NAME¶
BIO_s_connect, BIO_set_conn_hostname, BIO_set_conn_port, BIO_set_conn_ip,
BIO_set_conn_int_port, BIO_get_conn_hostname, BIO_get_conn_port,
BIO_get_conn_ip, BIO_get_conn_int_port, BIO_set_nbio, BIO_do_connect - connect
BIO
SYNOPSIS¶
#include <openssl/bio.h>
BIO_METHOD * BIO_s_connect(void);
BIO *BIO_new_connect(char *name);
long BIO_set_conn_hostname(BIO *b, char *name);
long BIO_set_conn_port(BIO *b, char *port);
long BIO_set_conn_ip(BIO *b, char *ip);
long BIO_set_conn_int_port(BIO *b, char *port);
char *BIO_get_conn_hostname(BIO *b);
char *BIO_get_conn_port(BIO *b);
char *BIO_get_conn_ip(BIO *b);
long BIO_get_conn_int_port(BIO *b);
long BIO_set_nbio(BIO *b, long n);
int 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_get_fd() places the underlying socket in
c if it is not NULL,
it also returns the socket . If
c is not NULL it should be of type (int
*).
BIO_set_conn_hostname() uses the string
name to set the hostname.
The hostname can be an IP address. The hostname can also include the port in
the form hostname:port . It is also acceptable to use the form
"hostname/any/other/path" or
"hostname:port/any/other/path".
BIO_set_conn_port() sets the port to
port.
port can be the
numerical form or a string such as "http". A string will be looked
up first using
getservbyname() on the host platform but if that fails a
standard table of port names will be used. Currently the list is http, telnet,
socks, https, ssl, ftp, gopher and wais.
BIO_set_conn_ip() sets the IP address to
ip using binary form,
that is four bytes specifying the IP address in big-endian form.
BIO_set_conn_int_port() sets the port using
port.
port
should be of type (int *).
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.
BIO_get_conn_ip() returns the IP address in binary form.
BIO_get_conn_int_port() returns the port as an int.
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_new_connect() combines
BIO_new() and
BIO_set_conn_hostname() into a single call: that is it creates a new
connect BIO with
name.
BIO_do_connect() attempts to connect the supplied BIO. It 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.
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 host name 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_port(),
BIO_get_conn_ip() and
BIO_get_conn_int_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_set_conn_ip(),
BIO_set_conn_int_port(),
BIO_get_conn_hostname(),
BIO_get_conn_port(),
BIO_get_conn_ip(),
BIO_get_conn_int_port(),
BIO_set_nbio() and
BIO_do_connect() are macros.
RETURN VALUES¶
BIO_s_connect() returns the connect BIO method.
BIO_get_fd() returns the socket or -1 if the BIO has not been
initialized.
BIO_set_conn_hostname(),
BIO_set_conn_port(),
BIO_set_conn_ip() and
BIO_set_conn_int_port() always return 1.
BIO_get_conn_hostname() returns the connected hostname or NULL is none
was set.
BIO_get_conn_port() returns a string representing the connected port or
NULL if not set.
BIO_get_conn_ip() returns a pointer to the connected IP address in binary
form or all zeros if not set.
BIO_get_conn_int_port() returns the connected port or 0 if none was set.
BIO_set_nbio() always returns 1.
BIO_do_connect() returns 1 if the connection was successfully established
and 0 or -1 if the connection failed.
EXAMPLE¶
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];
ERR_load_crypto_strings();
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);
/* whatever ... */
}
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¶
TBA