5 BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, BIO_set_ssl_renegotiate_bytes,
6 BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl,
7 BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id,
8 BIO_ssl_shutdown - SSL BIO
12 #include <openssl/bio.h>
13 #include <openssl/ssl.h>
15 const BIO_METHOD *BIO_f_ssl(void);
17 #define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl)
18 #define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp)
19 #define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL)
20 #define BIO_set_ssl_renegotiate_bytes(b,num) \
21 BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL);
22 #define BIO_set_ssl_renegotiate_timeout(b,seconds) \
23 BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL);
24 #define BIO_get_num_renegotiates(b) \
25 BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL);
27 BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
28 BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
29 BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx);
30 int BIO_ssl_copy_session_id(BIO *to,BIO *from);
31 void BIO_ssl_shutdown(BIO *bio);
33 #define BIO_do_handshake(b) BIO_ctrl(b,BIO_C_DO_STATE_MACHINE,0,NULL)
37 BIO_f_ssl() returns the SSL BIO method. This is a filter BIO which
38 is a wrapper round the OpenSSL SSL routines adding a BIO "flavour" to
41 I/O performed on an SSL BIO communicates using the SSL protocol with
42 the SSLs read and write BIOs. If an SSL connection is not established
43 then an attempt is made to establish one on the first I/O call.
45 If a BIO is appended to an SSL BIO using BIO_push() it is automatically
46 used as the SSL BIOs read and write BIOs.
48 Calling BIO_reset() on an SSL BIO closes down any current SSL connection
49 by calling SSL_shutdown(). BIO_reset() is then sent to the next BIO in
50 the chain: this will typically disconnect the underlying transport.
51 The SSL BIO is then reset to the initial accept or connect state.
53 If the close flag is set when an SSL BIO is freed then the internal
54 SSL structure is also freed using SSL_free().
56 BIO_set_ssl() sets the internal SSL pointer of BIO B<b> to B<ssl> using
59 BIO_get_ssl() retrieves the SSL pointer of BIO B<b>, it can then be
60 manipulated using the standard SSL library functions.
62 BIO_set_ssl_mode() sets the SSL BIO mode to B<client>. If B<client>
63 is 1 client mode is set. If B<client> is 0 server mode is set.
65 BIO_set_ssl_renegotiate_bytes() sets the renegotiate byte count
66 to B<num>. When set after every B<num> bytes of I/O (read and write)
67 the SSL session is automatically renegotiated. B<num> must be at
70 BIO_set_ssl_renegotiate_timeout() sets the renegotiate timeout to
71 B<seconds>. When the renegotiate timeout elapses the session is
72 automatically renegotiated.
74 BIO_get_num_renegotiates() returns the total number of session
75 renegotiations due to I/O or timeout.
77 BIO_new_ssl() allocates an SSL BIO using SSL_CTX B<ctx> and using
78 client mode if B<client> is non zero.
80 BIO_new_ssl_connect() creates a new BIO chain consisting of an
81 SSL BIO (using B<ctx>) followed by a connect BIO.
83 BIO_new_buffer_ssl_connect() creates a new BIO chain consisting
84 of a buffering BIO, an SSL BIO (using B<ctx>) and a connect
87 BIO_ssl_copy_session_id() copies an SSL session id between
88 BIO chains B<from> and B<to>. It does this by locating the
89 SSL BIOs in each chain and calling SSL_copy_session_id() on
90 the internal SSL pointer.
92 BIO_ssl_shutdown() closes down an SSL connection on BIO
93 chain B<bio>. It does this by locating the SSL BIO in the
94 chain and calling SSL_shutdown() on its internal SSL
97 BIO_do_handshake() attempts to complete an SSL handshake on the
98 supplied BIO and establish the SSL connection. It returns 1
99 if the connection was established successfully. A zero or negative
100 value is returned if the connection could not be established, the
101 call BIO_should_retry() should be used for non blocking connect BIOs
102 to determine if the call should be retried. If an SSL connection has
103 already been established this call has no effect.
107 SSL BIOs are exceptional in that if the underlying transport
108 is non blocking they can still request a retry in exceptional
109 circumstances. Specifically this will happen if a session
110 renegotiation takes place during a BIO_read() operation, one
111 case where this happens is when step up occurs.
113 The SSL flag SSL_AUTO_RETRY can be
114 set to disable this behaviour. That is when this flag is set
115 an SSL BIO using a blocking transport will never request a
118 Since unknown BIO_ctrl() operations are sent through filter
119 BIOs the servers name and port can be set using BIO_set_host()
120 on the BIO returned by BIO_new_ssl_connect() without having
121 to locate the connect BIO first.
123 Applications do not have to call BIO_do_handshake() but may wish
124 to do so to separate the handshake process from other I/O
129 This SSL/TLS client example, attempts to retrieve a page from an
130 SSL/TLS web server. The I/O routines are identical to those of the
131 unencrypted example in L<BIO_s_connect(3)>.
139 /* XXX Seed the PRNG if needed. */
141 ctx = SSL_CTX_new(TLS_client_method());
143 /* XXX Set verify paths and mode here. */
145 sbio = BIO_new_ssl_connect(ctx);
146 BIO_get_ssl(sbio, &ssl);
148 fprintf(stderr, "Can't locate SSL pointer\n");
149 ERR_print_errors_fp(stderr);
153 /* Don't want any retries */
154 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
156 /* XXX We might want to do other things with ssl here */
158 /* An empty host part means the loopback address */
159 BIO_set_conn_hostname(sbio, ":https");
161 out = BIO_new_fp(stdout, BIO_NOCLOSE);
162 if (BIO_do_connect(sbio) <= 0) {
163 fprintf(stderr, "Error connecting to server\n");
164 ERR_print_errors_fp(stderr);
167 if (BIO_do_handshake(sbio) <= 0) {
168 fprintf(stderr, "Error establishing SSL connection\n");
169 ERR_print_errors_fp(stderr);
173 /* XXX Could examine ssl here to get connection info */
175 BIO_puts(sbio, "GET / HTTP/1.0\n\n");
177 len = BIO_read(sbio, tmpbuf, 1024);
180 BIO_write(out, tmpbuf, len);
185 Here is a simple server example. It makes use of a buffering
186 BIO to allow lines to be read from the SSL BIO using BIO_gets.
187 It creates a pseudo web page containing the actual request from
188 a client and also echoes the request to standard output.
190 BIO *sbio, *bbio, *acpt, *out;
196 /* XXX Seed the PRNG if needed. */
198 ctx = SSL_CTX_new(TLS_server_method());
199 if (!SSL_CTX_use_certificate_file(ctx, "server.pem", SSL_FILETYPE_PEM)
200 || !SSL_CTX_use_PrivateKey_file(ctx, "server.pem", SSL_FILETYPE_PEM)
201 || !SSL_CTX_check_private_key(ctx)) {
202 fprintf(stderr, "Error setting up SSL_CTX\n");
203 ERR_print_errors_fp(stderr);
207 /* XXX Other things like set verify locations, EDH temp callbacks. */
209 /* New SSL BIO setup as server */
210 sbio = BIO_new_ssl(ctx,0);
211 BIO_get_ssl(sbio, &ssl);
213 fprintf(stderr, "Can't locate SSL pointer\n");
214 ERR_print_errors_fp(stderr);
218 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
219 bbio = BIO_new(BIO_f_buffer());
220 sbio = BIO_push(bbio, sbio);
221 acpt = BIO_new_accept("4433");
224 * By doing this when a new connection is established
225 * we automatically have sbio inserted into it. The
226 * BIO chain is now 'swallowed' by the accept BIO and
227 * will be freed when the accept BIO is freed.
229 BIO_set_accept_bios(acpt, sbio);
230 out = BIO_new_fp(stdout, BIO_NOCLOSE);
232 /* Setup accept BIO */
233 if (BIO_do_accept(acpt) <= 0) {
234 fprintf(stderr, "Error setting up accept BIO\n");
235 ERR_print_errors_fp(stderr);
239 if (BIO_do_accept(acpt) <= 0) {
240 fprintf(stderr, "Error in connection\n");
241 ERR_print_errors_fp(stderr);
245 /* We only want one connection so remove and free accept BIO */
246 sbio = BIO_pop(acpt);
249 if (BIO_do_handshake(sbio) <= 0) {
250 fprintf(stderr, "Error in SSL handshake\n");
251 ERR_print_errors_fp(stderr);
255 BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n");
256 BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n");
257 BIO_puts(sbio, "--------------------------------------------------\r\n");
260 len = BIO_gets(sbio, tmpbuf, 1024);
263 BIO_write(sbio, tmpbuf, len);
264 BIO_write(out, tmpbuf, len);
265 /* Look for blank line signifying end of headers*/
266 if (tmpbuf[0] == '\r' || tmpbuf[0] == '\n')
270 BIO_puts(sbio, "--------------------------------------------------\r\n");
271 BIO_puts(sbio, "\r\n");
277 In OpenSSL versions before 1.0.0 the BIO_pop() call was handled incorrectly,
278 the I/O BIO reference count was incorrectly incremented (instead of
279 decremented) and dissociated with the SSL BIO even if the SSL BIO was not
280 explicitly being popped (e.g. a pop higher up the chain). Applications which
281 included workarounds for this bug (e.g. freeing BIOs more than once) should
282 be modified to handle this fix or they may free up an already freed BIO.
286 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
288 Licensed under the OpenSSL license (the "License"). You may not use
289 this file except in compliance with the License. You can obtain a copy
290 in the file LICENSE in the source distribution or at
291 L<https://www.openssl.org/source/license.html>.