REQ packet format update

From The Open Source Backup Wiki (Amanda, MySQL Backup)

Hello,

The current format for a REQ packet is:

 SERVICE line
 OPTIONS line
 one DLE by line

For each DLE line, the first field are space separated and the option are name=value pair, but all name must be known.

We have 2 problems with this format:

 1. At each amanda release, it's become harder to parse, new field are
    added and it's hard to tell if it's the newer format or a
    previous, we use technique like comparing if it's char or numeric,
    ....
 2. We can't add Application-API property because all option must be
    known.

To fix 1: All the field must be a name=value pair.

To fix 2: We must differentiate between amanda option and Application-API property.

I propose the following new format:

1- The REQ packet for a NOOP request will not change (We must be compatible with previous release).
2- The SERVICE line will not change (needed to parse a NOOP request).
3- The OPTIONS line will not change (the features must be parsed before we know if the server sent the old or new format.
4- The DLE line will be changed to an xml like syntax as follow:
              <dle>
                <program>DUMP|GNUTAR|STAR|APPLICATION</program>
                <estimate>CLIENT|CALCSIZE|SERVER</estimate>     #if fe_xml_estimate
                <calcsize>NO|YES</calcsize>
                <backup-program>            #if application-api :program=APPLICATION
                   <name>...</name>
                   <property>               #can be repeated
                     <name>...</name>
                     <value>...</value>
                   </property>
                </dumper-program>
                <disk>...</disk>
                <diskdevice>...</diskdevice>
                <level>0..9</level>         #can be repeated for sendsize
                <spindle>...</spindle>
                <auth>BSD|BSDUDP|BSDTCP|SSH|RSH|KRB4|KRB5</auth>
                <record>YES|NO</record>
                <index>YES|NO</index>
                <exclude>
                   <file>...</file>         #can be repeated
                   <list>...</list>         #can be repeated
                   <optional>NO|YES</optional>
                </exclude>
                <include>
                   <file>...</file>         #can be repeated
                   <list>...</list>         #can be repeated
                   <optional>NO|YES</optional>
                </include>
                <compress>FAST|BEST|NO|CUSTOM
                   <custom-compress-program>...</custom-compress-program>
                </compress>
                <encrypt>NO|CUSTOM
                   <custom-encrypt-program>...</custom-encrypt-program>
                   <decrypt-option>...</decrypt-option>
                </encrypt>
                <kencrypt>YES|NO</kencrypt>
              </dle>

This new format will be easier to parse, it will be easy to add new field without breaking compatibility. Adding application-api property will not change the format.

The new packet format will be used only if the client and server support it, the older format will be used otherwise.