recent call last):
File "C:\Python27\nytimes\2062014\pycurltweets.py", line 115, in <module>
ts = TwitterStream()
File "C:\Python27\nytimes\2062014\pycurltweets.py", line 23, in __init__
self.oauth_token = oauth.token(key=OAUTH_KEYS['access_token_key'], secret=OAUTH_KEYS['access_token_secret'])
AttributeError: 'module' object has no attribute 'Token'

are you sure oauth2 is installed properly / is the correct version?
see http://data-scientist.ch/install-oauth2-for-python-on-windows/
open a python REPL shell and
import oauth2 as oauth
print oauth.OAUTH_VERSION
dir(oauth)
and post result

Alternative to tuntap

I'm trying to transmit TCP/IP over a radio that is connected to my computer (specifically, the USRP). Right now, it's done very simply using Tun/Tap to set up a new network interface. Here's the code:
from gnuradio import gr, gru, modulation_utils
from gnuradio import usrp
from gnuradio import eng_notation
from gnuradio.eng_option import eng_option
from optparse import OptionParser
import random
import time
import struct
import sys
import os
# from current dir
from transmit_path import transmit_path
from receive_path import receive_path
import fusb_options
#print os.getpid()
#raw_input('Attach and press enter')
# Linux specific...
# TUNSETIFF ifr flags from <linux/tun_if.h>
IFF_TUN = 0x0001 # tunnel IP packets
IFF_TAP = 0x0002 # tunnel ethernet frames
IFF_NO_PI = 0x1000 # don't pass extra packet info
IFF_ONE_QUEUE = 0x2000 # beats me ;)
def open_tun_interface(tun_device_filename):
from fcntl import ioctl
mode = IFF_TAP | IFF_NO_PI
TUNSETIFF = 0x400454ca
tun = os.open(tun_device_filename, os.O_RDWR)
ifs = ioctl(tun, TUNSETIFF, struct.pack("16sH", "gr%d", mode))
ifname = ifs[:16].strip("\x00")
return (tun, ifname)
# /////////////////////////////////////////////////////////////////////////////
# the flow graph
# /////////////////////////////////////////////////////////////////////////////
class my_top_block(gr.top_block):
def __init__(self, mod_class, demod_class,
rx_callback, options):
gr.top_block.__init__(self)
self.txpath = transmit_path(mod_class, options)
self.rxpath = receive_path(demod_class, rx_callback, options)
self.connect(self.txpath);
self.connect(self.rxpath);
def send_pkt(self, payload='', eof=False):
return self.txpath.send_pkt(payload, eof)
def carrier_sensed(self):
"""
Return True if the receive path thinks there's carrier
"""
return self.rxpath.carrier_sensed()
# /////////////////////////////////////////////////////////////////////////////
# Carrier Sense MAC
# /////////////////////////////////////////////////////////////////////////////
class cs_mac(object):
"""
Prototype carrier sense MAC
Reads packets from the TUN/TAP interface, and sends them to the PHY.
Receives packets from the PHY via phy_rx_callback, and sends them
into the TUN/TAP interface.
Of course, we're not restricted to getting packets via TUN/TAP, this
is just an example.
"""
def __init__(self, tun_fd, verbose=False):
self.tun_fd = tun_fd # file descriptor for TUN/TAP interface
self.verbose = verbose
self.tb = None # top block (access to PHY)
def set_top_block(self, tb):
self.tb = tb
def phy_rx_callback(self, ok, payload):
"""
Invoked by thread associated with PHY to pass received packet up.
#param ok: bool indicating whether payload CRC was OK
#param payload: contents of the packet (string)
"""
if self.verbose:
print "Rx: ok = %r len(payload) = %4d" % (ok, len(payload))
if ok:
os.write(self.tun_fd, payload)
def main_loop(self):
"""
Main loop for MAC.
Only returns if we get an error reading from TUN.
FIXME: may want to check for EINTR and EAGAIN and reissue read
"""
min_delay = 0.001 # seconds
while 1:
payload = os.read(self.tun_fd, 10*1024)
if not payload:
self.tb.send_pkt(eof=True)
break
if self.verbose:
print "Tx: len(payload) = %4d" % (len(payload),)
delay = min_delay
while self.tb.carrier_sensed():
sys.stderr.write('B')
time.sleep(delay)
if delay < 0.050:
delay = delay * 2 # exponential back-off
self.tb.send_pkt(payload)
# /////////////////////////////////////////////////////////////////////////////
# main
# /////////////////////////////////////////////////////////////////////////////
def main():
mods = modulation_utils.type_1_mods()
demods = modulation_utils.type_1_demods()
parser = OptionParser (option_class=eng_option, conflict_handler="resolve")
expert_grp = parser.add_option_group("Expert")
parser.add_option("-m", "--modulation", type="choice", choices=mods.keys(),
default='gmsk',
help="Select modulation from: %s [default=%%default]"
% (', '.join(mods.keys()),))
parser.add_option("-v","--verbose", action="store_true", default=False)
expert_grp.add_option("-c", "--carrier-threshold", type="eng_float", default=30,
help="set carrier detect threshold (dB) [default=%default]")
expert_grp.add_option("","--tun-device-filename", default="/dev/net/tun",
help="path to tun device file [default=%default]")
transmit_path.add_options(parser, expert_grp)
receive_path.add_options(parser, expert_grp)
for mod in mods.values():
mod.add_options(expert_grp)
for demod in demods.values():
demod.add_options(expert_grp)
fusb_options.add_options(expert_grp)
(options, args) = parser.parse_args ()
if len(args) != 0:
parser.print_help(sys.stderr)
sys.exit(1)
if options.rx_freq is None or options.tx_freq is None:
sys.stderr.write("You must specify -f FREQ or --freq FREQ\n")
parser.print_help(sys.stderr)
sys.exit(1)
# open the TUN/TAP interface
(tun_fd, tun_ifname) = open_tun_interface(options.tun_device_filename)
# Attempt to enable realtime scheduling
r = gr.enable_realtime_scheduling()
if r == gr.RT_OK:
realtime = True
else:
realtime = False
print "Note: failed to enable realtime scheduling"
# If the user hasn't set the fusb_* parameters on the command line,
# pick some values that will reduce latency.
if options.fusb_block_size == 0 and options.fusb_nblocks == 0:
if realtime: # be more aggressive
options.fusb_block_size = gr.prefs().get_long('fusb', 'rt_block_size', 1024)
options.fusb_nblocks = gr.prefs().get_long('fusb', 'rt_nblocks', 16)
else:
options.fusb_block_size = gr.prefs().get_long('fusb', 'block_size', 4096)
options.fusb_nblocks = gr.prefs().get_long('fusb', 'nblocks', 16)
#print "fusb_block_size =", options.fusb_block_size
#print "fusb_nblocks =", options.fusb_nblocks
# instantiate the MAC
mac = cs_mac(tun_fd, verbose=True)
# build the graph (PHY)
tb = my_top_block(mods[options.modulation],
demods[options.modulation],
mac.phy_rx_callback,
options)
mac.set_top_block(tb) # give the MAC a handle for the PHY
if tb.txpath.bitrate() != tb.rxpath.bitrate():
print "WARNING: Transmit bitrate = %sb/sec, Receive bitrate = %sb/sec" % (
eng_notation.num_to_str(tb.txpath.bitrate()),
eng_notation.num_to_str(tb.rxpath.bitrate()))
print "modulation: %s" % (options.modulation,)
print "freq: %s" % (eng_notation.num_to_str(options.tx_freq))
print "bitrate: %sb/sec" % (eng_notation.num_to_str(tb.txpath.bitrate()),)
print "samples/symbol: %3d" % (tb.txpath.samples_per_symbol(),)
#print "interp: %3d" % (tb.txpath.interp(),)
#print "decim: %3d" % (tb.rxpath.decim(),)
tb.rxpath.set_carrier_threshold(options.carrier_threshold)
print "Carrier sense threshold:", options.carrier_threshold, "dB"
print
print "Allocated virtual ethernet interface: %s" % (tun_ifname,)
print "You must now use ifconfig to set its IP address. E.g.,"
print
print " $ sudo ifconfig %s 192.168.200.1" % (tun_ifname,)
print
print "Be sure to use a different address in the same subnet for each machine."
print
tb.start() # Start executing the flow graph (runs in separate threads)
mac.main_loop() # don't expect this to return...
tb.stop() # but if it does, tell flow graph to stop.
tb.wait() # wait for it to finish
if __name__ == '__main__':
try:
main()
except KeyboardInterrupt:
pass
(Anyone familiar with GNU Radio will recognize this as tunnel.py)
My question is, is there a better way to move packets to and from the kernel than tun/tap? I've been looking at ipip or maybe using sockets, but I'm pretty sure those won't be very fast. Speed is what I'm most concerned with.

Remember that tunnel.py is a really, really rough example, and hasn't been updated in a while. It's not really meant to be a basis for other code, so be careful of how much you rely on the code.
Also, remember that TCP over unreliable radio links has significant issues:
http://en.wikipedia.org/wiki/Transmission_Control_Protocol#TCP_over_wireless_networks