fix: filter empty spns during host resolution to prevent bad edges (#99)

Author: rvazarkar

src/CommonLib/LDAPUtils.cs

@@ -571,6 +571,10 @@ public IEnumerable<string> DoRangedRetrieval(string distinguishedName, string at
         public async Task<string> ResolveHostToSid(string hostname, string domain)
         {
             var strippedHost = Helpers.StripServicePrincipalName(hostname).ToUpper().TrimEnd('$');
+            if (string.IsNullOrEmpty(strippedHost))
+            {
+                return null;
+            }
 
             if (_hostResolutionMap.TryGetValue(strippedHost, out var sid)) return sid;
 

test/unit/CommonLibHelperTests.cs

@@ -166,6 +166,15 @@ public void StripServicePrincipalName_InValidServicePrincipal_ExpectedHostName()
             var actual = SharpHoundCommonLib.Helpers.StripServicePrincipalName(testString);
             Assert.Equal(expected, actual);
         }
+        
+        [Fact]
+        public void StripServicePrincipalName_EmptyHost_Valid()
+        {
+            var testString = "MSSQLSvc/:1433";
+            var expected = "";
+            var actual = SharpHoundCommonLib.Helpers.StripServicePrincipalName(testString);
+            Assert.Equal(expected, actual);
+        }
 
         [Fact]
         public void B64ToBytes_String_ValidBase64String()