XML value compare and replace

I need a way to to check if a value in a file that has this XML format is less than or equal to current system date/time. if it is I need to override it with a future date/time:

Here is the data sample:

<?xml version="1.0" encoding="UTF-8"?><PORT_REQUEST><HEADER><DDD_T>060920171655</DDD_T>

I want to check if the value for the DDD_T if it is equal or less than current date if so to replace it with a future date "mmddccyyhhmm".

What is the best way to do this ? I am not sure from where to even start !

I'm afraid this looks more complex than it actually is:

awk -vFDT=$(date -d "+1day" +"%m%d%Y%H%M") -vSDT=$(date +"%Y%m%d%H%M")  '
match ($0, /<DDD_T>[^<]*<.DDD_T>/)      {TMP = substr ($0, RSTART+7, RLENGTH-15)
                                         if (SDT >= substr (TMP, 5, 4) substr (TMP, 1, 2) substr (TMP, 3, 2) substr (TMP, 9, 4)) \
                                         sub (TMP, FDT)
                                        }
1
' file
<?xml version="1.0" encoding="UTF-8"?><PORT_REQUEST><HEADER><DDD_T>061020172129</DDD_T>