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_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);

        long BIO_do_connect(BIO *b);

DESCRIPTION

       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.

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() 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.

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.

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>.