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
10 =for comment multiple includes
14 #include <openssl/bio.h>
15 #include <openssl/ssl.h>
17 const BIO_METHOD *BIO_f_ssl(void);
19 #define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl)
20 #define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp)
21 #define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL)
22 #define BIO_set_ssl_renegotiate_bytes(b,num) \
23 BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL);
24 #define BIO_set_ssl_renegotiate_timeout(b,seconds) \
25 BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL);
26 #define BIO_get_num_renegotiates(b) \
27 BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL);
29 BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
30 BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
31 BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx);
32 int BIO_ssl_copy_session_id(BIO *to,BIO *from);
33 void BIO_ssl_shutdown(BIO *bio);
35 #define BIO_do_handshake(b) BIO_ctrl(b,BIO_C_DO_STATE_MACHINE,0,NULL)
39 BIO_f_ssl() returns the SSL BIO method. This is a filter BIO which
40 is a wrapper round the OpenSSL SSL routines adding a BIO "flavour" to
43 I/O performed on an SSL BIO communicates using the SSL protocol with
44 the SSLs read and write BIOs. If an SSL connection is not established
45 then an attempt is made to establish one on the first I/O call.
47 If a BIO is appended to an SSL BIO using BIO_push() it is automatically
48 used as the SSL BIOs read and write BIOs.
50 Calling BIO_reset() on an SSL BIO closes down any current SSL connection
51 by calling SSL_shutdown(). BIO_reset() is then sent to the next BIO in
52 the chain: this will typically disconnect the underlying transport.
53 The SSL BIO is then reset to the initial accept or connect state.
55 If the close flag is set when an SSL BIO is freed then the internal
56 SSL structure is also freed using SSL_free().
58 BIO_set_ssl() sets the internal SSL pointer of BIO B<b> to B<ssl> using
61 BIO_get_ssl() retrieves the SSL pointer of BIO B<b>, it can then be
62 manipulated using the standard SSL library functions.
64 BIO_set_ssl_mode() sets the SSL BIO mode to B<client>. If B<client>
65 is 1 client mode is set. If B<client> is 0 server mode is set.
67 BIO_set_ssl_renegotiate_bytes() sets the renegotiate byte count
68 to B<num>. When set after every B<num> bytes of I/O (read and write)
69 the SSL session is automatically renegotiated. B<num> must be at
72 BIO_set_ssl_renegotiate_timeout() sets the renegotiate timeout to
73 B<seconds>. When the renegotiate timeout elapses the session is
74 automatically renegotiated.
76 BIO_get_num_renegotiates() returns the total number of session
77 renegotiations due to I/O or timeout.
79 BIO_new_ssl() allocates an SSL BIO using SSL_CTX B<ctx> and using
80 client mode if B<client> is non zero.
82 BIO_new_ssl_connect() creates a new BIO chain consisting of an
83 SSL BIO (using B<ctx>) followed by a connect BIO.
85 BIO_new_buffer_ssl_connect() creates a new BIO chain consisting
86 of a buffering BIO, an SSL BIO (using B<ctx>) and a connect
89 BIO_ssl_copy_session_id() copies an SSL session id between
90 BIO chains B<from> and B<to>. It does this by locating the
91 SSL BIOs in each chain and calling SSL_copy_session_id() on
92 the internal SSL pointer.
94 BIO_ssl_shutdown() closes down an SSL connection on BIO
95 chain B<bio>. It does this by locating the SSL BIO in the
96 chain and calling SSL_shutdown() on its internal SSL
99 BIO_do_handshake() attempts to complete an SSL handshake on the
100 supplied BIO and establish the SSL connection. It returns 1
101 if the connection was established successfully. A zero or negative
102 value is returned if the connection could not be established, the
103 call BIO_should_retry() should be used for non blocking connect BIOs
104 to determine if the call should be retried. If an SSL connection has
105 already been established this call has no effect.
109 SSL BIOs are exceptional in that if the underlying transport
110 is non blocking they can still request a retry in exceptional
111 circumstances. Specifically this will happen if a session
112 renegotiation takes place during a BIO_read() operation, one
113 case where this happens is when step up occurs.
115 The SSL flag SSL_AUTO_RETRY can be
116 set to disable this behaviour. That is when this flag is set
117 an SSL BIO using a blocking transport will never request a
120 Since unknown BIO_ctrl() operations are sent through filter
121 BIOs the servers name and port can be set using BIO_set_host()
122 on the BIO returned by BIO_new_ssl_connect() without having
123 to locate the connect BIO first.
125 Applications do not have to call BIO_do_handshake() but may wish
126 to do so to separate the handshake process from other I/O
131 This SSL/TLS client example, attempts to retrieve a page from an
132 SSL/TLS web server. The I/O routines are identical to those of the
133 unencrypted example in L<BIO_s_connect(3)>.
141 /* XXX Seed the PRNG if needed. */
143 ctx = SSL_CTX_new(TLS_client_method());
145 /* XXX Set verify paths and mode here. */
147 sbio = BIO_new_ssl_connect(ctx);
148 BIO_get_ssl(sbio, &ssl);
150 fprintf(stderr, "Can't locate SSL pointer\n");
151 ERR_print_errors_fp(stderr);
155 /* Don't want any retries */
156 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
158 /* XXX We might want to do other things with ssl here */
160 /* An empty host part means the loopback address */
161 BIO_set_conn_hostname(sbio, ":https");
163 out = BIO_new_fp(stdout, BIO_NOCLOSE);
164 if (BIO_do_connect(sbio) <= 0) {
165 fprintf(stderr, "Error connecting to server\n");
166 ERR_print_errors_fp(stderr);
169 if (BIO_do_handshake(sbio) <= 0) {
170 fprintf(stderr, "Error establishing SSL connection\n");
171 ERR_print_errors_fp(stderr);
175 /* XXX Could examine ssl here to get connection info */
177 BIO_puts(sbio, "GET / HTTP/1.0\n\n");
179 len = BIO_read(sbio, tmpbuf, 1024);
182 BIO_write(out, tmpbuf, len);
187 Here is a simple server example. It makes use of a buffering
188 BIO to allow lines to be read from the SSL BIO using BIO_gets.
189 It creates a pseudo web page containing the actual request from
190 a client and also echoes the request to standard output.
192 BIO *sbio, *bbio, *acpt, *out;
198 /* XXX Seed the PRNG if needed. */
200 ctx = SSL_CTX_new(TLS_server_method());
201 if (!SSL_CTX_use_certificate_file(ctx, "server.pem", SSL_FILETYPE_PEM)
202 || !SSL_CTX_use_PrivateKey_file(ctx, "server.pem", SSL_FILETYPE_PEM)
203 || !SSL_CTX_check_private_key(ctx)) {
204 fprintf(stderr, "Error setting up SSL_CTX\n");
205 ERR_print_errors_fp(stderr);
209 /* XXX Other things like set verify locations, EDH temp callbacks. */
211 /* New SSL BIO setup as server */
212 sbio = BIO_new_ssl(ctx,0);
213 BIO_get_ssl(sbio, &ssl);
215 fprintf(stderr, "Can't locate SSL pointer\n");
216 ERR_print_errors_fp(stderr);
220 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
221 bbio = BIO_new(BIO_f_buffer());
222 sbio = BIO_push(bbio, sbio);
223 acpt = BIO_new_accept("4433");
226 * By doing this when a new connection is established
227 * we automatically have sbio inserted into it. The
228 * BIO chain is now 'swallowed' by the accept BIO and
229 * will be freed when the accept BIO is freed.
231 BIO_set_accept_bios(acpt, sbio);
232 out = BIO_new_fp(stdout, BIO_NOCLOSE);
234 /* Setup accept BIO */
235 if (BIO_do_accept(acpt) <= 0) {
236 fprintf(stderr, "Error setting up accept BIO\n");
237 ERR_print_errors_fp(stderr);
241 if (BIO_do_accept(acpt) <= 0) {
242 fprintf(stderr, "Error in connection\n");
243 ERR_print_errors_fp(stderr);
247 /* We only want one connection so remove and free accept BIO */
248 sbio = BIO_pop(acpt);
251 if (BIO_do_handshake(sbio) <= 0) {
252 fprintf(stderr, "Error in SSL handshake\n");
253 ERR_print_errors_fp(stderr);
257 BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n");
258 BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n");
259 BIO_puts(sbio, "--------------------------------------------------\r\n");
262 len = BIO_gets(sbio, tmpbuf, 1024);
265 BIO_write(sbio, tmpbuf, len);
266 BIO_write(out, tmpbuf, len);
267 /* Look for blank line signifying end of headers*/
268 if (tmpbuf[0] == '\r' || tmpbuf[0] == '\n')
272 BIO_puts(sbio, "--------------------------------------------------\r\n");
273 BIO_puts(sbio, "\r\n");
279 In OpenSSL versions before 1.0.0 the BIO_pop() call was handled incorrectly,
280 the I/O BIO reference count was incorrectly incremented (instead of
281 decremented) and dissociated with the SSL BIO even if the SSL BIO was not
282 explicitly being popped (e.g. a pop higher up the chain). Applications which
283 included workarounds for this bug (e.g. freeing BIOs more than once) should
284 be modified to handle this fix or they may free up an already freed BIO.
288 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
290 Licensed under the OpenSSL license (the "License"). You may not use
291 this file except in compliance with the License. You can obtain a copy
292 in the file LICENSE in the source distribution or at
293 L<https://www.openssl.org/source/license.html>.