# portions extracted from ipaddresslib by Autonomous Zone Industries, LGPL (author: Greg Smith)
# portions adapted from nattraverso.ipdiscover
# portions authored by Brian Warner, working for Allmydata
# most recent version authored by Zooko O'Whielacronx, working for Allmydata

# from the Python Standard Library
import re, socket, sys

# from Twisted
from twisted.internet import defer
from twisted.internet import reactor
from twisted.internet.protocol import DatagramProtocol
from twisted.internet.utils import getProcessOutput
from twisted.python.procutils import which

def get_local_addresses_async(target='A.ROOT-SERVERS.NET'):
    """
    Return a Deferred that fires with a list of IPv4 addresses (as dotted-quad
    strings) that are currently configured on this host, sorted in descending
    order of how likely we think they are to work.

    @param target: we want to learn an IP address they could try using to
        connect to us; The default value is fine, but it might help if you
        pass the address of a host that you are actually trying to be
        reachable to.
    """
    addresses = []
    local_ip = get_local_ip_for(target)
    if local_ip:
        addresses.append(local_ip)

    if sys.platform == "cygwin":
        d = _cygwin_hack_find_addresses(target)
    else:
        d = _find_addresses_via_config()

    def _collect(res):
        for addr in res:
            if not addr in addresses:
                addresses.append(addr)
        return addresses
    d.addCallback(_collect)

    return d

def get_local_ip_for(target):
    """Find out what our IP address is for use by a given target.

    @returns:the IP address as a dotted-quad string which could be used by
              to connect to us. It might work for them, it might not. If
              there is no suitable address (perhaps we don't currently have an
              externally-visible interface), this will return None.
    """

    try:
        target_ipaddr = socket.gethostbyname(target)
    except socket.gaierror:
        # DNS isn't running
        return None
    udpprot = DatagramProtocol()
    port = reactor.listenUDP(0, udpprot)
    try:
        udpprot.transport.connect(target_ipaddr, 7)
        localip = udpprot.transport.getHost().host
    except socket.error:
        # no route to that host
        localip = None
    port.stopListening() # note, this returns a Deferred
    return localip

# k: result of sys.platform, v: which kind of IP configuration reader we use
_platform_map = {
    "linux-i386": "linux", # redhat
    "linux-ppc": "linux",  # redhat
    "linux2": "linux",     # debian
    "win32": "win32",
    "irix6-n32": "irix",
    "irix6-n64": "irix",
    "irix6": "irix",
    "openbsd2": "bsd",
    "darwin": "bsd",       # Mac OS X
    "freebsd4": "bsd",
    "freebsd5": "bsd",
    "netbsd1": "bsd",
    "sunos5": "sunos",
    "cygwin": "cygwin",
    }

class UnsupportedPlatformError(Exception):
    pass

# Wow, I'm really amazed at home much mileage we've gotten out of calling
# the external route.exe program on windows...  It appears to work on all
# versions so far.  Still, the real system calls would much be preferred...
# ... thus wrote Greg Smith in time immemorial...
_win32_path = 'route.exe'
_win32_args = ('print',)
_win32_re = re.compile('^\s*\d+\.\d+\.\d+\.\d+\s.+\s(?P<address>\d+\.\d+\.\d+\.\d+)\s+(?P<metric>\d+)\s*$', flags=re.M|re.I|re.S)

# These work in Redhat 6.x and Debian 2.2 potato
_linux_path = '/sbin/ifconfig'
_linux_re = re.compile('^\s*inet addr:(?P<address>\d+\.\d+\.\d+\.\d+)\s.+$', flags=re.M|re.I|re.S)

# NetBSD 1.4 (submitted by Rhialto), Darwin, Mac OS X
_netbsd_path = '/sbin/ifconfig'
_netbsd_args = ('-a',)
_netbsd_re = re.compile('^\s+inet (?P<address>\d+\.\d+\.\d+\.\d+)\s.+$', flags=re.M|re.I|re.S)

# Irix 6.5
_irix_path = '/usr/etc/ifconfig'

# Solaris 2.x
_sunos_path = '/usr/sbin/ifconfig'

# k: platform string as provided in the value of _platform_map
# v: tuple of (path_to_tool, args, regex,)
_tool_map = {
    "linux": (_linux_path, (), _linux_re,),
    "win32": (_win32_path, _win32_args, _win32_re,),
    "cygwin": (_win32_path, _win32_args, _win32_re,),
    "bsd": (_netbsd_path, _netbsd_args, _netbsd_re,),
    "irix": (_irix_path, _netbsd_args, _netbsd_re,),
    "sunos": (_sunos_path, _netbsd_args, _netbsd_re,),
    }
def _find_addresses_via_config():
    # originally by Greg Smith, hacked by Zooko to conform to Brian's API
    
    platform = _platform_map.get(sys.platform)
    if not platform:
        raise UnsupportedPlatformError(sys.platform)

    (pathtotool, args, regex,) = _tool_map[platform]
    
    l = []
    for executable in which(pathtotool):
        l.append(_query(executable, args, regex))
    dl = defer.DeferredList(l)
    def _gather_results(res):
        addresses = []
        for (succ, addrs,) in res:
            if succ:
                for addr in addrs:
                    if addr not in addresses:
                        addresses.append(addr)
        return addresses
    dl.addCallback(_gather_results)
    return dl

def _query(path, args, regex):
    d = getProcessOutput(path, args)
    def _parse(output):
        addresses = []
        outputsplit = output.split('\n')
        for outline in outputsplit:
            m = regex.match(outline)
            if m:
                addr = m.groupdict()['address']
                if addr not in addresses:
                    addresses.append(addr)
    
        return addresses
    d.addCallback(_parse)
    return d

def _cygwin_hack_find_addresses(target):
    addresses = []
    for h in [target, "localhost", "127.0.0.1",]:
        try:
            addr = get_local_ip_for(h)
            if addr not in addresses:
                addresses.append(addr)
        except socket.gaierror:
            pass

    return defer.succeed(addresses)