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|TCP socket predicates|
If Port is unbound, the system picks an arbitrary free port and unifies Port with the selected port number. Port is either an integer or the name of a registered service. See also tcp_connect/4.
tcp_socket(Socket), tcp_connect(Socket, Host:Port), tcp_open_socket(Socket, StreamPair)
Typical client applications should use the high level interface provided by tcp_connect/3 which avoids resource leaking if a step in the process fails, and can be hooked to support proxies. For example:
setup_call_cleanup( tcp_connect(Host:Port, StreamPair, ), talk(StreamPair), close(StreamPair))
:- multifile socket:tcp_connect_hook/4. socket:tcp_connect_hook(Socket, Address, Read, Write) :- proxy(ProxyAdress), tcp_connect(Socket, ProxyAdress), tcp_open_socket(Socket, Read, Write), proxy_connect(Address, Read, Write).
tcp_connect(+Address, -StreamPair, +Options).
true, do not attempt to use any proxies to obtain the connection
true, set nodelay on the resulting socket using
proxy_error(tried(ResultList))is raised by mode (+,-,+) if proxies are defines by proxy_for_url/3 but no proxy can establsh the connection. ResultList contains one or more terms of the form
false(Proxy)for a hook that simply failed or
error(Proxy, ErrorTerm)for a hook that raised an exception.
library(http/http_proxy)defines a hook that allows to connect through HTTP proxies that support the
select()call underlying wait_for_input/3. As input multiplexing typically happens in a background thread anyway we accept the loss of timeouts and interrupts.
library(http/http_open)) collect the results of failed proxies and raise an exception no proxy is capable of realizing the connection.
The default implementation recognises the values for Proxy
described below. The
proxy(Host,Port) which allows for HTTP proxies using the
setsockopt()and the socket interface (e.g.,
socket(7)on Linux) for details.
tcp_socket(Socket), tcp_setopt(Socket, bindtodevice(lo))
true, disable the Nagle optimization on this socket, which is enabled by default on almost all modern TCP/IP stacks. The Nagle optimization joins small packages, which is generally desirable, but sometimes not. Please note that the underlying TCP_NODELAY setting to
setsockopt()is not available on all platforms and systems may require additional privileges to change this option. If the option is not supported, tcp_setopt/2 raises a domain_error exception. See Wikipedia for details.
setsockopt()with the corresponding arguments.
swipl-win.exeexecutable) this flags defines whether or not any events are dispatched on behalf of the user interface. Default is
true. Only very specific situations require setting this to
fcntl()call. Currently only suitable to deal switch stream to non-blocking mode using:
tcp_fcntl(Stream, setfl, nonblock),
An attempt to read from a non-blocking stream while there is no data
available returns -1 (or
end_of_file for read/1),
at_end_of_stream/1 fails. On actual
getaddrinfo()and the IP-number is unified to Address using a term of the format
ip(Byte1,Byte2,Byte3,Byte4). Otherwise, if Address is bound to an
ip(Byte1,Byte2,Byte3,Byte4)term, it is resolved by
gethostbyaddr()and the canonical hostname is unified with HostName.
gethostname()and return the canonical name returned by
socks_error(Details)if the SOCKS negotiation failed.