1=pod
2
3=head1 NAME
4
5SSL_CTX_set0_chain, SSL_CTX_set1_chain, SSL_CTX_add0_chain_cert,
6SSL_CTX_add1_chain_cert, SSL_CTX_get0_chain_certs, SSL_CTX_clear_chain_certs,
7SSL_set0_chain, SSL_set1_chain, SSL_add0_chain_cert, SSL_add1_chain_cert,
8SSL_get0_chain_certs, SSL_clear_chain_certs, SSL_CTX_build_cert_chain,
9SSL_build_cert_chain, SSL_CTX_select_current_cert,
10SSL_select_current_cert, SSL_CTX_set_current_cert, SSL_set_current_cert - extra
11chain certificate processing
12
13=head1 SYNOPSIS
14
15 #include <openssl/ssl.h>
16
17 int SSL_CTX_set0_chain(SSL_CTX *ctx, STACK_OF(X509) *sk);
18 int SSL_CTX_set1_chain(SSL_CTX *ctx, STACK_OF(X509) *sk);
19 int SSL_CTX_add0_chain_cert(SSL_CTX *ctx, X509 *x509);
20 int SSL_CTX_add1_chain_cert(SSL_CTX *ctx, X509 *x509);
21 int SSL_CTX_get0_chain_certs(SSL_CTX *ctx, STACK_OF(X509) **sk);
22 int SSL_CTX_clear_chain_certs(SSL_CTX *ctx);
23
24 int SSL_set0_chain(SSL *ssl, STACK_OF(X509) *sk);
25 int SSL_set1_chain(SSL *ssl, STACK_OF(X509) *sk);
26 int SSL_add0_chain_cert(SSL *ssl, X509 *x509);
27 int SSL_add1_chain_cert(SSL *ssl, X509 *x509);
28 int SSL_get0_chain_certs(SSL *ssl, STACK_OF(X509) **sk);
29 int SSL_clear_chain_certs(SSL *ssl);
30
31 int SSL_CTX_build_cert_chain(SSL_CTX *ctx, flags);
32 int SSL_build_cert_chain(SSL *ssl, flags);
33
34 int SSL_CTX_select_current_cert(SSL_CTX *ctx, X509 *x509);
35 int SSL_select_current_cert(SSL *ssl, X509 *x509);
36 int SSL_CTX_set_current_cert(SSL_CTX *ctx, long op);
37 int SSL_set_current_cert(SSL *ssl, long op);
38
39=head1 DESCRIPTION
40
41SSL_CTX_set0_chain() and SSL_CTX_set1_chain() set the certificate chain
42associated with the current certificate of B<ctx> to B<sk>.
43
44SSL_CTX_add0_chain_cert() and SSL_CTX_add1_chain_cert() append the single
45certificate B<x509> to the chain associated with the current certificate of
46B<ctx>.
47
48SSL_CTX_get0_chain_certs() retrieves the chain associated with the current
49certificate of B<ctx>.
50
51SSL_CTX_clear_chain_certs() clears any existing chain associated with the
52current certificate of B<ctx>.  (This is implemented by calling
53SSL_CTX_set0_chain() with B<sk> set to B<NULL>).
54
55SSL_CTX_build_cert_chain() builds the certificate chain for B<ctx>.
56Normally this uses the chain store
57or the verify store if the chain store is not set.
58If the function is successful the built chain will replace any existing chain.
59The B<flags> parameter can be set to B<SSL_BUILD_CHAIN_FLAG_UNTRUSTED> to use
60existing chain certificates as untrusted CAs, B<SSL_BUILD_CHAIN_FLAG_NO_ROOT>
61to omit the root CA from the built chain, B<SSL_BUILD_CHAIN_FLAG_CHECK> to
62use all existing chain certificates only to build the chain (effectively
63sanity checking and rearranging them if necessary), the flag
64B<SSL_BUILD_CHAIN_FLAG_IGNORE_ERROR> ignores any errors during verification:
65if flag B<SSL_BUILD_CHAIN_FLAG_CLEAR_ERROR> is also set verification errors
66are cleared from the error queue.
67Details of the chain building process are described in
68L<openssl-verification-options(1)/Certification Path Building>.
69
70Each of these functions operates on the I<current> end entity
71(i.e. server or client) certificate. This is the last certificate loaded or
72selected on the corresponding B<ctx> structure.
73
74SSL_CTX_select_current_cert() selects B<x509> as the current end entity
75certificate, but only if B<x509> has already been loaded into B<ctx> using a
76function such as SSL_CTX_use_certificate().
77
78SSL_set0_chain(), SSL_set1_chain(), SSL_add0_chain_cert(),
79SSL_add1_chain_cert(), SSL_get0_chain_certs(), SSL_clear_chain_certs(),
80SSL_build_cert_chain(), SSL_select_current_cert() and SSL_set_current_cert()
81are similar except they apply to SSL structure B<ssl>.
82
83SSL_CTX_set_current_cert() changes the current certificate to a value based
84on the B<op> argument. Currently B<op> can be B<SSL_CERT_SET_FIRST> to use
85the first valid certificate or B<SSL_CERT_SET_NEXT> to set the next valid
86certificate after the current certificate. These two operations can be
87used to iterate over all certificates in an B<SSL_CTX> structure.
88
89SSL_set_current_cert() also supports the option B<SSL_CERT_SET_SERVER>.
90If B<ssl> is a server and has sent a certificate to a connected client
91this option sets that certificate to the current certificate and returns 1.
92If the negotiated cipher suite is anonymous (and thus no certificate will
93be sent) 2 is returned and the current certificate is unchanged. If B<ssl>
94is not a server or a certificate has not been sent 0 is returned and
95the current certificate is unchanged.
96
97All these functions are implemented as macros. Those containing a B<1>
98increment the reference count of the supplied certificate or chain so it must
99be freed at some point after the operation. Those containing a B<0> do
100not increment reference counts and the supplied certificate or chain
101B<MUST NOT> be freed after the operation.
102
103=head1 NOTES
104
105The chains associate with an SSL_CTX structure are copied to any SSL
106structures when SSL_new() is called. SSL structures will not be affected
107by any chains subsequently changed in the parent SSL_CTX.
108
109One chain can be set for each key type supported by a server. So, for example,
110an RSA and a DSA certificate can (and often will) have different chains.
111
112The functions SSL_CTX_build_cert_chain() and SSL_build_cert_chain() can
113be used to check application configuration and to ensure any necessary
114subordinate CAs are sent in the correct order. Misconfigured applications
115sending incorrect certificate chains often cause problems with peers.
116
117For example an application can add any set of certificates using
118SSL_CTX_use_certificate_chain_file() then call SSL_CTX_build_cert_chain()
119with the option B<SSL_BUILD_CHAIN_FLAG_CHECK> to check and reorder them.
120
121Applications can issue non fatal warnings when checking chains by setting
122the flag B<SSL_BUILD_CHAIN_FLAG_IGNORE_ERRORS> and checking the return
123value.
124
125Calling SSL_CTX_build_cert_chain() or SSL_build_cert_chain() is more
126efficient than the automatic chain building as it is only performed once.
127Automatic chain building is performed on each new session.
128
129If any certificates are added using these functions no certificates added
130using SSL_CTX_add_extra_chain_cert() will be used.
131
132=head1 RETURN VALUES
133
134SSL_set_current_cert() with B<SSL_CERT_SET_SERVER> return 1 for success, 2 if
135no server certificate is used because the cipher suites is anonymous and 0
136for failure.
137
138SSL_CTX_build_cert_chain() and SSL_build_cert_chain() return 1 for success
139and 0 for failure. If the flag B<SSL_BUILD_CHAIN_FLAG_IGNORE_ERROR> and
140a verification error occurs then 2 is returned.
141
142All other functions return 1 for success and 0 for failure.
143
144=head1 SEE ALSO
145
146L<ssl(7)>,
147L<SSL_CTX_add_extra_chain_cert(3)>
148
149=head1 HISTORY
150
151These functions were added in OpenSSL 1.0.2.
152
153=head1 COPYRIGHT
154
155Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.
156
157Licensed under the Apache License 2.0 (the "License").  You may not use
158this file except in compliance with the License.  You can obtain a copy
159in the file LICENSE in the source distribution or at
160L<https://www.openssl.org/source/license.html>.
161
162=cut
163