C++ Networking - Funky responses

[zylime]

Hey,

I'm pretty deep into my first UNIX networking project, but I am lacking some fundamentals still...

I send a command and read the response. What would cause me to get different read() responses when I run the same code? Like I run the program, exit, run the program, exit, run the program, exit. Sometimes I'll get the response I expect but other times I get unicode jibberish... I feel like I'm rolling the dice...

In the example below, sometimes the response is the expected one, "+++", and other times it is something like "k��־�<}�<*n�R". The jibberish changes. I've been tinkering with sleep() to see if that increases the probability of success.

char buffer[100], latiCmd[100];
      size_t cmdlen;
      ssize_t bytes_sent;

      snprintf(latiCmd, 100, "+++\r"); //start fresh!                           
      cmdlen = sizeof(latiCmd);
      bytes_sent = send(latisockfd,latiCmd,cmdlen,0);
      printf("Sent Escape to start fresh.\n");
      sleep(4);
      read(latisockfd,buffer,100);
      printf("Response0: %s",buffer);

I'm not hoping someone can correct my code... Can anybody point me in the direction of what could cause this? Do bytes just get "lost" frequently? The hardware folks said I just have to tinker with delays, but I'm not sure if that's really helping. I think I might just stay in a loop retrying the command until I read the response I want and only then move on in the program.

I suppose I'm just looking for keywords or anything that might hint me in a possible direction. I have a copy of vol 1 of stevens' unix networking book but I feel like I'm shooting in the dark!

Thanks for reading.

[S6k9GNh0]

send and read don't ensure that you actually read/send the entire message being sent or received. Every protocol has some method of message closure included in the message. For instance, IRC messages (and quite a few others) end with two bytes, "\r\n" (or in reality, some combination of those two). I don't know what you're sending and reading from so I can't give details.

EDIT: For clarification on how read() works in comparison to recv() (which I just now got doubted on), please read this page: http://pubs.opengroup.org/onlinepubs/009695399/functions/read.html

It claims that read(), when used with a socket descriptor, functions the same way as recv() with no flags.