QUIC: fixed unsent MTU probe acknowledgement. Previously if an MTU probe send failed early in ngx_quic_frame_sendto() due to allocation error or congestion control, the application level packet number was not increased, but was still saved as MTU probe packet number. Later when a packet with this number was acknowledged, the unsent MTU probe was acknowledged as well. This could result in discovering a bigger MTU than supported by the path, which could lead to EMSGSIZE (Message too long) errors while sending further packets. The problem existed since PMTUD was introduced in 58afcd72446f (1.25.2). Back then only the unlikely memory allocation error could trigger it. However in efcdaa66df2e congestion control was added to ngx_quic_frame_sendto() which can now trigger the issue with a higher probability.

/*
 * 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_ */