SSL_CTX_SET_MSG_CALLBACK(3ssl) OpenSSL SSL_CTX_SET_MSG_CALLBACK(3ssl) SSL_CTX_set_msg_callback, SSL_CTX_set_msg_callback_arg, SSL_set_msg_callback, SSL_set_msg_callback_arg, SSL_trace - #include void SSL_CTX_set_msg_callback(SSL_CTX *ctx, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg)); void SSL_CTX_set_msg_callback_arg(SSL_CTX *ctx, void *arg); void SSL_set_msg_callback(SSL *ssl, void (*cb)(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg)); void SSL_set_msg_callback_arg(SSL *ssl, void *arg); void SSL_trace(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg); SSL_CTX_set_msg_callback() SSL_set_msg_callback() cb SSL/TLS/QUIC ( ) . SSL_CTX_set_msg_callback_arg() SSL_set_msg_callback_arg() arg . SSL_CTX_set_msg_callback() SSL_CTX_set_msg_callback_arg() SSL SSL_new(3). SSL_set_msg_callback() SSL_set_msg_callback_arg() SSL. NULL cb . cb SSL/TLS/QUIC : write_p 0 1 . TLS1_3_VERSION TLS1_2_VERSION OSSL_QUIC1_VERSION . SSL3_RT_HEADER ( ) / . content_type (SSL3_RT_CHANGE_CIPHER_SPEC SSL3_RT_ALERT SSL3_RT_HANDSHAKE SSL3_RT_APPLICATION_DATA ). "". ( ). buf, len buf ( ) len . . ssl SSL . SSL_CTX_set_msg_callback_arg() SSL_set_msg_callback_arg(). SSL_trace() SSL_CTX_set_msg_callback() SSL_set_msg_callback(). BIO SSL_CTX_set_msg_callback_arg() SSL_set_msg_callback_arg(). SSL/TLS/QUIC BIO. . ( .) . . version : TLS 1.0 ClientHello SSL 3.0 version SSL3_VERSION. . : SSL3_RT_HEADER TLS. buf . SSL3_RT_INNER_CONTENT_TYPE TLSv1.3 . TLSv1.3 SSL3_RT_APPLICATION_DATA. "". buf "" . SSL3_RT_QUIC_DATAGRAM QUIC. SSL3_RT_QUIC_PACKET QUIC. SSL3_RT_QUIC_FRAME_FULL QUIC. . QUIC . SSL3_RT_QUIC_FRAME_HEADER QUIC . QUIC . SSL3_RT_QUIC_FRAME_PADDING QUIC . . . SSL_CTX_set_msg_callback() SSL_CTX_set_msg_callback_arg() SSL_set_msg_callback() SSL_set_msg_callback_arg() . ssl(7) SSL_new(3) SSL3_RT_INNER_CONTENT_TYPE OpenSSL 1.1.1. SSL3_RT_QUIC_DATAGRAM SSL3_RT_QUIC_PACKET SSL3_RT_QUIC_FRAME_FULL SSL3_RT_QUIC_FRAME_HEADER SSL3_RT_QUIC_FRAME_PADDING OpenSSL 3.2. OpenSSL 3.0 cb 0 version SSL3_RT_HEADER TLS. OpenSSL 3.2 cb 0 version SSL3_RT_HEADER DTLS. 2001-2023 OpenSSL. . Apache 2.0 ( ""). . LICENSE . 3 . . : . 3.6.2 7 2026 SSL_CTX_SET_MSG_CALLBACK(3ssl)