SSL: logging level of "no suitable signature algorithm". The "no suitable signature algorithm" errors are reported by OpenSSL 1.1.1 when using TLSv1.3 if there are no shared signature algorithms. In particular, this can happen if the client limits available signature algorithms to something we don't have a certificate for, or to an empty list. For example, the following command: openssl s_client -connect 127.0.0.1:8443 -sigalgs rsa_pkcs1_sha1 will always result in the "no suitable signature algorithm" error as the "rsa_pkcs1_sha1" algorithm refers solely to signatures which appear in certificates and not defined for use in TLS 1.3 handshake messages. The SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS error is what BoringSSL returns in the same situation.

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


#ifndef _NGX_SYSLOG_H_INCLUDED_
#define _NGX_SYSLOG_H_INCLUDED_


typedef struct {
    ngx_uint_t        facility;
    ngx_uint_t        severity;
    ngx_str_t         tag;

    ngx_addr_t        server;
    ngx_connection_t  conn;
    unsigned          busy:1;
    unsigned          nohostname:1;
} ngx_syslog_peer_t;


char *ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer);
u_char *ngx_syslog_add_header(ngx_syslog_peer_t *peer, u_char *buf);
void ngx_syslog_writer(ngx_log_t *log, ngx_uint_t level, u_char *buf,
    size_t len);
ssize_t ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len);


#endif /* _NGX_SYSLOG_H_INCLUDED_ */