recv() and send() in socket

lrios · 04-22-2008, 04:42 PM

Hello,

I am doing an simple chat server-client tcp and i want to pass messages between them, with recv(), and send() functions , but I dont work at all.

CLIENT

Code:

char *buffer[100];
puts("write the nick(se requeriran 3 pasos antes de ingresar)"); fgets(users[n_user].username, sizeof(users[n_user].username), stdin);	
*buffer = (users[n_user].username);
send(fdsocket, buffer, strlen(buffer), 0);
printf("Sending nick to server . . . %s\n", *buffer);

SERVER

Code:

char *buffer_c[100];
recv(fdsocket, buffer_c, MAXL_NICK, 0);
printf("Se conecto al chat -%s-\n", *buffer_c);

The server received garbage.

lukost · 04-22-2008, 04:47 PM

Have you checked Beej's Guide to Network Programming?
http://beej.us/guide/bgnet/

Cheers,
lukost

theNbomr · 04-22-2008, 05:37 PM

The line

Code:

*buffer = (users[n_user].username);

looks suspicious to me. The assignment should move only one pointer value (some assumptions here, due to lack of code) into a character buffer. The character buffer will contain garbage and no meaningful string or string terminator.
Perhaps you should be using

Code:

strcpy( buffer, users[n_user].username);

or some other function that moves bytes.
--- rod.

ta0kira · 04-22-2008, 10:23 PM

How big is users[n_user].username, anyway? Is it statically sized (sizeof implies "yes")? Any reason why you don't just send using that array?
ta0kira

lrios · 04-23-2008, 09:24 AM

[HTML]How big is users[n_user].username, anyway? Is it statically sized (sizeof implies "yes")? Any reason why you don't just send using that array?[/HTML]

ta0kira
This is my structure <chat.h>

int n_user;
struct struc_user {

int *number_user;
char username[100];

} users[100];

So ... this way is ok ? ?

client

Code:

fgets(users[n_user].username, sizeof(users[n_user].username), stdin);
strcpy( buffer, users[n_user].username);
send(fdsocket, buffer, strlen(buffer), 0);
printf("Sending nick to server . . . %s\n", *buffer);

server

Code:

char *buffer_c[100];
recv(fdsocket, buffer_c, MAXL_NICK, 0);
printf("Se conecto al chat -%s-\n", *buffer_c);

ta0kira · 04-23-2008, 11:32 AM

The buffers shouldn't be char*[], just char[]. I'd do this:

Code:

char buffer[100];
puts("write the nick(se requeriran 3 pasos antes de ingresar)");
if (fgets(users[n_user].username, sizeof(users[n_user].username), stdin))
{
send(fdsocket, users[n_user].username, strlen(users[n_user].username), 0);
printf("Sending nick to server . . . %s\n", *buffer);
}

If you really do need to copy to the buffer, I'd do it like this:

Code:

strncpy( buffer, users[n_user].username,
  (sizeof(buffer) < sizeof(users[n_user].username))?
   sizeof(buffer) : sizeof(users[n_user].username) );

ta0kira