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

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       Licensed  under  the  Apache License 2.0 (the "License").  You may not use this file except in compliance
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       <https://www.openssl.org/source/license.html>.

3.5.0                                              2025-06-04                      SSL_GET_PEER_CERT_CHAIN(3SSL)

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.

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

       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 X509_chain_up_ref().

       The following return values can occur:

       NULL
           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 peer.

ssl(7), SSL_get_peer_certificate(3), X509_up_ref(3), X509_chain_up_ref(3)

        #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);