SSL_CTX_GET0_PARAM(3ossl)

💖 SSL_CTX_GET0_PARAM — the OpenSSL manual, but make it make sense 💖

okay bestie, welcome to SSL_CTX_GET0_PARAM(3ossl), aka the page where we talk about getting and setting verification parameters. it's giving "certificate vibe check" energy and honestly? we're obsessed. 🎀

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✨ NAME ✨

SSL_CTX_get0_param, SSL_get0_param, SSL_CTX_set1_param, SSL_set1_param, SSL_CTX_set_purpose, SSL_CTX_set_trust, SSL_set_purpose, SSL_set_trust — get and set verification parameters. that's it, that's the whole job. 🫶

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🌸 SYNOPSIS 🌸

#include <openssl/ssl.h>

X509_VERIFY_PARAM *SSL_CTX_get0_param(SSL_CTX *ctx);
X509_VERIFY_PARAM *SSL_get0_param(SSL *ssl);
int SSL_CTX_set1_param(SSL_CTX *ctx, X509_VERIFY_PARAM *vpm);
int SSL_set1_param(SSL *ssl, X509_VERIFY_PARAM *vpm);

int SSL_CTX_set_purpose(SSL_CTX *ctx, int purpose);
int SSL_set_purpose(SSL *ssl, int purpose);

int SSL_CTX_set_trust(SSL_CTX *ctx, int trust);
int SSL_set_trust(SSL *ssl, int trust);

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💅 DESCRIPTION 💅

okay so. SSL_CTX_get0_param() and SSL_get0_param() hand you back an internal pointer to the verification parameters for ctx or ssl respectively. and listen — the returned pointer must NOT be freed by the calling application. do not free it. do not touch it with a free(). it is not yours, it never was, it's a borrow. 💀

then we got SSL_CTX_set1_param() and SSL_set1_param(), which set the verification parameters to vpm for ctx or ssl. simple. iconic.

and then the little shorthands, the shortcuts, the "we could do it the long way but why" girls:

• SSL_CTX_set_purpose() and SSL_set_purpose() set the purpose parameter on the verification parameters object. these are equivalent to calling X509_VERIFY_PARAM_set_purpose() directly. same energy, less typing.
• SSL_CTX_set_trust() and SSL_set_trust() are similarly shorthands which set the trust parameter on the verification parameters object. these are equivalent to calling X509_VERIFY_PARAM_set_trust() directly.

no cap, they literally just wrap those two calls. 🦋

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📝 NOTES 📝

so the usual flow, the typical main-character arc: you grab the parameters off an SSL_CTX or SSL structure using SSL_CTX_get0_param() or SSL_get0_param(), and then your app modifies them to suit its needs — for example, to add a hostname check. that's the move. that's the whole point. ✨

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🔥 RETURN VALUES 🔥

• SSL_CTX_get0_param() and SSL_get0_param() return a pointer to an X509_VERIFY_PARAM structure.
• SSL_CTX_set1_param(), SSL_set1_param(), SSL_CTX_set_purpose(), SSL_set_purpose(), SSL_CTX_set_trust() and SSL_set_trust() return 1 for success and 0 for failure.

fr fr, check that return value. 0 means it did not slay.

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🌈 EXAMPLES 🌈

wanna check that the hostname matches "www.foo.com" in the peer certificate? bestie, say less:

X509_VERIFY_PARAM *vpm = SSL_get0_param(ssl);
X509_VERIFY_PARAM_set1_host(vpm, "www.foo.com", 0);

look at her go. 🎀

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👀 SEE ALSO 👀

• ssl(7)
• X509_VERIFY_PARAM_set_flags(3)

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🧚 HISTORY 🧚

these functions were added in OpenSSL 1.0.2. vintage, lowkey. 💜

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👑 COPYRIGHT 👑

Copyright 2015-2022 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (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 <https://www.openssl.org/source/license.html>.

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okay that's the whole page, bestie — this was OpenSSL 3.5.9, dated 2026-09-29, filed under SSL_CTX_GET0_PARAM(3ossl). go forth and verify those params. mwah. 💖✨🫶