Connects to a hostname with optionally asyncronous DNS resolving

# EventBufferEvent::connectHost

(PECL event >= 1.2.6-beta)

EventBufferEvent::connectHost — Connects to a hostname with optionally asyncronous DNS resolving

### Description

public EventBufferEvent::connectHost(
EventDnsBase `$dns_base` ,
string `$hostname` ,
int `$port` ,
int `$family` = EventUtil::AF_UNSPEC
): bool

Resolves the DNS name hostname, looking for addresses of type `family` ( `EventUtil::AF_*` constants). If the name resolution fails, it invokes the event callback with an error event. If it succeeds, it launches a connection attempt just as EventBufferEvent::connect() would.

`dns_base` is optional. May be `null`, or an object created with EventDnsBase::__construct(). For asyncronous hostname resolving pass a valid event dns base resource. Otherwise the hostname resolving will block.

> Note:

> EventDnsBase is available only if `Event` configured --with-event-extra ( `event_extra` library, libevent protocol-specific functionality support including HTTP, DNS, and RPC ).

> Note:

> EventBufferEvent::connectHost() requires `libevent-2.0.3-alpha` or greater.

### Parameters

`dns_base`

  Object of EventDnsBase in case if DNS is to be resolved asyncronously. Otherwise `null`.

`hostname`

  Hostname to connect to. Recognized formats are:

      www.example.com (hostname)
       1.2.3.4 (ipv4address)
       ::1 (ipv6address)
      [::1] ([ipv6address])

`port`

  Port number

`family`

  Address family. `EventUtil::AF_UNSPEC`, `EventUtil::AF_INET`, or `EventUtil::AF_INET6`. See EventUtil constants.

### Return Values

Returns `true` on success or `false` on failure.

### Examples

Example #1 EventBufferEvent::connectHost() example

`<?php
/* Read callback */
function readcb($bev, $base) {
//$input = $bev->input; //$bev->getInput();
//$pos = $input->search("TTP");
$pos = $bev->input->search("TTP");
while (($n = $bev->input->remove($buf, 1024)) > 0) {
echo $buf;
}
}
/* Event callback */
function eventcb($bev, $events, $base) {
if ($events & EventBufferEvent::CONNECTED) {
echo "Connected.\n";
} elseif ($events & (EventBufferEvent::ERROR | EventBufferEvent::EOF)) {
if ($events & EventBufferEvent::ERROR) {
echo "DNS error: ", $bev->getDnsErrorString(), PHP_EOL;
}
echo "Closing\n";
$base->exit();
exit("Done\n");
}
}
$base = new EventBase();
$dns_base = new EventDnsBase($base, TRUE); // We'll use async DNS resolving
if (!$dns_base) {
exit("Failed to init DNS Base\n");
}
$bev = new EventBufferEvent($base, /* use internal socket */ NULL,
EventBufferEvent::OPT_CLOSE_ON_FREE | EventBufferEvent::OPT_DEFER_CALLBACKS,
"readcb", /* writecb */ NULL, "eventcb", $base
);
if (!$bev) {
exit("Failed creating bufferevent socket\n");
}
//$bev->setCallbacks("readcb", /* writecb */ NULL, "eventcb", $base);
$bev->enable(Event::READ | Event::WRITE);
$output = $bev->output; //$bev->getOutput();
if (!$output->add(
"GET {$argv[2]} HTTP/1.0\r\n".
"Host: {$argv[1]}\r\n".
"Connection: Close\r\n\r\n"
)) {
exit("Failed adding request to output buffer\n");
}
if (!$bev->connectHost($dns_base, $argv[1], 80, EventUtil::AF_UNSPEC)) {
exit("Can't connect to host {$argv[1]}\n");
}
$base->dispatch();
?>`

The above example will output something similar to:

    Connected.
    HTTP/1.0 301 Moved Permanently
    Location: http://www.google.co.uk/
    Content-Type: text/html; charset=UTF-8
    Date: Sat, 09 Mar 2013 12:21:19 GMT
    Expires: Mon, 08 Apr 2013 12:21:19 GMT
    Cache-Control: public, max-age=2592000
    Server: gws
    Content-Length: 221
    X-XSS-Protection: 1; mode=block
    X-Frame-Options: SAMEORIGIN

    <HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
    <TITLE>301 Moved</TITLE></HEAD><BODY>
    <H1>301 Moved</H1>
    The document has moved
    <A HREF="http://www.google.co.uk/">here</A>.
    </BODY></HTML>
    Closing
    Done

### See Also

- EventBufferEvent::connect() - Connect buffer event's file descriptor to given address or UNIX socket

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