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Title "SSL_CTX_add1_chain_cert 3"
way too many mistakes in technical documents.
.nh
\fBSSL_CTX_add0_chain_cert() and SSL_CTX_add1_chain_cert() append the single certificate x509 to the chain associated with the current certificate of \fBctx.
\fBSSL_CTX_get0_chain_certs() retrieves the chain associated with the current certificate of ctx.
\fBSSL_CTX_clear_chain_certs() clears any existing chain associated with the current certificate of ctx. (This is implemented by calling \fBSSL_CTX_set0_chain() with sk set to \s-1NULL\s0).
\fBSSL_CTX_build_cert_chain() builds the certificate chain for ctx normally this uses the chain store or the verify store if the chain store is not set. If the function is successful the built chain will replace any existing chain. The flags parameter can be set to \s-1SSL_BUILD_CHAIN_FLAG_UNTRUSTED\s0 to use existing chain certificates as untrusted CAs, \s-1SSL_BUILD_CHAIN_FLAG_NO_ROOT\s0 to omit the root \s-1CA\s0 from the built chain, \s-1SSL_BUILD_CHAIN_FLAG_CHECK\s0 to use all existing chain certificates only to build the chain (effectively sanity checking and rearranging them if necessary), the flag \fB\s-1SSL_BUILD_CHAIN_FLAG_IGNORE_ERROR\s0 ignores any errors during verification: if flag \s-1SSL_BUILD_CHAIN_FLAG_CLEAR_ERROR\s0 is also set verification errors are cleared from the error queue.
Each of these functions operates on the current end entity (i.e. server or client) certificate. This is the last certificate loaded or selected on the corresponding ctx structure.
\fBSSL_CTX_select_current_cert() selects x509 as the current end entity certificate, but only if x509 has already been loaded into ctx using a function such as SSL_CTX_use_certificate().
\fBSSL_set0_chain(), SSL_set1_chain(), SSL_add0_chain_cert(), \fBSSL_add1_chain_cert(), SSL_get0_chain_certs(), SSL_clear_chain_certs(), \fBSSL_build_cert_chain(), SSL_select_current_cert() and SSL_set_current_cert() are similar except they apply to \s-1SSL\s0 structure ssl.
\fBSSL_CTX_set_current_cert() changes the current certificate to a value based on the op argument. Currently op can be \s-1SSL_CERT_SET_FIRST\s0 to use the first valid certificate or \s-1SSL_CERT_SET_NEXT\s0 to set the next valid certificate after the current certificate. These two operations can be used to iterate over all certificates in an \s-1SSL_CTX\s0 structure.
\fBSSL_set_current_cert() also supports the option \s-1SSL_CERT_SET_SERVER\s0. If ssl is a server and has sent a certificate to a connected client this option sets that certificate to the current certificate and returns 1. If the negotiated cipher suite is anonymous (and thus no certificate will be sent) 2 is returned and the current certificate is unchanged. If ssl is not a server or a certificate has not been sent 0 is returned and the current certificate is unchanged.
All these functions are implemented as macros. Those containing a 1 increment the reference count of the supplied certificate or chain so it must be freed at some point after the operation. Those containing a 0 do not increment reference counts and the supplied certificate or chain \fB\s-1MUST NOT\s0 be freed after the operation.
One chain can be set for each key type supported by a server. So, for example, an \s-1RSA\s0 and a \s-1DSA\s0 certificate can (and often will) have different chains.
The functions SSL_CTX_build_cert_chain() and SSL_build_cert_chain() can be used to check application configuration and to ensure any necessary subordinate CAs are sent in the correct order. Misconfigured applications sending incorrect certificate chains often cause problems with peers.
For example an application can add any set of certificates using \fBSSL_CTX_use_certificate_chain_file() then call SSL_CTX_build_cert_chain() with the option \s-1SSL_BUILD_CHAIN_FLAG_CHECK\s0 to check and reorder them.
Applications can issue non fatal warnings when checking chains by setting the flag \s-1SSL_BUILD_CHAIN_FLAG_IGNORE_ERRORS\s0 and checking the return value.
Calling SSL_CTX_build_cert_chain() or SSL_build_cert_chain() is more efficient than the automatic chain building as it is only performed once. Automatic chain building is performed on each new session.
If any certificates are added using these functions no certificates added using SSL_CTX_add_extra_chain_cert() will be used.
\fBSSL_CTX_build_cert_chain() and SSL_build_cert_chain() return 1 for success and 0 for failure. If the flag \s-1SSL_BUILD_CHAIN_FLAG_IGNORE_ERROR\s0 and a verification error occurs then 2 is returned.
All other functions return 1 for success and 0 for failure.
Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.
Indexes created Wed Apr 29 00:23:26 UTC 2026