Merge ~lloydwaltersj/maas:backport-1807725-3.2 into maas:3.2

[Jack Lloyd-Walters]

Fix incorrect hostname from interface name

    MAAS currently creates a DNS record for each interface in a host
    by simply using its interface name. Whenever an interface has the
    '_' character, the code uses it anyway, which is currently breaking
    bind as this character is not allowed on domain names.
    This patch fixes that by verifying it and replacing the incorrect
    character.

    LP: #1807725

(cherry picked from commit 83b123eb37b88dd0b9974bed9ee4352474ddd0a0)

[MAAS Lander (maas-lander)]

UNIT TESTS
-b backport-1807725-3.2 lp:~lloydwaltersj/maas/+git/maas into -b 3.2 lp:~maas-committers/maas

STATUS: FAILED
LOG: http://maas-ci.internal:8080/job/maas-tester/2671/console
COMMIT: fb745a3e45ea6f948f984c96286df846fd292037

review: Needs Fixing

[Jack Lloyd-Walters (lloydwaltersj)]

jenkins: !test

[MAAS Lander (maas-lander)]

UNIT TESTS
-b backport-1807725-3.2 lp:~lloydwaltersj/maas/+git/maas into -b 3.2 lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: 9218a781c17d0cc456327d9d35c4b0fddce6d049

review: Approve

[Alexsander de Souza (alexsander-souza)]

+1

review: Approve

diff --git a/src/maasserver/models/staticipaddress.py b/src/maasserver/models/staticipaddress.py
index 469e405..4144a9e 100644
--- a/src/maasserver/models/staticipaddress.py
+++ b/src/maasserver/models/staticipaddress.py
@@ -50,7 +50,10 @@ from maasserver.models.domain import Domain
 from maasserver.models.subnet import Subnet
 from maasserver.models.timestampedmodel import TimestampedModel
 from maasserver.utils import orm
-from maasserver.utils.dns import get_ip_based_hostname
+from maasserver.utils.dns import (
+    get_iface_name_based_hostname,
+    get_ip_based_hostname,
+)
 from provisioningserver.utils.enum import map_enum_reverse
 
 _mapping_base_fields = (
@@ -755,7 +758,11 @@ class StaticIPAddressManager(Manager):
             # node, then consider adding the IP.
             if result.assigned or not assigned_ips[result.fqdn]:
                 if result.ip not in mapping[result.fqdn].ips:
-                    entry = mapping[f"{result.iface_name}.{result.fqdn}"]
+                    fqdn = "{}.{}".format(
+                        get_iface_name_based_hostname(result.iface_name),
+                        result.fqdn,
+                    )
+                    entry = mapping[fqdn]
                     entry.node_type = result.node_type
                     entry.system_id = result.system_id
                     if result.user_id is not None:
diff --git a/src/maasserver/models/tests/test_staticipaddress.py b/src/maasserver/models/tests/test_staticipaddress.py
index 6ec2ec7..b202a32 100644
--- a/src/maasserver/models/tests/test_staticipaddress.py
+++ b/src/maasserver/models/tests/test_staticipaddress.py
@@ -50,7 +50,10 @@ from maasserver.testing.testcase import (
     MAASTransactionServerTestCase,
 )
 from maasserver.utils import orm
-from maasserver.utils.dns import get_ip_based_hostname
+from maasserver.utils.dns import (
+    get_iface_name_based_hostname,
+    get_ip_based_hostname,
+)
 from maasserver.utils.orm import reload_object, transactional
 from maasserver.websockets.base import dehydrate_datetime
 
@@ -483,6 +486,47 @@ class TestStaticIPAddressManagerMapping(MAASServerTestCase):
         }
         self.assertEqual(expected, mapping)
 
+    def test_get_hostname_ip_mapping_sanitized_iface_name(self):
+        hostname = factory.make_name("hostname")
+        domainname = factory.make_name("domain")
+        factory.make_Domain(name=domainname)
+        full_hostname = f"{hostname}.{domainname}"
+        subnet = factory.make_Subnet()
+        node = factory.make_Node_with_Interface_on_Subnet(
+            extra_ifnames=["eth_1"],
+            hostname=full_hostname,
+            interface_count=2,
+            subnet=subnet,
+        )
+        boot_interface = node.get_boot_interface()
+        staticip = factory.make_StaticIPAddress(
+            alloc_type=IPADDRESS_TYPE.STICKY,
+            ip=factory.pick_ip_in_Subnet(subnet),
+            subnet=subnet,
+            interface=boot_interface,
+        )
+        iface2 = node.current_config.interface_set.exclude(
+            id=boot_interface.id
+        ).first()
+        sip2 = factory.make_StaticIPAddress(
+            alloc_type=IPADDRESS_TYPE.STICKY,
+            ip=factory.pick_ip_in_Subnet(subnet),
+            subnet=subnet,
+            interface=iface2,
+        )
+        mapping = StaticIPAddress.objects.get_hostname_ip_mapping(subnet)
+        sanitized_if2name = get_iface_name_based_hostname(iface2.name)
+        expected = {
+            full_hostname: HostnameIPMapping(
+                node.system_id, 30, {staticip.ip}, node.node_type
+            ),
+            "%s.%s"
+            % (sanitized_if2name, full_hostname): HostnameIPMapping(
+                node.system_id, 30, {sip2.ip}, node.node_type
+            ),
+        }
+        self.assertEqual(expected, mapping)
+
     def make_mapping(self, node, raw_ttl=False):
         if raw_ttl or node.address_ttl is not None:
             ttl = node.address_ttl
diff --git a/src/maasserver/utils/dns.py b/src/maasserver/utils/dns.py
index 0c8cde5..76f553a 100644
--- a/src/maasserver/utils/dns.py
+++ b/src/maasserver/utils/dns.py
@@ -91,6 +91,16 @@ def get_ip_based_hostname(ip):
     return hostname
 
 
+def get_iface_name_based_hostname(iface_name):
+    """Given the specified interface name, creates an automatically generated
+    hostname by converting the '_' characters in it to '-' characters.
+
+    :param iface_name: Input value for the interface name.
+    """
+    hostname = iface_name.replace("_", "-")
+    return hostname
+
+
 def validate_url(url, schemes=("http", "https")):
     """Validator for URLs.
 
diff --git a/src/maasserver/utils/tests/test_dns.py b/src/maasserver/utils/tests/test_dns.py
index e6be8ab..41cfe80 100644
--- a/src/maasserver/utils/tests/test_dns.py
+++ b/src/maasserver/utils/tests/test_dns.py
@@ -8,6 +8,7 @@ from django.core.validators import URLValidator
 from testtools.matchers import Equals, HasLength
 
 from maasserver.utils.dns import (
+    get_iface_name_based_hostname,
     get_ip_based_hostname,
     validate_domain_name,
     validate_hostname,
@@ -244,3 +245,11 @@ class TestIpBasedHostnameGenerator(MAASTestCase):
             get_ip_based_hostname("2001:67c:1562::15"),
             Equals("2001-67c-1562--15"),
         )
+
+
+class TestIfaceBasedHostnameGenerator(MAASTestCase):
+    def test_interface_name_changed(self):
+        self.assertEqual(get_iface_name_based_hostname("eth_0"), "eth-0")
+
+    def test_interface_name_unchanged(self):
+        self.assertEqual(get_iface_name_based_hostname("eth0"), "eth0")