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 RETURN VALUES 133 134BIO_f_ssl() returns the SSL B<BIO_METHOD> structure. 135 136BIO_set_ssl(), BIO_get_ssl(), BIO_set_ssl_mode(), BIO_set_ssl_renegotiate_bytes(), 137BIO_set_ssl_renegotiate_timeout() and BIO_get_num_renegotiates() return 1 on 138success or a value which is less than or equal to 0 if an error occurred. 139 140BIO_new_ssl(), BIO_new_ssl_connect() and BIO_new_buffer_ssl_connect() return 141a valid B<BIO> structure on success or B<NULL> if an error occurred. 142 143BIO_ssl_copy_session_id() returns 1 on success or 0 on error. 144 145BIO_do_handshake() returns 1 if the connection was established successfully. 146A zero or negative value is returned if the connection could not be established. 147 148=head1 EXAMPLES 149 150This SSL/TLS client example attempts to retrieve a page from an 151SSL/TLS web server. The I/O routines are identical to those of the 152unencrypted example in L<BIO_s_connect(3)>. 153 154 BIO *sbio, *out; 155 int len; 156 char tmpbuf[1024]; 157 SSL_CTX *ctx; 158 SSL *ssl; 159 160 /* XXX Seed the PRNG if needed. */ 161 162 ctx = SSL_CTX_new(TLS_client_method()); 163 164 /* XXX Set verify paths and mode here. */ 165 166 sbio = BIO_new_ssl_connect(ctx); 167 BIO_get_ssl(sbio, &ssl); 168 if (ssl == NULL) { 169 fprintf(stderr, "Can't locate SSL pointer\n"); 170 ERR_print_errors_fp(stderr); 171 exit(1); 172 } 173 174 /* Don't want any retries */ 175 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); 176 177 /* XXX We might want to do other things with ssl here */ 178 179 /* An empty host part means the loopback address */ 180 BIO_set_conn_hostname(sbio, ":https"); 181 182 out = BIO_new_fp(stdout, BIO_NOCLOSE); 183 if (BIO_do_connect(sbio) <= 0) { 184 fprintf(stderr, "Error connecting to server\n"); 185 ERR_print_errors_fp(stderr); 186 exit(1); 187 } 188 if (BIO_do_handshake(sbio) <= 0) { 189 fprintf(stderr, "Error establishing SSL connection\n"); 190 ERR_print_errors_fp(stderr); 191 exit(1); 192 } 193 194 /* XXX Could examine ssl here to get connection info */ 195 196 BIO_puts(sbio, "GET / HTTP/1.0\n\n"); 197 for (;;) { 198 len = BIO_read(sbio, tmpbuf, 1024); 199 if (len <= 0) 200 break; 201 BIO_write(out, tmpbuf, len); 202 } 203 BIO_free_all(sbio); 204 BIO_free(out); 205 206Here is a simple server example. It makes use of a buffering 207BIO to allow lines to be read from the SSL BIO using BIO_gets. 208It creates a pseudo web page containing the actual request from 209a client and also echoes the request to standard output. 210 211 BIO *sbio, *bbio, *acpt, *out; 212 int len; 213 char tmpbuf[1024]; 214 SSL_CTX *ctx; 215 SSL *ssl; 216 217 /* XXX Seed the PRNG if needed. */ 218 219 ctx = SSL_CTX_new(TLS_server_method()); 220 if (!SSL_CTX_use_certificate_file(ctx, "server.pem", SSL_FILETYPE_PEM) 221 || !SSL_CTX_use_PrivateKey_file(ctx, "server.pem", SSL_FILETYPE_PEM) 222 || !SSL_CTX_check_private_key(ctx)) { 223 fprintf(stderr, "Error setting up SSL_CTX\n"); 224 ERR_print_errors_fp(stderr); 225 exit(1); 226 } 227 228 /* XXX Other things like set verify locations, EDH temp callbacks. */ 229 230 /* New SSL BIO setup as server */ 231 sbio = BIO_new_ssl(ctx, 0); 232 BIO_get_ssl(sbio, &ssl); 233 if (ssl == NULL) { 234 fprintf(stderr, "Can't locate SSL pointer\n"); 235 ERR_print_errors_fp(stderr); 236 exit(1); 237 } 238 239 SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); 240 bbio = BIO_new(BIO_f_buffer()); 241 sbio = BIO_push(bbio, sbio); 242 acpt = BIO_new_accept("4433"); 243 244 /* 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. 249 */ 250 BIO_set_accept_bios(acpt, sbio); 251 out = BIO_new_fp(stdout, BIO_NOCLOSE); 252 253 /* Setup accept BIO */ 254 if (BIO_do_accept(acpt) <= 0) { 255 fprintf(stderr, "Error setting up accept BIO\n"); 256 ERR_print_errors_fp(stderr); 257 exit(1); 258 } 259 260 /* We only want one connection so remove and free accept BIO */ 261 sbio = BIO_pop(acpt); 262 BIO_free_all(acpt); 263 264 if (BIO_do_handshake(sbio) <= 0) { 265 fprintf(stderr, "Error in SSL handshake\n"); 266 ERR_print_errors_fp(stderr); 267 exit(1); 268 } 269 270 BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n"); 271 BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n"); 272 BIO_puts(sbio, "--------------------------------------------------\r\n"); 273 274 for (;;) { 275 len = BIO_gets(sbio, tmpbuf, 1024); 276 if (len <= 0) 277 break; 278 BIO_write(sbio, tmpbuf, len); 279 BIO_write(out, tmpbuf, len); 280 /* Look for blank line signifying end of headers*/ 281 if (tmpbuf[0] == '\r' || tmpbuf[0] == '\n') 282 break; 283 } 284 285 BIO_puts(sbio, "--------------------------------------------------\r\n"); 286 BIO_puts(sbio, "\r\n"); 287 BIO_flush(sbio); 288 BIO_free_all(sbio); 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 2000-2019 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