From 105cf6666f51017d59521250698697f5ff60f1a4 Mon Sep 17 00:00:00 2001
From: Sean Fisk <sean@seanfisk.com>
Date: Fri, 4 Sep 2015 16:12:20 -0400
Subject: [PATCH 1/2] Detect internal_ip interface from default gateway

Add the option to specify `interface='default_gateway'` to the
`internal_ip` segment, which displays the IP address of the interface
connected to the default gateway.
---
 powerline/segments/common/net.py | 14 +++++++++++++-
 tests/test_segments.py           | 23 +++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/powerline/segments/common/net.py b/powerline/segments/common/net.py
index 0af5762d..85bf737b 100644
--- a/powerline/segments/common/net.py
+++ b/powerline/segments/common/net.py
@@ -101,15 +101,22 @@ else:
 			return 0
 
 	def internal_ip(pl, interface='auto', ipv=4):
+		family = netifaces.AF_INET6 if ipv == 6 else netifaces.AF_INET
 		if interface == 'auto':
 			try:
 				interface = next(iter(sorted(netifaces.interfaces(), key=_interface_key, reverse=True)))
 			except StopIteration:
 				pl.info('No network interfaces found')
 				return None
+		elif interface == 'default_gateway':
+			try:
+				interface = netifaces.gateways()['default'][family][1]
+			except KeyError:
+				pl.info('No default gateway found for IPv{0}', ipv)
+				return None
 		addrs = netifaces.ifaddresses(interface)
 		try:
-			return addrs[netifaces.AF_INET6 if ipv == 6 else netifaces.AF_INET][0]['addr']
+			return addrs[family][0]['addr']
 		except (KeyError, IndexError):
 			return None
 
@@ -130,6 +137,11 @@ Requires ``netifaces`` module to work properly.
 	#. ``teredo`` followed by number or the end of string.
 	#. Any other interface that is not ``lo*``.
 	#. ``lo`` followed by number or the end of string.
+
+	Use ``default_gateway`` to detect the interface based on the machine's
+	`default gateway <https://en.wikipedia.org/wiki/Default_gateway>`_ (i.e.,
+	the router to which it is connected).
+
 :param int ipv:
 	4 or 6 for ipv4 and ipv6 respectively, depending on which IP address you 
 	need exactly.
diff --git a/tests/test_segments.py b/tests/test_segments.py
index b3c77029..58292909 100644
--- a/tests/test_segments.py
+++ b/tests/test_segments.py
@@ -397,6 +397,29 @@ class TestNet(TestCommon):
 			interfaces[:] = ()
 			self.assertEqual(self.module.internal_ip(pl=pl, ipv=6), None)
 
+		gateways = {
+			'default': {
+				netifaces.AF_INET: ('192.168.100.1', 'enp2s0'),
+				netifaces.AF_INET6: ('feff::5446:5eff:fe5a:0001', 'enp2s0')
+			}
+		}
+
+		with replace_module_module(
+			self.module, 'netifaces',
+			interfaces=(lambda: interfaces),
+			ifaddresses=(lambda interface: addr[interface]),
+			gateways=(lambda: gateways),
+			AF_INET=netifaces.AF_INET,
+			AF_INET6=netifaces.AF_INET6,
+		):
+			# default gateway has specified address family
+			self.assertEqual(self.module.internal_ip(pl=pl, interface='default_gateway', ipv=4), '192.168.100.200')
+			self.assertEqual(self.module.internal_ip(pl=pl, interface='default_gateway', ipv=6), 'feff::5446:5eff:fe5a:7777%enp2s0')
+			# default gateway doesn't have specified address family
+			gateways['default'] = {}
+			self.assertEqual(self.module.internal_ip(pl=pl, interface='default_gateway', ipv=4), None)
+			self.assertEqual(self.module.internal_ip(pl=pl, interface='default_gateway', ipv=6), None)
+
 	def test_network_load(self):
 		def gb(interface):
 			return None

From 2c1213116ed68fff15169a61d94852c97840dd3c Mon Sep 17 00:00:00 2001
From: Sean Fisk <sean@seanfisk.com>
Date: Sat, 5 Sep 2015 18:02:11 -0400
Subject: [PATCH 2/2] Log when IP address family not found for interface

---
 powerline/segments/common/net.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/powerline/segments/common/net.py b/powerline/segments/common/net.py
index 85bf737b..eb5b4bcf 100644
--- a/powerline/segments/common/net.py
+++ b/powerline/segments/common/net.py
@@ -118,6 +118,7 @@ else:
 		try:
 			return addrs[family][0]['addr']
 		except (KeyError, IndexError):
+			pl.info("No IPv{0} address found for interface {1}", ipv, interface)
 			return None