I'm writing a program which uses sockets and now I want to start testing if actually works
I wrote a small test program which opens a connection to "127.0.0.1" and transmits two messages to my program.

Program:
1. socket()
2. bind()
3. listen()
4. accept()
5. recv() loop.

Test program:
1. socket()
2. connect()
3. send(msg1)
4. send(msg2)

the accept/connect part completes without any problems but recv() returns 0 before the test program transmits it's 1st message. As I understand this means that the socket has disconnected.
Both send() returns -1.

Isn't it possible to run both my program and test program on the same pc or do I need to the setup differently?

BR, Thomas Fogh

networking works fine on the same machine no worries.

have you heard of netcat?
man nc

it's ideal for this stuff, it's better to test the client and server
seperately when you have trouble,
netcat enables you to do this quite easily.

e.g; try

ls | nc -lp 50666

then point your browser at
http://localhost:50666

Thanks, that looks pretty good
But how do I send two binary messages from NC?

ahh, binary eh?
well that's a horse of a different colour.
I always keep to ascii protocols where possible.

nc will pass binary as well as ascii.
it just makes life more difficult for you.

something like?
cat msg1 msg2 | nc -vv -w 2 host port

Ok, I'll try that. Thanks!
BTW:
I have a struct:
typedef struct {
char msg_id;
long length;
} msg_t;

sizeof(msg_t.msg_id) = 1
sizeof(msg_t.length) = 4
sizeof(msg_t) = 8
I guess this is because my OS is 32 bit, but can I (easily) avoid having to send 8 bytes, and instead just the 5 I need?
(Without making a send-function for every message struct I have.)

what are you doing?

I'd be tempted to use line buffered ascii data to start with,
at least until you understand how sockets operate.
if they are readable messages why not transmit them as such.

sockets aren't difficult, they are just awkward and confusing at times.

you see a lot of inet protocols are text based, SMTP and HTTP to name but two.
try nc localhost 25 and play with the mail server for instance. the advantage is
you can debug easy using tools like nc.

An XMMS plugin to edit the playlist and control playback over a Wifi connection.
(A PSP connected to a PS3 with Ubuntu.)
I want to display album pictures so I need to send binary.

so quite a complex protocol then?
but using an ascii protocol does not preclude sending binary data.

I've done it myself.

Not that I'm trying to dissuade you but if it's a complex protocol
not human readable, with lots of messages you'll need a suite of functions
to help debug it too.

if you are sendin a TCP packet with a message in it why not make it
readable.

It's not to bad
And I found my error. I thought connect() returned a new socket like accept() does. Whoops!
I only have around 20 messages and only 3-4 complex ones, so I think I'll stick with the binary.
Thank you for your help and suggestions, though! (It's always nice to learn a new linux "command" )

i'd be interested to see it when it's done

I'll try to remember to post an update on this thread.
And I'll upload it the XMMS site, when it's done.
(Hopefully in a couple of weeks depended on this crappy weather )

BTW, is TCP error-free or do I need to implement a CRC check?