[950-harden-deferred-unpack] Hardened deffered unpacking so it no longer throws

src/bin/dhcp4/dhcp4_messages.cc

@@ -101,6 +101,7 @@ extern const isc::log::MessageID DHCP4_PACKET_NAK_0002 = "DHCP4_PACKET_NAK_0002"
 extern const isc::log::MessageID DHCP4_PACKET_NAK_0003 = "DHCP4_PACKET_NAK_0003";
 extern const isc::log::MessageID DHCP4_PACKET_NAK_0004 = "DHCP4_PACKET_NAK_0004";
 extern const isc::log::MessageID DHCP4_PACKET_OPTIONS_SKIPPED = "DHCP4_PACKET_OPTIONS_SKIPPED";
+extern const isc::log::MessageID DHCP4_PACKET_OPTION_UNPACK_FAIL = "DHCP4_PACKET_OPTION_UNPACK_FAIL";
 extern const isc::log::MessageID DHCP4_PACKET_PACK = "DHCP4_PACKET_PACK";
 extern const isc::log::MessageID DHCP4_PACKET_PACK_FAIL = "DHCP4_PACKET_PACK_FAIL";
 extern const isc::log::MessageID DHCP4_PACKET_PROCESS_EXCEPTION = "DHCP4_PACKET_PROCESS_EXCEPTION";
@@ -238,7 +239,8 @@ const char* values[] = {
     "DHCP4_PACKET_NAK_0002", "%1: invalid address %2 requested by INIT-REBOOT",
     "DHCP4_PACKET_NAK_0003", "%1: failed to advertise a lease, client sent ciaddr %2, requested-ip-address %3",
     "DHCP4_PACKET_NAK_0004", "%1: failed to grant a lease, client sent ciaddr %2, requested-ip-address %3",
-    "DHCP4_PACKET_OPTIONS_SKIPPED", "An error upacking an option, caused subsequent options to be skipped: %1",
+    "DHCP4_PACKET_OPTIONS_SKIPPED", "An error unpacking an option, caused subsequent options to be skipped: %1",
+    "DHCP4_PACKET_OPTION_UNPACK_FAIL", "An error unpacking the option %1: %2",
     "DHCP4_PACKET_PACK", "%1: preparing on-wire format of the packet to be sent",
     "DHCP4_PACKET_PACK_FAIL", "%1: preparing on-wire-format of the packet to be sent failed %2",
     "DHCP4_PACKET_PROCESS_EXCEPTION", "exception occurred during packet processing",

src/bin/dhcp4/dhcp4_messages.h

@@ -102,6 +102,7 @@ extern const isc::log::MessageID DHCP4_PACKET_NAK_0002;
 extern const isc::log::MessageID DHCP4_PACKET_NAK_0003;
 extern const isc::log::MessageID DHCP4_PACKET_NAK_0004;
 extern const isc::log::MessageID DHCP4_PACKET_OPTIONS_SKIPPED;
+extern const isc::log::MessageID DHCP4_PACKET_OPTION_UNPACK_FAIL;
 extern const isc::log::MessageID DHCP4_PACKET_PACK;
 extern const isc::log::MessageID DHCP4_PACKET_PACK_FAIL;
 extern const isc::log::MessageID DHCP4_PACKET_PROCESS_EXCEPTION;

src/bin/dhcp4/dhcp4_messages.mes

@@ -558,7 +558,12 @@ identification information. The second argument contains the IPv4 address
 in the ciaddr field. The third argument contains the IPv4 address in the
 requested-ip-address option (if present).
 
-% DHCP4_PACKET_OPTIONS_SKIPPED An error upacking an option, caused subsequent options to be skipped: %1
+% DHCP4_PACKET_OPTION_UNPACK_FAIL An error unpacking the option %1: %2
+A debug message issued when an option failed to unpack correctly, making it
+to be left unpacked in the packet. The first argument is the option code,
+the second the error.
+
+% DHCP4_PACKET_OPTIONS_SKIPPED An error unpacking an option, caused subsequent options to be skipped: %1
 A debug message issued when an option failed to unpack correctly, making it
 impossible to unpack the remaining options in the packet.  The server will
 server will still attempt to service the packet.

src/bin/dhcp4/dhcp4_srv.cc

@@ -3598,14 +3598,28 @@ Dhcpv4Srv::deferredUnpack(Pkt4Ptr& query)
         OptionPtr opt = query->getOption(code);
         if (!opt) {
             // should not happen but do not crash anyway
+            LOG_DEBUG(bad_packet4_logger, DBG_DHCP4_DETAIL,
+                      DHCP4_PACKET_OPTION_UNPACK_FAIL)
+                .arg(code)
+                .arg("can't find the option in the query");
             continue;
         }
         const OptionBuffer buf = opt->getData();
+        try {
+            // Unpack the option
+            opt = def->optionFactory(Option::V4, code, buf);
+        } catch (const std::exception& e) {
+            // Failed to parse the option.
+            LOG_DEBUG(bad_packet4_logger, DBG_DHCP4_DETAIL,
+                      DHCP4_PACKET_OPTION_UNPACK_FAIL)
+                .arg(code)
+                .arg(e.what());
+            continue;
+        }
         while (query->delOption(code)) {
             // continue
         }
-        // Unpack the option and add it
+        // Add the unpacked option.
-        opt = def->optionFactory(Option::V4, code, buf.cbegin(), buf.cend());
         query->addOption(opt);
     }
 }

src/bin/dhcp4/tests/vendor_opts_unittest.cc

@@ -684,7 +684,7 @@ TEST_F(VendorOptsTest, option43FailRaw) {
     // The vendor-encapsulated-options has an incompatible data
     // so won't have the expected content. Here the processing
     // of suboptions tries to unpack the uitn32 foo suboption and
-    // raises an exception.
+    // raises an exception which is caught so the option stays unpacked.
     string config = "{ \"interfaces-config\": {"
         "    \"interfaces\": [ \"*\" ] }, "
         "\"subnet4\": [ "
@@ -742,7 +742,9 @@ TEST_F(VendorOptsTest, option43FailRaw) {
     query->addOption(prl);
 
     srv.classifyPacket(query);
-    EXPECT_THROW(srv.deferredUnpack(query), InvalidOptionValue);
+    EXPECT_NO_THROW(srv.deferredUnpack(query));
+    ASSERT_TRUE(query->getOption(vopt->getType()));
+    EXPECT_EQ(vopt, query->getOption(vopt->getType()));
 }
 
 // Verifies raw option 43 can be handled (global)
@@ -1321,7 +1323,7 @@ TEST_F(VendorOptsTest, clientOption43FailRaw) {
     // The vendor-encapsulated-options has an incompatible data
     // so won't have the expected content. Here the processing
     // of suboptions tries to unpack the uint32 foo suboption and
-    // raises an exception.
+    // raises an exception which is caught.
     string config = "{ \"interfaces-config\": {"
         "    \"interfaces\": [ \"*\" ] }, "
         "\"subnet4\": [ "
@@ -1346,9 +1348,9 @@ TEST_F(VendorOptsTest, clientOption43FailRaw) {
     client.addExtraOption(vopt);
 
     // Let's check whether the server is not able to process this packet
-    // and raises an exception so the response is empty.
+    // and raises an exception which is caught so the response is not empty.
     EXPECT_NO_THROW(client.doDiscover());
-    EXPECT_FALSE(client.getContext().response_);
+    EXPECT_TRUE(client.getContext().response_);
 }
 
 // Verifies raw option 43 sent by a client can be handled (global)