Handling protocol not supported error message when working with protocol 2 and 3

Hi all,

I'm finishing the implementation of the protocol 3.0 and now I'm working
in how to connect to server using protocol 3.0 when the server doesn't
support it 7.3- .

As suggested in a previous mail about how to handle with both protocol
versions, I'm trying first to connect using version 3.0. The problem is
if the server is a 7.3 or earlier, it would answer with a non supported
protocol error message, but as I'm in the protocol 3.0 version mode, I
would expect a error message in the new format and not in the 2.0 format.

How I could handle it?

I know this error happens early in the connection establishment, when I
send the StartupPacket and I could use this info to do some choices
about when to use the version 2 or 3. The problem is that I also could
get a lot of errors when sending the startup packet, as password
incorrect, database and others.

I was thinking about examining the first 4 bytes ( as this is where the
message length is located) and try if these bytes could be translated to
"FATA" which would mean the "FATAL: unsupported frontend protocol\n"
error. But I think this would be a big hack. Is there a more elegant
solution?

I know this question was alread raised some time ago, but I couldn't
find it.

Thanks in advance.

--
Regards,

Francisco Figueiredo Jr.

------
"My grandfather once told me that there are two
kinds of people: those
who work and those who take the credit. He told me
to try to be in the
first group; there was less competition there."
- Indira Gandhi