PHP, Data stream no EOF - yet

[Lvcien]

A socket stream is opened with fsockopen() (possibly [pfsockopen() in the future]

A random amount of data is obtained from the stream with fgets()
From there the stream waits for data, this data will be sent to the stream using fwrite().

This fgets/fwrite cycle will repeated several times.

My question is this, How do I know when the stream stops sending data(no EOF is sent as this isn't the end) and is waiting for data to be sent to it.

[jatar_k]

Welcome to WebmasterWorld Lvcien,

Maybe take a look through the Stream Functions [php.net]

you could also try sending a newline

do you control the actual stream?

[Lvcien]

No, the stream is not controlled.

Basically, you're connecting to a network device(switch, router, etc) with a raw socket. This is used with multiple devices so the input it recieves is different per device so I can't, for example read up to the > in router>, etc.

At a certain point, when the data stops streaming it waits for say a user name or a password to log into the device, Or perhaps a command to enter a privileged mode (ie: enable).

This is the idea I had but I can't figure out the positioning in the loop.

do
{ do
{
$data_rcvd .= fgets($connection, 128);

} while(strcasecmp($data_rcvd,$data_cmp) == 0);

$data_cmp .= $data_rcvd;

} while(strcasecmp($data_rcvd,$data_cmp) == 0);

Basically, this should loop while the two values do not match, as $data_rcvd has additional data appended onto each cycle EXECPT then no more data passes through, and at that point the other string $data_cmp WILL match, and then you know to pass the data to the device...

Does this sound correct?

Does while(strcasecmp($data_rcvd,$data_cmp) == 0) in this loop, loop currently when the match? or when they don't?

Thanks!

[jatar_k]

it would loop while they match

[php.net...]

<?php
$var1 = "Hello";
$var2 = "hello";
if (strcasecmp($var1, $var2) == 0) {
echo '$var1 is equal to $var2 in a case-insensitive string comparison';
}
?>

[Lvcien]

I don't have the full source with me at the moment so I can't test it, but I think this will do it:

do
{
$data_cmp .= $data_rcvd;
$data_rcvd .= fgets($connection, 128);
} while(strcasecmp($data_rcvd,$data_cmp)!= 0);

For this example let's say that the data is pulled in two parts (ie: foo bar)

Do the loop:
Set $data_cmp equal to $data_rcvd which is currently nothing ("")
Get the data (foo)

$data_cmp = "";
$data_rcvd = foo;

Since the variable DO NOT match, repeat the loop

Append $data_rcvd to $data_cmp which is currently nothing still (""), which becomes $data_cmp = "foo"
Get the data (bar) and append it to $data_rcvd;

$data_cmp = "foo";
$data_rcvd = "foobar";

Again, the don't match - repeat the loop

Append $data_rcvd to $data_cmp which is currently "foo", which becomes $data_cmp = "foobar"
Get the data (""), now nothing as no more data is sent and append it to $data_rcvd, which is still "foobar"

$data_cmp = "foo";
$data_rcvd = "foobar"

Now the variables match so the loop is broken.

Does this sound correct?

Thanks!

[edited by: Lvcien at 4:27 pm (utc) on Feb. 6, 2007]

[jatar_k]

I think you had a little typo in your last example as you meant

$data_cmp = "foobar";
$data_rcvd = "foobar"

but, yes, in theory and talking it through it does seem right

[Lvcien]

Excellent, I just pulled the source and I'll give it a shot and let you know.

Thanks.

[Lvcien]

This is the code

$data_cmp = "."; 
    do
    { 
     if (strcasecmp($data_rcvd,$data_cmp)== 0)
     { 
      break;
     }
      $data_cmp = $data_rcvd;
      $data_rcvd .= fgets($connection, 128);
    } while(strcasecmp($data_rcvd,$data_cmp)!= 0);

Fatal error: Maximum execution time of 60 seconds exceeded in

Times out at this line: $data_rcvd .= fgets($connection, 128);

Which I don't understand... is it really that slow?

edit:

Did a little more research on this... seems that $data_rcvd .= fgets($connection, 128); hangs when there is no data being sent until, data sends again - ie: it stops at "Enter Password:" After 30 seconds or so, this prompt times out and data is sent.

Maybe there is a function or some other way that can check a stream for data, before a fgets() is sent...

[edited by: Lvcien at 9:17 pm (utc) on Feb. 6, 2007]

[jatar_k]

may not be in the first iteration

and it could be that slow, do you control all the machines you are working with?

you could play around with max_execution_time and see how long it actually takes.

hmm, this is one of those itmes I would love to have my good friend the admin and myself sitting playing around ;)

<after edit>

try looking through the stream functions to see if there is something, that's my first thought

[Lvcien]

I checked the stream functions and I can't find anything that would work...

edit:

Maybe something involving

[php.net...]

or

[php.net...]
[php.net...]

hmm...

[edited by: Lvcien at 10:40 pm (utc) on Feb. 6, 2007]

[jatar_k]

the timeout was the one that caught my eye

I also saw something about 'making it return immediately'

ah, this was it
[php.net...]

[Lvcien]

I noticed that last night but didn't have time to play with it...

There's a free script called PHPTelnet (google it) -- I may just hack that code up and see what it's doing.. I'll give this a shot.

[Lvcien]

stream_set_blocking($connection,0);

seems to work, I'll have to work out a few bugs before my application works as needed. I'll post the corrected code here as soon as I get a chance.

Thanks!

[jatar_k]

sweet, thought it might but you never know how functions will work exactly though they sound good