1=pod 2 3=head1 NAME 4 5BIO_do_handshake, 6BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, 7BIO_set_ssl_renegotiate_bytes, 8BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl, 9BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id, 10BIO_ssl_shutdown - SSL BIO 11 12=head1 SYNOPSIS 13 14=for comment multiple includes 15 16 #include <openssl/bio.h> 17 #include <openssl/ssl.h> 18 19 const BIO_METHOD *BIO_f_ssl(void); 20 21 long BIO_set_ssl(BIO *b, SSL *ssl, long c); 22 long BIO_get_ssl(BIO *b, SSL **sslp); 23 long BIO_set_ssl_mode(BIO *b, long client); 24 long BIO_set_ssl_renegotiate_bytes(BIO *b, long num); 25 long BIO_set_ssl_renegotiate_timeout(BIO *b, long seconds); 26 long BIO_get_num_renegotiates(BIO *b); 27 28 BIO *BIO_new_ssl(SSL_CTX *ctx, int client); 29 BIO *BIO_new_ssl_connect(SSL_CTX *ctx); 30 BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx); 31 int BIO_ssl_copy_session_id(BIO *to, BIO *from); 32 void BIO_ssl_shutdown(BIO *bio); 33 34 long BIO_do_handshake(BIO *b); 35 36=head1 DESCRIPTION 37 38BIO_f_ssl() returns the SSL BIO method. This is a filter BIO which 39is a wrapper round the OpenSSL SSL routines adding a BIO "flavour" to 40SSL I/O. 41 42I/O performed on an SSL BIO communicates using the SSL protocol with 43the SSLs read and write BIOs. If an SSL connection is not established 44then an attempt is made to establish one on the first I/O call. 45 46If a BIO is appended to an SSL BIO using BIO_push() it is automatically 47used as the SSL BIOs read and write BIOs. 48 49Calling BIO_reset() on an SSL BIO closes down any current SSL connection 50by calling SSL_shutdown(). BIO_reset() is then sent to the next BIO in 51the chain: this will typically disconnect the underlying transport. 52The SSL BIO is then reset to the initial accept or connect state. 53 54If the close flag is set when an SSL BIO is freed then the internal 55SSL structure is also freed using SSL_free(). 56 57BIO_set_ssl() sets the internal SSL pointer of BIO B<b> to B<ssl> using 58the close flag B<c>. 59 60BIO_get_ssl() retrieves the SSL pointer of BIO B<b>, it can then be 61manipulated using the standard SSL library functions. 62 63BIO_set_ssl_mode() sets the SSL BIO mode to B<client>. If B<client> 64is 1 client mode is set. If B<client> is 0 server mode is set. 65 66BIO_set_ssl_renegotiate_bytes() sets the renegotiate byte count 67to B<num>. When set after every B<num> bytes of I/O (read and write) 68the SSL session is automatically renegotiated. B<num> must be at 69least 512 bytes. 70 71BIO_set_ssl_renegotiate_timeout() sets the renegotiate timeout to 72B<seconds>. When the renegotiate timeout elapses the session is 73automatically renegotiated. 74 75BIO_get_num_renegotiates() returns the total number of session 76renegotiations due to I/O or timeout. 77 78BIO_new_ssl() allocates an SSL BIO using SSL_CTX B<ctx> and using 79client mode if B<client> is non zero. 80 81BIO_new_ssl_connect() creates a new BIO chain consisting of an 82SSL BIO (using B<ctx>) followed by a connect BIO. 83 84BIO_new_buffer_ssl_connect() creates a new BIO chain consisting 85of a buffering BIO, an SSL BIO (using B<ctx>) and a connect 86BIO. 87 88BIO_ssl_copy_session_id() copies an SSL session id between 89BIO chains B<from> and B<to>. It does this by locating the 90SSL BIOs in each chain and calling SSL_copy_session_id() on 91the internal SSL pointer. 92 93BIO_ssl_shutdown() closes down an SSL connection on BIO 94chain B<bio>. It does this by locating the SSL BIO in the 95chain and calling SSL_shutdown() on its internal SSL 96pointer. 97 98BIO_do_handshake() attempts to complete an SSL handshake on the 99supplied BIO and establish the SSL connection. It returns 1 100if the connection was established successfully. A zero or negative 101value is returned if the connection could not be established, the 102call BIO_should_retry() should be used for non blocking connect BIOs 103to determine if the call should be retried. If an SSL connection has 104already been established this call has no effect. 105 106=head1 NOTES 107 108SSL BIOs are exceptional in that if the underlying transport 109is non blocking they can still request a retry in exceptional 110circumstances. Specifically this will happen if a session 111renegotiation takes place during a BIO_read_ex() operation, one 112case where this happens is when step up occurs. 113 114The SSL flag SSL_AUTO_RETRY can be 115set to disable this behaviour. That is when this flag is set 116an SSL BIO using a blocking transport will never request a 117retry. 118 119Since unknown BIO_ctrl() operations are sent through filter 120BIOs the servers name and port can be set using BIO_set_host() 121on the BIO returned by BIO_new_ssl_connect() without having 122to locate the connect BIO first. 123 124Applications do not have to call BIO_do_handshake() but may wish 125to do so to separate the handshake process from other I/O 126processing. 127 128BIO_set_ssl(), BIO_get_ssl(), BIO_set_ssl_mode(), 129BIO_set_ssl_renegotiate_bytes(), BIO_set_ssl_renegotiate_timeout(), 130BIO_get_num_renegotiates(), and BIO_do_handshake() are implemented as macros. 131 132=head1 EXAMPLE 133 134This SSL/TLS client example, attempts to retrieve a page from an 135SSL/TLS web server. The I/O routines are identical to those of the 136unencrypted example in L<BIO_s_connect(3)>. 137 138 BIO *sbio, *out; 139 int len; 140 char tmpbuf[1024]; 141 SSL_CTX *ctx; 142 SSL *ssl; 143 144 /* XXX Seed the PRNG if needed. */ 145 146 ctx = SSL_CTX_new(TLS_client_method()); 147 148 /* XXX Set verify paths and mode here. */ 149 150 sbio = BIO_new_ssl_connect(ctx); 151 BIO_get_ssl(sbio, &ssl); 152 if (ssl == NULL) { 153 fprintf(stderr, "Can't locate SSL pointer\n"); 154 ERR_print_errors_fp(stderr); 155 exit(1); 156 } 157 158 /* Don't want any retries */ 159 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); 160 161 /* XXX We might want to do other things with ssl here */ 162 163 /* An empty host part means the loopback address */ 164 BIO_set_conn_hostname(sbio, ":https"); 165 166 out = BIO_new_fp(stdout, BIO_NOCLOSE); 167 if (BIO_do_connect(sbio) <= 0) { 168 fprintf(stderr, "Error connecting to server\n"); 169 ERR_print_errors_fp(stderr); 170 exit(1); 171 } 172 if (BIO_do_handshake(sbio) <= 0) { 173 fprintf(stderr, "Error establishing SSL connection\n"); 174 ERR_print_errors_fp(stderr); 175 exit(1); 176 } 177 178 /* XXX Could examine ssl here to get connection info */ 179 180 BIO_puts(sbio, "GET / HTTP/1.0\n\n"); 181 for (;;) { 182 len = BIO_read(sbio, tmpbuf, 1024); 183 if (len <= 0) 184 break; 185 BIO_write(out, tmpbuf, len); 186 } 187 BIO_free_all(sbio); 188 BIO_free(out); 189 190Here is a simple server example. It makes use of a buffering 191BIO to allow lines to be read from the SSL BIO using BIO_gets. 192It creates a pseudo web page containing the actual request from 193a client and also echoes the request to standard output. 194 195 BIO *sbio, *bbio, *acpt, *out; 196 int len; 197 char tmpbuf[1024]; 198 SSL_CTX *ctx; 199 SSL *ssl; 200 201 /* XXX Seed the PRNG if needed. */ 202 203 ctx = SSL_CTX_new(TLS_server_method()); 204 if (!SSL_CTX_use_certificate_file(ctx, "server.pem", SSL_FILETYPE_PEM) 205 || !SSL_CTX_use_PrivateKey_file(ctx, "server.pem", SSL_FILETYPE_PEM) 206 || !SSL_CTX_check_private_key(ctx)) { 207 fprintf(stderr, "Error setting up SSL_CTX\n"); 208 ERR_print_errors_fp(stderr); 209 exit(1); 210 } 211 212 /* XXX Other things like set verify locations, EDH temp callbacks. */ 213 214 /* New SSL BIO setup as server */ 215 sbio = BIO_new_ssl(ctx, 0); 216 BIO_get_ssl(sbio, &ssl); 217 if (ssl == NULL) { 218 fprintf(stderr, "Can't locate SSL pointer\n"); 219 ERR_print_errors_fp(stderr); 220 exit(1); 221 } 222 223 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); 224 bbio = BIO_new(BIO_f_buffer()); 225 sbio = BIO_push(bbio, sbio); 226 acpt = BIO_new_accept("4433"); 227 228 /* 229 * By doing this when a new connection is established 230 * we automatically have sbio inserted into it. The 231 * BIO chain is now 'swallowed' by the accept BIO and 232 * will be freed when the accept BIO is freed. 233 */ 234 BIO_set_accept_bios(acpt, sbio); 235 out = BIO_new_fp(stdout, BIO_NOCLOSE); 236 237 /* Setup accept BIO */ 238 if (BIO_do_accept(acpt) <= 0) { 239 fprintf(stderr, "Error setting up accept BIO\n"); 240 ERR_print_errors_fp(stderr); 241 exit(1); 242 } 243 244 /* We only want one connection so remove and free accept BIO */ 245 sbio = BIO_pop(acpt); 246 BIO_free_all(acpt); 247 248 if (BIO_do_handshake(sbio) <= 0) { 249 fprintf(stderr, "Error in SSL handshake\n"); 250 ERR_print_errors_fp(stderr); 251 exit(1); 252 } 253 254 BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n"); 255 BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n"); 256 BIO_puts(sbio, "--------------------------------------------------\r\n"); 257 258 for (;;) { 259 len = BIO_gets(sbio, tmpbuf, 1024); 260 if (len <= 0) 261 break; 262 BIO_write(sbio, tmpbuf, len); 263 BIO_write(out, tmpbuf, len); 264 /* Look for blank line signifying end of headers*/ 265 if (tmpbuf[0] == '\r' || tmpbuf[0] == '\n') 266 break; 267 } 268 269 BIO_puts(sbio, "--------------------------------------------------\r\n"); 270 BIO_puts(sbio, "\r\n"); 271 BIO_flush(sbio); 272 BIO_free_all(sbio); 273 274=head1 RETURN VALUES 275 276BIO_f_ssl() returns the SSL B<BIO_METHOD> structure. 277 278BIO_set_ssl(), BIO_get_ssl(), BIO_set_ssl_mode(), BIO_set_ssl_renegotiate_bytes(), 279BIO_set_ssl_renegotiate_timeout() and BIO_get_num_renegotiates() return 1 on 280success or a value which is less than or equal to 0 if an error occurred. 281 282BIO_new_ssl(), BIO_new_ssl_connect() and BIO_new_buffer_ssl_connect() return 283a valid B<BIO> structure on success or B<NULL> if an error occurred. 284 285BIO_ssl_copy_session_id() returns 1 on success or 0 on error. 286 287BIO_do_handshake() returns 1 if the connection was established successfully. 288A zero or negative value is returned if the connection could not be established. 289 290=head1 HISTORY 291 292In OpenSSL before 1.0.0 the BIO_pop() call was handled incorrectly, 293the I/O BIO reference count was incorrectly incremented (instead of 294decremented) and dissociated with the SSL BIO even if the SSL BIO was not 295explicitly being popped (e.g. a pop higher up the chain). Applications which 296included workarounds for this bug (e.g. freeing BIOs more than once) should 297be modified to handle this fix or they may free up an already freed BIO. 298 299=head1 COPYRIGHT 300 301Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved. 302 303Licensed under the OpenSSL license (the "License"). You may not use 304this file except in compliance with the License. You can obtain a copy 305in the file LICENSE in the source distribution or at 306L<https://www.openssl.org/source/license.html>. 307 308=cut 309