# HG changeset patch
# User Roman Arutyunyan <arut@nginx.com>
# Date 1643611590 -10800
# Mon Jan 31 09:46:30 2022 +0300
# Branch quic
# Node ID 3436b441239b494e6f63db3b8d26a71682b4f106
# Parent b42a041d23a2226ec6def395bd0b084889b85473
HTTP/3: proper uni stream closure detection.

Previously, closure detection for server-initiated uni streams was not properly
implemented. Instead, HTTP/3 code relied on QUIC code posting the read event
and setting rev->error when it needed to close the stream. Then, regular
uni stream read handler called c->recv() and received error, which closed the
stream. This was an ad-hoc solution. If, for whatever reason, the read
handler was called earlier, c->recv() would return 0, which would also close
the stream.

Now server-initiated uni streams have a separate read event handler for
tracking stream closure. The handler calls c->recv(), which normally returns
0, but may return error in case of closure.

diff --git a/src/http/v3/ngx_http_v3_uni.c b/src/http/v3/ngx_http_v3_uni.c
--- a/src/http/v3/ngx_http_v3_uni.c
+++ b/src/http/v3/ngx_http_v3_uni.c
@@ -26,7 +26,8 @@ typedef struct {

static void ngx_http_v3_close_uni_stream(ngx_connection_t *c);
static void ngx_http_v3_uni_read_handler(ngx_event_t *rev);
-static void ngx_http_v3_dummy_write_handler(ngx_event_t *wev);
+static void ngx_http_v3_uni_dummy_read_handler(ngx_event_t *wev);
+static void ngx_http_v3_uni_dummy_write_handler(ngx_event_t *wev);
static void ngx_http_v3_push_cleanup(void *data);
static ngx_connection_t *ngx_http_v3_get_uni_stream(ngx_connection_t *c,
ngx_uint_t type);
@@ -68,7 +69,7 @@ ngx_http_v3_init_uni_stream(ngx_connecti
c->data = us;

c->read->handler = ngx_http_v3_uni_read_handler;
- c->write->handler = ngx_http_v3_dummy_write_handler;
+ c->write->handler = ngx_http_v3_uni_dummy_write_handler;

ngx_http_v3_uni_read_handler(c->read);
}
@@ -252,7 +253,33 @@ failed:


static void
-ngx_http_v3_dummy_write_handler(ngx_event_t *wev)
+ngx_http_v3_uni_dummy_read_handler(ngx_event_t *rev)
+{
+ u_char ch;
+ ngx_connection_t *c;
+
+ c = rev->data;
+
+ ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "http3 dummy read handler");
+
+ if (rev->ready) {
+ if (c->recv(c, &ch, 1) != 0) {
+ ngx_http_v3_finalize_connection(c, NGX_HTTP_V3_ERR_NO_ERROR, NULL);
+ ngx_http_v3_close_uni_stream(c);
+ return;
+ }
+ }
+
+ if (ngx_handle_read_event(rev, 0) != NGX_OK) {
+ ngx_http_v3_finalize_connection(c, NGX_HTTP_V3_ERR_INTERNAL_ERROR,
+ NULL);
+ ngx_http_v3_close_uni_stream(c);
+ }
+}
+
+
+static void
+ngx_http_v3_uni_dummy_write_handler(ngx_event_t *wev)
{
ngx_connection_t *c;

@@ -393,8 +420,8 @@ ngx_http_v3_get_uni_stream(ngx_connectio

sc->data = us;

- sc->read->handler = ngx_http_v3_uni_read_handler;
- sc->write->handler = ngx_http_v3_dummy_write_handler;
+ sc->read->handler = ngx_http_v3_uni_dummy_read_handler;
+ sc->write->handler = ngx_http_v3_uni_dummy_write_handler;

if (index >= 0) {
h3c->known_streams[index] = sc;
@@ -409,6 +436,8 @@ ngx_http_v3_get_uni_stream(ngx_connectio
goto failed;
}

+ ngx_post_event(sc->read, &ngx_posted_events);
+
return sc;

failed:
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