Socket_read returning '1' ..? - php

Question

I have recently started practicing with sockets on PHP and got an issue for which I find no documentation. Similar cases I've seen in C++, but not a clear answer to this. The code:
do {
$input = socket_read($client, 12,PHP_BINARY_READ);
echo $input;
} while(TRUE);
Is supposed to block on the socket (code for creation, bind, etc not included) and get either 12 bytes or whatever information is available from the other side.
Oddly I just get a '1' in the variable $input if 12 bytes are read. If I send from the client side more than 12 bytes then I receive '1[REST_OF_DATA]' in the value of $input.
Any idea why this is happening?
If I change this to more data and to PHP_NORMAL_READ then I correctly receive the data.
PHP manual online does not say anything abou socket_read returning '1'..
**EDIT: Ok thanks for yout early answers :). I am saving to a file and reading (not echoing to browser) expecting any character. I think I may have just discovered something that could be good if someone with knowledge of C++ sockets can verify. Anyways, my read code actually was this (not what I posted above):
do {
$input = ($seq_id == 0) ? socket_read($client, 12,PHP_BINARY_READ) : socket_read($client,1024,PHP_BINARY_READ);
echo $input;
} while(TRUE);
I was expecting 12 bytes at the first read, then chunks of 1024, reason for that condition check. The weird '1' comes from this. If I replace that with the line I posted above the data is read normally. In fact, even reading like this:
$input = ($seq_ID == 0) ? socket_read($client,12,PHP_BINARY_READ) : socket_read($client, 12,PHP_BINARY_READ);
Results in : 1st read = '1' 2nd read = correct data, 3rd read = correct data..

Answer 1

The 12 you specify is the maximum length to read, so 12 can mean a return string of a size from 0-12 characters (binary string in PHP, 1 char = 1 byte).
Additionally as that can be binary, I suggest you use var_dump and a hexdump of the return string value to actually find out how many bytes were returned, echo might hide some control characters, your browser might hide whitespace.

Answer 2

For the comments above, yes $seq_id should increment. I just wanted to shorten the code. So now, the answer is not important for me anymore but remains an enigma, after upgrading my Ubuntu version this month I have been unable to replicate the error with the same script:
<?php
set_time_limit(0);
$address = "192.168.1.1";
$port = 3320;
$server_users = 3;
$mysock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP) or die("Could not create socket\n");
$bind_result = socket_bind($mysock,$address, $port) or die("Could not bind to address\n");
$listen_result = socket_listen($mysock, $server_users) or die("Could not set up socket listener\n");
$client = socket_accept($mysock) or die("Could not accept the connection to socket\n");
$seq_id =0;
do {
$input = ($seq_id == 0) ? socket_read($client, 12,PHP_BINARY_READ) : socket_read($client,1024,PHP_BINARY_READ);
echo $input;
} while(TRUE);
?>
I execute it in terminal:
$php -q myscript.php
And test it using netcat:
$netcat 192.168.1.1 3320
Note that the question is about socket_read returning 1 as it results, which is not documented anywhere