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Diffstat (limited to 'openssl/doc/crypto/BIO_f_ssl.pod')
| -rw-r--r-- | openssl/doc/crypto/BIO_f_ssl.pod | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/openssl/doc/crypto/BIO_f_ssl.pod b/openssl/doc/crypto/BIO_f_ssl.pod new file mode 100644 index 000000000..f0b731731 --- /dev/null +++ b/openssl/doc/crypto/BIO_f_ssl.pod @@ -0,0 +1,313 @@ +=pod + +=head1 NAME + +BIO_f_ssl, BIO_set_ssl, BIO_get_ssl, BIO_set_ssl_mode, BIO_set_ssl_renegotiate_bytes, +BIO_get_num_renegotiates, BIO_set_ssl_renegotiate_timeout, BIO_new_ssl, +BIO_new_ssl_connect, BIO_new_buffer_ssl_connect, BIO_ssl_copy_session_id, +BIO_ssl_shutdown - SSL BIO + +=head1 SYNOPSIS + + #include <openssl/bio.h> + #include <openssl/ssl.h> + + BIO_METHOD *BIO_f_ssl(void); + + #define BIO_set_ssl(b,ssl,c) BIO_ctrl(b,BIO_C_SET_SSL,c,(char *)ssl) + #define BIO_get_ssl(b,sslp) BIO_ctrl(b,BIO_C_GET_SSL,0,(char *)sslp) + #define BIO_set_ssl_mode(b,client) BIO_ctrl(b,BIO_C_SSL_MODE,client,NULL) + #define BIO_set_ssl_renegotiate_bytes(b,num) \ + BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_BYTES,num,NULL); + #define BIO_set_ssl_renegotiate_timeout(b,seconds) \ + BIO_ctrl(b,BIO_C_SET_SSL_RENEGOTIATE_TIMEOUT,seconds,NULL); + #define BIO_get_num_renegotiates(b) \ + BIO_ctrl(b,BIO_C_SET_SSL_NUM_RENEGOTIATES,0,NULL); + + BIO *BIO_new_ssl(SSL_CTX *ctx,int client); + BIO *BIO_new_ssl_connect(SSL_CTX *ctx); + BIO *BIO_new_buffer_ssl_connect(SSL_CTX *ctx); + int BIO_ssl_copy_session_id(BIO *to,BIO *from); + void BIO_ssl_shutdown(BIO *bio); + + #define BIO_do_handshake(b) BIO_ctrl(b,BIO_C_DO_STATE_MACHINE,0,NULL) + +=head1 DESCRIPTION + +BIO_f_ssl() returns the SSL BIO method. This is a filter BIO which +is a wrapper round the OpenSSL SSL routines adding a BIO "flavour" to +SSL I/O. + +I/O performed on an SSL BIO communicates using the SSL protocol with +the SSLs read and write BIOs. If an SSL connection is not established +then an attempt is made to establish one on the first I/O call. + +If a BIO is appended to an SSL BIO using BIO_push() it is automatically +used as the SSL BIOs read and write BIOs. + +Calling BIO_reset() on an SSL BIO closes down any current SSL connection +by calling SSL_shutdown(). BIO_reset() is then sent to the next BIO in +the chain: this will typically disconnect the underlying transport. +The SSL BIO is then reset to the initial accept or connect state. + +If the close flag is set when an SSL BIO is freed then the internal +SSL structure is also freed using SSL_free(). + +BIO_set_ssl() sets the internal SSL pointer of BIO B<b> to B<ssl> using +the close flag B<c>. + +BIO_get_ssl() retrieves the SSL pointer of BIO B<b>, it can then be +manipulated using the standard SSL library functions. + +BIO_set_ssl_mode() sets the SSL BIO mode to B<client>. If B<client> +is 1 client mode is set. If B<client> is 0 server mode is set. + +BIO_set_ssl_renegotiate_bytes() sets the renegotiate byte count +to B<num>. When set after every B<num> bytes of I/O (read and write) +the SSL session is automatically renegotiated. B<num> must be at +least 512 bytes. + +BIO_set_ssl_renegotiate_timeout() sets the renegotiate timeout to +B<seconds>. When the renegotiate timeout elapses the session is +automatically renegotiated. + +BIO_get_num_renegotiates() returns the total number of session +renegotiations due to I/O or timeout. + +BIO_new_ssl() allocates an SSL BIO using SSL_CTX B<ctx> and using +client mode if B<client> is non zero. + +BIO_new_ssl_connect() creates a new BIO chain consisting of an +SSL BIO (using B<ctx>) followed by a connect BIO. + +BIO_new_buffer_ssl_connect() creates a new BIO chain consisting +of a buffering BIO, an SSL BIO (using B<ctx>) and a connect +BIO. + +BIO_ssl_copy_session_id() copies an SSL session id between +BIO chains B<from> and B<to>. It does this by locating the +SSL BIOs in each chain and calling SSL_copy_session_id() on +the internal SSL pointer. + +BIO_ssl_shutdown() closes down an SSL connection on BIO +chain B<bio>. It does this by locating the SSL BIO in the +chain and calling SSL_shutdown() on its internal SSL +pointer. + +BIO_do_handshake() attempts to complete an SSL handshake on the +supplied BIO and establish the SSL connection. It returns 1 +if the connection was established successfully. A zero or negative +value is returned if the connection could not be established, the +call BIO_should_retry() should be used for non blocking connect BIOs +to determine if the call should be retried. If an SSL connection has +already been established this call has no effect. + +=head1 NOTES + +SSL BIOs are exceptional in that if the underlying transport +is non blocking they can still request a retry in exceptional +circumstances. Specifically this will happen if a session +renegotiation takes place during a BIO_read() operation, one +case where this happens is when SGC or step up occurs. + +In OpenSSL 0.9.6 and later the SSL flag SSL_AUTO_RETRY can be +set to disable this behaviour. That is when this flag is set +an SSL BIO using a blocking transport will never request a +retry. + +Since unknown BIO_ctrl() operations are sent through filter +BIOs the servers name and port can be set using BIO_set_host() +on the BIO returned by BIO_new_ssl_connect() without having +to locate the connect BIO first. + +Applications do not have to call BIO_do_handshake() but may wish +to do so to separate the handshake process from other I/O +processing. + +=head1 RETURN VALUES + +TBA + +=head1 EXAMPLE + +This SSL/TLS client example, attempts to retrieve a page from an +SSL/TLS web server. The I/O routines are identical to those of the +unencrypted example in L<BIO_s_connect(3)|BIO_s_connect(3)>. + + BIO *sbio, *out; + int len; + char tmpbuf[1024]; + SSL_CTX *ctx; + SSL *ssl; + + ERR_load_crypto_strings(); + ERR_load_SSL_strings(); + OpenSSL_add_all_algorithms(); + + /* We would seed the PRNG here if the platform didn't + * do it automatically + */ + + ctx = SSL_CTX_new(SSLv23_client_method()); + + /* We'd normally set some stuff like the verify paths and + * mode here because as things stand this will connect to + * any server whose certificate is signed by any CA. + */ + + sbio = BIO_new_ssl_connect(ctx); + + BIO_get_ssl(sbio, &ssl); + + if(!ssl) { + fprintf(stderr, "Can't locate SSL pointer\n"); + /* whatever ... */ + } + + /* Don't want any retries */ + SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); + + /* We might want to do other things with ssl here */ + + BIO_set_conn_hostname(sbio, "localhost:https"); + + out = BIO_new_fp(stdout, BIO_NOCLOSE); + if(BIO_do_connect(sbio) <= 0) { + fprintf(stderr, "Error connecting to server\n"); + ERR_print_errors_fp(stderr); + /* whatever ... */ + } + + if(BIO_do_handshake(sbio) <= 0) { + fprintf(stderr, "Error establishing SSL connection\n"); + ERR_print_errors_fp(stderr); + /* whatever ... */ + } + + /* Could examine ssl here to get connection info */ + + BIO_puts(sbio, "GET / HTTP/1.0\n\n"); + for(;;) { + len = BIO_read(sbio, tmpbuf, 1024); + if(len <= 0) break; + BIO_write(out, tmpbuf, len); + } + BIO_free_all(sbio); + BIO_free(out); + +Here is a simple server example. It makes use of a buffering +BIO to allow lines to be read from the SSL BIO using BIO_gets. +It creates a pseudo web page containing the actual request from +a client and also echoes the request to standard output. + + BIO *sbio, *bbio, *acpt, *out; + int len; + char tmpbuf[1024]; + SSL_CTX *ctx; + SSL *ssl; + + ERR_load_crypto_strings(); + ERR_load_SSL_strings(); + OpenSSL_add_all_algorithms(); + + /* Might seed PRNG here */ + + ctx = SSL_CTX_new(SSLv23_server_method()); + + if (!SSL_CTX_use_certificate_file(ctx,"server.pem",SSL_FILETYPE_PEM) + || !SSL_CTX_use_PrivateKey_file(ctx,"server.pem",SSL_FILETYPE_PEM) + || !SSL_CTX_check_private_key(ctx)) { + + fprintf(stderr, "Error setting up SSL_CTX\n"); + ERR_print_errors_fp(stderr); + return 0; + } + + /* Might do other things here like setting verify locations and + * DH and/or RSA temporary key callbacks + */ + + /* New SSL BIO setup as server */ + sbio=BIO_new_ssl(ctx,0); + + BIO_get_ssl(sbio, &ssl); + + if(!ssl) { + fprintf(stderr, "Can't locate SSL pointer\n"); + /* whatever ... */ + } + + /* Don't want any retries */ + SSL_set_mode(ssl, SSL_MODE_AUTO_RETRY); + + /* Create the buffering BIO */ + + bbio = BIO_new(BIO_f_buffer()); + + /* Add to chain */ + sbio = BIO_push(bbio, sbio); + + acpt=BIO_new_accept("4433"); + + /* By doing this when a new connection is established + * we automatically have sbio inserted into it. The + * BIO chain is now 'swallowed' by the accept BIO and + * will be freed when the accept BIO is freed. + */ + + BIO_set_accept_bios(acpt,sbio); + + out = BIO_new_fp(stdout, BIO_NOCLOSE); + + /* Setup accept BIO */ + if(BIO_do_accept(acpt) <= 0) { + fprintf(stderr, "Error setting up accept BIO\n"); + ERR_print_errors_fp(stderr); + return 0; + } + + /* Now wait for incoming connection */ + if(BIO_do_accept(acpt) <= 0) { + fprintf(stderr, "Error in connection\n"); + ERR_print_errors_fp(stderr); + return 0; + } + + /* We only want one connection so remove and free + * accept BIO + */ + + sbio = BIO_pop(acpt); + + BIO_free_all(acpt); + + if(BIO_do_handshake(sbio) <= 0) { + fprintf(stderr, "Error in SSL handshake\n"); + ERR_print_errors_fp(stderr); + return 0; + } + + BIO_puts(sbio, "HTTP/1.0 200 OK\r\nContent-type: text/plain\r\n\r\n"); + BIO_puts(sbio, "\r\nConnection Established\r\nRequest headers:\r\n"); + BIO_puts(sbio, "--------------------------------------------------\r\n"); + + for(;;) { + len = BIO_gets(sbio, tmpbuf, 1024); + if(len <= 0) break; + BIO_write(sbio, tmpbuf, len); + BIO_write(out, tmpbuf, len); + /* Look for blank line signifying end of headers*/ + if((tmpbuf[0] == '\r') || (tmpbuf[0] == '\n')) break; + } + + BIO_puts(sbio, "--------------------------------------------------\r\n"); + BIO_puts(sbio, "\r\n"); + + /* Since there is a buffering BIO present we had better flush it */ + BIO_flush(sbio); + + BIO_free_all(sbio); + +=head1 SEE ALSO + +TBA |