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.

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

--
Maxim Dounin
http://mdounin.ru/
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