Merge pull request #4305 from minrk/even-more-ways-to-get-ifaces

Add even more ways to populate localinterfaces

use netifaces for faster IPython.utils.localinterfaces when availlable, 

Parse subprocess output from ifconfig / ip addr / ipconfig.
Lower priority than netifaces, but still higher priority than socket.gethostbyname.

Fallback to gethostname otherwise.

Should be much faster in worst case scenario where machine are badly configurred and can wait up to ~30s to start ipython. Slighly slower in other cases.

IPython/utils/localinterfaces.py

@@ -5,12 +5,14 b' LOCALHOST : The loopback interface, or the first interface that points to this'
             machine.  It will *almost* always be '127.0.0.1'
 
 LOCAL_IPS : A list of IP addresses, loopback first, that point to this machine.
+            This will include LOCALHOST, PUBLIC_IPS, and aliases for all hosts,
+            such as '0.0.0.0'.
 
 PUBLIC_IPS : A list of public IP addresses that point to this machine.
              Use these to tell remote clients where to find you.
 """
 #-----------------------------------------------------------------------------
-#  Copyright (C) 2010-2011  The IPython Development Team
+#  Copyright (C) 2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
@@ -20,9 +22,13 b' PUBLIC_IPS : A list of public IP addresses that point to this machine.'
 # Imports
 #-----------------------------------------------------------------------------
 
+import os
 import socket
 
 from .data import uniq_stable
+from .process import get_output_error_code
+from .py3compat import bytes_to_str
+from .warn import warn
 
 #-----------------------------------------------------------------------------
 # Code
@@ -31,7 +37,7 b' from .data import uniq_stable'
 LOCAL_IPS = []
 PUBLIC_IPS = []
 
-LOCALHOST = '127.0.0.1'
+LOCALHOST = ''
 
 def _only_once(f):
     """decorator to only run a function once"""
@@ -51,17 +57,124 b' def _requires_ips(f):'
         return f(*args, **kwargs)
     return ips_loaded
 
-@_only_once
-def _load_ips():
-    """load the IPs that point to this machine
+# subprocess-parsing ip finders
+class NoIPAddresses(Exception):
+    pass
+
+def _populate_from_list(addrs):
+    """populate local and public IPs from flat list of all IPs"""
+    if not addrs:
+        raise NoIPAddresses
     
-    This function will only ever be called once.
+    global LOCALHOST
+    public_ips = []
+    local_ips = []
+    
+    for ip in addrs:
+        local_ips.append(ip)
+        if not ip.startswith('127.'):
+            public_ips.append(ip)
+        elif not LOCALHOST:
+            LOCALHOST = ip
+    
+    if not LOCALHOST:
+        LOCALHOST = '127.0.0.1'
+        local_ips.insert(0, LOCALHOST)
+        
+    local_ips.extend(['0.0.0.0', ''])
+    
+    LOCAL_IPS[:] = uniq_stable(local_ips)
+    PUBLIC_IPS[:] = uniq_stable(public_ips)
+
+def _load_ips_ifconfig():
+    """load ip addresses from `ifconfig` output (posix)"""
+    
+    out, err, rc = get_output_error_code('ifconfig')
+    if rc:
+        # no ifconfig, it's usually in /sbin and /sbin is not on everyone's PATH
+        out, err, rc = get_output_error_code('/sbin/ifconfig')
+    if rc:
+        raise IOError("no ifconfig: %s" % err)
+    
+    lines = bytes_to_str(out).splitlines()
+    addrs = []
+    for line in lines:
+        blocks = line.lower().split()
+        if blocks[0] == 'inet':
+            addrs.append(blocks[1])
+    _populate_from_list(addrs)
+
+
+def _load_ips_ip():
+    """load ip addresses from `ip addr` output (Linux)"""
+    out, err, rc = get_output_error_code('ip addr')
+    if rc:
+        raise IOError("no ip: %s" % err)
+    
+    lines = bytes_to_str(out).splitlines()
+    addrs = []
+    for line in lines:
+        blocks = line.lower().split()
+        if blocks[0] == 'inet':
+            addrs.append(blocks[1].split('/')[0])
+    _populate_from_list(addrs)
+
+
+def _load_ips_ipconfig():
+    """load ip addresses from `ipconfig` output (Windows)"""
+    out, err, rc = get_output_error_code('ipconfig')
+    if rc:
+        raise IOError("no ipconfig: %s" % err)
+    
+    lines = bytes_to_str(out).splitlines()
+    addrs = ['127.0.0.1']
+    for line in lines:
+        line = line.lower().split()
+        if line[:2] == ['ipv4', 'address']:
+            addrs.append(line.split()[-1])
+    _populate_from_list(addrs)
+
+
+def _load_ips_netifaces():
+    """load ip addresses with netifaces"""
+    import netifaces
+    global LOCALHOST
+    local_ips = []
+    public_ips = []
+    
+    # list of iface names, 'lo0', 'eth0', etc.
+    for iface in netifaces.interfaces():
+        # list of ipv4 addrinfo dicts
+        ipv4s = netifaces.ifaddresses(iface).get(netifaces.AF_INET, [])
+        for entry in ipv4s:
+            addr = entry.get('addr')
+            if not addr:
+                continue
+            if not (iface.startswith('lo') or addr.startswith('127.')):
+                public_ips.append(addr)
+            elif not LOCALHOST:
+                LOCALHOST = addr
+            local_ips.append(addr)
+    if not LOCALHOST:
+        # we never found a loopback interface (can this ever happen?), assume common default
+        LOCALHOST = '127.0.0.1'
+        local_ips.insert(0, LOCALHOST)
+    local_ips.extend(['0.0.0.0', ''])
+    LOCAL_IPS[:] = uniq_stable(local_ips)
+    PUBLIC_IPS[:] = uniq_stable(public_ips)
+
+
+def _load_ips_gethostbyname():
+    """load ip addresses with socket.gethostbyname_ex
+    
+    This can be slow.
     """
     global LOCALHOST
     try:
         LOCAL_IPS[:] = socket.gethostbyname_ex('localhost')[2]
     except socket.error:
-        pass
+        # assume common default
+        LOCAL_IPS[:] = ['127.0.0.1']
     
     try:
         hostname = socket.gethostname()
@@ -74,7 +187,7 b' def _load_ips():'
     finally:
         PUBLIC_IPS[:] = uniq_stable(PUBLIC_IPS)
         LOCAL_IPS.extend(PUBLIC_IPS)
-
+    
     # include all-interface aliases: 0.0.0.0 and ''
     LOCAL_IPS.extend(['0.0.0.0', ''])
 
@@ -82,6 +195,57 b' def _load_ips():'
 
     LOCALHOST = LOCAL_IPS[0]
 
+def _load_ips_dumb():
+    """Fallback in case of unexpected failure"""
+    global LOCALHOST
+    LOCALHOST = '127.0.0.1'
+    LOCAL_IPS[:] = [LOCALHOST, '0.0.0.0', '']
+    PUBLIC_IPS[:] = []
+
+@_only_once
+def _load_ips():
+    """load the IPs that point to this machine
+    
+    This function will only ever be called once.
+    
+    It will use netifaces to do it quickly if available.
+    Then it will fallback on parsing the output of ifconfig / ip addr / ipconfig, as appropriate.
+    Finally, it will fallback on socket.gethostbyname_ex, which can be slow.
+    """
+    
+    try:
+        # first priority, use netifaces
+        try:
+            return _load_ips_netifaces()
+        except ImportError:
+            pass
+        
+        # second priority, parse subprocess output (how reliable is this?)
+        
+        if os.name == 'nt':
+            try:
+                return _load_ips_ipconfig()
+            except (IOError, NoIPAddresses):
+                pass
+        else:
+            try:
+                return _load_ips_ifconfig()
+            except (IOError, NoIPAddresses):
+                pass
+            try:
+                return _load_ips_ip()
+            except (IOError, NoIPAddresses):
+                pass
+        
+        # lowest priority, use gethostbyname
+        
+        return _load_ips_gethostbyname()
+    except Exception as e:
+        # unexpected error shouldn't crash, load dumb default values instead.
+        warn("Unexpected error discovering local network interfaces: %s" % e)
+    _load_ips_dumb()
+
+
 @_requires_ips
 def local_ips():
     """return the IP addresses that point to this machine"""