chgserver: implement validate command
validate will load the repo config and check if the server has up-to-date
config to continue serve the client. In case it does not, the server will
send instructions to the client about what to do next, including to retry
with a different address or to unlink an outdated socket file to stop an
old server.
== Local
Ready.
Un and Deux
Eins und Zwei
One and Two
Nope
Eins und Zwei
Hello, John Smith
Ready.
Uno und Due
== Remote
Ready.
REQ: foo?one=Vo&two=Efvy
-> Vo!boe!Efvy
Un and Deux
REQ: bar?b=Fjot&a=[xfj
-> Fjot!voe![xfj
Eins und Zwei
REQ: batch?cmds=foo:one=Pof,two=Uxp;bar:b=Fjot,a=[xfj
-> Pof!boe!Uxp;Fjot!voe![xfj
REQ: greet?name=Kpio!Tnjui
-> Ifmmp-!Kpio!Tnjui
REQ: batch?cmds=bar:b=Vop,a=Evf
-> Vop!voe!Evf
One and Two
Nope
Eins und Zwei
Hello, John Smith
Ready.
Uno und Due