Support devices with multiple IPv4 addresses

Add a get_ipv4_addresses() method to ethtool.etherinfo to support devices
with multiple IPv4 addresses (rhbz#759150)

Previously, get_etherinfo() made queries to NETLINK with NLQRY_ADDR, and
callback_nl_address handled responses of family AF_INET (IPv4) by writing to
fields within a struct etherinfo.

If multiple AF_INET responses come back, each overwrote the last, and the
last one won.

This patch generalizes things by moving the relevant fields:
   char *ipv4_address;                 /**< Configured IPv4 address */
   int ipv4_netmask;                   /**< Configured IPv4 netmask */
   char *ipv4_broadcast;
from (struct etherinfo) into a new Python class, currently named
PyNetlinkIPv4Address.

This object has a sane repr():
>>> ethtool.get_interfaces_info('eth1')[0].get_ipv4_addresses()
[ethtool.NetlinkIPv4Address(address='192.168.1.10', netmask=24, broadcast='192.168.1.255')]

and attributes:
>>> print [iface.address for iface in ethtool.get_interfaces_info('eth1')[0].get_ipv4_addresses()]
['192.168.1.10']
>>> print [iface.netmask for iface in ethtool.get_interfaces_info('eth1')[0].get_ipv4_addresses()]
[24]
>>> print [iface.broadcast for iface in ethtool.get_interfaces_info('eth1')[0].get_ipv4_addresses()]
['192.168.1.255']

The (struct etherinfo) then gains a new field:
   PyObject *ipv4_addresses;        /**< list of PyNetlinkIPv4Address instances */

which is created before starting the query, and populated by the callback as
responses come in.

All direct usage of the old fields (which assumed a single IPv4 address)
are changed to use the last entry in the list (if any), to mimic the old
behavior.

dump_etherinfo() and _ethtool_etherinfo_str() are changed to loop over all
of the IPv4 addresses when outputting, rather than just outputting one.

Caveats:
* the exact terminology is probably incorrect: I'm not a networking
  specialist
* the relationship between each of devices, get_interfaces_info() results,
  and addresses seems both unclear and messy to me: how changable is the
  API?

>>> ethtool.get_interfaces_info('eth1')[0].get_ipv4_addresses()
[ethtool.NetlinkIPv4Address(address='192.168.1.10', netmask=24, broadcast='192.168.1.255')]

It seems that an etherinfo object relates to a device: perhaps it should be
named as such?  But it may be too late to make this change.

Notes:
The _ethtool_etherinfo_members array within python-ethtool/etherinfo_obj.c
was broken: it defined 4 attributes of type PyObject*, to be extracted from
etherinfo_py->data, which is of a completed different type.  If these
PyMemberDef fields were ever used, Python would segfault.  Thankfully
_ethtool_etherinfo_getter() has handlers for these attributes, and gets
called first.

This is a modified version of the patch applied downstream in RHEL 6.4
within python-ethtool-0.6-3.el6:
  python-ethtool-0.6-add-get_ipv4_addresses-method.patch
ported to take account of 508ffffbb3c48eeeb11eeab2bf971180fe4e1940

1 files changed, 95 insertions, 36 deletions

diff --git a/python-ethtool/etherinfo_obj.c b/python-ethtool/etherinfo_obj.c
index b158a47..dad426b 100644
--- a/python-ethtool/etherinfo_obj.c
+++ b/python-ethtool/etherinfo_obj.c
@@ -91,6 +91,41 @@ int _ethtool_etherinfo_init(etherinfo_py *self, PyObject *args, PyObject *kwds)
 	return 0;
 }
 
+/*
+  The old approach of having a single IPv4 address per device meant each result
+  that came in from netlink overwrote the old result.
+
+  Mimic it by returning the last entry in the list (if any).
+
+  The return value is a *borrowed reference* (or NULL)
+*/
+static PyNetlinkIPv4Address*
+get_last_address(etherinfo_py *self)
+{
+	Py_ssize_t size;
+	PyObject *list;
+
+	assert(self);
+	list = self->data->ethinfo->ipv4_addresses;
+	if (!list) {
+		return NULL;
+	}
+
+	if (!PyList_Check(list)) {
+		return NULL;
+	}
+
+	size = PyList_Size(list);
+	if (size > 0) {
+		PyObject *item = PyList_GetItem(list, size - 1);
+		if (Py_TYPE(item) == &ethtool_netlink_ipv4_address_Type) {
+			return (PyNetlinkIPv4Address*)item;
+		}
+	}
+
+	return NULL;
+}
+
 /**
  * ethtool.etherinfo function for retrieving data from a Python object.
  *
@@ -102,6 +137,7 @@ int _ethtool_etherinfo_init(etherinfo_py *self, PyObject *args, PyObject *kwds)
 PyObject *_ethtool_etherinfo_getter(etherinfo_py *self, PyObject *attr_o)
 {
 	char *attr = PyString_AsString(attr_o);
+	PyNetlinkIPv4Address *py_addr;
 
 	if( !self || !self->data ) {
 		PyErr_SetString(PyExc_AttributeError, "No data available");
@@ -115,13 +151,32 @@ PyObject *_ethtool_etherinfo_getter(etherinfo_py *self, PyObject *attr_o)
 		return RETURN_STRING(self->data->ethinfo->hwaddress);
 	} else if( strcmp(attr, "ipv4_address") == 0 ) {
 		get_etherinfo(self->data, NLQRY_ADDR);
-		return RETURN_STRING(self->data->ethinfo->ipv4_address);
+		/* For compatiblity with old approach, return last IPv4 address: */
+		py_addr = get_last_address(self);
+		if (py_addr) {
+		  if (py_addr->ipv4_address) {
+		      Py_INCREF(py_addr->ipv4_address);
+		      return py_addr->ipv4_address;
+		  }
+		}
+		Py_RETURN_NONE;
 	} else if( strcmp(attr, "ipv4_netmask") == 0 ) {
 		get_etherinfo(self->data, NLQRY_ADDR);
-		return PyInt_FromLong(self->data->ethinfo->ipv4_netmask);
+		py_addr = get_last_address(self);
+		if (py_addr) {
+		  return PyInt_FromLong(py_addr->ipv4_netmask);
+		}
+		return PyInt_FromLong(0);
 	} else if( strcmp(attr, "ipv4_broadcast") == 0 ) {
 		get_etherinfo(self->data, NLQRY_ADDR);
-		return RETURN_STRING(self->data->ethinfo->ipv4_broadcast);
+		py_addr = get_last_address(self);
+		if (py_addr) {
+		  if (py_addr->ipv4_broadcast) {
+		      Py_INCREF(py_addr->ipv4_broadcast);
+		      return py_addr->ipv4_broadcast;
+		  }
+		}
+		Py_RETURN_NONE;
 	} else {
 		return PyObject_GenericGetAttr((PyObject *)self, attr_o);
 	}
@@ -170,19 +225,21 @@ PyObject *_ethtool_etherinfo_str(etherinfo_py *self)
 		Py_DECREF(tmp);
 	}
 
-	if( self->data->ethinfo->ipv4_address ) {
-		PyObject *tmp = PyString_FromFormat("\tIPv4 address: %s/%i",
-						   self->data->ethinfo->ipv4_address,
-						   self->data->ethinfo->ipv4_netmask);
-		if( self->data->ethinfo->ipv4_broadcast ) {
-			PyObject *tmp2 = PyString_FromFormat("	  Broadcast: %s",
-							     self->data->ethinfo->ipv4_broadcast);
-			PyString_Concat(&tmp, tmp2);
-			Py_DECREF(tmp2);
-		}
-		PyString_Concat(&tmp, PyString_FromString("\n"));
-		PyString_Concat(&ret, tmp);
-		Py_DECREF(tmp);
+	if( self->data->ethinfo->ipv4_addresses ) {
+               Py_ssize_t i;
+               for (i = 0; i < PyList_Size(self->data->ethinfo->ipv4_addresses); i++) {
+                       PyNetlinkIPv4Address *py_addr = (PyNetlinkIPv4Address *)PyList_GetItem(self->data->ethinfo->ipv4_addresses, i);
+                       PyObject *tmp = PyString_FromFormat("\tIPv4 address: ");
+                       PyString_Concat(&tmp, py_addr->ipv4_address);
+                       PyString_ConcatAndDel(&tmp, PyString_FromFormat("/%d", py_addr->ipv4_netmask));
+                       if (py_addr->ipv4_broadcast ) {
+                                PyString_ConcatAndDel(&tmp,
+                                                      PyString_FromString("	  Broadcast: "));
+                                PyString_Concat(&tmp, py_addr->ipv4_broadcast);
+                       }
+                       PyString_ConcatAndDel(&tmp, PyString_FromString("\n"));
+                       PyString_ConcatAndDel(&ret, tmp);
+               }
 	}
 
 	if( self->data->ethinfo->ipv6_addresses ) {
@@ -203,6 +260,24 @@ PyObject *_ethtool_etherinfo_str(etherinfo_py *self)
 	return ret;
 }
 
+static PyObject *
+_ethtool_etherinfo_get_ipv4_addresses(etherinfo_py *self, PyObject *notused) {
+	PyObject *ret;
+
+	if( !self || !self->data ) {
+		PyErr_SetString(PyExc_AttributeError, "No data available");
+		return NULL;
+	}
+
+	get_etherinfo(self->data, NLQRY_ADDR);
+
+	/* Transfer ownership of reference: */
+	ret = self->data->ethinfo->ipv4_addresses;
+	self->data->ethinfo->ipv4_addresses = NULL;
+
+	return ret;
+}
+
 
 /**
  * Returns a tuple list of ethertool.etherinfo_ipv6addr objects, containing configured
@@ -276,30 +351,14 @@ PyObject * _ethtool_etherinfo_get_ipv6_addresses(etherinfo_py *self, PyObject *n
  *
  */
 static PyMethodDef _ethtool_etherinfo_methods[] = {
-	{"get_ipv6_addresses", _ethtool_etherinfo_get_ipv6_addresses, METH_NOARGS,
+	{"get_ipv4_addresses", (PyCFunction)_ethtool_etherinfo_get_ipv4_addresses, METH_NOARGS,
+	 "Retrieve configured IPv4 addresses.  Returns a list of NetlinkIP4Address objects"},
+	{"get_ipv6_addresses", (PyCFunction)_ethtool_etherinfo_get_ipv6_addresses, METH_NOARGS,
 	 "Retrieve configured IPv6 addresses.  Returns a tuple list of etherinfo_ipv6addr objects"},
 	{NULL}  /**< No methods defined */
 };
 
 /**
- * Defines all accessible object members
- *
- */
-static PyMemberDef _ethtool_etherinfo_members[] = {
-    {"device", T_OBJECT_EX, offsetof(etherinfo_py, data), 0,
-     "Device name of the interface"},
-    {"mac_address", T_OBJECT_EX, offsetof(etherinfo_py, data), 0,
-     "MAC address / hardware address of the interface"},
-    {"ipv4_address", T_OBJECT_EX, offsetof(etherinfo_py, data), 0,
-     "IPv4 address"},
-    {"ipv4_netmask", T_INT, offsetof(etherinfo_py, data), 0,
-     "IPv4 netmask in bits"},
-    {"ipv4_broadcast", T_OBJECT_EX, offsetof(etherinfo_py, data), 0,
-     "IPv4 broadcast address"},
-    {NULL}  /* End of member list */
-};
-
-/**
  * Definition of the functions a Python class/object requires.
  *
  */
@@ -333,7 +392,7 @@ PyTypeObject ethtool_etherinfoType = {
     0,		               /* tp_iter */
     0,		               /* tp_iternext */
     _ethtool_etherinfo_methods,            /* tp_methods */
-    _ethtool_etherinfo_members,            /* tp_members */
+    0,                         /* tp_members */
     0,                         /* tp_getset */
     0,                         /* tp_base */
     0,                         /* tp_dict */