(no version information, might be only in CVS)
php_stream_sock_open_host()
establishes a connect to the specified
host and port.
socktype specifies the
connection semantics that should apply to the connection.
Values for socktype are
system dependent, but will usually include (at a minimum) SOCK_STREAM for sequenced,
reliable, two-way connection based streams (TCP), or SOCK_DGRAM for connectionless,
unreliable messages of a fixed maximum length (UDP).
persistent is a flag
the controls whether the stream is opened as a persistent
stream. Generally speaking, this parameter will usually be
0.
If not NULL, timeout
specifies a maximum time to allow for the connection to be
made. If the connection attempt takes longer than the timeout
value, the connection attempt is aborted and NULL is returned
to indicate that the stream could not be opened.
注: The timeout value does not include the time taken to perform a DNS lookup. The reason for this is because there is no portable way to implement a non-blocking DNS lookup.
The timeout only applies to the connection phase; if you need to set timeouts for subsequent read or write operations, you should use php_stream_sock_set_timeout() to configure the timeout duration for your stream once it has been opened.
The streams API places no restrictions on the values you
use for socktype, but
encourages you to consider the portability of values you
choose before you release your extension.