SSL_GET_VERSION(3)

okay bestie, welcome to the SSL_GET_VERSION(3) page from the Library Functions Manual — it's giving protocol-detective energy, and honestly it's iconic. This one is all about getting the protocol information of a connection. 🎀

✨ NAME ✨

SSL_get_version, SSL_is_dtls, and SSL_version — the trio that gets the protocol information of a connection. slay. 💅

🌸 SYNOPSIS 🌸

The synopsis has this library line, exactly:

library “libssl” libcrypto #include <openssl/ssl.h>

Then the function signatures, no cap:

const char *
SSL_get_version(const SSL *ssl);

int
SSL_is_dtls(const SSL *ssl);

int
SSL_version(const SSL *ssl);

💖 DESCRIPTION 💖

• SSL_get_version() returns the name of the protocol used for the connection ssl. name-drop that protocol, bestie.
• SSL_is_dtls() returns 1 if the connection is using DTLS, 0 if not.
• SSL_version() returns an integer constant representing that protocol.

Important handshake vibe check: these functions only return reliable results after the initial handshake has been completed. So don't ask before the handshake is done — it's literally not ready. 😭

🔥 RETURN VALUES 🔥

The following strings or integers can be returned by SSL_get_version() and SSL_version():

• "TLSv1" or TLS1_VERSION — the connection uses the TLSv1.0 protocol. 💖
• "TLSv1.1" or TLS1_1_VERSION — the connection uses the TLSv1.1 protocol. ✨
• "TLSv1.2" or TLS1_2_VERSION — the connection uses the TLSv1.2 protocol. 🦋
• "TLSv1.3" or TLS1_3_VERSION — the connection uses the TLSv1.3 protocol. 🌸
• "DTLSv1" or DTLS1_VERSION — the connection uses the Datagram Transport Layer Security 1.0 protocol. 🎀
• "DTLSv1.2" or DTLS1_2_VERSION — the connection uses the Datagram Transport Layer Security 1.2 protocol. 🌈
• "unknown" — this indicates an unknown protocol version; it cannot currently happen with LibreSSL. 💀

SSL_is_dtls() returns 1 if the connection uses DTLS, 0 if not. 🫶

🎀 SEE ALSO 🎀

• ssl(3) — go read this too, iykyk.

👑 HISTORY 👑

• SSL_get_version() and SSL_version() first appeared in SSLeay 0.8.0 and have been available since OpenBSD 2.4. ⭐
• SSL_is_dtls() first appeared in OpenSSL 1.1.0 and has been available since OpenBSD 6.9. 💜

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xoxo, your favorite manual page — this footer moment comes from Debian, dated June 8, 2025, signing off as SSL_GET_VERSION(3) 💋✨