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Make HTTP_IN filter send 100 continue in blocking mode only.

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When mod_proxy_http prefetches input data it calls the HTTP_IN filter
in nonblocking mode, but since it does not want 100 continue to be sent
for every case (e.g. 100-continue forwarding), it hacks r->expecting_100
(save in req->expecting_100, reset, eventually restore..) all over the
place.

Let's avoid this by making the HTTP_IN filter send 100 continue only
when called in blocking mode (once still), instead of the first time
it's called.

* modules/http/http_filters.c (struct http_filter_ctx): Add the seen_data
  bit and rename eos_sent to at_eos (HTTP_IN does not send any EOS).

* modules/http/http_filters.c (ap_http_filter): Move 100 continue
  handling outside the initialization/once block, and do it in blocking
  mode only. Track in ctx->seen_data whether some data were already
  received, and if so don't send 100 continue per RFC 7231 5.1.1.

* modules/proxy/mod_proxy_http.c: Remove req->expecting_100 (and its
  danse with r->expecting_100) now that reading from the input filters
  does the right thing.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1883639 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Yann Ylavic
2020-11-19 12:12:04 +00:00
parent 7fb5cc1c73
commit 7c220fc675
2 changed files with 49 additions and 91 deletions
Download Patch File Download Diff File Expand all files Collapse all files

75
modules/http/http_filters.c
View File

@@ -79,7 +79,8 @@ typedef struct http_filter_ctx
BODY_CHUNK_END_LF, /* got CR after data, expect LF */
BODY_CHUNK_TRAILER /* trailers */
} state;
unsigned int eos_sent :1;
unsigned int at_eos:1,
seen_data:1;
} http_ctx_t;
/**
@@ -270,7 +271,7 @@ static apr_status_t read_chunked_trailers(http_ctx_t *ctx, ap_filter_t *f,
r->status = saved_status;
e = apr_bucket_eos_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(b, e);
ctx->eos_sent = 1;
ctx->at_eos = 1;
rv = APR_SUCCESS;
}
else {
@@ -402,53 +403,52 @@ apr_status_t ap_http_filter(ap_filter_t *f, apr_bucket_brigade *b,
* proxied *response*, proxy responses MUST be exempt.
*/
if (ctx->state == BODY_NONE && f->r->proxyreq != PROXYREQ_RESPONSE) {
e = apr_bucket_eos_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(b, e);
ctx->eos_sent = 1;
return APR_SUCCESS;
ctx->at_eos = 1; /* send EOS below */
}
}
{
/* Since we're about to read data, send 100-Continue if needed.
* Only valid on chunked and C-L bodies where the C-L is > 0. */
if ((ctx->state == BODY_CHUNK
* Only valid on chunked and C-L bodies where the C-L is > 0.
*
* If the read is to be nonblocking though, the caller may not want to
* handle this just now (e.g. mod_proxy_http), and is prepared to read
* nothing if the client really waits for 100 continue, so we don't
* send it now and wait for later blocking read.
*
* In any case, even if r->expecting remains set at the end of the
* request handling, ap_set_keepalive() will finally do the right
* thing (i.e. "Connection: close" the connection).
*/
if (block == APR_BLOCK_READ
&& (ctx->state == BODY_CHUNK
|| (ctx->state == BODY_LENGTH && ctx->remaining > 0))
&& f->r->expecting_100 && f->r->proto_num >= HTTP_VERSION(1,1)
&& !(f->r->eos_sent || f->r->bytes_sent)) {
&& !(ctx->at_eos || f->r->eos_sent || f->r->bytes_sent)) {
if (!ap_is_HTTP_SUCCESS(f->r->status)) {
ctx->state = BODY_NONE;
ctx->eos_sent = 1;
ctx->at_eos = 1; /* send EOS below */
}
else if (!ctx->seen_data) {
int saved_status = f->r->status;
f->r->status = HTTP_CONTINUE;
ap_send_interim_response(f->r, 0);
AP_DEBUG_ASSERT(!f->r->expecting_100);
f->r->status = saved_status;
}
else {
char *tmp;
int len;
apr_bucket_brigade *bb;
bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);
/* if we send an interim response, we're no longer
* in a state of expecting one.
/* https://tools.ietf.org/html/rfc7231#section-5.1.1
* A server MAY omit sending a 100 (Continue) response if it
* has already received some or all of the message body for
* the corresponding request [...]
*/
f->r->expecting_100 = 0;
tmp = apr_pstrcat(f->r->pool, AP_SERVER_PROTOCOL " ",
ap_get_status_line(HTTP_CONTINUE), CRLF CRLF, NULL);
len = strlen(tmp);
ap_xlate_proto_to_ascii(tmp, len);
e = apr_bucket_pool_create(tmp, len, f->r->pool,
f->c->bucket_alloc);
APR_BRIGADE_INSERT_HEAD(bb, e);
e = apr_bucket_flush_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(bb, e);
rv = ap_pass_brigade(f->c->output_filters, bb);
if (rv != APR_SUCCESS) {
return AP_FILTER_ERROR;
}
}
}
}
/* sanity check in case we're read twice */
if (ctx->eos_sent) {
if (ctx->at_eos) {
e = apr_bucket_eos_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(b, e);
return APR_SUCCESS;
@@ -492,8 +492,10 @@ apr_status_t ap_http_filter(ap_filter_t *f, apr_bucket_brigade *b,
if (!APR_BUCKET_IS_METADATA(e)) {
rv = apr_bucket_read(e, &buffer, &len, APR_BLOCK_READ);
if (rv == APR_SUCCESS) {
if (len > 0) {
ctx->seen_data = 1;
}
rv = parse_chunk_size(ctx, buffer, len,
f->r->server->limit_req_fieldsize, strict);
}
@@ -549,6 +551,9 @@ apr_status_t ap_http_filter(ap_filter_t *f, apr_bucket_brigade *b,
/* How many bytes did we just read? */
apr_brigade_length(b, 0, &totalread);
if (totalread > 0) {
ctx->seen_data = 1;
}
/* If this happens, we have a bucket of unknown length. Die because
* it means our assumptions have changed. */
@@ -595,7 +600,7 @@ apr_status_t ap_http_filter(ap_filter_t *f, apr_bucket_brigade *b,
if (ctx->state == BODY_LENGTH && ctx->remaining == 0) {
e = apr_bucket_eos_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(b, e);
ctx->eos_sent = 1;
ctx->at_eos = 1;
}
break;

63
modules/proxy/mod_proxy_http.c
View File

@@ -259,7 +259,6 @@ typedef struct {
apr_interval_time_t idle_timeout;
unsigned int can_go_async :1,
expecting_100 :1,
do_100_continue :1,
prefetch_nonblocking :1,
force10 :1;
@@ -531,21 +530,6 @@ static int spool_reqbody_cl(proxy_http_req_t *req, apr_off_t *bytes_spooled)
apr_file_t *tmpfile = NULL;
apr_off_t limit;
/* Send "100 Continue" now if the client expects one, before
* blocking on the body, otherwise we'd wait for each other.
*/
if (req->expecting_100) {
int saved_status = r->status;
r->expecting_100 = 1;
r->status = HTTP_CONTINUE;
ap_send_interim_response(r, 0);
AP_DEBUG_ASSERT(!r->expecting_100);
r->status = saved_status;
req->expecting_100 = 0;
}
body_brigade = apr_brigade_create(p, bucket_alloc);
*bytes_spooled = 0;
@@ -719,7 +703,7 @@ static int ap_proxy_http_prefetch(proxy_http_req_t *req,
apr_read_type_e block;
int rv;
if (req->force10 && req->expecting_100) {
if (req->force10 && r->expecting_100) {
return HTTP_EXPECTATION_FAILED;
}
@@ -821,18 +805,6 @@ static int ap_proxy_http_prefetch(proxy_http_req_t *req,
apr_brigade_length(temp_brigade, 1, &bytes);
bytes_read += bytes;
/* From https://tools.ietf.org/html/rfc7231#section-5.1.1
* A server MAY omit sending a 100 (Continue) response if it has
* already received some or all of the message body for the
* corresponding request, or if [snip].
*/
if (req->expecting_100 && bytes > 0) {
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, status, r, APLOGNO(10206)
"prefetching request body while 100-continue is"
"expected, omit sending interim response");
req->expecting_100 = 0;
}
/*
* Save temp_brigade in input_brigade. (At least) in the SSL case
* temp_brigade contains transient buckets whose data would get
@@ -1629,8 +1601,9 @@ int ap_proxy_http_process_response(proxy_http_req_t *req)
*
* So let's make it configurable.
*
* We need to set "r->expecting_100 = 1" otherwise origin
* server behaviour will apply.
* We need to force "r->expecting_100 = 1" for RFC behaviour
* otherwise ap_send_interim_response() does nothing when
* the client did not ask for 100-continue.
*
* 101 Switching Protocol has its own configuration which
* shouldn't be interfered by "proxy-interim-response".
@@ -1645,12 +1618,8 @@ int ap_proxy_http_process_response(proxy_http_req_t *req)
if (!policy
|| (!strcasecmp(policy, "RFC")
&& (proxy_status != HTTP_CONTINUE
|| (req->expecting_100 = 1)))) {
|| (r->expecting_100 = 1)))) {
switch (proxy_status) {
case HTTP_CONTINUE:
r->expecting_100 = req->expecting_100;
req->expecting_100 = 0;
break;
case HTTP_SWITCHING_PROTOCOLS:
AP_DEBUG_ASSERT(upgrade != NULL);
apr_table_setn(r->headers_out, "Connection", "Upgrade");
@@ -1723,12 +1692,10 @@ int ap_proxy_http_process_response(proxy_http_req_t *req)
* here though, because error_override or a potential retry on
* another backend could finally read that data and finalize
* the request processing, making keep-alive possible. So what
* we do is restoring r->expecting_100 for ap_set_keepalive()
* to do the right thing according to the final response and
* we do is leaving r->expecting_100 alone, ap_set_keepalive()
* will do the right thing according to the final response and
* any later update of r->expecting_100.
*/
r->expecting_100 = req->expecting_100;
req->expecting_100 = 0;
}
/* Once only! */
@@ -1740,7 +1707,7 @@ int ap_proxy_http_process_response(proxy_http_req_t *req)
/* If we didn't send the full body yet, do it now */
if (do_100_continue) {
req->expecting_100 = 0;
r->expecting_100 = 0;
status = send_continue_body(req);
if (status != OK) {
return status;
@@ -2228,17 +2195,7 @@ static int proxy_http_handler(request_rec *r, proxy_worker *worker,
/* Should we handle end-to-end or ping 100-continue? */
if ((r->expecting_100 && (dconf->forward_100_continue || input_brigade))
|| PROXY_DO_100_CONTINUE(worker, r)) {
/* We need to reset r->expecting_100 or prefetching will cause
* ap_http_filter() to send "100 Continue" response by itself. So
* we'll use req->expecting_100 in mod_proxy_http to determine whether
* the client should be forwarded "100 continue", and r->expecting_100
* will be restored at the end of the function with the actual value of
* req->expecting_100 (i.e. cleared only if mod_proxy_http sent the
* "100 Continue" according to its policy).
*/
req->do_100_continue = 1;
req->expecting_100 = (r->expecting_100 != 0);
r->expecting_100 = 0;
}
/* Should we block while prefetching the body or try nonblocking and flush
@@ -2385,10 +2342,6 @@ cleanup:
ap_proxy_release_connection(proxy_function, req->backend,
r->server);
}
if (req->expecting_100) {
/* Restore r->expecting_100 if we didn't touch it */
r->expecting_100 = req->expecting_100;
}
return status;
}