Usage example:
mkdir dbdir && cd dbdir
certutil -N -d .
certutil -S -s "CN=ech-public.com" -n ech-public.com -x -t "C,C,C" -m 1234 -d .
certutil -S -s "CN=ech-private-backend.com" -n ech-private-backend.com -x -t "C,C,C" -m 2345 -d .
../dist/Debug/bin/selfserv -a ech-public.com -a ech-private-backend.com -n ech-public.com -n ech-private-backend.com -p 8443 -d dbdir/ -X publicname:ech-public.com
(Copy echconfig from selfserv output and paste into the below command)
../dist/Debug/bin/tstclnt -D -p 8443 -v -A tests/ssl/sslreq.dat -h ech-private-backend.com -o -N <echconfig> -v