BIO_S_CONNECT(3) BSD Library Functions Manual BIO_S_CONNECT(3)NAME
BIO_s_connect, BIO_new_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, dummy);
long
BIO_get_conn_int_port(BIO *b, int port);
long
BIO_set_nbio(BIO *b, long n);
int
BIO_do_connect(BIO *b);
DESCRIPTIONBIO_s_connect() returns the connect BIO method. This is a wrapper around
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 under‐
lying connection. If no connection is established and the port and host‐
name (see below) is set up properly, then a connection is established
first.
Connect BIOs support BIO_puts(3) but not BIO_gets(3).
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(3) 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(3) 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 forms
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(3) on the host platform, but if that fails a built-in 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 con‐
nect process.
BIO_new_connect() combines BIO_new(3) and BIO_set_conn_hostname() into a
single call. 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(3) 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 connec‐
tion 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 appropri‐
ate.
It addition to BIO_should_read(3) and BIO_should_write(3) it is also pos‐
sible for BIO_should_io_special(3) to be true during the initial connec‐
tion process with the reason BIO_RR_CONNECT. If this is returned, it 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 VALUESBIO_s_connect() returns the connect BIO method.
BIO_get_fd(3) returns the socket or -1 if the BIO has not been initial‐
ized.
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 if none is
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.
EXAMPLES
This 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);
BSD April 25, 2024 BSD
