43c34894d7
Describe the usage of the OCSP callback functions on both the client and the server side. Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
73 lines
3.3 KiB
Text
73 lines
3.3 KiB
Text
=pod
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=head1 NAME
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SSL_CTX_set_tlsext_status_cb, SSL_CTX_set_tlsext_status_arg,
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SSL_set_tlsext_status_type, SSL_get_tlsext_status_ocsp_resp,
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SSL_set_tlsext_status_ocsp_resp - OCSP Certificate Status Request functions
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=head1 SYNOPSIS
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#include <openssl/tls1.h>
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long SSL_CTX_set_tlsext_status_cb(SSL_CTX *ctx,
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int (*callback)(SSL *, void *));
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long SSL_CTX_set_tlsext_status_arg(SSL_CTX *ctx, void *arg);
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long SSL_set_tlsext_status_type(SSL *s, int type);
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long SSL_get_tlsext_status_ocsp_resp(ssl, unsigned char **resp);
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long SSL_set_tlsext_status_ocsp_resp(ssl, unsigned char *resp, int len);
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=head1 DESCRIPTION
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A client application may request that a server send back an OCSP status response
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(also known as OCSP stapling). To do so the client should call the
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SSL_set_tlsext_status_type() function prior to the start of the handshake.
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Currently the only supported type is B<TLSEXT_STATUSTYPE_ocsp>. This value
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should be passed in the B<type> argument. The client should additionally provide
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a callback function to decide what to do with the returned OCSP response by
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calling SSL_CTX_set_tlsext_status_cb(). The callback function should determine
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whether the returned OCSP response is acceptable or not. The callback will be
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passed as an argument the value previously set via a call to
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SSL_CTX_set_tlsext_status_arg(). Note that the callback will not be called in
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the event of a handshake where session resumption occurs (because there are no
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Certificates exchanged in such a handshake).
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The response returned by the server can be obtained via a call to
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SSL_get_tlsext_status_ocsp_resp(). The value B<*resp> will be updated to point
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to the OCSP response data and the return value will be the length of that data.
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Typically a callback would obtain an OCSP_RESPONSE object from this data via a
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call to the d2i_OCSP_RESPONSE() function. If the server has not provided any
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response data then B<*resp> will be NULL and the return value from
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SSL_get_tlsext_status_ocsp_resp() will be -1.
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A server application must also call the SSL_CTX_set_tlsext_status_cb() function
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if it wants to be able to provide clients with OCSP Certificate Status
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responses. Typically the server callback would obtain the server certificate
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that is being sent back to the client via a call to SSL_get_certificate();
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obtain the OCSP response to be sent back; and then set that response data by
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calling SSL_set_tlsext_status_ocsp_resp(). A pointer to the response data should
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be provided in the B<resp> argument, and the length of that data should be in
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the B<len> argument.
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=head1 RETURN VALUES
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The callback when used on the client side should return a negative value on
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error; 0 if the response is not acceptable (in which case the handshake will
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fail) or a positive value if it is acceptable.
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The callback when used on the server side should return with either
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SSL_TLSEXT_ERR_OK (meaning that the OCSP response that has been set should be
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returned), SSL_TLSEXT_ERR_NOACK (meaning that an OCSP response should not be
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returned) or SSL_TLSEXT_ERR_ALERT_FATAL (meaning that a fatal error has
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occurred).
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SSL_CTX_set_tlsext_status_cb(), SSL_CTX_set_tlsext_status_arg(),
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SSL_set_tlsext_status_type() and SSL_set_tlsext_status_ocsp_resp() return 0 on
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error or 1 on success.
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SSL_get_tlsext_status_ocsp_resp() returns the length of the OCSP response data
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or -1 if there is no OCSP response data.
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=cut
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