[4206] Fix for empty client-id in v4

src/bin/dhcp4/dhcp4_messages.mes

@@ -457,6 +457,11 @@ This error message is issued when preparing an on-wire format of the packet
 has failed. The first argument identifies the client and the DHCP transaction.
 The second argument includes the error string.
 
+% DHCP4_PACKET_PROCESS_EXCEPTION exception occurred during packet processing: %1
+This error message indicates that an exception was raised during packet processing
+that was not caught by other, more specific exception handlers. This packet will
+be dropped and the server will continue operation.
+
 % DHCP4_PACKET_RECEIVED %1: %2 (type %3) received from %4 to %5 on interface %6
 A debug message noting that the server has received the specified type of
 packet on the specified interface. The first argument specifies the

src/bin/dhcp4/dhcp4_srv.cc

@@ -428,6 +428,8 @@ Dhcpv4Srv::run() {
         Pkt4Ptr rsp;
 
         try {
+
+        try {
             uint32_t timeout = 1000;
             LOG_DEBUG(packet4_logger, DBG_DHCP4_DETAIL, DHCP4_BUFFER_WAIT).arg(timeout);
             query = receivePacket(timeout);
@@ -787,6 +789,19 @@ Dhcpv4Srv::run() {
                 .arg(rsp->getLabel())
                 .arg(e.what());
         }
+
+        } catch (const std::exception& e) {
+            // General catch-all exception that are not caught by more specific
+            // catches. This one is for exceptions derived from std::exception.
+            LOG_ERROR(packet4_logger, DHCP4_PACKET_PROCESS_EXCEPTION)
+                .arg(e.what());
+        } catch (...) {
+            // General catch-all exception that are not caught by more specific
+            // catches. This one is for other exceptions, not derived from
+            // std::exception.
+            LOG_ERROR(packet4_logger, DHCP4_PACKET_PROCESS_EXCEPTION)
+                .arg("an unknown exception not derived from std::exception");
+        }
     }
 
     return (true);