SSL_get_peer_certificate, SSL_get0_peer_certificate, SSL_get1_peer_certificate - get the X509 certificate

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3.5.0                                              2025-06-04                     SSL_GET_PEER_CERTIFICATE(3SSL)

       These functions return a pointer to the X509 certificate the peer presented. If the peer did not present
       a certificate, NULL is returned.

SSL_get0_peer_certificate()      and     SSL_get1_peer_certificate()     were     added     in     3.0.0.
       SSL_get_peer_certificate() was deprecated in 3.0.0.

       SSL_get_peer_certificate, SSL_get0_peer_certificate, SSL_get1_peer_certificate - get the X509 certificate
       of the peer

       Due to the protocol definition, a TLS/SSL server will always send a certificate, if present. A client
       will only send a certificate when explicitly requested to do so by the server (see
       SSL_CTX_set_verify(3)). If an anonymous cipher is used, no certificates are sent.

       That a certificate is returned does not indicate information about the verification state, use
       SSL_get_verify_result(3) to check the verification state.

       The reference count of the X509 object returned by SSL_get1_peer_certificate() is incremented by one, so
       that it will not be destroyed when the session containing the peer certificate is freed. The X509 object
       must be explicitly freed using X509_free().

       The reference count of the X509 object returned by SSL_get0_peer_certificate() is not incremented, and
       must not be freed.

       SSL_get_peer_certificate() is an alias of SSL_get1_peer_certificate().

       The following return values can occur:

       NULL
           No certificate was presented by the peer or no connection was established.

       Pointer to an X509 certificate
           The return value points to the certificate presented by the peer.

ssl(7), SSL_get_verify_result(3), SSL_CTX_set_verify(3)

        #include <openssl/ssl.h>

        X509 *SSL_get0_peer_certificate(const SSL *ssl);
        X509 *SSL_get1_peer_certificate(const SSL *ssl);

       The following function has been deprecated since OpenSSL 3.0, and can be hidden entirely by defining
       OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        X509 *SSL_get_peer_certificate(const SSL *ssl);