From 0b22d5e63a842ad66e10509321104088a3d920c2 Mon Sep 17 00:00:00 2001
From: David Kennedy <david.kennedy@associates.cisa.dhs.gov>
Date: Mon, 30 Oct 2023 17:57:45 -0400
Subject: [PATCH] added isValidDomain to host validation; added INVALID_HOST to
 error messages

---
 src/registrar/forms/domain.py   | 19 ++++++++++++++++---
 src/registrar/models/domain.py  | 27 ++++++++++++++++++++++++++-
 src/registrar/utility/errors.py |  3 +++
 3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/src/registrar/forms/domain.py b/src/registrar/forms/domain.py
index 3aca7af6d..992d283a4 100644
--- a/src/registrar/forms/domain.py
+++ b/src/registrar/forms/domain.py
@@ -51,9 +51,8 @@ class DomainNameserverForm(forms.Form):
 
         ip_list = self.extract_ip_list(ip)
 
-        if ip and not server and ip_list:
-            self.add_error("server", NameserverError(code=nsErrorCodes.MISSING_HOST))
-        elif server:
+        # validate if the form has a server or an ip
+        if ip and ip_list or server:
             self.validate_nameserver_ip_combo(domain, server, ip_list)
 
         return cleaned_data
@@ -86,6 +85,20 @@ class DomainNameserverForm(forms.Form):
                         code=nsErrorCodes.MISSING_IP, nameserver=domain, ip=ip_list
                     ),
                 )
+            elif e.code == nsErrorCodes.MISSING_HOST:
+                self.add_error(
+                    "server",
+                    NameserverError(
+                        code=nsErrorCodes.MISSING_HOST, nameserver=domain, ip=ip_list
+                    ),
+                )
+            elif e.code == nsErrorCodes.INVALID_HOST:
+                self.add_error(
+                    "server",
+                    NameserverError(
+                        code=nsErrorCodes.INVALID_HOST, nameserver=server, ip=ip_list
+                    ),
+                )
             else:
                 self.add_error("ip", str(e))
 
diff --git a/src/registrar/models/domain.py b/src/registrar/models/domain.py
index 07e49dfdd..5f201865c 100644
--- a/src/registrar/models/domain.py
+++ b/src/registrar/models/domain.py
@@ -304,6 +304,25 @@ class Domain(TimeStampedModel, DomainHelper):
         regex = re.compile(full_pattern)
         return bool(regex.match(nameserver))
 
+    @classmethod
+    def isValidDomain(cls, nameserver: str):
+        """Checks for validity of nameserver string based on these rules:
+        - first character is alpha
+        - last character is not - or .
+        - all characters alpha, 0-9, -, or .
+        - 2 character min, 24 character max
+        """
+        # pattern to test for valid domain
+        # pattern = r'^[a-zA-Z][a-zA-Z0-9-.]{0,22}[a-zA-Z0-9]$'
+        pattern = r"^[a-zA-Z][a-zA-Z0-9-.]*(\.[a-zA-Z0-9-]+){2}[a-zA-Z0-9]$"
+
+        # attempt to match the pattern
+        match = re.match(pattern, nameserver)
+
+        # return true if nameserver matches, and length less than 25;
+        # otherwise false
+        return bool(match) and len(nameserver) < 25
+
     @classmethod
     def checkHostIPCombo(cls, name: str, nameserver: str, ip: list[str]):
         """Checks the parameters past for a valid combination
@@ -311,6 +330,8 @@ class Domain(TimeStampedModel, DomainHelper):
             - nameserver is a subdomain but is missing ip
             - nameserver is not a subdomain but has ip
             - nameserver is a subdomain but an ip passed is invalid
+            - nameserver is not a valid domain
+            - ip is provided but is missing domain
 
         Args:
             hostname (str)- nameserver or subdomain
@@ -319,7 +340,11 @@ class Domain(TimeStampedModel, DomainHelper):
             NameserverError (if exception hit)
         Returns:
             None"""
-        if cls.isSubdomain(name, nameserver) and (ip is None or ip == []):
+        if ip and not nameserver:
+            raise NameserverError(code=nsErrorCodes.MISSING_HOST)
+        elif nameserver and not cls.isValidDomain(nameserver):
+            raise NameserverError(code=nsErrorCodes.INVALID_HOST, nameserver=nameserver)
+        elif cls.isSubdomain(name, nameserver) and (ip is None or ip == []):
             raise NameserverError(code=nsErrorCodes.MISSING_IP, nameserver=nameserver)
 
         elif not cls.isSubdomain(name, nameserver) and (ip is not None and ip != []):
diff --git a/src/registrar/utility/errors.py b/src/registrar/utility/errors.py
index c1d3c5849..9b9cfea0e 100644
--- a/src/registrar/utility/errors.py
+++ b/src/registrar/utility/errors.py
@@ -66,6 +66,7 @@ class NameserverErrorCodes(IntEnum):
         - 4 TOO_MANY_HOSTS  more than the max allowed host values
         - 5 UNABLE_TO_UPDATE_DOMAIN unable to update the domain
         - 6 MISSING_HOST host is missing for a nameserver
+        - 7 INVALID_HOST host is invalid for a nameserver
     """
 
     MISSING_IP = 1
@@ -74,6 +75,7 @@ class NameserverErrorCodes(IntEnum):
     TOO_MANY_HOSTS = 4
     UNABLE_TO_UPDATE_DOMAIN = 5
     MISSING_HOST = 6
+    INVALID_HOST = 7
 
 
 class NameserverError(Exception):
@@ -102,6 +104,7 @@ class NameserverError(Exception):
         NameserverErrorCodes.MISSING_HOST: (
             "Name server must be provided to enter IP address."
         ),
+        NameserverErrorCodes.INVALID_HOST: ("Name server, {}, is not valid."),
     }
 
     def __init__(self, *args, code=None, nameserver=None, ip=None, **kwargs):