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138 .\" ======================================================================
140 .IX Title "BIO_f_ssl 3"
141 .TH BIO_f_ssl 3 "0.9.7a" "2003-02-19" "OpenSSL"
144 BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, BIO_set_ssl_renegotiate_bytes,
145 BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl,
146 BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id,
147 BIO_ssl_shutdown \- \s-1SSL\s0 \s-1BIO\s0
149 .IX Header "SYNOPSIS"
151 \& #include <openssl/bio.h>
152 \& #include <openssl/ssl.h>
155 \& BIO_METHOD *BIO_f_ssl(void);
158 \& #define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl)
159 \& #define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp)
160 \& #define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL)
161 \& #define BIO_set_ssl_renegotiate_bytes(b,num) \e
162 \& BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL);
163 \& #define BIO_set_ssl_renegotiate_timeout(b,seconds) \e
164 \& BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL);
165 \& #define BIO_get_num_renegotiates(b) \e
166 \& BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL);
169 \& BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
170 \& BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
171 \& BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx);
172 \& int BIO_ssl_copy_session_id(BIO *to,BIO *from);
173 \& void BIO_ssl_shutdown(BIO *bio);
176 \& #define BIO_do_handshake(b) BIO_ctrl(b,BIO_C_DO_STATE_MACHINE,0,NULL)
179 .IX Header "DESCRIPTION"
180 \&\fIBIO_f_ssl()\fR returns the \s-1SSL\s0 \s-1BIO\s0 method. This is a filter \s-1BIO\s0 which
181 is a wrapper round the OpenSSL \s-1SSL\s0 routines adding a \s-1BIO\s0 \*(L"flavour\*(R" to
184 I/O performed on an \s-1SSL\s0 \s-1BIO\s0 communicates using the \s-1SSL\s0 protocol with
185 the SSLs read and write BIOs. If an \s-1SSL\s0 connection is not established
186 then an attempt is made to establish one on the first I/O call.
188 If a \s-1BIO\s0 is appended to an \s-1SSL\s0 \s-1BIO\s0 using \fIBIO_push()\fR it is automatically
189 used as the \s-1SSL\s0 BIOs read and write BIOs.
191 Calling \fIBIO_reset()\fR on an \s-1SSL\s0 \s-1BIO\s0 closes down any current \s-1SSL\s0 connection
192 by calling \fISSL_shutdown()\fR. \fIBIO_reset()\fR is then sent to the next \s-1BIO\s0 in
193 the chain: this will typically disconnect the underlying transport.
194 The \s-1SSL\s0 \s-1BIO\s0 is then reset to the initial accept or connect state.
196 If the close flag is set when an \s-1SSL\s0 \s-1BIO\s0 is freed then the internal
197 \&\s-1SSL\s0 structure is also freed using \fISSL_free()\fR.
199 \&\fIBIO_set_ssl()\fR sets the internal \s-1SSL\s0 pointer of \s-1BIO\s0 \fBb\fR to \fBssl\fR using
200 the close flag \fBc\fR.
202 \&\fIBIO_get_ssl()\fR retrieves the \s-1SSL\s0 pointer of \s-1BIO\s0 \fBb\fR, it can then be
203 manipulated using the standard \s-1SSL\s0 library functions.
205 \&\fIBIO_set_ssl_mode()\fR sets the \s-1SSL\s0 \s-1BIO\s0 mode to \fBclient\fR. If \fBclient\fR
206 is 1 client mode is set. If \fBclient\fR is 0 server mode is set.
208 \&\fIBIO_set_ssl_renegotiate_bytes()\fR sets the renegotiate byte count
209 to \fBnum\fR. When set after every \fBnum\fR bytes of I/O (read and write)
210 the \s-1SSL\s0 session is automatically renegotiated. \fBnum\fR must be at
213 \&\fIBIO_set_ssl_renegotiate_timeout()\fR sets the renegotiate timeout to
214 \&\fBseconds\fR. When the renegotiate timeout elapses the session is
215 automatically renegotiated.
217 \&\fIBIO_get_num_renegotiates()\fR returns the total number of session
218 renegotiations due to I/O or timeout.
220 \&\fIBIO_new_ssl()\fR allocates an \s-1SSL\s0 \s-1BIO\s0 using \s-1SSL_CTX\s0 \fBctx\fR and using
221 client mode if \fBclient\fR is non zero.
223 \&\fIBIO_new_ssl_connect()\fR creates a new \s-1BIO\s0 chain consisting of an
224 \&\s-1SSL\s0 \s-1BIO\s0 (using \fBctx\fR) followed by a connect \s-1BIO\s0.
226 \&\fIBIO_new_buffer_ssl_connect()\fR creates a new \s-1BIO\s0 chain consisting
227 of a buffering \s-1BIO\s0, an \s-1SSL\s0 \s-1BIO\s0 (using \fBctx\fR) and a connect
230 \&\fIBIO_ssl_copy_session_id()\fR copies an \s-1SSL\s0 session id between
231 \&\s-1BIO\s0 chains \fBfrom\fR and \fBto\fR. It does this by locating the
232 \&\s-1SSL\s0 BIOs in each chain and calling \fISSL_copy_session_id()\fR on
233 the internal \s-1SSL\s0 pointer.
235 \&\fIBIO_ssl_shutdown()\fR closes down an \s-1SSL\s0 connection on \s-1BIO\s0
236 chain \fBbio\fR. It does this by locating the \s-1SSL\s0 \s-1BIO\s0 in the
237 chain and calling \fISSL_shutdown()\fR on its internal \s-1SSL\s0
240 \&\fIBIO_do_handshake()\fR attempts to complete an \s-1SSL\s0 handshake on the
241 supplied \s-1BIO\s0 and establish the \s-1SSL\s0 connection. It returns 1
242 if the connection was established successfully. A zero or negative
243 value is returned if the connection could not be established, the
244 call \fIBIO_should_retry()\fR should be used for non blocking connect BIOs
245 to determine if the call should be retried. If an \s-1SSL\s0 connection has
246 already been established this call has no effect.
249 \&\s-1SSL\s0 BIOs are exceptional in that if the underlying transport
250 is non blocking they can still request a retry in exceptional
251 circumstances. Specifically this will happen if a session
252 renegotiation takes place during a \fIBIO_read()\fR operation, one
253 case where this happens is when \s-1SGC\s0 or step up occurs.
255 In OpenSSL 0.9.6 and later the \s-1SSL\s0 flag \s-1SSL_AUTO_RETRY\s0 can be
256 set to disable this behaviour. That is when this flag is set
257 an \s-1SSL\s0 \s-1BIO\s0 using a blocking transport will never request a
260 Since unknown \fIBIO_ctrl()\fR operations are sent through filter
261 BIOs the servers name and port can be set using \fIBIO_set_host()\fR
262 on the \s-1BIO\s0 returned by \fIBIO_new_ssl_connect()\fR without having
263 to locate the connect \s-1BIO\s0 first.
265 Applications do not have to call \fIBIO_do_handshake()\fR but may wish
266 to do so to separate the handshake process from other I/O
269 .IX Header "RETURN VALUES"
273 This \s-1SSL/TLS\s0 client example, attempts to retrieve a page from an
274 \&\s-1SSL/TLS\s0 web server. The I/O routines are identical to those of the
275 unencrypted example in BIO_s_connect(3).
280 \& char tmpbuf[1024];
285 \& ERR_load_crypto_strings();
286 \& ERR_load_SSL_strings();
287 \& OpenSSL_add_all_algorithms();
290 \& /* We would seed the PRNG here if the platform didn't
291 \& * do it automatically
295 \& ctx = SSL_CTX_new(SSLv23_client_method());
298 \& /* We'd normally set some stuff like the verify paths and
299 \& * mode here because as things stand this will connect to
300 \& * any server whose certificate is signed by any CA.
304 \& sbio = BIO_new_ssl_connect(ctx);
307 \& BIO_get_ssl(sbio, &ssl);
311 \& fprintf(stderr, "Can't locate SSL pointer\en");
312 \& /* whatever ... */
316 \& /* Don't want any retries */
317 \& SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
320 \& /* We might want to do other things with ssl here */
323 \& BIO_set_conn_hostname(sbio, "localhost:https");
326 \& out = BIO_new_fp(stdout, BIO_NOCLOSE);
327 \& if(BIO_do_connect(sbio) <= 0) {
328 \& fprintf(stderr, "Error connecting to server\en");
329 \& ERR_print_errors_fp(stderr);
330 \& /* whatever ... */
334 \& if(BIO_do_handshake(sbio) <= 0) {
335 \& fprintf(stderr, "Error establishing SSL connection\en");
336 \& ERR_print_errors_fp(stderr);
337 \& /* whatever ... */
341 \& /* Could examine ssl here to get connection info */
344 \& BIO_puts(sbio, "GET / HTTP/1.0\en\en");
346 \& len = BIO_read(sbio, tmpbuf, 1024);
347 \& if(len <= 0) break;
348 \& BIO_write(out, tmpbuf, len);
350 \& BIO_free_all(sbio);
353 Here is a simple server example. It makes use of a buffering
354 \&\s-1BIO\s0 to allow lines to be read from the \s-1SSL\s0 \s-1BIO\s0 using BIO_gets.
355 It creates a pseudo web page containing the actual request from
356 a client and also echoes the request to standard output.
359 \& BIO *sbio, *bbio, *acpt, *out;
361 \& char tmpbuf[1024];
366 \& ERR_load_crypto_strings();
367 \& ERR_load_SSL_strings();
368 \& OpenSSL_add_all_algorithms();
371 \& /* Might seed PRNG here */
374 \& ctx = SSL_CTX_new(SSLv23_server_method());
377 \& if (!SSL_CTX_use_certificate_file(ctx,"server.pem",SSL_FILETYPE_PEM)
378 \& || !SSL_CTX_use_PrivateKey_file(ctx,"server.pem",SSL_FILETYPE_PEM)
379 \& || !SSL_CTX_check_private_key(ctx)) {
382 \& fprintf(stderr, "Error setting up SSL_CTX\en");
383 \& ERR_print_errors_fp(stderr);
388 \& /* Might do other things here like setting verify locations and
389 \& * DH and/or RSA temporary key callbacks
393 \& /* New SSL BIO setup as server */
394 \& sbio=BIO_new_ssl(ctx,0);
397 \& BIO_get_ssl(sbio, &ssl);
401 \& fprintf(stderr, "Can't locate SSL pointer\en");
402 \& /* whatever ... */
406 \& /* Don't want any retries */
407 \& SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
410 \& /* Create the buffering BIO */
413 \& bbio = BIO_new(BIO_f_buffer());
416 \& /* Add to chain */
417 \& sbio = BIO_push(bbio, sbio);
420 \& acpt=BIO_new_accept("4433");
423 \& /* By doing this when a new connection is established
424 \& * we automatically have sbio inserted into it. The
425 \& * BIO chain is now 'swallowed' by the accept BIO and
426 \& * will be freed when the accept BIO is freed.
430 \& BIO_set_accept_bios(acpt,sbio);
433 \& out = BIO_new_fp(stdout, BIO_NOCLOSE);
436 \& /* Setup accept BIO */
437 \& if(BIO_do_accept(acpt) <= 0) {
438 \& fprintf(stderr, "Error setting up accept BIO\en");
439 \& ERR_print_errors_fp(stderr);
444 \& /* Now wait for incoming connection */
445 \& if(BIO_do_accept(acpt) <= 0) {
446 \& fprintf(stderr, "Error in connection\en");
447 \& ERR_print_errors_fp(stderr);
452 \& /* We only want one connection so remove and free
457 \& sbio = BIO_pop(acpt);
460 \& BIO_free_all(acpt);
463 \& if(BIO_do_handshake(sbio) <= 0) {
464 \& fprintf(stderr, "Error in SSL handshake\en");
465 \& ERR_print_errors_fp(stderr);
470 \& BIO_puts(sbio, "HTTP/1.0 200 OK\er\enContent-type: text/html\er\en\er\en");
471 \& BIO_puts(sbio, "<pre>\er\enConnection Established\er\enRequest headers:\er\en");
472 \& BIO_puts(sbio, "--------------------------------------------------\er\en");
476 \& len = BIO_gets(sbio, tmpbuf, 1024);
477 \& if(len <= 0) break;
478 \& BIO_write(sbio, tmpbuf, len);
479 \& BIO_write(out, tmpbuf, len);
480 \& /* Look for blank line signifying end of headers*/
481 \& if((tmpbuf[0] == '\er') || (tmpbuf[0] == '\en')) break;
485 \& BIO_puts(sbio, "--------------------------------------------------\er\en");
486 \& BIO_puts(sbio, "</pre>\er\en");
489 \& /* Since there is a buffering BIO present we had better flush it */
493 \& BIO_free_all(sbio);
496 .IX Header "SEE ALSO"