From 6c9387a9385dea83447a093b35f97e5fcfd39a5d Mon Sep 17 00:00:00 2001
From: Thomas Markwalder <tmark@isc.org>
Date: Thu, 2 Oct 2025 15:25:49 -0400
Subject: [PATCH] [#4142] dhcpsrv and v4 UTs

modified:   src/bin/dhcp4/tests/fqdn_unittest.cc
modified:   src/lib/dhcpsrv/tests/d2_client_unittest.cc
---
 src/bin/dhcp4/tests/fqdn_unittest.cc        | 60 ++++++++++++++++++++-
 src/lib/dhcpsrv/tests/d2_client_unittest.cc | 40 ++++++++++++++
 2 files changed, 99 insertions(+), 1 deletion(-)

diff --git a/src/bin/dhcp4/tests/fqdn_unittest.cc b/src/bin/dhcp4/tests/fqdn_unittest.cc
index a5d3e4c21a..4bb5dc18d4 100644
--- a/src/bin/dhcp4/tests/fqdn_unittest.cc
+++ b/src/bin/dhcp4/tests/fqdn_unittest.cc
@@ -2253,7 +2253,7 @@ TEST_F(NameDhcpv4SrvTest, sanitizeHostDefault) {
         },
         {
             "qualified host name with nuls",
-            std::string("four-ok-host\000.other.org",23),
+            std::string("four-ok-host\000.other.org", 23),
             "four-ok-host.other.org"
         }
     };
@@ -3203,4 +3203,62 @@ TEST_F(NameDhcpv4SrvTest, poolDdnsParametersTest) {
     }
 }
 
+// Verifies that when the FQDN option is scrubbed empty it is logged
+// and ignored.
+TEST_F(NameDhcpv4SrvTest, hostnameScrubbedEmpty) {
+    Dhcp4Client client(srv_, Dhcp4Client::SELECTING);
+
+    // Configure DHCP server.
+    configure(CONFIGS[2], *client.getServer());
+
+    // Set the hostname option.
+    ASSERT_NO_THROW(client.includeHostname("___"));
+
+    // Send the DHCPDISCOVER and make sure that the server responded.
+    ASSERT_NO_THROW(client.doDiscover());
+    auto resp = client.getContext().response_;
+    ASSERT_TRUE(resp);
+    ASSERT_EQ(DHCPOFFER, static_cast<int>(resp->getType()));
+
+    // Should have logged that it was scrubbed empty.
+    std::string log = "DHCP4_CLIENT_HOSTNAME_SCRUBBED_EMPTY"
+                      " [hwtype=1 67:c6:69:73:51:ff], cid=[no info], tid=0x0:"
+                      " sanitiziing client's Hostname option '___'"
+                      " yielded an empty string";
+    EXPECT_EQ(1, countFile(log));
+
+    // Hostname should not be in the response.
+    ASSERT_FALSE(resp->getOption(DHO_HOST_NAME));
+}
+
+// Verifies that when the FQDN option is scrubbed empty it is logged
+// and ignored.
+TEST_F(NameDhcpv4SrvTest, fqdnScrubbedEmpty) {
+    Dhcp4Client client(srv_, Dhcp4Client::SELECTING);
+
+    // Configure DHCP server.
+    configure(CONFIGS[2], *client.getServer());
+
+    // Include the Client FQDN option.
+    ASSERT_NO_THROW(client.includeFQDN(Option4ClientFqdn::FLAG_S | Option4ClientFqdn::FLAG_E,
+                                       "___", Option4ClientFqdn::PARTIAL));
+
+    // Send the DHCPDISCOVER and make sure that the server responded.
+    ASSERT_NO_THROW(client.doDiscover());
+    auto resp = client.getContext().response_;
+    ASSERT_TRUE(resp);
+    ASSERT_EQ(DHCPOFFER, static_cast<int>(resp->getType()));
+
+    // Should have logged that it was scrubbed empty.
+    std::string log = "DHCP4_CLIENT_FQDN_SCRUBBED_EMPTY"
+                      " [hwtype=1 67:c6:69:73:51:ff], cid=[no info], tid=0x0:"
+                      " sanitiziing client's FQDN option '___'"
+                      " yielded an empty string";
+    EXPECT_EQ(1, countFile(log));
+
+    // Hostname should not be in the response.
+    ASSERT_FALSE(resp->getOption(DHO_FQDN));
+}
+
+
 } // end of anonymous namespace
diff --git a/src/lib/dhcpsrv/tests/d2_client_unittest.cc b/src/lib/dhcpsrv/tests/d2_client_unittest.cc
index 68ad2189d6..520acbbb88 100644
--- a/src/lib/dhcpsrv/tests/d2_client_unittest.cc
+++ b/src/lib/dhcpsrv/tests/d2_client_unittest.cc
@@ -9,6 +9,7 @@
 #include <dhcp/option6_client_fqdn.h>
 #include <dhcpsrv/d2_client_mgr.h>
 #include <testutils/test_to_element.h>
+#include <testutils/gtest_utils.h>
 #include <exceptions/exceptions.h>
 #include <util/str.h>
 
@@ -1257,4 +1258,43 @@ TEST_F(D2ClientMgrParamsTest, sanitizeFqdnV6) {
     }
 }
 
+/// @brief Tests adjustDomainName template method with Option4ClientFqdn
+/// when sanitizing scrubs input name empty.
+TEST_F(D2ClientMgrParamsTest, adjustDomainNameV4ScrubbedEmpty) {
+    D2ClientMgr mgr;
+
+    // Create enabled configuration
+    subnet_->setDdnsSendUpdates(false);
+    subnet_->setDdnsQualifyingSuffix("suffix.com");
+    subnet_->setHostnameCharSet("[^A-Za-z0-9.-]");
+    subnet_->setHostnameCharReplacement("");
+
+    Option4ClientFqdn request(0, Option4ClientFqdn::RCODE_CLIENT(),
+                              "___", Option4ClientFqdn::FULL);
+
+    Option4ClientFqdn response(request);
+    ASSERT_THROW_MSG(mgr.adjustDomainName<Option4ClientFqdn>(request, response, *ddns_params_),
+                     FQDNScrubbedEmpty, "___.");
+}
+
+/// @brief Tests adjustDomainName template method with Option4ClientFqdn
+/// when sanitizing scrubs input name empty.
+TEST_F(D2ClientMgrParamsTest, adjustDomainNameV6ScrubbedEmpty) {
+    D2ClientMgr mgr;
+
+    // Create enabled configuration
+    subnet_->setDdnsSendUpdates(false);
+    subnet_->setDdnsQualifyingSuffix("suffix.com");
+    subnet_->setHostnameCharSet("[^A-Za-z0-9.-]");
+    subnet_->setHostnameCharReplacement("");
+
+    Option6ClientFqdn request(0, "___", Option6ClientFqdn::FULL);
+
+    Option6ClientFqdn response(request);
+    ASSERT_THROW_MSG(mgr.adjustDomainName<Option6ClientFqdn>(request, response, *ddns_params_),
+                     FQDNScrubbedEmpty, "___.");
+}
+
+
+
 } // end of anonymous namespace
-- 
2.47.3