Opinion please.

[Carp]

I am making a client server app. I cant figure out a good protocol. I came up with the following packet for the signno process.

000000x1USERNAME00x2PASSWORD00x3CLIENT0000

Broken down, it means:

0000 = packet start/end
00x1 = username is coming Next
USERNAME
00x2 = password is coming Next
PASSWORD
00x3 = client verson is coming
CLIENT VERSION
0000 = packet start/end

I was wondering what everyone thinks of this? Any susgesions? Thanks in advance!

^{Kevin Carpenter
Freelance Computer Programmer}

[RoD]

probly better in c++ section.

[Carp]

I'm not asking a C++ question, I'm asking a general programming question

[Travis Dane]

Originally posted by Carp
I'm not asking a C++ question, I'm asking a general programming question

General Discussions
Non-programming related topics

[Hammer]

You need to include message/field lengths. That way you can avoid classic problems such as "what happens if the password contain 00x3?".

I'd suggest something like this (this is only a guide, adapt it as you see fit):

AAABCCC...

Where AAA is a message length indicator (always 3 bytes, padded with leading zeros), 
B is the message type indicator, 
and C is the message.

Eg

007UHAMMER009PSeCuRiTy

007 - 7 bytes of data coming up next
U - User id follows
HAMMER - the user (duh!)
009 - 9 bytes of data coming up next
P - Password follows
SeCuRiTy - the password.

It's important to use a length indicator, as socket input to your program will appear as a stream of data. One call to recv() isn't going to get you one complete message. If you want to know more, ask (or read a TCP/IP programmers book/reference)

Of course, you may want to consider some form of encryption if you're sending passwords over a socket.