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* modules/ssl/ssl_engine_io.c (ssl_io_filter_coalesce): Further tweaks

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to logic, comments and debugging:
  - allow buffering up to exactly COALESCE_BYTES rather than COALESCE_BYTES-1.
  - put bucket type name in logging output
  - do not coalesce a single-bucket prefix of length equal to the
    buffer size (which would be a pointless memory copy).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1876037 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Joe Orton
2020-04-02 08:54:29 +00:00
parent 343cdd9bb4
commit add4e2892b
1 changed files with 31 additions and 16 deletions
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47
modules/ssl/ssl_engine_io.c
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@@ -1704,8 +1704,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
unsigned count = 0;
/* The brigade consists of zero-or-more small data buckets which
* can be coalesced (the prefix), followed by the remainder of the
* brigade.
* can be coalesced (referred to as the "prefix"), followed by the
* remainder of the brigade.
*
* Find the last bucket - if any - of that prefix. count gives
* the number of buckets in the prefix. The "prefix" must contain
@@ -1720,8 +1720,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
e != APR_BRIGADE_SENTINEL(bb)
&& !APR_BUCKET_IS_METADATA(e)
&& e->length != (apr_size_t)-1
&& e->length < COALESCE_BYTES
&& (buffered + bytes + e->length) < COALESCE_BYTES;
&& e->length <= COALESCE_BYTES
&& (buffered + bytes + e->length) <= COALESCE_BYTES;
e = APR_BUCKET_NEXT(e)) {
/* don't count zero-length buckets */
if (e->length) {
@@ -1752,7 +1752,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
rv = apr_bucket_read(e, &discard, &ignore, APR_NONBLOCK_READ);
if (rv != APR_SUCCESS && !APR_STATUS_IS_EAGAIN(rv)) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, f->c, APLOGNO(10232)
"coalesce failed to read from data bucket");
"coalesce failed to read from %s bucket",
e->type->name);
return AP_FILTER_ERROR;
}
}
@@ -1761,8 +1762,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
/* If the read above made the bucket morph, it may now fit
* entirely within the buffer. Otherwise, split it so it does
* fit. */
if (e->length >= COALESCE_BYTES
|| e->length + buffered + bytes >= COALESCE_BYTES) {
if (e->length > COALESCE_BYTES
|| e->length + buffered + bytes > COALESCE_BYTES) {
rv = apr_bucket_split(e, COALESCE_BYTES - (buffered + bytes));
}
@@ -1773,8 +1774,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
else if (rv == APR_SUCCESS) {
ap_log_cerror(APLOG_MARK, APLOG_TRACE4, 0, f->c,
"coalesce: adding %" APR_SIZE_T_FMT " bytes "
"from split bucket, adding %" APR_SIZE_T_FMT,
e->length, bytes + buffered);
"from split %s bucket, total %" APR_SIZE_T_FMT,
e->length, e->type->name, bytes + buffered);
count++;
bytes += e->length;
@@ -1790,14 +1791,26 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
upto = e;
/* Coalesce the prefix, if:
* a) more than one bucket is found to coalesce, or
* b) the brigade contains only a single data bucket, or
* c) the data bucket is not last but we have buffered data already.
/* Coalesce the prefix, if any of the following are true:
*
* a) the prefix is more than one bucket
* OR
* b) the prefix is the entire brigade, which is a single bucket
* AND the prefix length is smaller than the buffer size,
* OR
* c) the prefix is a single bucket
* AND there is buffered data from a previous pass.
*
* The aim with (b) is to buffer a small bucket so it can be
* coalesced with future invocations of this filter. e.g. three
* calls each with a single 100 byte HEAP bucket should get
* coalesced together. But an invocation with a 8192 byte HEAP
* should pass through untouched.
*/
if (bytes > 0
&& (count > 1
|| (upto == APR_BRIGADE_SENTINEL(bb))
|| (upto == APR_BRIGADE_SENTINEL(bb)
&& bytes < COALESCE_BYTES)
|| (ctx && ctx->bytes > 0))) {
/* If coalescing some bytes, ensure a context has been
* created. */
@@ -1808,7 +1821,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
ap_log_cerror(APLOG_MARK, APLOG_TRACE4, 0, f->c,
"coalesce: have %" APR_SIZE_T_FMT " bytes, "
"adding %" APR_SIZE_T_FMT " more", ctx->bytes, bytes);
"adding %" APR_SIZE_T_FMT " more (buckets=%u)",
ctx->bytes, bytes, count);
/* Iterate through the prefix segment. For non-fatal errors
* in this loop it is safe to break out and fall back to the
@@ -1823,7 +1837,8 @@ static apr_status_t ssl_io_filter_coalesce(ap_filter_t *f,
if (APR_BUCKET_IS_METADATA(e)
|| e->length == (apr_size_t)-1) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, f->c, APLOGNO(02012)
"unexpected bucket type during coalesce");
"unexpected %s bucket during coalesce",
e->type->name);
break; /* non-fatal error; break out */
}