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BIO_s_connect(3)
Contents
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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
libcrypto, -lcrypto
#include <openssl/bio.h>
BIO_METHOD * BIO_s_connect(void);
#define BIO_set_conn_hostname(b,name) BIO_ctrl(b,BIO_C_SET_CONNECT,0,(char *)name)
#define BIO_set_conn_port(b,port) BIO_ctrl(b,BIO_C_SET_CONNECT,1,(char *)port)
#define BIO_set_conn_ip(b,ip) BIO_ctrl(b,BIO_C_SET_CONNECT,2,(char *)ip)
#define BIO_set_conn_int_port(b,port) BIO_ctrl(b,BIO_C_SET_CONNECT,3,(char *)port)
#define BIO_get_conn_hostname(b) BIO_ptr_ctrl(b,BIO_C_GET_CONNECT,0)
#define BIO_get_conn_port(b) BIO_ptr_ctrl(b,BIO_C_GET_CONNECT,1)
#define BIO_get_conn_ip(b,ip) BIO_ptr_ctrl(b,BIO_C_SET_CONNECT,2)
#define BIO_get_conn_int_port(b,port) BIO_int_ctrl(b,BIO_C_SET_CONNECT,3,port)
#define BIO_set_nbio(b,n) BIO_ctrl(b,BIO_C_SET_NBIO,(n),NULL)
#define BIO_do_connect(b) BIO_do_handshake(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_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 bigendian
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_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.
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_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.
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);
TBA
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