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133 .\" ========================================================================
135 .IX Title "BIO_f_ssl 3"
136 .TH BIO_f_ssl 3 "2015-01-08" "0.9.8zd" "OpenSSL"
137 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
138 .\" way too many mistakes in technical documents.
142 BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, BIO_set_ssl_renegotiate_bytes,
143 BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl,
144 BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id,
145 BIO_ssl_shutdown \- SSL BIO
147 .IX Header "SYNOPSIS"
149 \& #include <openssl/bio.h>
150 \& #include <openssl/ssl.h>
152 \& BIO_METHOD *BIO_f_ssl(void);
154 \& #define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl)
155 \& #define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp)
156 \& #define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL)
157 \& #define BIO_set_ssl_renegotiate_bytes(b,num) \e
158 \& BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL);
159 \& #define BIO_set_ssl_renegotiate_timeout(b,seconds) \e
160 \& BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL);
161 \& #define BIO_get_num_renegotiates(b) \e
162 \& BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL);
164 \& BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
165 \& BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
166 \& BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx);
167 \& int BIO_ssl_copy_session_id(BIO *to,BIO *from);
168 \& void BIO_ssl_shutdown(BIO *bio);
170 \& #define BIO_do_handshake(b) BIO_ctrl(b,BIO_C_DO_STATE_MACHINE,0,NULL)
173 .IX Header "DESCRIPTION"
174 \&\fIBIO_f_ssl()\fR returns the \s-1SSL BIO\s0 method. This is a filter \s-1BIO\s0 which
175 is a wrapper round the OpenSSL \s-1SSL\s0 routines adding a \s-1BIO \s0\*(L"flavour\*(R" to
178 I/O performed on an \s-1SSL BIO\s0 communicates using the \s-1SSL\s0 protocol with
179 the SSLs read and write BIOs. If an \s-1SSL\s0 connection is not established
180 then an attempt is made to establish one on the first I/O call.
182 If a \s-1BIO\s0 is appended to an \s-1SSL BIO\s0 using \fIBIO_push()\fR it is automatically
183 used as the \s-1SSL\s0 BIOs read and write BIOs.
185 Calling \fIBIO_reset()\fR on an \s-1SSL BIO\s0 closes down any current \s-1SSL\s0 connection
186 by calling \fISSL_shutdown()\fR. \fIBIO_reset()\fR is then sent to the next \s-1BIO\s0 in
187 the chain: this will typically disconnect the underlying transport.
188 The \s-1SSL BIO\s0 is then reset to the initial accept or connect state.
190 If the close flag is set when an \s-1SSL BIO\s0 is freed then the internal
191 \&\s-1SSL\s0 structure is also freed using \fISSL_free()\fR.
193 \&\fIBIO_set_ssl()\fR sets the internal \s-1SSL\s0 pointer of \s-1BIO \s0\fBb\fR to \fBssl\fR using
194 the close flag \fBc\fR.
196 \&\fIBIO_get_ssl()\fR retrieves the \s-1SSL\s0 pointer of \s-1BIO \s0\fBb\fR, it can then be
197 manipulated using the standard \s-1SSL\s0 library functions.
199 \&\fIBIO_set_ssl_mode()\fR sets the \s-1SSL BIO\s0 mode to \fBclient\fR. If \fBclient\fR
200 is 1 client mode is set. If \fBclient\fR is 0 server mode is set.
202 \&\fIBIO_set_ssl_renegotiate_bytes()\fR sets the renegotiate byte count
203 to \fBnum\fR. When set after every \fBnum\fR bytes of I/O (read and write)
204 the \s-1SSL\s0 session is automatically renegotiated. \fBnum\fR must be at
207 \&\fIBIO_set_ssl_renegotiate_timeout()\fR sets the renegotiate timeout to
208 \&\fBseconds\fR. When the renegotiate timeout elapses the session is
209 automatically renegotiated.
211 \&\fIBIO_get_num_renegotiates()\fR returns the total number of session
212 renegotiations due to I/O or timeout.
214 \&\fIBIO_new_ssl()\fR allocates an \s-1SSL BIO\s0 using \s-1SSL_CTX \s0\fBctx\fR and using
215 client mode if \fBclient\fR is non zero.
217 \&\fIBIO_new_ssl_connect()\fR creates a new \s-1BIO\s0 chain consisting of an
218 \&\s-1SSL BIO \s0(using \fBctx\fR) followed by a connect \s-1BIO.\s0
220 \&\fIBIO_new_buffer_ssl_connect()\fR creates a new \s-1BIO\s0 chain consisting
221 of a buffering \s-1BIO,\s0 an \s-1SSL BIO \s0(using \fBctx\fR) and a connect
224 \&\fIBIO_ssl_copy_session_id()\fR copies an \s-1SSL\s0 session id between
225 \&\s-1BIO\s0 chains \fBfrom\fR and \fBto\fR. It does this by locating the
226 \&\s-1SSL\s0 BIOs in each chain and calling \fISSL_copy_session_id()\fR on
227 the internal \s-1SSL\s0 pointer.
229 \&\fIBIO_ssl_shutdown()\fR closes down an \s-1SSL\s0 connection on \s-1BIO\s0
230 chain \fBbio\fR. It does this by locating the \s-1SSL BIO\s0 in the
231 chain and calling \fISSL_shutdown()\fR on its internal \s-1SSL\s0
234 \&\fIBIO_do_handshake()\fR attempts to complete an \s-1SSL\s0 handshake on the
235 supplied \s-1BIO\s0 and establish the \s-1SSL\s0 connection. It returns 1
236 if the connection was established successfully. A zero or negative
237 value is returned if the connection could not be established, the
238 call \fIBIO_should_retry()\fR should be used for non blocking connect BIOs
239 to determine if the call should be retried. If an \s-1SSL\s0 connection has
240 already been established this call has no effect.
243 \&\s-1SSL\s0 BIOs are exceptional in that if the underlying transport
244 is non blocking they can still request a retry in exceptional
245 circumstances. Specifically this will happen if a session
246 renegotiation takes place during a \fIBIO_read()\fR operation, one
247 case where this happens is when \s-1SGC\s0 or step up occurs.
249 In OpenSSL 0.9.6 and later the \s-1SSL\s0 flag \s-1SSL_AUTO_RETRY\s0 can be
250 set to disable this behaviour. That is when this flag is set
251 an \s-1SSL BIO\s0 using a blocking transport will never request a
254 Since unknown \fIBIO_ctrl()\fR operations are sent through filter
255 BIOs the servers name and port can be set using \fIBIO_set_host()\fR
256 on the \s-1BIO\s0 returned by \fIBIO_new_ssl_connect()\fR without having
257 to locate the connect \s-1BIO\s0 first.
259 Applications do not have to call \fIBIO_do_handshake()\fR but may wish
260 to do so to separate the handshake process from other I/O
263 .IX Header "RETURN VALUES"
267 This \s-1SSL/TLS\s0 client example, attempts to retrieve a page from an
268 \&\s-1SSL/TLS\s0 web server. The I/O routines are identical to those of the
269 unencrypted example in \fIBIO_s_connect\fR\|(3).
274 \& char tmpbuf[1024];
278 \& ERR_load_crypto_strings();
279 \& ERR_load_SSL_strings();
280 \& OpenSSL_add_all_algorithms();
282 \& /* We would seed the PRNG here if the platform didn\*(Aqt
283 \& * do it automatically
286 \& ctx = SSL_CTX_new(SSLv23_client_method());
288 \& /* We\*(Aqd normally set some stuff like the verify paths and
289 \& * mode here because as things stand this will connect to
290 \& * any server whose certificate is signed by any CA.
293 \& sbio = BIO_new_ssl_connect(ctx);
295 \& BIO_get_ssl(sbio, &ssl);
298 \& fprintf(stderr, "Can\*(Aqt locate SSL pointer\en");
299 \& /* whatever ... */
302 \& /* Don\*(Aqt want any retries */
303 \& SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
305 \& /* We might want to do other things with ssl here */
307 \& BIO_set_conn_hostname(sbio, "localhost:https");
309 \& out = BIO_new_fp(stdout, BIO_NOCLOSE);
310 \& if(BIO_do_connect(sbio) <= 0) {
311 \& fprintf(stderr, "Error connecting to server\en");
312 \& ERR_print_errors_fp(stderr);
313 \& /* whatever ... */
316 \& if(BIO_do_handshake(sbio) <= 0) {
317 \& fprintf(stderr, "Error establishing SSL connection\en");
318 \& ERR_print_errors_fp(stderr);
319 \& /* whatever ... */
322 \& /* Could examine ssl here to get connection info */
324 \& BIO_puts(sbio, "GET / HTTP/1.0\en\en");
326 \& len = BIO_read(sbio, tmpbuf, 1024);
327 \& if(len <= 0) break;
328 \& BIO_write(out, tmpbuf, len);
330 \& BIO_free_all(sbio);
334 Here is a simple server example. It makes use of a buffering
335 \&\s-1BIO\s0 to allow lines to be read from the \s-1SSL BIO\s0 using BIO_gets.
336 It creates a pseudo web page containing the actual request from
337 a client and also echoes the request to standard output.
340 \& BIO *sbio, *bbio, *acpt, *out;
342 \& char tmpbuf[1024];
346 \& ERR_load_crypto_strings();
347 \& ERR_load_SSL_strings();
348 \& OpenSSL_add_all_algorithms();
350 \& /* Might seed PRNG here */
352 \& ctx = SSL_CTX_new(SSLv23_server_method());
354 \& if (!SSL_CTX_use_certificate_file(ctx,"server.pem",SSL_FILETYPE_PEM)
355 \& || !SSL_CTX_use_PrivateKey_file(ctx,"server.pem",SSL_FILETYPE_PEM)
356 \& || !SSL_CTX_check_private_key(ctx)) {
358 \& fprintf(stderr, "Error setting up SSL_CTX\en");
359 \& ERR_print_errors_fp(stderr);
363 \& /* Might do other things here like setting verify locations and
364 \& * DH and/or RSA temporary key callbacks
367 \& /* New SSL BIO setup as server */
368 \& sbio=BIO_new_ssl(ctx,0);
370 \& BIO_get_ssl(sbio, &ssl);
373 \& fprintf(stderr, "Can\*(Aqt locate SSL pointer\en");
374 \& /* whatever ... */
377 \& /* Don\*(Aqt want any retries */
378 \& SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
380 \& /* Create the buffering BIO */
382 \& bbio = BIO_new(BIO_f_buffer());
384 \& /* Add to chain */
385 \& sbio = BIO_push(bbio, sbio);
387 \& acpt=BIO_new_accept("4433");
389 \& /* By doing this when a new connection is established
390 \& * we automatically have sbio inserted into it. The
391 \& * BIO chain is now \*(Aqswallowed\*(Aq by the accept BIO and
392 \& * will be freed when the accept BIO is freed.
395 \& BIO_set_accept_bios(acpt,sbio);
397 \& out = BIO_new_fp(stdout, BIO_NOCLOSE);
399 \& /* Setup accept BIO */
400 \& if(BIO_do_accept(acpt) <= 0) {
401 \& fprintf(stderr, "Error setting up accept BIO\en");
402 \& ERR_print_errors_fp(stderr);
406 \& /* Now wait for incoming connection */
407 \& if(BIO_do_accept(acpt) <= 0) {
408 \& fprintf(stderr, "Error in connection\en");
409 \& ERR_print_errors_fp(stderr);
413 \& /* We only want one connection so remove and free
417 \& sbio = BIO_pop(acpt);
419 \& BIO_free_all(acpt);
421 \& if(BIO_do_handshake(sbio) <= 0) {
422 \& fprintf(stderr, "Error in SSL handshake\en");
423 \& ERR_print_errors_fp(stderr);
427 \& BIO_puts(sbio, "HTTP/1.0 200 OK\er\enContent\-type: text/plain\er\en\er\en");
428 \& BIO_puts(sbio, "\er\enConnection Established\er\enRequest headers:\er\en");
429 \& BIO_puts(sbio, "\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\er\en");
432 \& len = BIO_gets(sbio, tmpbuf, 1024);
433 \& if(len <= 0) break;
434 \& BIO_write(sbio, tmpbuf, len);
435 \& BIO_write(out, tmpbuf, len);
436 \& /* Look for blank line signifying end of headers*/
437 \& if((tmpbuf[0] == \*(Aq\er\*(Aq) || (tmpbuf[0] == \*(Aq\en\*(Aq)) break;
440 \& BIO_puts(sbio, "\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\er\en");
441 \& BIO_puts(sbio, "\er\en");
443 \& /* Since there is a buffering BIO present we had better flush it */
446 \& BIO_free_all(sbio);
449 .IX Header "SEE ALSO"