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
133 This SSL/TLS client example, attempts to retrieve a page from an
134 SSL/TLS web server. The I/O routines are identical to those of the
135 unencrypted example in L<BIO_s_connect(3)>.
143 /* We would seed the PRNG here if the platform didn't
144 * do it automatically
147 ctx = SSL_CTX_new(TLS_client_method());
149 /* We'd normally set some stuff like the verify paths and
150 * mode here because as things stand this will connect to
151 * any server whose certificate is signed by any CA.
154 sbio = BIO_new_ssl_connect(ctx);
156 BIO_get_ssl(sbio, &ssl);
159 fprintf(stderr, "Can't locate SSL pointer\n");
163 /* Don't want any retries */
164 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
166 /* We might want to do other things with ssl here */
168 /* An empty host part means the loopback address */
169 BIO_set_conn_hostname(sbio, ":https");
171 out = BIO_new_fp(stdout, BIO_NOCLOSE);
172 if(BIO_do_connect(sbio) <= 0) {
173 fprintf(stderr, "Error connecting to server\n");
174 ERR_print_errors_fp(stderr);
178 if(BIO_do_handshake(sbio) <= 0) {
179 fprintf(stderr, "Error establishing SSL connection\n");
180 ERR_print_errors_fp(stderr);
184 /* Could examine ssl here to get connection info */
186 BIO_puts(sbio, "GET / HTTP/1.0\n\n");
188 len = BIO_read(sbio, tmpbuf, 1024);
190 BIO_write(out, tmpbuf, len);
195 Here is a simple server example. It makes use of a buffering
196 BIO to allow lines to be read from the SSL BIO using BIO_gets.
197 It creates a pseudo web page containing the actual request from
198 a client and also echoes the request to standard output.
200 BIO *sbio, *bbio, *acpt, *out;
206 /* Might seed PRNG here */
208 ctx = SSL_CTX_new(TLS_server_method());
210 if (!SSL_CTX_use_certificate_file(ctx,"server.pem",SSL_FILETYPE_PEM)
211 || !SSL_CTX_use_PrivateKey_file(ctx,"server.pem",SSL_FILETYPE_PEM)
212 || !SSL_CTX_check_private_key(ctx)) {
214 fprintf(stderr, "Error setting up SSL_CTX\n");
215 ERR_print_errors_fp(stderr);
219 /* Might do other things here like setting verify locations and
220 * DH and/or RSA temporary key callbacks
223 /* New SSL BIO setup as server */
224 sbio=BIO_new_ssl(ctx,0);
226 BIO_get_ssl(sbio, &ssl);
229 fprintf(stderr, "Can't locate SSL pointer\n");
233 /* Don't want any retries */
234 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
236 /* Create the buffering BIO */
238 bbio = BIO_new(BIO_f_buffer());
241 sbio = BIO_push(bbio, sbio);
243 acpt=BIO_new_accept("4433");
245 /* By doing this when a new connection is established
246 * we automatically have sbio inserted into it. The
247 * BIO chain is now 'swallowed' by the accept BIO and
248 * will be freed when the accept BIO is freed.
251 BIO_set_accept_bios(acpt,sbio);
253 out = BIO_new_fp(stdout, BIO_NOCLOSE);
255 /* Setup accept BIO */
256 if(BIO_do_accept(acpt) <= 0) {
257 fprintf(stderr, "Error setting up accept BIO\n");
258 ERR_print_errors_fp(stderr);
262 /* Now wait for incoming connection */
263 if(BIO_do_accept(acpt) <= 0) {
264 fprintf(stderr, "Error in connection\n");
265 ERR_print_errors_fp(stderr);
269 /* We only want one connection so remove and free
273 sbio = BIO_pop(acpt);
277 if(BIO_do_handshake(sbio) <= 0) {
278 fprintf(stderr, "Error in SSL handshake\n");
279 ERR_print_errors_fp(stderr);
283 BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n");
284 BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n");
285 BIO_puts(sbio, "--------------------------------------------------\r\n");
288 len = BIO_gets(sbio, tmpbuf, 1024);
290 BIO_write(sbio, tmpbuf, len);
291 BIO_write(out, tmpbuf, len);
292 /* Look for blank line signifying end of headers*/
293 if((tmpbuf[0] == '\r') || (tmpbuf[0] == '\n')) break;
296 BIO_puts(sbio, "--------------------------------------------------\r\n");
297 BIO_puts(sbio, "\r\n");
299 /* Since there is a buffering BIO present we had better flush it */
306 In OpenSSL versions before 1.0.0 the BIO_pop() call was handled incorrectly,
307 the I/O BIO reference count was incorrectly incremented (instead of
308 decremented) and dissociated with the SSL BIO even if the SSL BIO was not
309 explicitly being popped (e.g. a pop higher up the chain). Applications which
310 included workarounds for this bug (e.g. freeing BIOs more than once) should
311 be modified to handle this fix or they may free up an already freed BIO.