ntp: add function to change authentication-specific address

When an NTS source will be replaced, the authentication-specific address
of the NTS-KE server will need to be changed too.

ntp_auth.c

@@ -422,3 +422,17 @@ NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response, NTP_PacketInf
 
   return 1;
 }
+
+/* ================================================== */
+
+void
+NAU_ChangeAddress(NAU_Instance instance, IPAddr *address)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+    case NTP_AUTH_SYMMETRIC:
+      break;
+    default:
+      assert(0);
+  }
+}

ntp_auth.h

@@ -81,4 +81,7 @@ extern int NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request
 extern int NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response,
                                  NTP_PacketInfo *info);
 
+/* Change an authentication-specific address (e.g. after replacing a source) */
+extern void NAU_ChangeAddress(NAU_Instance instance, IPAddr *address);
+
 #endif

ntp_core.c

@@ -710,6 +710,9 @@ NCR_ChangeRemoteAddress(NCR_Instance inst, NTP_Remote_Address *remote_addr, int
   SRC_SetRefid(inst->source, UTI_IPToRefid(&remote_addr->ip_addr),
                &inst->remote_addr.ip_addr);
   SRC_ResetInstance(inst->source);
+
+  if (!ntp_only)
+    NAU_ChangeAddress(inst->auth, &remote_addr->ip_addr);
 }
 
 /* ================================================== */