Replace the HTTP/2 session's ad-hoc buffer with isc_buffer_t

This commit replaces a static ad-hoc HTTP/2 session's temporary buffer
with a realloc-able isc_buffer_t object, which is being allocated on
as needed basis, lowering the memory consumption somewhat. The buffer
is needed in very rare cases, so allocating it prematurely is not
wise.

Also, it fixes a bug in http_readcb() where the ad-hoc buffer appeared
to be improperly used, leading to a situation when the processed data
from the receiving regions can be processed twice, while unprocessed
data will never be processed.

diff --git a/lib/isc/netmgr/http.c b/lib/isc/netmgr/http.c
index 4d19593aef08993e096c5d5a47ae248c96e0d926..d32b908191b1cee007b9c377a059b9d61894ca24 100644 (file)
--- a/lib/isc/netmgr/http.c
+++ b/lib/isc/netmgr/http.c
@@ -139,8 +139,7 @@ struct isc_nm_http_session {
        isc_nmhandle_t *client_httphandle;
        isc_nmsocket_t *serversocket;
 
-       uint8_t buf[MAX_DNS_MESSAGE_SIZE];
-       size_t bufsize;
+       isc_buffer_t *buf;
 
        isc_tlsctx_t *tlsctx;
        uint32_t max_concurrent_streams;
@@ -322,6 +321,10 @@ isc__nm_httpsession_detach(isc_nm_http_session_t **sessionp) {
                session->ngsession = NULL;
        }
 
+       if (session->buf != NULL) {
+               isc_buffer_free(&session->buf);
+       }
+
        /* We need an acquire memory barrier here */
        (void)isc_refcount_current(&session->references);
 
@@ -956,10 +959,14 @@ http_readcb(isc_nmhandle_t *handle, isc_result_t result, isc_region_t *region,
        }
 
        if ((size_t)readlen < region->length) {
-               INSIST(session->bufsize == 0);
-               INSIST(region->length - readlen < MAX_DNS_MESSAGE_SIZE);
-               memmove(session->buf, region->base, region->length - readlen);
-               session->bufsize = region->length - readlen;
+               size_t unread_size = region->length - readlen;
+               if (session->buf == NULL) {
+                       isc_buffer_allocate(session->mctx, &session->buf,
+                                           unread_size);
+                       isc_buffer_setautorealloc(session->buf, true);
+               }
+               isc_buffer_putmem(session->buf, region->base + readlen,
+                                 unread_size);
                isc_nm_pauseread(session->handle);
        }
 
@@ -1244,18 +1251,18 @@ http_do_bio(isc_nm_http_session_t *session, isc_nmhandle_t *send_httphandle,
                        /* We have not yet started reading from this handle */
                        isc_nm_read(session->handle, http_readcb, session);
                        session->reading = true;
-               } else if (session->bufsize > 0) {
+               } else if (session->buf != NULL) {
+                       size_t remaining =
+                               isc_buffer_remaininglength(session->buf);
                        /* Leftover data in the buffer, use it */
                        size_t readlen = nghttp2_session_mem_recv(
-                               session->ngsession, session->buf,
-                               session->bufsize);
+                               session->ngsession,
+                               isc_buffer_current(session->buf), remaining);
 
-                       if (readlen == session->bufsize) {
-                               session->bufsize = 0;
+                       if (readlen == remaining) {
+                               isc_buffer_free(&session->buf);
                        } else {
-                               memmove(session->buf, session->buf + readlen,
-                                       session->bufsize - readlen);
-                               session->bufsize -= readlen;
+                               isc_buffer_forward(session->buf, readlen);
                        }
 
                        http_do_bio(session, send_httphandle, send_cb,