Add DNSMASQ_DATA_MISSING envvar to lease-change script.

2 files changed, 13 insertions, 1 deletions

diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
index 67c8055..fea89fa 100644
--- a/man/dnsmasq.8
+++ b/man/dnsmasq.8
@@ -1712,7 +1712,13 @@ If dnsmasq was compiled with HAVE_BROKEN_RTC, then
 the length of the lease (in seconds) is stored in
 DNSMASQ_LEASE_LENGTH, otherwise the time of lease expiry is stored in
 DNSMASQ_LEASE_EXPIRES. The number of seconds until lease expiry is
-always stored in DNSMASQ_TIME_REMAINING. 
+always stored in DNSMASQ_TIME_REMAINING.
+
+DNSMASQ_DATA_MISSING is set to "1" during "old" events for existing
+leases generated at startup to indicate that data not stored in the
+persistent lease database will not be present. This comprises everything
+other than IP address, hostname, MAC address, DUID, IAID and lease length
+or expiry time.
 
 If a lease used to have a hostname, which is
 removed, an "old" event is generated with the new state of the lease, 
diff --git a/src/helper.c b/src/helper.c
index 39e4b89..14330f3 100644
--- a/src/helper.c
+++ b/src/helper.c
@@ -421,6 +421,9 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	      
 	      end = extradata + data.ed_len;
 	      buf = extradata;
+
+	      lua_pushnumber(lua, data.ed_len == 0 ? 1 : 0);
+	      lua_setfield(lua, -2, "data_missing");
 	      
 	      if (!is6)
 		buf = grab_extradata_lua(buf, end, "vendor_class");
@@ -599,6 +602,9 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	  
 	  end = extradata + data.ed_len;
 	  buf = extradata;
+
+	  if (data.ed_len == 0)
+	    my_setenv("DNSMASQ_DATA_MISSING", "1", &err);
 	  
 	  if (!is6)
 	    buf = grab_extradata(buf, end, "DNSMASQ_VENDOR_CLASS", &err);