osmopy/obscvty.py

# Copyright (C) 2012, 2013 Holger Hans Peter Freyther
# Copyright (C) 2013 Katerina Barone-Adesi
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

#
# VTY helper code for OpenBSC
#
import re
import socket
import sys, subprocess
import os
import time

"""VTYInteract: interact with an osmocom vty

Specify a VTY to connect to, and run commands on it.
Connections will be reestablished as necessary.
Methods: __init__, command, enabled_command, verify, w_verify"""

debug_tcp_sockets = (os.getenv('OSMOPY_DEBUG_TCP_SOCKETS', '0') != '0')

def cmd(what):
    print '\n> %s' % what
    sys.stdout.flush()
    subprocess.call(what, shell=True)
    sys.stdout.flush()
    sys.stderr.flush()
    print ''
    sys.stdout.flush()

def print_used_tcp_sockets():
    global debug_tcp_sockets
    if not debug_tcp_sockets:
        return
    cmd('ls -l /proc/' + str(os.getpid()) + '/fd');
    cmd('ss -tn');
    cmd('ss -tln');
    cmd('ps xua | grep osmo');

class VTYInteract(object):
    """__init__(self, name, host, port):

    name is the name the vty prints for commands, ie OpenBSC
    host is the hostname to connect to
    port is the port to connect on"""

    all_sockets = []

    def __init__(self, name, host, port):
        print_used_tcp_sockets()

        self.name = name
        self.host = host
        self.port = port

        self.socket = None
        self.norm_end = re.compile('\r\n%s(?:\(([\w-]*)\))?> $' % self.name)
        self.priv_end = re.compile('\r\n%s(?:\(([\w-]*)\))?# $' % self.name)
        self.last_node = ''

    def _connect_socket(self):
        if self.socket is not None:
            return
        retries = 30
        took = 0
        while True:
            took += 1
            try:
                self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                self.socket.setblocking(1)
                self.socket.connect((self.host, self.port))
            except IOError:
                retries -= 1
                if retries <= 0:
                    raise
                # possibly the binary hasn't launched yet
                if debug_tcp_sockets:
                    print "Connecting socket failed, retrying..."
                time.sleep(.1)
                continue
            break

        if debug_tcp_sockets:
            VTYInteract.all_sockets.append(self.socket)
            print "Socket: in %d tries, connected to %s:%d %r (%d sockets open)" % (
                    took, self.host, self.port, self.socket,
                    len(VTYInteract.all_sockets))
        self.socket.recv(4096)

    def _close_socket(self):
        global debug_tcp_sockets
        if self.socket is None:
            return

        if debug_tcp_sockets:
            try:
                VTYInteract.all_sockets.remove(self.socket)
            except ValueError:
                pass
            print "Socket: closing %s:%d %r (%d sockets open)" % (
                    self.host, self.port, self.socket,
                    len(VTYInteract.all_sockets))
        self.socket.close()
        self.socket = None

    def _is_end(self, text, ends):
        """
            >>> vty = VTYInteract('OsmoNAT', 'localhost', 9999)
            >>> end = [vty.norm_end, vty.priv_end]

            Simple test
            >>> text1 = 'abc\\r\\nOsmoNAT> '
            >>> vty._is_end(text1, end)
            11

            Simple test with the enabled node
            >>> text2 = 'abc\\r\\nOsmoNAT# '
            >>> vty._is_end(text2, end)
            11

            Now the more complicated one
            >>> text3 = 'abc\\r\\nOsmoNAT(config)# '
            >>> vty._is_end(text3, end)
            19

            Now the more complicated one
            >>> text4 = 'abc\\r\\nOsmoNAT(config-nat)# '
            >>> vty._is_end(text4, end)
            23

            Now the more complicated one
            >>> text5 = 'abc\\r\\nmoo'
            >>> vty._is_end(text5, end)
            0

            Check for node name extraction
            >>> text6 = 'abc\\r\\nOsmoNAT(config-nat)# '
            >>> vty._is_end(text6, end)
            23
            >>> vty.node()
            'config-nat'

            Check for empty node name extraction
            >>> text7 = 'abc\\r\\nOsmoNAT# '
            >>> vty._is_end(text7, end)
            11
            >>> vty.node() is None
            True

        """
        self.last_node = None
        for end in ends:
            match = end.search(text)
            if match:
                self.last_node = match.group(1)
                return match.end() - match.start()
        return 0

    def _common_command(self, request, close=False, ends=None):
        global debug_tcp_sockets
        if not ends:
            ends = [self.norm_end, self.priv_end]

        self._connect_socket()

        # Now send the command
        self.socket.send("%s\r" % request)
        res = ""
        end = ""

        # Unfortunately, timeout and recv don't always play nicely
        while True:
            data = self.socket.recv(4096)
            res = "%s%s" % (res, data)
            if not res:  # yes, this is ugly
                raise IOError("Failed to read data (did the app crash?)")
            end = self._is_end(res, ends)
            if end > 0:
                break

        if close:
            self._close_socket()
        return res[len(request) + 2: -end]

    """A generator function yielding lines separated by delim.
       Behaves similar to a file readlines() method.

       Example of use:
        for line in vty.readlines():
            print line
    """
    def readlines(self, recv_buffer=4096, delim='\n'):
        buffer = ''
        data = True
        while data:
            data = self.socket.recv(recv_buffer)
            buffer += data

            while buffer.find(delim) != -1:
                line, buffer = buffer.split('\n', 1)
                yield line
        return

    # There's no close parameter, as close=True makes this useless
    def enable(self):
        self.command("enable")

    """Run a command on the vty"""

    def command(self, request, close=False):
        return self._common_command(request, close)

    """Run enable, followed by another command"""
    def enabled_command(self, request, close=False):
        self.enable()
        return self._common_command(request, close)

    """Verify, ignoring leading/trailing whitespace"""
    # inspired by diff -w, though not identical
    def w_verify(self, command, results, close=False, loud=True):
        return self.verify(command, results, close, loud, lambda x: x.strip())

    """Verify that a command has the expected results

    command = the command to verify
    results = the expected results [line1, line2, ...]
    close = True to close the socket after running the verify
    loud = True to show what was expected and what actually happend, stdout
    f = A function to run over the expected and actual results, before compare

    Returns True iff the expected and actual results match"""
    def verify(self, command, results, close=False, loud=True, f=None):
        res = self.command(command, close).split('\r\n')
        if f:
            res = map(f, res)
            results = map(f, results)

        if loud:
            if res != results:
                print "Rec: %s\nExp: %s" % (res, results)

        return res == results

    def node(self):
        return self.last_node

if __name__ == "__main__":
    import doctest
    doctest.testmod()