Mercurial > hg > nginx-quic
view src/mail/ngx_mail_smtp_handler.c @ 8551:c35b255d80dc quic
HTTP/3: close connection on keepalive_requests * 2.
After receiving GOAWAY, client is not supposed to create new streams. However,
until client reads this frame, we allow it to create new streams, which are
gracefully rejected. To prevent client from abusing this algorithm, a new
limit is introduced. Upon reaching keepalive_requests * 2, server now closes
the entire QUIC connection claiming excessive load.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Thu, 29 Jul 2021 16:01:37 +0300 |
parents | da0a85e91587 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #include <ngx_mail.h> #include <ngx_mail_smtp_module.h> static void ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx); static void ngx_mail_smtp_resolve_name(ngx_event_t *rev); static void ngx_mail_smtp_resolve_name_handler(ngx_resolver_ctx_t *ctx); static void ngx_mail_smtp_block_reading(ngx_event_t *rev); static void ngx_mail_smtp_greeting(ngx_mail_session_t *s, ngx_connection_t *c); static void ngx_mail_smtp_invalid_pipelining(ngx_event_t *rev); static ngx_int_t ngx_mail_smtp_create_buffer(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_helo(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_auth(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_mail(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_starttls(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_rset(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_rcpt(ngx_mail_session_t *s, ngx_connection_t *c); static ngx_int_t ngx_mail_smtp_discard_command(ngx_mail_session_t *s, ngx_connection_t *c, char *err); static void ngx_mail_smtp_log_rejected_command(ngx_mail_session_t *s, ngx_connection_t *c, char *err); static u_char smtp_ok[] = "250 2.0.0 OK" CRLF; static u_char smtp_bye[] = "221 2.0.0 Bye" CRLF; static u_char smtp_starttls[] = "220 2.0.0 Start TLS" CRLF; static u_char smtp_next[] = "334 " CRLF; static u_char smtp_username[] = "334 VXNlcm5hbWU6" CRLF; static u_char smtp_password[] = "334 UGFzc3dvcmQ6" CRLF; static u_char smtp_invalid_command[] = "500 5.5.1 Invalid command" CRLF; static u_char smtp_invalid_pipelining[] = "503 5.5.0 Improper use of SMTP command pipelining" CRLF; static u_char smtp_invalid_argument[] = "501 5.5.4 Invalid argument" CRLF; static u_char smtp_auth_required[] = "530 5.7.1 Authentication required" CRLF; static u_char smtp_bad_sequence[] = "503 5.5.1 Bad sequence of commands" CRLF; static ngx_str_t smtp_unavailable = ngx_string("[UNAVAILABLE]"); static ngx_str_t smtp_tempunavail = ngx_string("[TEMPUNAVAIL]"); void ngx_mail_smtp_init_session(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_resolver_ctx_t *ctx; ngx_mail_core_srv_conf_t *cscf; cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module); if (cscf->resolver == NULL) { s->host = smtp_unavailable; ngx_mail_smtp_greeting(s, c); return; } #if (NGX_HAVE_UNIX_DOMAIN) if (c->sockaddr->sa_family == AF_UNIX) { s->host = smtp_tempunavail; ngx_mail_smtp_greeting(s, c); return; } #endif c->log->action = "in resolving client address"; ctx = ngx_resolve_start(cscf->resolver, NULL); if (ctx == NULL) { ngx_mail_close_connection(c); return; } ctx->addr.sockaddr = c->sockaddr; ctx->addr.socklen = c->socklen; ctx->handler = ngx_mail_smtp_resolve_addr_handler; ctx->data = s; ctx->timeout = cscf->resolver_timeout; s->resolver_ctx = ctx; c->read->handler = ngx_mail_smtp_block_reading; if (ngx_resolve_addr(ctx) != NGX_OK) { ngx_mail_close_connection(c); } } static void ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx) { ngx_connection_t *c; ngx_mail_session_t *s; s = ctx->data; c = s->connection; if (ctx->state) { ngx_log_error(NGX_LOG_ERR, c->log, 0, "%V could not be resolved (%i: %s)", &c->addr_text, ctx->state, ngx_resolver_strerror(ctx->state)); if (ctx->state == NGX_RESOLVE_NXDOMAIN) { s->host = smtp_unavailable; } else { s->host = smtp_tempunavail; } ngx_resolve_addr_done(ctx); ngx_mail_smtp_greeting(s, s->connection); return; } c->log->action = "in resolving client hostname"; s->host.data = ngx_pstrdup(c->pool, &ctx->name); if (s->host.data == NULL) { ngx_resolve_addr_done(ctx); ngx_mail_close_connection(c); return; } s->host.len = ctx->name.len; ngx_resolve_addr_done(ctx); ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0, "address resolved: %V", &s->host); c->read->handler = ngx_mail_smtp_resolve_name; ngx_post_event(c->read, &ngx_posted_events); } static void ngx_mail_smtp_resolve_name(ngx_event_t *rev) { ngx_connection_t *c; ngx_mail_session_t *s; ngx_resolver_ctx_t *ctx; ngx_mail_core_srv_conf_t *cscf; c = rev->data; s = c->data; cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module); ctx = ngx_resolve_start(cscf->resolver, NULL); if (ctx == NULL) { ngx_mail_close_connection(c); return; } ctx->name = s->host; ctx->handler = ngx_mail_smtp_resolve_name_handler; ctx->data = s; ctx->timeout = cscf->resolver_timeout; s->resolver_ctx = ctx; c->read->handler = ngx_mail_smtp_block_reading; if (ngx_resolve_name(ctx) != NGX_OK) { ngx_mail_close_connection(c); } } static void ngx_mail_smtp_resolve_name_handler(ngx_resolver_ctx_t *ctx) { ngx_uint_t i; ngx_connection_t *c; ngx_mail_session_t *s; s = ctx->data; c = s->connection; if (ctx->state) { ngx_log_error(NGX_LOG_ERR, c->log, 0, "\"%V\" could not be resolved (%i: %s)", &ctx->name, ctx->state, ngx_resolver_strerror(ctx->state)); if (ctx->state == NGX_RESOLVE_NXDOMAIN) { s->host = smtp_unavailable; } else { s->host = smtp_tempunavail; } } else { #if (NGX_DEBUG) { u_char text[NGX_SOCKADDR_STRLEN]; ngx_str_t addr; addr.data = text; for (i = 0; i < ctx->naddrs; i++) { addr.len = ngx_sock_ntop(ctx->addrs[i].sockaddr, ctx->addrs[i].socklen, text, NGX_SOCKADDR_STRLEN, 0); ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0, "name was resolved to %V", &addr); } } #endif for (i = 0; i < ctx->naddrs; i++) { if (ngx_cmp_sockaddr(ctx->addrs[i].sockaddr, ctx->addrs[i].socklen, c->sockaddr, c->socklen, 0) == NGX_OK) { goto found; } } s->host = smtp_unavailable; } found: ngx_resolve_name_done(ctx); ngx_mail_smtp_greeting(s, c); } static void ngx_mail_smtp_block_reading(ngx_event_t *rev) { ngx_connection_t *c; ngx_mail_session_t *s; ngx_resolver_ctx_t *ctx; c = rev->data; s = c->data; ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp reading blocked"); if (ngx_handle_read_event(rev, 0) != NGX_OK) { if (s->resolver_ctx) { ctx = s->resolver_ctx; if (ctx->handler == ngx_mail_smtp_resolve_addr_handler) { ngx_resolve_addr_done(ctx); } else if (ctx->handler == ngx_mail_smtp_resolve_name_handler) { ngx_resolve_name_done(ctx); } s->resolver_ctx = NULL; } ngx_mail_close_connection(c); } } static void ngx_mail_smtp_greeting(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_msec_t timeout; ngx_mail_core_srv_conf_t *cscf; ngx_mail_smtp_srv_conf_t *sscf; ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp greeting for \"%V\"", &s->host); cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module); sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); timeout = sscf->greeting_delay ? sscf->greeting_delay : cscf->timeout; ngx_add_timer(c->read, timeout); if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_close_connection(c); } if (c->read->ready) { ngx_post_event(c->read, &ngx_posted_events); } if (sscf->greeting_delay) { c->read->handler = ngx_mail_smtp_invalid_pipelining; return; } c->read->handler = ngx_mail_smtp_init_protocol; s->out = sscf->greeting; ngx_mail_send(c->write); } static void ngx_mail_smtp_invalid_pipelining(ngx_event_t *rev) { ngx_connection_t *c; ngx_mail_session_t *s; ngx_mail_core_srv_conf_t *cscf; ngx_mail_smtp_srv_conf_t *sscf; c = rev->data; s = c->data; c->log->action = "in delay pipelining state"; if (rev->timedout) { ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "delay greeting"); rev->timedout = 0; cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module); c->read->handler = ngx_mail_smtp_init_protocol; ngx_add_timer(c->read, cscf->timeout); if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_close_connection(c); return; } sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); s->out = sscf->greeting; } else { ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "invalid pipelining"); if (s->buffer == NULL) { if (ngx_mail_smtp_create_buffer(s, c) != NGX_OK) { return; } } if (ngx_mail_smtp_discard_command(s, c, "client was rejected before greeting: \"%V\"") != NGX_OK) { return; } ngx_str_set(&s->out, smtp_invalid_pipelining); s->quit = 1; } ngx_mail_send(c->write); } void ngx_mail_smtp_init_protocol(ngx_event_t *rev) { ngx_connection_t *c; ngx_mail_session_t *s; c = rev->data; c->log->action = "in auth state"; if (rev->timedout) { ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT, "client timed out"); c->timedout = 1; ngx_mail_close_connection(c); return; } s = c->data; if (s->buffer == NULL) { if (ngx_mail_smtp_create_buffer(s, c) != NGX_OK) { return; } } s->mail_state = ngx_smtp_start; c->read->handler = ngx_mail_smtp_auth_state; ngx_mail_smtp_auth_state(rev); } static ngx_int_t ngx_mail_smtp_create_buffer(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_mail_smtp_srv_conf_t *sscf; if (ngx_array_init(&s->args, c->pool, 2, sizeof(ngx_str_t)) == NGX_ERROR) { ngx_mail_session_internal_server_error(s); return NGX_ERROR; } sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); s->buffer = ngx_create_temp_buf(c->pool, sscf->client_buffer_size); if (s->buffer == NULL) { ngx_mail_session_internal_server_error(s); return NGX_ERROR; } return NGX_OK; } void ngx_mail_smtp_auth_state(ngx_event_t *rev) { ngx_int_t rc; ngx_connection_t *c; ngx_mail_session_t *s; c = rev->data; s = c->data; ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp auth state"); if (rev->timedout) { ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT, "client timed out"); c->timedout = 1; ngx_mail_close_connection(c); return; } if (s->out.len) { ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp send handler busy"); s->blocked = 1; if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_close_connection(c); return; } return; } s->blocked = 0; rc = ngx_mail_read_command(s, c); if (rc == NGX_AGAIN) { if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_session_internal_server_error(s); return; } return; } if (rc == NGX_ERROR) { return; } ngx_str_set(&s->out, smtp_ok); if (rc == NGX_OK) { switch (s->mail_state) { case ngx_smtp_start: switch (s->command) { case NGX_SMTP_HELO: case NGX_SMTP_EHLO: rc = ngx_mail_smtp_helo(s, c); break; case NGX_SMTP_AUTH: rc = ngx_mail_smtp_auth(s, c); break; case NGX_SMTP_QUIT: s->quit = 1; ngx_str_set(&s->out, smtp_bye); break; case NGX_SMTP_MAIL: rc = ngx_mail_smtp_mail(s, c); break; case NGX_SMTP_RCPT: rc = ngx_mail_smtp_rcpt(s, c); break; case NGX_SMTP_RSET: rc = ngx_mail_smtp_rset(s, c); break; case NGX_SMTP_NOOP: break; case NGX_SMTP_STARTTLS: rc = ngx_mail_smtp_starttls(s, c); ngx_str_set(&s->out, smtp_starttls); break; default: rc = NGX_MAIL_PARSE_INVALID_COMMAND; break; } break; case ngx_smtp_auth_login_username: rc = ngx_mail_auth_login_username(s, c, 0); ngx_str_set(&s->out, smtp_password); s->mail_state = ngx_smtp_auth_login_password; break; case ngx_smtp_auth_login_password: rc = ngx_mail_auth_login_password(s, c); break; case ngx_smtp_auth_plain: rc = ngx_mail_auth_plain(s, c, 0); break; case ngx_smtp_auth_cram_md5: rc = ngx_mail_auth_cram_md5(s, c); break; case ngx_smtp_auth_external: rc = ngx_mail_auth_external(s, c, 0); break; } } if (s->buffer->pos < s->buffer->last) { s->blocked = 1; } switch (rc) { case NGX_DONE: ngx_mail_auth(s, c); return; case NGX_ERROR: ngx_mail_session_internal_server_error(s); return; case NGX_MAIL_PARSE_INVALID_COMMAND: s->mail_state = ngx_smtp_start; s->state = 0; ngx_str_set(&s->out, smtp_invalid_command); /* fall through */ case NGX_OK: s->args.nelts = 0; if (s->buffer->pos == s->buffer->last) { s->buffer->pos = s->buffer->start; s->buffer->last = s->buffer->start; } if (s->state) { s->arg_start = s->buffer->pos; } if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_session_internal_server_error(s); return; } ngx_mail_send(c->write); } } static ngx_int_t ngx_mail_smtp_helo(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_str_t *arg; ngx_mail_smtp_srv_conf_t *sscf; if (s->args.nelts != 1) { ngx_str_set(&s->out, smtp_invalid_argument); s->state = 0; return NGX_OK; } arg = s->args.elts; s->smtp_helo.len = arg[0].len; s->smtp_helo.data = ngx_pnalloc(c->pool, arg[0].len); if (s->smtp_helo.data == NULL) { return NGX_ERROR; } ngx_memcpy(s->smtp_helo.data, arg[0].data, arg[0].len); ngx_str_null(&s->smtp_from); ngx_str_null(&s->smtp_to); sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); if (s->command == NGX_SMTP_HELO) { s->out = sscf->server_name; } else { s->esmtp = 1; #if (NGX_MAIL_SSL) if (c->ssl == NULL) { ngx_mail_ssl_conf_t *sslcf; sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module); if (sslcf->starttls == NGX_MAIL_STARTTLS_ON) { s->out = sscf->starttls_capability; return NGX_OK; } if (sslcf->starttls == NGX_MAIL_STARTTLS_ONLY) { s->out = sscf->starttls_only_capability; return NGX_OK; } } #endif s->out = sscf->capability; } return NGX_OK; } static ngx_int_t ngx_mail_smtp_auth(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_int_t rc; ngx_mail_core_srv_conf_t *cscf; ngx_mail_smtp_srv_conf_t *sscf; #if (NGX_MAIL_SSL) if (ngx_mail_starttls_only(s, c)) { return NGX_MAIL_PARSE_INVALID_COMMAND; } #endif if (s->args.nelts == 0) { ngx_str_set(&s->out, smtp_invalid_argument); s->state = 0; return NGX_OK; } sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); rc = ngx_mail_auth_parse(s, c); switch (rc) { case NGX_MAIL_AUTH_LOGIN: ngx_str_set(&s->out, smtp_username); s->mail_state = ngx_smtp_auth_login_username; return NGX_OK; case NGX_MAIL_AUTH_LOGIN_USERNAME: ngx_str_set(&s->out, smtp_password); s->mail_state = ngx_smtp_auth_login_password; return ngx_mail_auth_login_username(s, c, 1); case NGX_MAIL_AUTH_PLAIN: ngx_str_set(&s->out, smtp_next); s->mail_state = ngx_smtp_auth_plain; return NGX_OK; case NGX_MAIL_AUTH_CRAM_MD5: if (!(sscf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED)) { return NGX_MAIL_PARSE_INVALID_COMMAND; } if (s->salt.data == NULL) { cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module); if (ngx_mail_salt(s, c, cscf) != NGX_OK) { return NGX_ERROR; } } if (ngx_mail_auth_cram_md5_salt(s, c, "334 ", 4) == NGX_OK) { s->mail_state = ngx_smtp_auth_cram_md5; return NGX_OK; } return NGX_ERROR; case NGX_MAIL_AUTH_EXTERNAL: if (!(sscf->auth_methods & NGX_MAIL_AUTH_EXTERNAL_ENABLED)) { return NGX_MAIL_PARSE_INVALID_COMMAND; } ngx_str_set(&s->out, smtp_username); s->mail_state = ngx_smtp_auth_external; return NGX_OK; } return rc; } static ngx_int_t ngx_mail_smtp_mail(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_str_t *arg, cmd; ngx_mail_smtp_srv_conf_t *sscf; sscf = ngx_mail_get_module_srv_conf(s, ngx_mail_smtp_module); if (!(sscf->auth_methods & NGX_MAIL_AUTH_NONE_ENABLED)) { ngx_mail_smtp_log_rejected_command(s, c, "client was rejected: \"%V\""); ngx_str_set(&s->out, smtp_auth_required); return NGX_OK; } /* auth none */ if (s->smtp_from.len) { ngx_str_set(&s->out, smtp_bad_sequence); return NGX_OK; } if (s->args.nelts == 0) { ngx_str_set(&s->out, smtp_invalid_argument); return NGX_OK; } arg = s->args.elts; arg += s->args.nelts - 1; cmd.len = arg->data + arg->len - s->cmd.data; cmd.data = s->cmd.data; s->smtp_from.len = cmd.len; s->smtp_from.data = ngx_pnalloc(c->pool, cmd.len); if (s->smtp_from.data == NULL) { return NGX_ERROR; } ngx_memcpy(s->smtp_from.data, cmd.data, cmd.len); ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp mail from:\"%V\"", &s->smtp_from); ngx_str_set(&s->out, smtp_ok); return NGX_OK; } static ngx_int_t ngx_mail_smtp_rcpt(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_str_t *arg, cmd; if (s->smtp_from.len == 0) { ngx_str_set(&s->out, smtp_bad_sequence); return NGX_OK; } if (s->args.nelts == 0) { ngx_str_set(&s->out, smtp_invalid_argument); return NGX_OK; } arg = s->args.elts; arg += s->args.nelts - 1; cmd.len = arg->data + arg->len - s->cmd.data; cmd.data = s->cmd.data; s->smtp_to.len = cmd.len; s->smtp_to.data = ngx_pnalloc(c->pool, cmd.len); if (s->smtp_to.data == NULL) { return NGX_ERROR; } ngx_memcpy(s->smtp_to.data, cmd.data, cmd.len); ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0, "smtp rcpt to:\"%V\"", &s->smtp_to); s->auth_method = NGX_MAIL_AUTH_NONE; return NGX_DONE; } static ngx_int_t ngx_mail_smtp_rset(ngx_mail_session_t *s, ngx_connection_t *c) { ngx_str_null(&s->smtp_from); ngx_str_null(&s->smtp_to); ngx_str_set(&s->out, smtp_ok); return NGX_OK; } static ngx_int_t ngx_mail_smtp_starttls(ngx_mail_session_t *s, ngx_connection_t *c) { #if (NGX_MAIL_SSL) ngx_mail_ssl_conf_t *sslcf; if (c->ssl == NULL) { sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module); if (sslcf->starttls) { /* * RFC3207 requires us to discard any knowledge * obtained from client before STARTTLS. */ ngx_str_null(&s->smtp_helo); ngx_str_null(&s->smtp_from); ngx_str_null(&s->smtp_to); s->buffer->pos = s->buffer->start; s->buffer->last = s->buffer->start; c->read->handler = ngx_mail_starttls_handler; return NGX_OK; } } #endif return NGX_MAIL_PARSE_INVALID_COMMAND; } static ngx_int_t ngx_mail_smtp_discard_command(ngx_mail_session_t *s, ngx_connection_t *c, char *err) { ssize_t n; n = c->recv(c, s->buffer->last, s->buffer->end - s->buffer->last); if (n == NGX_ERROR || n == 0) { ngx_mail_close_connection(c); return NGX_ERROR; } if (n > 0) { s->buffer->last += n; } if (n == NGX_AGAIN) { if (ngx_handle_read_event(c->read, 0) != NGX_OK) { ngx_mail_session_internal_server_error(s); return NGX_ERROR; } return NGX_AGAIN; } ngx_mail_smtp_log_rejected_command(s, c, err); s->buffer->pos = s->buffer->start; s->buffer->last = s->buffer->start; return NGX_OK; } static void ngx_mail_smtp_log_rejected_command(ngx_mail_session_t *s, ngx_connection_t *c, char *err) { u_char ch; ngx_str_t cmd; ngx_uint_t i; if (c->log->log_level < NGX_LOG_INFO) { return; } cmd.len = s->buffer->last - s->buffer->start; cmd.data = s->buffer->start; for (i = 0; i < cmd.len; i++) { ch = cmd.data[i]; if (ch != CR && ch != LF) { continue; } cmd.data[i] = '_'; } cmd.len = i; ngx_log_error(NGX_LOG_INFO, c->log, 0, err, &cmd); }