Changeset 4261999 in mod_gnutls

Timestamp:

Jan 28, 2015, 5:51:36 PM (8 years ago)

Author:

Thomas Klute <thomas2.klute@…>

Branches:

asyncio, debian/master, debian/stretch-backports, jessie-backports, main, master, proxy-ticket, upstream

Children:

265eafc

Parents:

398d1a0

Message:

gnutls_io_input_read: Retry gnutls_record_recv if necessary

While testing TLS proxy back end connection, requests occasionally
failed (empty response) with strange log messages like these:

[http:info] [pid 17004:tid 140701602649856] (20014)Internal error: [remote A.B.C.D:443] AH01590: Error reading chunk
[proxy_http:error] [pid 17004:tid 140701602649856] (28)No space left on device: [client A.B.C.E:36002] AH01110: error reading response

Investigation of the Apache source code (in particular mod_proxy_http
and the default http filter) indicated that these were the results of
APR_EGENERAL errors returned from the mod_gnutls input filter
(mgs_filter_input) while receiving the response from the back end
server.

The reason behind these errors was that gnutls_io_input_read (called
directly or through gnutls_io_input_getline) did not handle
interruptions of the GnuTLS receive function gnutls_record_recv
properly. The GnuTLS documentation states that "If GNUTLS_E_INTERRUPTED
or GNUTLS_E_AGAIN is returned, you must call this function again to get
the data." Adding a retry loop like the ones already used for some other
GnuTLS library calls in gnutls_io.c around the gnutls_record_recv call
solved the problem.

File:

• src/gnutls_io.c (modified) (2 diffs)

src/gnutls_io.c

@@ -231 +231 @@
     while (1) {
 
-        rc = gnutls_record_recv(ctxt->session, buf + bytes,
-                wanted - bytes);
+        do
+            rc = gnutls_record_recv(ctxt->session, buf + bytes,
+                                    wanted - bytes);
+        while (rc == GNUTLS_E_INTERRUPTED || rc == GNUTLS_E_AGAIN);
 
         if (rc > 0) {
@@ -312 +314 @@
 
             if (ctxt->input_rc == APR_SUCCESS) {
+                ap_log_cerror(APLOG_MARK, APLOG_INFO, ctxt->input_rc, ctxt->c,
+                              "%s: GnuTLS error: %s (%d)",
+                              __func__, gnutls_strerror(rc), rc);
                 ctxt->input_rc = APR_EGENERAL;
             }