Updated: 2021/Apr/14

SSL_get_peer_cert_chain(3)          OpenSSL         SSL_get_peer_cert_chain(3)

       SSL_get_peer_cert_chain, SSL_get0_verified_chain - get the X509
       certificate chain of the peer

       libcrypto, -lcrypto

        #include <openssl/ssl.h>

        STACK_OF(X509) *SSL_get_peer_cert_chain(const SSL *ssl);
        STACK_OF(X509) *SSL_get0_verified_chain(const SSL *ssl);

       SSL_get_peer_cert_chain() returns a pointer to STACK_OF(X509)
       certificates forming the certificate chain sent by the peer. If called
       on the client side, the stack also contains the peer's certificate; if
       called on the server side, the peer's certificate must be obtained
       separately using SSL_get_peer_certificate(3).  If the peer did not
       present a certificate, NULL is returned.

       NB: SSL_get_peer_cert_chain() returns the peer chain as sent by the
       peer: it only consists of certificates the peer has sent (in the order
       the peer has sent them) it is not a verified chain.

       SSL_get0_verified_chain() returns the verified certificate chain of the
       peer including the peer's end entity certificate. It must be called
       after a session has been successfully established. If peer verification
       was not successful (as indicated by SSL_get_verify_result() not
       returning X509_V_OK) the chain may be incomplete or invalid.

       If the session is resumed peers do not send certificates so a NULL
       pointer is returned by these functions. Applications can call
       SSL_session_reused() to determine whether a session is resumed.

       The reference count of each certificate in the returned STACK_OF(X509)
       object is not incremented and the returned stack may be invalidated by
       renegotiation.  If applications wish to use any certificates in the
       returned chain indefinitely they must increase the reference counts
       using X509_up_ref() or obtain a copy of the whole chain with

       The following return values can occur:

           No certificate was presented by the peer or no connection was
           established or the certificate chain is no longer available when a
           session is reused.

       Pointer to a STACK_OF(X509)
           The return value points to the certificate chain presented by the

       ssl(7), SSL_get_peer_certificate(3), X509_up_ref(3),

       Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at

1.1.1i                            2018-09-23        SSL_get_peer_cert_chain(3)