SSL: logging level of "no suitable key share". The "no suitable key share" errors are reported by OpenSSL 1.1.1 when using TLSv1.3 if there are no shared groups (that is, elliptic curves). In particular, it is easy enough to trigger by using only a single curve in ssl_ecdh_curve: ssl_ecdh_curve secp384r1; and using a different curve in the client: openssl s_client -connect 127.0.0.1:443 -curves prime256v1 On the client side it is seen as "sslv3 alert handshake failure", "SSL alert number 40": 0:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:ssl/record/rec_layer_s3.c:1528:SSL alert number 40 It can be also triggered with default ssl_ecdh_curve by using a curve which is not in the default list (X25519, prime256v1, X448, secp521r1, secp384r1): openssl s_client -connect 127.0.0.1:8443 -curves brainpoolP512r1 Given that many clients hardcode prime256v1, these errors might become a common problem with TLSv1.3 if ssl_ecdh_curve is redefined. Previously this resulted in not using ECDH with such clients, but with TLSv1.3 it is no longer possible and will result in a handshake failure. The SSL_R_NO_SHARED_GROUP error is what BoringSSL returns in the same situation. Seen at: https://serverfault.com/questions/932102/nginx-ssl-handshake-error-no-suitable-key-share

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_MAIL_POP3_MODULE_H_INCLUDED_
#define _NGX_MAIL_POP3_MODULE_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_mail.h>


typedef struct {
    ngx_str_t    capability;
    ngx_str_t    starttls_capability;
    ngx_str_t    starttls_only_capability;
    ngx_str_t    auth_capability;

    ngx_uint_t   auth_methods;

    ngx_array_t  capabilities;
} ngx_mail_pop3_srv_conf_t;


void ngx_mail_pop3_init_session(ngx_mail_session_t *s, ngx_connection_t *c);
void ngx_mail_pop3_init_protocol(ngx_event_t *rev);
void ngx_mail_pop3_auth_state(ngx_event_t *rev);
ngx_int_t ngx_mail_pop3_parse_command(ngx_mail_session_t *s);


extern ngx_module_t  ngx_mail_pop3_module;


#endif /* _NGX_MAIL_POP3_MODULE_H_INCLUDED_ */