BIO_S_CONNECT(3ossl) OpenSSL BIO_S_CONNECT(3ossl)
NAME
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_set_sock_type,
BIO_get_sock_type, BIO_get0_dgram_bio, BIO_do_connect - connect BIO
SYNOPSIS
#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);
int BIO_set_sock_type(BIO *b, int sock_type);
int BIO_get_sock_type(BIO *b);
int BIO_get0_dgram_bio(BIO *B, BIO **dgram_bio);
long BIO_do_connect(BIO *b);
DESCRIPTION
BIO_s_connect(3) 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() and 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.
BIO_set_sock_type() can be used to set a socket type value as would be
passed in a call to socket(2). The only currently supported values are
SOCK_STREAM (the default) and SOCK_DGRAM. If SOCK_DGRAM is configured,
the connection created is a UDP datagram socket handled via
BIO_s_datagram(3). I/O calls such as BIO_read(3) and BIO_write(3) are
forwarded transparently to an internal BIO_s_datagram(3) instance. The
created BIO_s_datagram(3) instance can be retrieved using
BIO_get0_dgram_bio() if desired, which writes a pointer to the
BIO_s_datagram(3) instance to *dgram_bio. The lifetime of the internal
BIO_s_connect(3) and does not need to be
freed by the caller.
BIO_get_sock_type() retrieves the value set using BIO_set_sock_type().
NOTES
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.
RETURN VALUES
BIO_s_connect(3) 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.
BIO_set_sock_type() returns 1 on success or 0 on failure.
BIO_get_sock_type() returns a socket type or 0 if the call is not
supported.
BIO_get0_dgram_bio() returns 1 on success or 0 on failure.
EXAMPLES
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);
SEE ALSO
BIO_ADDR(3), BIO_parse_hostserv(3)
HISTORY
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.
Connect BIOs support BIO_gets() since OpenSSL 3.2.
COPYRIGHT
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>.
3.3.2 2024-09-04 BIO_S_CONNECT(3ossl)
openssl 3.3.2 - Generated Thu Sep 5 18:12:14 CDT 2024