BIO_s_connect, BIO_new_connect, BIO_set_conn_hostname, BIO_set_conn_port,
BIO_set_conn_address, BIO_set_conn_ip_family, BIO_get_conn_hostname,
BIO_get_conn_port, BIO_get_conn_address, BIO_get_conn_ip_family, BIO_set_nbio,
BIO_do_connect - connect BIO
#include <openssl/bio.h>
const BIO_METHOD *BIO_s_connect(void);
BIO *BIO_new_connect(const char *name);
long BIO_set_conn_hostname(BIO *b, char *name);
long BIO_set_conn_port(BIO *b, char *port);
long BIO_set_conn_address(BIO *b, BIO_ADDR *addr);
long BIO_set_conn_ip_family(BIO *b, long family);
const char *BIO_get_conn_hostname(BIO *b);
const char *BIO_get_conn_port(BIO *b);
const BIO_ADDR *BIO_get_conn_address(BIO *b);
const long BIO_get_conn_ip_family(BIO *b);
long BIO_set_nbio(BIO *b, long n);
long BIO_do_connect(BIO *b);
BIO_s_connect() returns the connect BIO method. This is a wrapper round
the platform's TCP/IP socket connection routines.
Using connect BIOs, TCP/IP connections can be made and data transferred using
only BIO routines. In this way any platform specific operations are hidden by
the BIO abstraction.
Read and write operations on a connect BIO will perform I/O on the underlying
connection. If no connection is established and the port and hostname (see
below) is set up properly then a connection is established first.
Connect BIOs support
BIO_puts() but not
BIO_gets().
If the close flag is set on a connect BIO then any active connection is shutdown
and the socket closed when the BIO is freed.
Calling
BIO_reset() on a connect BIO will close any active connection and
reset the BIO into a state where it can connect to the same host again.
BIO_new_connect() combines
BIO_new() and
BIO_set_conn_hostname() into a single call: that is it creates a new
connect BIO with hostname
name.
BIO_set_conn_hostname() uses the string
name to set the hostname.
The hostname can be an IP address; if the address is an IPv6 one, it must be
enclosed with brackets "[" and "]". The hostname can also
include the port in the form hostname:port; see
BIO_parse_hostserv(3)
and
BIO_set_conn_port() for details.
BIO_set_conn_port() sets the port to
port.
port can be the
numerical form or a service string such as "http", which will be
mapped to a port number using the system function
getservbyname().
BIO_set_conn_address() sets the address and port information using a
BIO_ADDR(3ssl).
BIO_set_conn_ip_family() sets the IP family.
BIO_get_conn_hostname() returns the hostname of the connect BIO or NULL
if the BIO is initialized but no hostname is set. This return value is an
internal pointer which should not be modified.
BIO_get_conn_port() returns the port as a string. This return value is an
internal pointer which should not be modified.
BIO_get_conn_address() returns the address information as a BIO_ADDR.
This return value is an internal pointer which should not be modified.
BIO_get_conn_ip_family() returns the IP family of the connect BIO.
BIO_set_nbio() sets the non blocking I/O flag to
n. If
n is
zero then blocking I/O is set. If
n is 1 then non blocking I/O is set.
Blocking I/O is the default. The call to
BIO_set_nbio() should be made
before the connection is established because non blocking I/O is set during
the connect process.
BIO_do_connect() attempts to connect the supplied BIO. This performs an
SSL/TLS handshake as far as supported by the BIO. For non-SSL BIOs the
connection is done typically at TCP level. If domain name resolution yields
multiple IP addresses all of them are tried after
connect() failures.
The function returns 1 if the connection was established successfully. A zero
or negative value is returned if the connection could not be established. The
call
BIO_should_retry() should be used for non blocking connect BIOs to
determine if the call should be retried. If a connection has already been
established this call has no effect.
If blocking I/O is set then a non positive return value from any I/O call is
caused by an error condition, although a zero return will normally mean that
the connection was closed.
If the port name is supplied as part of the hostname then this will override any
value set with
BIO_set_conn_port(). This may be undesirable if the
application does not wish to allow connection to arbitrary ports. This can be
avoided by checking for the presence of the ':' character in the passed
hostname and either indicating an error or truncating the string at that
point.
The values returned by
BIO_get_conn_hostname(),
BIO_get_conn_address(), and
BIO_get_conn_port() are updated when
a connection attempt is made. Before any connection attempt the values
returned are those set by the application itself.
Applications do not have to call
BIO_do_connect() but may wish to do so
to separate the connection process from other I/O processing.
If non blocking I/O is set then retries will be requested as appropriate.
It addition to
BIO_should_read() and
BIO_should_write() it is also
possible for
BIO_should_io_special() to be true during the initial
connection process with the reason BIO_RR_CONNECT. If this is returned then
this is an indication that a connection attempt would block, the application
should then take appropriate action to wait until the underlying socket has
connected and retry the call.
BIO_set_conn_hostname(),
BIO_set_conn_port(),
BIO_get_conn_hostname(),
BIO_set_conn_address(),
BIO_get_conn_port(),
BIO_get_conn_address(),
BIO_set_conn_ip_family(),
BIO_get_conn_ip_family(),
BIO_set_nbio(), and
BIO_do_connect() are macros.
BIO_s_connect() returns the connect BIO method.
BIO_set_conn_address(),
BIO_set_conn_port(), and
BIO_set_conn_ip_family() return 1 or <=0 if an error occurs.
BIO_set_conn_hostname() returns 1 on success and <=0 on failure.
BIO_get_conn_address() returns the address information or NULL if none
was set.
BIO_get_conn_hostname() returns the connected hostname or NULL if none
was set.
BIO_get_conn_ip_family() returns the address family or -1 if none was
set.
BIO_get_conn_port() returns a string representing the connected port or
NULL if not set.
BIO_set_nbio() returns 1 or <=0 if an error occurs.
BIO_do_connect() returns 1 if the connection was successfully established
and <=0 if the connection failed.
This is example connects to a webserver on the local host and attempts to
retrieve a page and copy the result to standard output.
BIO *cbio, *out;
int len;
char tmpbuf[1024];
cbio = BIO_new_connect("localhost:http");
out = BIO_new_fp(stdout, BIO_NOCLOSE);
if (BIO_do_connect(cbio) <= 0) {
fprintf(stderr, "Error connecting to server\n");
ERR_print_errors_fp(stderr);
exit(1);
}
BIO_puts(cbio, "GET / HTTP/1.0\n\n");
for (;;) {
len = BIO_read(cbio, tmpbuf, 1024);
if (len <= 0)
break;
BIO_write(out, tmpbuf, len);
}
BIO_free(cbio);
BIO_free(out);
BIO_ADDR(3),
BIO_parse_hostserv(3)
BIO_set_conn_int_port(),
BIO_get_conn_int_port(),
BIO_set_conn_ip(), and
BIO_get_conn_ip() were removed in OpenSSL
1.1.0. Use
BIO_set_conn_address() and
BIO_get_conn_address()
instead.
Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<
https://www.openssl.org/source/license.html>.