Mailing List Archive

Author: icing
Date: Sat Jul 2 09:39:22 2022
New Revision: 1902409

URL: http://svn.apache.org/viewvc?rev=1902409&view=rev
Log:
*) mod_http2: fixed trailer handling. Empty response bodies
prevented trailers from being sent to a client. See
<https://github.com/icing/mod_h2/issues/233> for how
this affected gRPC use.


Added:
httpd/httpd/trunk/changes-entries/h2_trailers.txt
Modified:
httpd/httpd/trunk/modules/http2/h2_stream.c
httpd/httpd/trunk/modules/http2/h2_stream.h

Added: httpd/httpd/trunk/changes-entries/h2_trailers.txt
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/changes-entries/h2_trailers.txt?rev=1902409&view=auto
==============================================================================
--- httpd/httpd/trunk/changes-entries/h2_trailers.txt (added)
+++ httpd/httpd/trunk/changes-entries/h2_trailers.txt Sat Jul 2 09:39:22 2022
@@ -0,0 +1,5 @@
+ *) mod_http2: fixed trailer handling. Empty response bodies
+ prevented trailers from being sent to a client. See
+ <https://github.com/icing/mod_h2/issues/233> for how
+ this affected gRPC use.
+ [Stefan Eissing]
\ No newline at end of file

Modified: httpd/httpd/trunk/modules/http2/h2_stream.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/http2/h2_stream.c?rev=1902409&r1=1902408&r2=1902409&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/http2/h2_stream.c (original)
+++ httpd/httpd/trunk/modules/http2/h2_stream.c Sat Jul 2 09:39:22 2022
@@ -942,8 +942,10 @@ static apr_status_t buffer_output_receiv
rv = h2_beam_receive(stream->output, stream->session->c1, stream->out_buffer,
APR_NONBLOCK_READ, stream->session->max_stream_mem - buf_len);
if (APR_SUCCESS != rv) {
- ap_log_cerror(APLOG_MARK, APLOG_TRACE1, rv, c1,
- H2_STRM_MSG(stream, "out_buffer, receive unsuccessful"));
+ if (APR_EAGAIN != rv) {
+ ap_log_cerror(APLOG_MARK, APLOG_TRACE1, rv, c1,
+ H2_STRM_MSG(stream, "out_buffer, receive unsuccessful"));
+ }
goto cleanup;
}
}
@@ -1121,7 +1123,10 @@ static apr_status_t buffer_output_proces
is_empty = 0;
while (b != APR_BRIGADE_SENTINEL(stream->out_buffer)) {
if (APR_BUCKET_IS_METADATA(b)) {
- if (APR_BUCKET_IS_EOS(b)) {
+ if (AP_BUCKET_IS_HEADERS(b)) {
+ break;
+ }
+ else if (APR_BUCKET_IS_EOS(b)) {
is_empty = 1;
break;
}
@@ -1311,13 +1316,13 @@ apr_status_t h2_stream_in_consumed(h2_st
return APR_SUCCESS;
}

-static apr_off_t output_data_buffered(h2_stream *stream, int *peos)
+static apr_off_t output_data_buffered(h2_stream *stream, int *peos, int *pheader_blocked)
{
/* How much data do we have in our buffers that we can write? */
apr_off_t buf_len = 0;
apr_bucket *b;

- *peos = 0;
+ *peos = *pheader_blocked = 0;
if (stream->out_buffer) {
b = APR_BRIGADE_FIRST(stream->out_buffer);
while (b != APR_BRIGADE_SENTINEL(stream->out_buffer)) {
@@ -1330,6 +1335,7 @@ static apr_off_t output_data_buffered(h2
break;
}
else if (AP_BUCKET_IS_HEADERS(b)) {
+ *pheader_blocked = 1;
break;
}
}
@@ -1353,7 +1359,7 @@ static ssize_t stream_data_cb(nghttp2_se
h2_session *session = (h2_session *)puser;
conn_rec *c1 = session->c1;
apr_off_t buf_len;
- int eos;
+ int eos, header_blocked;
apr_status_t rv;
h2_stream *stream;

@@ -1406,60 +1412,81 @@ static ssize_t stream_data_cb(nghttp2_se
}

/* How much data do we have in our buffers that we can write? */
- buf_len = output_data_buffered(stream, &eos);
- if (buf_len < length && !eos) {
+check_and_receive:
+ buf_len = output_data_buffered(stream, &eos, &header_blocked);
+ while (buf_len < length && !eos && !header_blocked) {
/* read more? */
ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c1,
H2_SSSN_STRM_MSG(session, stream_id,
"need more (read len=%ld, %ld in buffer)"),
(long)length, (long)buf_len);
rv = buffer_output_receive(stream);
- /* process all headers sitting at the buffer head. */
- while (APR_SUCCESS == rv && !eos && !stream->sent_trailers) {
- rv = buffer_output_process_headers(stream);
- if (APR_SUCCESS != rv && APR_EAGAIN != rv) {
- ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, c1,
- H2_STRM_LOG(APLOGNO(10300), stream,
- "data_cb, error processing headers"));
- return NGHTTP2_ERR_CALLBACK_FAILURE;
- }
- buf_len = output_data_buffered(stream, &eos);
+ if (APR_EOF == rv) {
+ eos = 1;
+ rv = APR_SUCCESS;
}

- if (APR_SUCCESS != rv && !APR_STATUS_IS_EAGAIN(rv)) {
+ if (APR_SUCCESS == rv) {
+ /* re-assess */
+ buf_len = output_data_buffered(stream, &eos, &header_blocked);
+ }
+ else if (APR_STATUS_IS_EAGAIN(rv)) {
+ /* currently, no more is available */
+ break;
+ }
+ else if (APR_SUCCESS != rv) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, c1,
H2_STRM_LOG(APLOGNO(02938), stream, "data_cb, reading data"));
return NGHTTP2_ERR_CALLBACK_FAILURE;
}
+ }

- if (stream->sent_trailers) {
- AP_DEBUG_ASSERT(eos);
- AP_DEBUG_ASSERT(buf_len == 0);
- return NGHTTP2_ERR_DEFERRED;
+ if (buf_len == 0 && header_blocked) {
+ /* we are blocked from having data to send by a HEADER bucket sitting
+ * at buffer start. Send it and check again what DATA we can send. */
+ rv = buffer_output_process_headers(stream);
+ if (APR_SUCCESS == rv) {
+ goto check_and_receive;
+ }
+ else if (APR_STATUS_IS_EAGAIN(rv)) {
+ /* unable to send the HEADER at this time. */
+ eos = 0;
+ goto cleanup;
+ }
+ else {
+ ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, c1,
+ H2_STRM_LOG(APLOGNO(10300), stream,
+ "data_cb, error processing headers"));
+ return NGHTTP2_ERR_CALLBACK_FAILURE;
}
}

if (buf_len > (apr_off_t)length) {
- eos = 0;
+ eos = 0; /* Any EOS we have in the buffer does not apply yet */
}
else {
length = (size_t)buf_len;
}
+
+ if (stream->sent_trailers) {
+ /* We already sent trailers and will/can not send more DATA. */
+ eos = 0;
+ }
+
if (length) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c1,
H2_STRM_MSG(stream, "data_cb, sending len=%ld, eos=%d"),
(long)length, eos);
*data_flags |= NGHTTP2_DATA_FLAG_NO_COPY;
}
- else if (!eos) {
- /* no data available and output is not closed, need to suspend */
+ else if (!eos && !stream->sent_trailers) {
+ /* We have not reached the end of DATA yet, DEFER sending */
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c1,
H2_STRM_LOG(APLOGNO(03071), stream, "data_cb, suspending"));
- ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, c1,
- H2_SSSN_STRM_MSG(session, stream_id, "suspending"));
return NGHTTP2_ERR_DEFERRED;
}

+cleanup:
if (eos) {
*data_flags |= NGHTTP2_DATA_FLAG_EOF;
}
@@ -1502,7 +1529,7 @@ apr_status_t h2_stream_read_output(h2_st
}

rv = buffer_output_receive(stream);
- if (APR_SUCCESS != rv) goto cleanup;
+ if (APR_SUCCESS != rv && APR_EAGAIN != rv) goto cleanup;

/* process all headers sitting at the buffer head. */
while (1) {

Modified: httpd/httpd/trunk/modules/http2/h2_stream.h
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/http2/h2_stream.h?rev=1902409&r1=1902408&r2=1902409&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/http2/h2_stream.h (original)
+++ httpd/httpd/trunk/modules/http2/h2_stream.h Sat Jul 2 09:39:22 2022
@@ -80,14 +80,14 @@ struct h2_stream {

struct h2_bucket_beam *output;
apr_bucket_brigade *out_buffer;
- unsigned int output_eos : 1; /* output EOS in buffer/sent */
- unsigned int sent_trailers : 1; /* trailers have been submitted */

int rst_error; /* stream error for RST_STREAM */
unsigned int aborted : 1; /* was aborted */
unsigned int scheduled : 1; /* stream has been scheduled */
unsigned int input_closed : 1; /* no more request data/trailers coming */
unsigned int push_policy; /* which push policy to use for this request */
+ unsigned int sent_trailers : 1; /* trailers have been submitted */
+ unsigned int output_eos : 1; /* output EOS in buffer/sent */

conn_rec *c2; /* connection processing stream */