NAME

     tls_conn_version, tls_conn_cipher, tls_conn_cipher_strength, tls_conn_alpn_selected, tls_conn_servername,
     tls_conn_session_resumed, tls_peer_cert_provided, tls_peer_cert_contains_name, tls_peer_cert_chain_pem,
     tls_peer_cert_issuer, tls_peer_cert_subject, tls_peer_cert_hash, tls_peer_cert_notbefore,
     tls_peer_cert_notafter — inspect an established TLS connection

SYNOPSIS

     #include <tls.h>

     const char *
     tls_conn_version(struct tls *ctx);

     const char *
     tls_conn_cipher(struct tls *ctx);

     int
     tls_conn_cipher_strength(struct tls *ctx);

     const char *
     tls_conn_alpn_selected(struct tls *ctx);

     const char *
     tls_conn_servername(struct tls *ctx);

     int
     tls_conn_session_resumed(struct tls *ctx);

     int
     tls_peer_cert_provided(struct tls *ctx);

     int
     tls_peer_cert_contains_name(struct tls *ctx, const char *name);

     const uint8_t *
     tls_peer_cert_chain_pem(struct tls *ctx, size_t *size);

     const char *
     tls_peer_cert_issuer(struct tls *ctx);

     const char *
     tls_peer_cert_subject(struct tls *ctx);

     const char *
     tls_peer_cert_hash(struct tls *ctx);

     time_t
     tls_peer_cert_notbefore(struct tls *ctx);

     time_t
     tls_peer_cert_notafter(struct tls *ctx);

DESCRIPTION

     These functions return information about a TLS connection and will only succeed after the handshake is
     complete (the connection information applies to both clients and servers, unless noted otherwise):

     tls_conn_version() returns a string corresponding to a TLS version negotiated with the peer connected to
     ctx.

     tls_conn_cipher() returns a string corresponding to the cipher suite negotiated with the peer connected to
     ctx.

     tls_conn_cipher_strength() returns the strength in bits for the symmetric cipher that is being used with
     the peer connected to ctx.

     tls_conn_alpn_selected() returns a string that specifies the ALPN protocol selected for use with the peer
     connected to ctx.  If no protocol was selected then NULL is returned.

     tls_conn_servername() returns a string corresponding to the servername that the client connected to ctx
     requested by sending a TLS Server Name Indication extension (server only).

     tls_conn_session_resumed() indicates whether a TLS session has been resumed during the handshake with the
     server connected to ctx (client only).

     tls_peer_cert_provided() checks if the peer of ctx has provided a certificate.

     tls_peer_cert_contains_name() checks if the peer of a TLS ctx has provided a certificate that contains a
     SAN or CN that matches name.

     tls_peer_cert_chain_pem() returns a pointer to memory containing a PEM-encoded certificate chain for the
     peer certificate from ctx.

     tls_peer_cert_subject() returns a string corresponding to the subject of the peer certificate from ctx.

     tls_peer_cert_issuer() returns a string corresponding to the issuer of the peer certificate from ctx.

     tls_peer_cert_hash() returns a string corresponding to a hash of the raw peer certificate from ctx prefixed
     by a hash name followed by a colon.  The hash currently used is SHA256, though this could change in the
     future.  The hash string for a certificate in file mycert.crt can be generated using the commands:

           h=$(openssl x509 -outform der -in mycert.crt | sha256)
           printf "SHA256:${h}\n"

     tls_peer_cert_notbefore() returns the time corresponding to the start of the validity period of the peer
     certificate from ctx.

     tls_peer_cert_notafter() returns the time corresponding to the end of the validity period of the peer
     certificate from ctx.

RETURN VALUES

     The tls_conn_session_resumed() function returns 1 if a TLS session was resumed or 0 if it was not.

     The tls_peer_cert_provided() and tls_peer_cert_contains_name() functions return 1 if the check succeeds or
     0 if it does not.

     tls_peer_cert_notbefore() and tls_peer_cert_notafter() return a time in epoch-seconds on success or -1 on
     error.

     The functions that return a pointer return NULL on error or an out of memory condition.

SEE ALSO

     tls_configure(3), tls_handshake(3), tls_init(3), tls_ocsp_process_response(3)

HISTORY

     tls_conn_version(), tls_conn_cipher(), tls_peer_cert_provided(), tls_peer_cert_contains_name(),
     tls_peer_cert_issuer(), tls_peer_cert_subject(), tls_peer_cert_hash(), tls_peer_cert_notbefore(), and
     tls_peer_cert_notafter() appeared in OpenBSD 5.9.

     tls_conn_servername() and tls_conn_alpn_selected() appeared in OpenBSD 6.1.

     tls_conn_session_resumed() appeared in OpenBSD 6.3.

     tls_conn_cipher_strength() appeared in OpenBSD 6.7.

AUTHORS

     Bob Beck <beck@openbsd.org>
     Joel Sing <jsing@openbsd.org>