超越PHP - Exceed PHP: fsockopen

Description

resource fsockopen ( string target, int port [, int &errno [, string &errstr [, float timeout]]])

Initiates a socket connection to the resource specified by target. PHP supports targets in the Internet and Unix domains as described in 附录 N. A list of supported transports can also be retrieved using stream_get_transports().

注: If you need to set a timeout for reading/writing data over the socket, use stream_set_timeout(), as the timeout parameter to fsockopen() only applies while connecting the socket.

As of PHP 4.3.0, if you have compiled in OpenSSL support, you may prefix the hostname with either 'ssl://' or 'tls://' to use an SSL or TLS client connection over TCP/IP to connect to the remote host.

fsockopen() returns a file pointer which may be used together with the other file functions (such as fgets(), fgetss(), fwrite(), fclose(), and feof()).

If the call fails, it will return FALSE and if the optional errno and errstr arguments are present they will be set to indicate the actual system level error that occurred in the system-level connect() call. If the value returned in errno is 0 and the function returned FALSE, it is an indication that the error occurred before the connect() call. This is most likely due to a problem initializing the socket. Note that the errno and errstr arguments will always be passed by reference.

Depending on the environment, the Unix domain or the optional connect timeout may not be available.

The socket will by default be opened in blocking mode. You can switch it to non-blocking mode by using stream_set_blocking().
例子 1. fsockopen() Example

<?php $fp = fsockopen("www.example.com", 80, $errno, $errstr, 30); if (!$fp) { echo "$errstr ($errno)<br />\n"; } else { $out = "GET / HTTP/1.1\r\n"; $out .= "Host: www.example.com\r\n"; $out .= "Connection: Close\r\n\r\n"; fwrite($fp, $out); while (!feof($fp)) { echo fgets($fp, 128); } fclose($fp); } ?>
The example below shows how to retrieve the day and time from the UDP service "daytime" (port 13) in your own machine.
例子 2. Using UDP connection

<?php $fp = fsockopen("udp://127.0.0.1", 13, $errno, $errstr); if (!$fp) { echo "ERROR: $errno - $errstr<br />\n"; } else { fwrite($fp, "\n"); echo fread($fp, 26); fclose($fp); } ?>

警告

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.

注: 当指定数字的 IPv6 地址（例如 fe80::1）时必须将 IP 地址放在方括号内。例如 tcp://[fe80::1]:80。

注: The timeout parameter was introduced in PHP 3.0.9 and UDP support was added in PHP 4.

See also pfsockopen(), stream_set_blocking(), stream_set_timeout(), fgets(), fgetss(), fwrite(), fclose(), feof(), and the Curl extension.

add a note User Contributed Notes
fsockopen

info at TAKETHISOUT dot ski-info-online dot com
08-Jan-2002 10:30

This is a "gotcha" that "got me" and discusses the
careful use of HTTP/1.1 over HTTP/1.0
 
I had a script that suffered
dreadful performance and return Hex values amongst the correct data. This
was eventually traced to my inclusion of HTTP/1.1 in the line which
read:

-- CODE (watch wrap) --
  $request = "GET
$document" . "?" . "$query" . "
HTTP/1.1\r\n";
  $request .= "Host:
$myServer\r\n\r\n";
-- CODE --

By sending a HTTP/1.1 request
it declares that it is willing to 'speak' HTTP/1.1, of course, but there
are some aspects of HTTP/1.1 that make it necessary to handle the socket
differently from HTTP/1.0. 

In the RFC 2616, Section 3.6
defines:

[...]
All HTTP/1.1 applications MUST be able to receive
and decode the "chunked" transfer-coding,
[...]

This
was the cause of the extraneous HEX values being displayed.

Regards
the loss of performance, this is also due to using HTTP/1.1, which defaults
to having keepalive on until you tell it to close the connection, or it
times out. Therefore the socket was being kept open by the
script.

Simply changing the line in the script to HTTP/1.0
completely fixed the problem.

Speaking with one of the members in
PHP-dev his words were:

[Comment from Hartmut Holzgraefe]
"I
stumbled over the same 'chunked' problem not to long ago as a rule of
thumb: never use HTTP/1.1 unless you really know that you have to, claiming
to be a HTTP/1.0 client is no problem."

I have posted this as
it was something I found very difficult to debug as there is actually
nothing wrong with the script. This sort of problem often requires an in
depth knowledge of an area that most developers would not have or consider.
I would doubt that many, in any, who are reading this have ever read the
HTTP RFC 2616 (I doubt also that it is a rivetting read :))  I hope this
helps any future developers who are considering the use of high level
socket connections with HTTP/1.1.

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