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, 52 insertions, 24 deletions

diff --git a/python-ethtool/etherinfo.c b/python-ethtool/etherinfo.c
index 2cebdfb..3f2a3e6 100644
--- a/python-ethtool/etherinfo.c
+++ b/python-ethtool/etherinfo.c
@@ -92,12 +92,8 @@ void free_etherinfo(struct etherinfo *ptr)
 	if( ptr->hwaddress ) {
 		free(ptr->hwaddress);
 	}
-	if( ptr->ipv4_address ) {
-		free(ptr->ipv4_address);
-	}
-	if( ptr->ipv4_broadcast ) {
-		free(ptr->ipv4_broadcast);
-	}
+	Py_XDECREF(ptr->ipv4_addresses);
+
 	if( ptr->ipv6_addresses ) {
 		free_ipv6addresses(ptr->ipv6_addresses);
 	}
@@ -171,6 +167,36 @@ static void callback_nl_link(struct nl_object *obj, void *arg)
 	SET_STR_VALUE(ethi->hwaddress, hwaddr);
 }
 
+/**
+ * For use by callback_nl_address
+ * Returns 0 for success; -1 for error (though this is currently ignored)
+ */
+static int
+append_object_for_netlink_address(struct etherinfo *ethi,
+                                  struct nl_object *obj,
+                                  struct rtnl_addr *addr)
+{
+	PyObject *addr_obj;
+
+	assert(ethi);
+	assert(ethi->ipv4_addresses);
+	assert(addr);
+
+	addr_obj = make_python_address_from_rtnl_addr(obj, addr);
+	if (!addr_obj) {
+	  return -1;
+	}
+
+	if (-1 == PyList_Append(ethi->ipv4_addresses, addr_obj)) {
+	  Py_DECREF(addr_obj);
+	  return -1;
+	}
+
+	Py_DECREF(addr_obj);
+
+	/* Success */
+	return 0;
+}
 
 /**
  *  libnl callback function.  Does the real parsing of a record returned by NETLINK.  This function
@@ -199,17 +225,7 @@ static void callback_nl_address(struct nl_object *obj, void *arg)
 		inet_ntop(family, nl_addr_get_binary_addr(addr), (char *)&ip_str, 64);
 
 		if( family == AF_INET ) {
-			struct nl_addr *brdcst = rtnl_addr_get_broadcast((struct rtnl_addr *)obj);
-			char brdcst_str[66];
-
-			SET_STR_VALUE(ethi->ipv4_address, ip_str);
-			ethi->ipv4_netmask = rtnl_addr_get_prefixlen((struct rtnl_addr*) obj);
-
-			if( brdcst ) {
-				memset(&brdcst_str, 0, 66);
-				inet_ntop(family, nl_addr_get_binary_addr(brdcst), (char *)&brdcst_str, 64);
-				SET_STR_VALUE(ethi->ipv4_broadcast, brdcst_str);
-			}
+                        (void)append_object_for_netlink_address(ethi, obj, (struct rtnl_addr*) addr);
 		} else {
 			ethi->ipv6_addresses = etherinfo_add_ipv6(ethi->ipv6_addresses,
 								  ip_str,
@@ -244,13 +260,18 @@ void dump_etherinfo(FILE *fp, struct etherinfo *ptr)
 		fprintf(fp, "MAC address: %s", ptr->hwaddress);
 	}
 	fprintf(fp, "\n");
-	if( ptr->ipv4_address ) {
-		fprintf(fp, "\tIPv4 Address: %s/%i",
-			ptr->ipv4_address, ptr->ipv4_netmask);
-		if( ptr->ipv4_broadcast ) {
-			fprintf(fp, "  -  Broadcast: %s", ptr->ipv4_broadcast);
-		}
-		fprintf(fp, "\n");
+	if( ptr->ipv4_addresses ) {
+		Py_ssize_t i;
+		for (i = 0; i < PyList_Size(ptr->ipv4_addresses); i++) {
+			PyNetlinkIPv4Address *addr = (PyNetlinkIPv4Address *)PyList_GetItem(ptr->ipv4_addresses, i);
+			fprintf(fp, "\tIPv4 Address: %s/%i",
+                                PyString_AsString(addr->ipv4_address),
+                                addr->ipv4_netmask);
+                        if( addr->ipv4_broadcast ) {
+                              fprintf(fp, "  -  Broadcast: %s", PyString_AsString(addr->ipv4_broadcast));
+                        }
+                        fprintf(fp, "\n");
+                }
 	}
 	if( ptr->ipv6_addresses ) {
 		struct ipv6address *ipv6 = ptr->ipv6_addresses;
@@ -338,6 +359,13 @@ int get_etherinfo(struct etherinfo_obj_data *data, nlQuery query)
                         ethinf->ipv6_addresses = NULL;
                 }
 
+                /* Likewise for IPv4 addresses: */
+                Py_XDECREF(ethinf->ipv4_addresses);
+                ethinf->ipv4_addresses = PyList_New(0);
+                if (!ethinf->ipv4_addresses) {
+                        return 0;
+                }
+
                 /* Retrieve all address information */
 		nl_cache_foreach_filter(addr_cache, (struct nl_object *)addr, callback_nl_address, ethinf);
 		rtnl_addr_put(addr);