SSL: use of the SSL_OP_IGNORE_UNEXPECTED_EOF option. A new behaviour was introduced in OpenSSL 1.1.1e, when a peer does not send close_notify before closing the connection. Previously, it was to return SSL_ERROR_SYSCALL with errno 0, known since at least OpenSSL 0.9.7, and is handled gracefully in nginx. Now it returns SSL_ERROR_SSL with a distinct reason SSL_R_UNEXPECTED_EOF_WHILE_READING ("unexpected eof while reading"). This leads to critical errors seen in nginx within various routines such as SSL_do_handshake(), SSL_read(), SSL_shutdown(). The behaviour was restored in OpenSSL 1.1.1f, but presents in OpenSSL 3.0 by default. Use of the SSL_OP_IGNORE_UNEXPECTED_EOF option added in OpenSSL 3.0 allows to set a compatible behaviour to return SSL_ERROR_ZERO_RETURN: https://git.openssl.org/?p=openssl.git;a=commitdiff;h=09b90e0 See for additional details: https://github.com/openssl/openssl/issues/11381

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


#ifndef _NGX_MAIL_IMAP_MODULE_H_INCLUDED_
#define _NGX_MAIL_IMAP_MODULE_H_INCLUDED_


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


typedef struct {
    size_t       client_buffer_size;

    ngx_str_t    capability;
    ngx_str_t    starttls_capability;
    ngx_str_t    starttls_only_capability;

    ngx_uint_t   auth_methods;

    ngx_array_t  capabilities;
} ngx_mail_imap_srv_conf_t;


void ngx_mail_imap_init_session(ngx_mail_session_t *s, ngx_connection_t *c);
void ngx_mail_imap_init_protocol(ngx_event_t *rev);
void ngx_mail_imap_auth_state(ngx_event_t *rev);
ngx_int_t ngx_mail_imap_parse_command(ngx_mail_session_t *s);


extern ngx_module_t  ngx_mail_imap_module;


#endif /* _NGX_MAIL_IMAP_MODULE_H_INCLUDED_ */