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_SHMTX_H_INCLUDED_
#define _NGX_SHMTX_H_INCLUDED_


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


typedef struct {
    ngx_atomic_t   lock;
#if (NGX_HAVE_POSIX_SEM)
    ngx_atomic_t   wait;
#endif
} ngx_shmtx_sh_t;


typedef struct {
#if (NGX_HAVE_ATOMIC_OPS)
    ngx_atomic_t  *lock;
#if (NGX_HAVE_POSIX_SEM)
    ngx_atomic_t  *wait;
    ngx_uint_t     semaphore;
    sem_t          sem;
#endif
#else
    ngx_fd_t       fd;
    u_char        *name;
#endif
    ngx_uint_t     spin;
} ngx_shmtx_t;


ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr,
    u_char *name);
void ngx_shmtx_destroy(ngx_shmtx_t *mtx);
ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx);
void ngx_shmtx_lock(ngx_shmtx_t *mtx);
void ngx_shmtx_unlock(ngx_shmtx_t *mtx);
ngx_uint_t ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid);


#endif /* _NGX_SHMTX_H_INCLUDED_ */