library: fetch the MAC address from the interfaces

library/network_connections.py

@@ -60,6 +60,19 @@ class Util:
             return v
         return default
 
+    @staticmethod
+    def check_output(argv, lang = None):
+        # subprocess.check_output is python 2.7.
+        with open('/dev/null', 'wb') as DEVNULL:
+            import subprocess, os
+            ev = os.environ.copy()
+            ev['LANG'] = lang if lang is not None else 'C'
+            p = subprocess.Popen(argv, stdout=subprocess.PIPE, stderr=DEVNULL, env=ev)
+            out = p.communicate()[0]
+            if p.returncode != 0:
+                raise MyError('failure calling %s: exit with %s' % (argv, p.returncode))
+        return out
+
     @classmethod
     def create_uuid(cls):
         cls.NM()
@@ -159,6 +172,49 @@ class Util:
         # FIXME: encoding issues regarding python unicode string
         return True
 
+    @staticmethod
+    def mac_aton(mac_str, force_len=None):
+        # we also accept None and '' for convenience.
+        # - None yiels None
+        # - '' yields []
+        if mac_str is None:
+            return mac_str
+        i = 0
+        b = []
+        for c in mac_str:
+            if i == 2:
+                if c != ':':
+                    raise MyError('not a valid MAC address: "%s"' % (mac_str))
+                i = 0
+                continue
+            try:
+                if i == 0:
+                    n = int(c, 16) * 16
+                    i = 1
+                else:
+                    assert(i == 1)
+                    n = n + int(c, 16)
+                    i = 2
+                    b.append(n)
+            except:
+                raise MyError('not a valid MAC address: "%s"' % (mac_str))
+        if i == 1:
+            raise MyError('not a valid MAC address: "%s"' % (mac_str))
+        if force_len is not None:
+            if force_len != len(b):
+                raise MyError('not a valid MAC address of length %s: "%s"' % (force_len, mac_str))
+        return b
+
+    @staticmethod
+    def mac_ntoa(mac):
+        if mac is None:
+            return None
+        return ':'.join(['%02x' % c for c in mac])
+
+    @staticmethod
+    def mac_norm(mac_str, force_len = None):
+        return Util.mac_ntoa(Util.mac_aton(mac_str, force_len))
+
     @staticmethod
     def boolean(arg):
         import ansible.module_utils.basic as basic
@@ -225,6 +281,84 @@ class Util:
 
 ###############################################################################
 
+class SysUtil:
+
+    @staticmethod
+    def _sysctl_read(filename):
+        try_count = 0
+        while True:
+            try_count += 1
+            try:
+                with open(filename, 'r') as f:
+                    return f.read()
+            except Exception as e:
+                if try_count < 5:
+                    continue
+                raise
+
+    @staticmethod
+    def _link_read_ifindex(ifname):
+        c = SysUtil._sysctl_read('/sys/class/net/' + ifname + '/ifindex')
+        return int(c.strip())
+
+    @staticmethod
+    def _link_read_address(ifname):
+        c = SysUtil._sysctl_read('/sys/class/net/' + ifname + '/address')
+        return Util.mac_norm(c.strip())
+
+    @staticmethod
+    def _link_read_permaddress(ifname):
+        out = Util.check_output(['ethtool', '-P', ifname])
+        import re
+        m = re.match('^Permanent address: ([0-9A-Fa-f:]*)\n$', out)
+        if not m:
+            return None
+        return Util.mac_norm(m.group(1))
+
+    @staticmethod
+    def _link_infos_fetch():
+        import os
+        links = {}
+        for ifname in os.listdir('/sys/class/net/'):
+            ifindex = SysUtil._link_read_ifindex(ifname)
+            links[ifname] = {
+                'ifindex': ifindex,
+                'ifname': ifname,
+                'address': SysUtil._link_read_address(ifname),
+                'perm-address': SysUtil._link_read_permaddress(ifname),
+            }
+        return links
+
+    @classmethod
+    def link_infos(cls, refresh=False):
+        if refresh:
+            l = None
+        else:
+            l = getattr(cls, '_link_infos', None)
+        if l is None:
+            try_count = 0
+            b = None
+            while True:
+                try:
+                    # there is a race in that we lookup properties by ifname
+                    # and interfaces can be renamed. Try to avoid that by fetching
+                    # the info twice and repeat until we get the same result.
+                    if b is None:
+                        b = SysUtil._link_infos_fetch()
+                    l = SysUtil._link_infos_fetch()
+                    if l != b:
+                        b = l
+                        raise Exception("cannot read stable link-infos. They keep changing")
+                except:
+                    if try_count < 50:
+                        raise
+                    continue
+                break
+            cls._link_infos = l
+        return l
+
+###############################################################################
+
 class ArgUtil:
     @staticmethod
     def connection_find_by_name(name, connections, n_connections = None):
@@ -328,6 +462,20 @@ class ArgValidatorIP(ArgValidatorStr):
             return addr
         return { "family": family, "address": addr }
 
+class ArgValidatorMac(ArgValidatorStr):
+    def __init__(self, name, force_len = None, required = False, default_value = None):
+        ArgValidatorStr.__init__(self, name, required, default_value, None)
+        self.force_len = force_len
+    def _validate(self, value, name):
+        v = ArgValidatorStr._validate(self, value, name)
+        try:
+            addr = Util.mac_aton(v, self.force_len)
+        except MyError as e:
+            raise ValidationError(name, 'value "%s" is not a valid MAC address' % (value))
+        if not addr:
+            raise ValidationError(name, 'value "%s" is not a valid MAC address' % (value))
+        return Util.mac_ntoa(addr)
+
 class ArgValidatorIPAddr(ArgValidatorStr):
     def __init__(self, name, family = None, required = False, default_value = None):
         ArgValidatorStr.__init__(self, name, required, default_value, None)
@@ -457,7 +605,7 @@ class ArgValidator_DictConnection(ArgValidatorDict):
                 ArgValidatorStr ('slave_type', enum_values = ArgValidator_DictConnection.VALID_SLAVE_TYPES),
                 ArgValidatorStr ('master'),
                 ArgValidatorStr ('interface_name'),
-                ArgValidatorStr ('mac'),
+                ArgValidatorMac ('mac'),
                 ArgValidatorStr ('parent'),
                 ArgValidatorInt ('vlan_id', val_min = 0, val_max = 4095, default_value = None),
                 ArgValidatorBool('ignore_errors', default_value = None),

library/test_network_connections.py

@@ -224,7 +224,7 @@ class TestValidator(unittest.TestCase):
                         'route_metric4': None,
                         'route_metric6': None,
                     },
-                    'mac': None,
+                    'mac': 'aa:bb:cc',
                     'master': None,
                     'name': '5',
                     'parent': None,
@@ -239,10 +239,14 @@ class TestValidator(unittest.TestCase):
                 {
                     'name': '5',
                     'type': 'ethernet',
+                    'mac': 'AA:bb:cC',
                 }
             ]),
         )
 
+        with self.assertRaises(n.ValidationError):
+            n.AnsibleUtil.ARGS_CONNECTIONS.validate([ { 'name': 'b', 'type': 'ethernet', 'mac': 'aa:b' } ])
+
 
 if __name__ == '__main__':
     unittest.main()