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BIO_f_ssl() docs.
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@ -91,6 +91,15 @@ case of a file BIO some data may be available in the FILE structures
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internal buffers but it is not possible to determine this in a
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portably way. For other types of BIO they may not be supported.
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Filter BIOs if the do not internally handle a particular BIO_ctrl()
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operation usually pass the operation to the next BIO in the chain.
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This often means there is no need to locate the required BIO for
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a particular operation, it can be called on a chain and it will
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be automatically passed to the relevant BIO.
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Source/sink BIOs will return an error if the do not recognise the
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BIO_ctrl() operation.
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=head1 SEE ALSO
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TBA
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175
doc/crypto/BIO_f_ssl.pod
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175
doc/crypto/BIO_f_ssl.pod
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@ -0,0 +1,175 @@
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=pod
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=head1 NAME
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BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, BIO_set_ssl_renegotiate_bytes,
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BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl,
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BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id,
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BIO_ssl_shutdown - SSL BIO
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=head1 SYNOPSIS
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#include <openssl/bio.h>
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#include <openssl/ssl.h>
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BIO_METHOD *BIO_f_ssl(void);
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#define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl)
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#define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp)
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#define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL)
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#define BIO_set_ssl_renegotiate_bytes(b,num) \
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BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL);
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#define BIO_set_ssl_renegotiate_timeout(b,seconds) \
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BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL);
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#define BIO_get_num_renegotiates(b) \
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BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL);
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BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
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BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
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BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx);
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int BIO_ssl_copy_session_id(BIO *to,BIO *from);
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void BIO_ssl_shutdown(BIO *bio);
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=head1 DESCRIPTION
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BIO_f_ssl() returns the SSL BIO method. This is a filter BIO which
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is a wrapper round the OpenSSL SSL routines adding a BIO "flavour" to
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SSL I/O.
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I/O performed on an SSL BIO communicates using the SSL protocol with
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the SSLs read and write BIOs.
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If a BIO is appended to an SSL BIO using BIO_push() it is automatically
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used as the SSL BIOs read and write BIOs.
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Calling BIO_reset() on an SSL BIO closes down any current SSL connection
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by calling SSL_shutdown(). BIO_reset() is then sent to the next BIO in
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the chain: this will typically disconnect the underlying transport.
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The SSL BIO is then reset to the initial accept or connect state.
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If the close flag is set when an SSL BIO is freed then the internal
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SSL structure is also freed using SSL_free().
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BIO_set_ssl() sets the internal SSL pointer of BIO B<b> to B<ssl> using
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the close flag B<c>.
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BIO_get_ssl() retrieves the SSL pointer of BIO B<b>, it can then be
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manipulated using the standard SSL library functions.
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BIO_set_ssl_mode() sets the SSL BIO mode to B<client>. If B<client>
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is 1 client mode is set. If B<client> is 0 server mode is set.
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BIO_set_ssl_renegotiate_bytes() sets the renegotiate byte count
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to B<num>. When set after every B<num> bytes of I/O (read and write)
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the SSL session is automatically renegotiated. B<num> must be at
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least 512 bytes.
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BIO_set_ssl_renegotiate_timeout() sets the renegotiate timeout to
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B<seconds>. When the renegotiate timeout elapses the sesssion is
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automatically renegotiated.
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BIO_get_num_renegotiates() returns the total number of session
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renegotiations due to I/O or timeout.
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BIO_new_ssl() allocates an SSL BIO using SSL_CTX B<ctx> and using
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client mode if B<client> is non zero.
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BIO_new_ssl_connect() creates a new BIO chain consisting of an
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SSL BIO (using B<ctx>) followed by a connect BIO.
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BIO_new_buffer_ssl_connect() creates a new BIO chain consisting
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of a buffering BIO, an SSL BIO (using B<ctx>) and a connect
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BIO.
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BIO_ssl_copy_session_id() copies an SSL session id between
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BIO chains B<from> and B<to>. It does this by locating the
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SSL BIOs in each chain and calling SSL_copy_session_id() on
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the internal SSL pointer.
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BIO_ssl_shutdown() closes down an SSL connection on BIO
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chain B<bio>. It does this by locating the SSL BIO in the
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chain and calling SSL_shutdown() on its internal SSL
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pointer.
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=head1 NOTES
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SSL BIOs are exceptional in that if the underlying transport
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is non blocking they can still request a retry in exceptional
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circumstances. Specifically this will happen if a session
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renegotiation takes place during a BIO_read() operation, one
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case where this happens is when SGC or step up occurs.
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In OpenSSL 0.9.6 and later the SSL flag SSL_AUTO_RETRY can be
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set to disable this behaviour. That is when this flag is set
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an SSL BIO using a blocking transport will never request a
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retry.
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Since unknown BIO_ctrl() operations are sent through filter
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BIOs the servers name and port can be set using BIO_set_host()
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on the BIO returned by BIO_new_ssl_connect() without having
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to locate the connect BIO first.
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=head1 RETURN VALUES
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TBA
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=head1 EXAMPLE
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This SSL/TLS client example, attempts to retrieve a page from an
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SSL/TLS web server. The I/O routines are identical to those of the
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unencrypted example in L<BIO_s_connect(3)|BIO_s_connect(3)>.
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BIO *sbio, *out;
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int len;
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char tmpbuf[1024];
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SSL_CTX *ctx;
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SSL *ssl;
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ERR_load_crypto_strings();
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ERR_load_SSL_strings();
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OpenSSL_add_all_algorithms();
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ctx = SSL_CTX_new(SSLv23_client_method());
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/* We'd normally set some stuff like the verify paths and
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* mode here because as things stand this will connect to
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* any server whose certificate is signed by any CA.
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*/
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sbio = BIO_new_ssl_connect(ctx);
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BIO_get_ssl(sbio, &ssl);
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if(!ssl) {
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fprintf(stderr, "Can't locate SSL pointer\n");
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/* whatever ... */
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}
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/* Don't want any retries */
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SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY);
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/* We might want to do other things with ssl here */
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BIO_set_conn_hostname(sbio, "localhost:https");
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out = BIO_new_fp(stdout, BIO_NOCLOSE);
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if(BIO_do_connect(sbio) <= 0) {
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fprintf(stderr, "Error connecting to server\n");
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ERR_print_errors_fp(stderr);
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/* whatever ... */
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}
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/* Could examine ssl here to get connection info */
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BIO_puts(sbio, "GET / HTTP/1.0\n\n");
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for(;;) {
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len = BIO_read(sbio, tmpbuf, 1024);
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if(len <= 0) break;
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BIO_write(out, tmpbuf, len);
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}
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BIO_free_all(sbio);
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BIO_free(out);
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=head1 SEE ALSO
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TBA
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should be combined with non blocking I/O so successive reads will request
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a retry instead of blocking.
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See the L<BIO_should_retry(3)|BIO_should_retry(3)> for details of how to
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See L<BIO_should_retry(3)|BIO_should_retry(3)> for details of how to
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determine the cause of a retry and other I/O issues.
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If the BIO_gets() function is not supported by a BIO then it possible to
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@ -60,6 +60,7 @@ work around this by adding a buffering BIO L<BIO_f_buffer(3)|BIO_f_buffer(3)>
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to the chain.
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=head1 SEE ALSO
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L<BIO_should_retry(3)|BIO_should_retry(3)>
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TBA
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