> On 18 Jan 2024, at 23:44, Maxim Dounin <mdounin@mdounin.ru> wrote:
>
> Hello!
>
> On Thu, Jan 18, 2024 at 08:15:33PM +0400, Sergey Kandaurov wrote:
>
>> On Thu, Jan 18, 2024 at 07:06:06PM +0400, Roman Arutyunyan wrote:
>>> Hi,
>>>
>>> # HG changeset patch
>>> # User Roman Arutyunyan <arut@nginx.com>
>>> # Date 1702476295 -14400
>>> # Wed Dec 13 18:04:55 2023 +0400
>>> # Node ID 7324e8e73595c3093fcc2cbd2b5d6b1a947be3b0
>>> # Parent ee40e2b1d0833b46128a357fbc84c6e23be9be07
>>> Stream: socket peek in preread phase.
>>>
>>> Previously, preread buffer was always read out from socket, which made it
>>> impossible to terminate SSL on the connection without introducing additional
>>> SSL BIOs. The following patches will rely on this.
>>>
>>> Now, when possible, recv(MSG_PEEK) is used instead, which keeps data in socket.
>>> It's called if SSL is not already terminated and if an egde-triggered event
>>> method is used. For epoll, EPOLLRDHUP support is also required.
>>>
>>> diff --git a/src/stream/ngx_stream_core_module.c b/src/stream/ngx_stream_core_module.c
>>> --- a/src/stream/ngx_stream_core_module.c
>>> +++ b/src/stream/ngx_stream_core_module.c
>>> @@ -10,6 +10,11 @@
>>> #include <ngx_stream.h>
>>>
>>>
>>> +static ngx_uint_t ngx_stream_preread_can_peek(ngx_connection_t *c);
>>> +static ngx_int_t ngx_stream_preread_peek(ngx_stream_session_t *s,
>>> + ngx_stream_phase_handler_t *ph);
>>> +static ngx_int_t ngx_stream_preread(ngx_stream_session_t *s,
>>> + ngx_stream_phase_handler_t *ph);
>>> static ngx_int_t ngx_stream_core_preconfiguration(ngx_conf_t *cf);
>>> static void *ngx_stream_core_create_main_conf(ngx_conf_t *cf);
>>> static char *ngx_stream_core_init_main_conf(ngx_conf_t *cf, void *conf);
>>> @@ -203,8 +208,6 @@ ngx_int_t
>>> ngx_stream_core_preread_phase(ngx_stream_session_t *s,
>>> ngx_stream_phase_handler_t *ph)
>>> {
>>> - size_t size;
>>> - ssize_t n;
>>> ngx_int_t rc;
>>> ngx_connection_t *c;
>>> ngx_stream_core_srv_conf_t *cscf;
>>> @@ -217,56 +220,33 @@ ngx_stream_core_preread_phase(ngx_stream
>>>
>>> if (c->read->timedout) {
>>> rc = NGX_STREAM_OK;
>>> + goto done;
>>> + }
>>>
>>> - } else if (c->read->timer_set) {
>>> - rc = NGX_AGAIN;
>>> + if (!c->read->timer_set) {
>>> + rc = ph->handler(s);
>>>
>>> - } else {
>>> - rc = ph->handler(s);
>>> + if (rc != NGX_AGAIN) {
>>> + goto done;
>>> + }
>>> }
>>>
>>> - while (rc == NGX_AGAIN) {
>>> -
>>> + if (c->buffer == NULL) {
>>> + c->buffer = ngx_create_temp_buf(c->pool, cscf->preread_buffer_size);
>>> if (c->buffer == NULL) {
>>> - c->buffer = ngx_create_temp_buf(c->pool, cscf->preread_buffer_size);
>>> - if (c->buffer == NULL) {
>>> - rc = NGX_ERROR;
>>> - break;
>>> - }
>>> + rc = NGX_ERROR;
>>> + goto done;
>>> }
>>> -
>>> - size = c->buffer->end - c->buffer->last;
>>> -
>>> - if (size == 0) {
>>> - ngx_log_error(NGX_LOG_ERR, c->log, 0, "preread buffer full");
>>> - rc = NGX_STREAM_BAD_REQUEST;
>>> - break;
>>> - }
>>> + }
>>>
>>> - if (c->read->eof) {
>>> - rc = NGX_STREAM_OK;
>>> - break;
>>> - }
>>> -
>>> - if (!c->read->ready) {
>>> - break;
>>> - }
>>> -
>>> - n = c->recv(c, c->buffer->last, size);
>>> + if (ngx_stream_preread_can_peek(c)) {
>>> + rc = ngx_stream_preread_peek(s, ph);
>>>
>>> - if (n == NGX_ERROR || n == 0) {
>>> - rc = NGX_STREAM_OK;
>>> - break;
>>> - }
>>> + } else {
>>> + rc = ngx_stream_preread(s, ph);
>>> + }
>>>
>>> - if (n == NGX_AGAIN) {
>>> - break;
>>> - }
>>> -
>>> - c->buffer->last += n;
>>> -
>>> - rc = ph->handler(s);
>>> - }
>>> +done:
>>>
>>> if (rc == NGX_AGAIN) {
>>> if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
>>> @@ -311,6 +291,129 @@ ngx_stream_core_preread_phase(ngx_stream
>>> }
>>>
>>>
>>> +static ngx_uint_t
>>> +ngx_stream_preread_can_peek(ngx_connection_t *c)
>>> +{
>>> +#if (NGX_STREAM_SSL)
>>> + if (c->ssl) {
>>> + return 0;
>>> + }
>>> +#endif
>>> +
>>> + if ((ngx_event_flags & NGX_USE_CLEAR_EVENT) == 0) {
>>> + return 0;
>>> + }
>>> +
>>> +#if (NGX_HAVE_KQUEUE)
>>> + if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
>>> + return 1;
>>> + }
>>> +#endif
>>> +
>>> +#if (NGX_HAVE_EPOLLRDHUP)
>>> + if ((ngx_event_flags & NGX_USE_EPOLL_EVENT) && ngx_use_epoll_rdhup) {
>>> + return 1;
>>> + }
>>> +#endif
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +
>>> +static ngx_int_t
>>> +ngx_stream_preread_peek(ngx_stream_session_t *s, ngx_stream_phase_handler_t *ph)
>>> +{
>>> + ssize_t n;
>>> + ngx_int_t rc;
>>> + ngx_err_t err;
>>> + ngx_connection_t *c;
>>> +
>>> + c = s->connection;
>>> +
>>> + n = recv(c->fd, (char *) c->buffer->last,
>>> + c->buffer->end - c->buffer->last, MSG_PEEK);
>>> +
>>> + err = ngx_socket_errno;
>>> +
>>> + ngx_log_debug1(NGX_LOG_DEBUG_STREAM, c->log, 0, "stream recv(): %z", n);
>>> +
>>> + if (n == -1) {
>>> + if (err == NGX_EAGAIN) {
>>> + c->read->ready = 0;
>>> + return NGX_AGAIN;
>>> + }
>>> +
>>> + ngx_connection_error(c, err, "recv() failed");
>>> + return NGX_STREAM_OK;
>>> + }
>>> +
>>> + if (n == 0) {
>>> + return NGX_STREAM_OK;
>>> + }
>>> +
>>> + c->buffer->last += n;
>>> +
>>> + rc = ph->handler(s);
>>> +
>>> + if (rc != NGX_AGAIN) {
>>> + c->buffer->last = c->buffer->pos;
>>> + return rc;
>>> + }
>>> +
>>> + if (c->buffer->last == c->buffer->end) {
>>> + ngx_log_error(NGX_LOG_ERR, c->log, 0, "preread buffer full");
>>> + return NGX_STREAM_BAD_REQUEST;
>>> + }
>>> +
>>> + if (c->read->pending_eof) {
>>> + return NGX_STREAM_OK;
>>> + }
>>> +
>>> + c->buffer->last = c->buffer->pos;
>>> +
>>> + return NGX_AGAIN;
>>> +}
>>> +
>>> +
>>> +static ngx_int_t
>>> +ngx_stream_preread(ngx_stream_session_t *s, ngx_stream_phase_handler_t *ph)
>>> +{
>>> + ssize_t n;
>>> + ngx_int_t rc;
>>> + ngx_connection_t *c;
>>> +
>>> + c = s->connection;
>>> +
>>> + while (c->read->ready) {
>>> +
>>> + n = c->recv(c, c->buffer->last, c->buffer->end - c->buffer->last);
>>> +
>>> + if (n == NGX_AGAIN) {
>>> + return NGX_AGAIN;
>>> + }
>>> +
>>> + if (n == NGX_ERROR || n == 0) {
>>> + return NGX_STREAM_OK;
>>> + }
>>> +
>>> + c->buffer->last += n;
>>> +
>>> + rc = ph->handler(s);
>>> +
>>> + if (rc != NGX_AGAIN) {
>>> + return rc;
>>> + }
>>> +
>>> + if (c->buffer->last == c->buffer->end) {
>>> + ngx_log_error(NGX_LOG_ERR, c->log, 0, "preread buffer full");
>>> + return NGX_STREAM_BAD_REQUEST;
>>> + }
>>> + }
>>> +
>>> + return NGX_AGAIN;
>>> +}
>>> +
>>> +
>>> ngx_int_t
>>> ngx_stream_core_content_phase(ngx_stream_session_t *s,
>>> ngx_stream_phase_handler_t *ph)
>>
>> Looks good.
>
> I'm somewhat sceptical about the idea of functionality which
> depends on the edge-triggered event methods being available.
>

We discussed this with Roman days back:
https://mailman.nginx.org/pipermail/nginx-devel/2023-December/O6XC56D5BPSE6F45IZSRYEKOSGL3VVYB.html

> If/when the patch series is reviewed, please make sure it gets my
> approval before commit.
>

You're welcome to participate.

--
Sergey Kandaurov
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