Ping+Port Routine?

[Adam]

Hi! I'm trying to write a small application for an online gaming site
(flight sims), where people can add their local server to a list.

Basically, I just need to be able to loop/ping each respective server
- via a specific port (2934 or 2935) to see whether the server is
still "live", so the hosters don't have to manually update their
status on the site.

Everything I've seen seems overly complex. Efforts so far have
returned info via a traditional PING, but I can't seem to find an easy
way of getting the required *port* info. The script would have to run
from a regular hosted site, so I wouldn't have much access to the
server's "innards".

Any ideas?

TIA - Adam.

[Jerry Stuckle]

Adam wrote:

Hi! I'm trying to write a small application for an online gaming site
(flight sims), where people can add their local server to a list.

Basically, I just need to be able to loop/ping each respective server
- via a specific port (2934 or 2935) to see whether the server is
still "live", so the hosters don't have to manually update their
status on the site.

Everything I've seen seems overly complex. Efforts so far have
returned info via a traditional PING, but I can't seem to find an easy
way of getting the required *port* info. The script would have to run
from a regular hosted site, so I wouldn't have much access to the
server's "innards".

Any ideas?

TIA - Adam.

Ping uses an internally defined port for responses - not just any port.
You can't ping a specific port - it wouldn't know how to respond.

Probably the easiest way would be to use fsockopen to open a socket to
the appropriate system/port.

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Adam]

On Wed, 21 Sep 2005 07:05:41 -0500, Jerry Stuckle wrote:

Adam wrote:

Hi! I'm trying to write a small application for an online gaming site
(flight sims), where people can add their local server to a list.

Basically, I just need to be able to loop/ping each respective server
- via a specific port (2934 or 2935) to see whether the server is
still "live", so the hosters don't have to manually update their
status on the site.

Everything I've seen seems overly complex. Efforts so far have
returned info via a traditional PING, but I can't seem to find an easy
way of getting the required *port* info. The script would have to run
from a regular hosted site, so I wouldn't have much access to the
server's "innards".

Any ideas?

TIA - Adam.

Ping uses an internally defined port for responses - not just any port.
You can't ping a specific port - it wouldn't know how to respond.

Probably the easiest way would be to use fsockopen to open a socket to
the appropriate system/port.

Thanks for that. I've managed to send an initial "handshake" packet
out to the game server using:

$handle = fsockopen("udp://$host", $port, $errno, $errstr, $timeout);

It triggers the game server to respond with a 67 byte long reply
(which I can see using a packet sniffer). So far so good.

However ... try as I might, I just can't read this data. I've tried
all sorts of combinations of "fread", "unpack" etc. eg:

$contents = fread($handle, 67);

The above seems to return nothing. How do I go about reading this
packet of data? Is the PHP code executing before the packet has had a
chance to arrive?

Thanks,

Adam.

[Jerry Stuckle]

Adam wrote:

On Wed, 21 Sep 2005 07:05:41 -0500, Jerry Stuckle wrote:

Thanks for that. I've managed to send an initial "handshake" packet
out to the game server using:

$handle = fsockopen("udp://$host", $port, $errno, $errstr, $timeout);

It triggers the game server to respond with a 67 byte long reply
(which I can see using a packet sniffer). So far so good.

However ... try as I might, I just can't read this data. I've tried
all sorts of combinations of "fread", "unpack" etc. eg:

$contents = fread($handle, 67);

The above seems to return nothing. How do I go about reading this
packet of data? Is the PHP code executing before the packet has had a
chance to arrive?

Thanks,

Adam.

From the PHP manual:

Warning:
UDP sockets will sometimes appear to have opened without an error, even
if the remote host is unreachable. The error will only become apparent
when you read or write data to/from the socket. The reason for this is
because UDP is a "connectionless " protocol, which means that the
operating system does not try to establish a link for the socket until
it actually needs to send or receive data.

So - just because you get a handle back doesn't mean you've successfully
opened the socket. You may not actually be opening it. You many need
to use a packet sniffer to see what's actually going across your link.

Otherwise, if just opening the socket gets you the response, I would
expect you to get the response. Are you sure you don't need to send
something first, i.e. a newline char?

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Adam]

On Thu, 22 Sep 2005 11:23:15 -0500, Jerry Stuckle wrote:

Adam wrote:

On Wed, 21 Sep 2005 07:05:41 -0500, Jerry Stuckle wrote:

Thanks for that. I've managed to send an initial "handshake" packet
out to the game server using:

$handle = fsockopen("udp://$host", $port, $errno, $errstr, $timeout);

It triggers the game server to respond with a 67 byte long reply
(which I can see using a packet sniffer). So far so good.

However ... try as I might, I just can't read this data. I've tried
all sorts of combinations of "fread", "unpack" etc. eg:

$contents = fread($handle, 67);

The above seems to return nothing. How do I go about reading this
packet of data? Is the PHP code executing before the packet has had a
chance to arrive?

Thanks,

Adam.

From the PHP manual:

Warning:
UDP sockets will sometimes appear to have opened without an error, even
if the remote host is unreachable. The error will only become apparent
when you read or write data to/from the socket. The reason for this is
because UDP is a "connectionless " protocol, which means that the
operating system does not try to establish a link for the socket until
it actually needs to send or receive data.

So - just because you get a handle back doesn't mean you've successfully
opened the socket. You may not actually be opening it. You many need
to use a packet sniffer to see what's actually going across your link.

Otherwise, if just opening the socket gets you the response, I would
expect you to get the response. Are you sure you don't need to send
something first, i.e. a newline char?

Jerry - thanks for persevering with me on this one <g>. Yep - I'd read
that warning in the manual.

There's no problem with *writing* to the [opened] socket. Using a
packet sniffer, I can see the data go out and - what's more - I can
see a response packet appear on the client. This is what's happening:

1) Open socket (in client).
2) Write to socket (gets sent successfully to game server).
3) Client gets response back from server (socket still open).
4) Futile attempts to read the 67 bytes long incoming packet (!!).
5) Close socket (in client).

For step 4, I've tried fread, fgets .. all sorts - but it occurs to me
that this may be a PHP/OS related thing, as I've seen (in my Googling)
reference to a *read* socket bug in PHP in earlier builds for Win32.

Are you suggesting I send something [again] before steps 3,4? Is it a
*timing* problem? Either the PHP script isn't waiting long enough for
the incoming packet or the packet has beenand gone before the script
has had a chance to read it?

All examples I've tried using (eg. HTTP/port 80) seem to work fine - a
request gets sent and the response is processed properly and
displayed.

My setup is Apache/2.0.52 (Win32) PHP/4.3.9. I'll try running the
client script from a Linux machine.

Adam.

[Jerry Stuckle]

Adam wrote:

On Thu, 22 Sep 2005 11:23:15 -0500, Jerry Stuckle wrote:

Jerry - thanks for persevering with me on this one <g>. Yep - I'd read
that warning in the manual.

There's no problem with *writing* to the [opened] socket. Using a
packet sniffer, I can see the data go out and - what's more - I can
see a response packet appear on the client. This is what's happening:

1) Open socket (in client).
2) Write to socket (gets sent successfully to game server).
3) Client gets response back from server (socket still open).
4) Futile attempts to read the 67 bytes long incoming packet (!!).
5) Close socket (in client).

For step 4, I've tried fread, fgets .. all sorts - but it occurs to me
that this may be a PHP/OS related thing, as I've seen (in my Googling)
reference to a *read* socket bug in PHP in earlier builds for Win32.

Are you suggesting I send something [again] before steps 3,4? Is it a
*timing* problem? Either the PHP script isn't waiting long enough for
the incoming packet or the packet has beenand gone before the script
has had a chance to read it?

All examples I've tried using (eg. HTTP/port 80) seem to work fine - a
request gets sent and the response is processed properly and
displayed.

My setup is Apache/2.0.52 (Win32) PHP/4.3.9. I'll try running the
client script from a Linux machine.

Adam.

Hi, Adam,

OK, I didn't realize you were sending to the remote machine first. OK,
so we know the socket itself is open, you can write to it, and you get a
response back.

Next thing - fread stops as soon as a packet is available. This may or
may not be the entire message. An extreme example - say the remote
system is sending you 100K worth of data. This won't all come in one
packet - you probably will have at least dozens of them. fread() will
read one packet, and you'll have to keep to keep receiving until you get
all the data, and assemble the packets.

How does this apply in your case? Well, is it possible you're getting a
short (or empty) packet before the data? It's perfectly legal for the
remote to do so. If so, you'll have to loop on your fread() call until
you get all 67 bytes of data.
--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Adam]

On Fri, 23 Sep 2005 10:07:59 -0500, Jerry Stuckle wrote:

Adam wrote:

On Thu, 22 Sep 2005 11:23:15 -0500, Jerry Stuckle wrote:

Jerry - thanks for persevering with me on this one <g>. Yep - I'd read
that warning in the manual.

There's no problem with *writing* to the [opened] socket. Using a
packet sniffer, I can see the data go out and - what's more - I can
see a response packet appear on the client. This is what's happening:

1) Open socket (in client).
2) Write to socket (gets sent successfully to game server).
3) Client gets response back from server (socket still open).
4) Futile attempts to read the 67 bytes long incoming packet (!!).
5) Close socket (in client).

For step 4, I've tried fread, fgets .. all sorts - but it occurs to me
that this may be a PHP/OS related thing, as I've seen (in my Googling)
reference to a *read* socket bug in PHP in earlier builds for Win32.

Are you suggesting I send something [again] before steps 3,4? Is it a
*timing* problem? Either the PHP script isn't waiting long enough for
the incoming packet or the packet has beenand gone before the script
has had a chance to read it?

All examples I've tried using (eg. HTTP/port 80) seem to work fine - a
request gets sent and the response is processed properly and
displayed.

My setup is Apache/2.0.52 (Win32) PHP/4.3.9. I'll try running the
client script from a Linux machine.

Adam.

Hi, Adam,

OK, I didn't realize you were sending to the remote machine first. OK,
so we know the socket itself is open, you can write to it, and you get a
response back.

Next thing - fread stops as soon as a packet is available. This may or
may not be the entire message. An extreme example - say the remote
system is sending you 100K worth of data. This won't all come in one
packet - you probably will have at least dozens of them. fread() will
read one packet, and you'll have to keep to keep receiving until you get
all the data, and assemble the packets.

How does this apply in your case? Well, is it possible you're getting a
short (or empty) packet before the data? It's perfectly legal for the
remote to do so. If so, you'll have to loop on your fread() call until
you get all 67 bytes of data.

Well ... the story continues <ggg>. Basically though, it appears that
whichever way I try to read the data, it hangs. This is using fread,
fgets, socket reads ... you name it. The *impression* I get is that
the packet has already been and gone - and all attempts to read the
socket fail - because the [remote] server is no longer sending.

I know (via the portsniffer) that the incoming packet is less than 100
bytes long. It's not a file (I don't think) so it won't have an eof
marker.

I've just installed PHP5 with socket support on a Linux machine to see
whether any of the socket_* commands or new PHP5 functions will work.

Watch this space <g> ...

Adam.

[Adam]

Still no luck :-((

I have Ethereal running on both client and server. Both versions
confirm that:

1) A request goes out to the server on port 2934. This is around 70
bytes: A header plus around 30 bytes of data.
2) The server responds with a welcome of around 120 bytes.
3) This packet duly arrives at the client.

OK - now to the code. I've tried every combination of socket connect &
write, streams .. you name it ...but here are my two main variations:
// Set up the connection =============== ====
$remote_host = 'udp://192.168.1.126';
$remote_port = 2934;
$timeout = 1;

// This is the outgoing msg (in hex) ==========
$hello =
"\x20\x00\x09\x 42\x46\x4f\x31\ x00\x00\x00\x00 \x01\x83\x05\x0 7\x0d\x12";

// This part embeds the client's IP address (in hex, backwards!)
// This is what the connecting flight sim appears to send
$hello .="\x03\x01\xa8 \xc0";

// The rest of the data packet:- (sim version etc).
$hello .= "\x03\x84\x0f\x 87\x12\x02\x00\ x00";

// The returned data (I should be so lucky!) =====
$ret = '';

// Open the socket =============== =
$socket = fsockopen($remo te_host, $remote_port, $errno, $errstr,
$timeout);
if (!$socket) {
echo "Connection Failed - Please check manually."; }
else {
// Send the packet ===
fputs($socket, "$hello");
// fputs($socket, "$hello\r\n "); // Try with a return? ===

echo "Sent to <b>$remote_host :$remote_port</b><br>";

// So far so good ... the packet gets received
// by the server (confirmed by sniffer) ...
// and a reply gets sent to the client IP+port ..

//... BUT ... neither of these appear to work =======
//$ret = fgets($socket, 64);
$ret = fread($socket, 2048);
// Tried all sorts values from 1 to 2048 =====

echo "[" . $ret . "]";
fclose($socket) ;
};
echo "<hr>Closed ";

That's it! H-E-L-P !!! I wonder whether you/anyonecan shed any light
on this!

Adam.

[Jerry Stuckle]

Adam wrote:

Still no luck :-((

I have Ethereal running on both client and server. Both versions
confirm that:

1) A request goes out to the server on port 2934. This is around 70
bytes: A header plus around 30 bytes of data.
2) The server responds with a welcome of around 120 bytes.
3) This packet duly arrives at the client.

OK - now to the code. I've tried every combination of socket connect &
write, streams .. you name it ...but here are my two main variations:
// Set up the connection =============== ====
$remote_host = 'udp://192.168.1.126';
$remote_port = 2934;
$timeout = 1;

// This is the outgoing msg (in hex) ==========
$hello =
"\x20\x00\x09\x 42\x46\x4f\x31\ x00\x00\x00\x00 \x01\x83\x05\x0 7\x0d\x12";

// This part embeds the client's IP address (in hex, backwards!)
// This is what the connecting flight sim appears to send
$hello .="\x03\x01\xa8 \xc0";

// The rest of the data packet:- (sim version etc).
$hello .= "\x03\x84\x0f\x 87\x12\x02\x00\ x00";

// The returned data (I should be so lucky!) =====
$ret = '';

// Open the socket =============== =
$socket = fsockopen($remo te_host, $remote_port, $errno, $errstr,
$timeout);
if (!$socket) {
echo "Connection Failed - Please check manually."; }
else {
// Send the packet ===
fputs($socket, "$hello");
// fputs($socket, "$hello\r\n "); // Try with a return? ===

echo "Sent to <b>$remote_host :$remote_port</b><br>";

// So far so good ... the packet gets received
// by the server (confirmed by sniffer) ...
// and a reply gets sent to the client IP+port ..

//... BUT ... neither of these appear to work =======
//$ret = fgets($socket, 64);
$ret = fread($socket, 2048);
// Tried all sorts values from 1 to 2048 =====

echo "[" . $ret . "]";
fclose($socket) ;
};
echo "<hr>Closed ";

That's it! H-E-L-P !!! I wonder whether you/anyonecan shed any light
on this!

Adam.

Adam,

Let's back up a little. I'm wondering if we're looking at the wrong
problem.

A couple of thoughts here. First of all, where are you running the
sniffer? Is it on this machine, or somewhere upstream?

Also, are you using a firewall or a router anyplace? If so, are they
set up properly to pass the incoming data onto your program?

--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attgl obal.net
=============== ===

[Adam]

On Mon, 26 Sep 2005 06:59:08 -0500, Jerry Stuckle wrote:

Adam wrote:

Still no luck :-((

I have Ethereal running on both client and server. Both versions
confirm that:

1) A request goes out to the server on port 2934. This is around 70
bytes: A header plus around 30 bytes of data.
2) The server responds with a welcome of around 120 bytes.
3) This packet duly arrives at the client.

OK - now to the code. I've tried every combination of socket connect &
write, streams .. you name it ...but here are my two main variations:
// Set up the connection =============== ====
$remote_host = 'udp://192.168.1.126';
$remote_port = 2934;
$timeout = 1;

// This is the outgoing msg (in hex) ==========
$hello =
"\x20\x00\x09\x 42\x46\x4f\x31\ x00\x00\x00\x00 \x01\x83\x05\x0 7\x0d\x12";

// This part embeds the client's IP address (in hex, backwards!)
// This is what the connecting flight sim appears to send
$hello .="\x03\x01\xa8 \xc0";

// The rest of the data packet:- (sim version etc).
$hello .= "\x03\x84\x0f\x 87\x12\x02\x00\ x00";

// The returned data (I should be so lucky!) =====
$ret = '';

// Open the socket =============== =
$socket = fsockopen($remo te_host, $remote_port, $errno, $errstr,
$timeout);
if (!$socket) {
echo "Connection Failed - Please check manually."; }
else {
// Send the packet ===
fputs($socket, "$hello");
// fputs($socket, "$hello\r\n "); // Try with a return? ===

echo "Sent to <b>$remote_host :$remote_port</b><br>";

// So far so good ... the packet gets received
// by the server (confirmed by sniffer) ...
// and a reply gets sent to the client IP+port ..

//... BUT ... neither of these appear to work =======
//$ret = fgets($socket, 64);
$ret = fread($socket, 2048);
// Tried all sorts values from 1 to 2048 =====

echo "[" . $ret . "]";
fclose($socket) ;
};
echo "<hr>Closed ";

That's it! H-E-L-P !!! I wonder whether you/anyonecan shed any light
on this!

Adam.

Adam,

Let's back up a little. I'm wondering if we're looking at the wrong
problem.

A couple of thoughts here. First of all, where are you running the
sniffer? Is it on this machine, or somewhere upstream?

I've got Ethereal running on both machines:

1) Client: Linux - running the PHP script. No firewall.
2) Server: WinXP - running the sim in multiplayer mode. Firewall in
place (Norton PFW) but this server connects OK to other XP machines
running the sim in client mode.
Also, are you using a firewall or a router anyplace? If so, are they
set up properly to pass the incoming data onto your program?

The router only sits between the network and the ADSL.

Anyway - I can *see* the packets leaving/arriving on each machine - so
I think the firewall thing is OK. The packets appear addressed
properly, and contain data.

Having done a fair bit of googling around, it seems PHP's sockets
implementation is a bit quirky. All sorts of oddities come into the
equation - the "magic_quot es" setting, stream_set_bloc king and so on.

I could paste the dumps of each packet if that helps any.

Over to you, Mastah! <g>.

Adam.