Worked around a problem with select/poll/epoll and gnutls

[ira/wip.git] / source4 / lib / stream / packet.c

diff --git a/source4/lib/stream/packet.c b/source4/lib/stream/packet.c
index f614e9490a18d6c0ca8fcf39d5e51375fef614de..f5e2b843cd04e8bb658b3b397157f3635aa50e06 100644 (file)
--- a/source4/lib/stream/packet.c
+++ b/source4/lib/stream/packet.c
@@ -47,6 +47,8 @@ struct packet_context {
        bool busy;
        bool destructor_called;
 
+       bool unreliable_select;
+
        struct send_element {
                struct send_element *next, *prev;
                DATA_BLOB blob;
@@ -176,6 +178,21 @@ _PUBLIC_ void packet_set_nofree(struct packet_context *pc)
        pc->nofree = true;
 }
 
+/*
+  tell the packet system that select/poll/epoll on the underlying
+  socket may not be a reliable way to determine if data is available
+  for receive. This happens with underlying socket systems such as the
+  one implemented on top of GNUTLS, where there may be data in
+  encryption/compression buffers that could be received by
+  socket_recv(), while there is no data waiting at the real socket
+  level as seen by select/poll/epoll. The GNUTLS library is supposed
+  to cope with this by always leaving some data sitting in the socket
+  buffer, but it does not seem to be reliable.
+ */
+_PUBLIC_ void packet_set_unreliable_select(struct packet_context *pc)
+{
+       pc->unreliable_select = true;
+}
 
 /*
   tell the caller we have an error
@@ -230,6 +247,7 @@ _PUBLIC_ void packet_recv(struct packet_context *pc)
        NTSTATUS status;
        size_t nread = 0;
        DATA_BLOB blob;
+       bool recv_retry = false;
 
        if (pc->processing) {
                EVENT_FD_NOT_READABLE(pc->fde);
@@ -269,6 +287,8 @@ _PUBLIC_ void packet_recv(struct packet_context *pc)
                return;
        }
 
+again:
+
        if (npending + pc->num_read < npending) {
                packet_error(pc, NT_STATUS_INVALID_PARAMETER);
                return;
@@ -308,17 +328,33 @@ _PUBLIC_ void packet_recv(struct packet_context *pc)
                packet_error(pc, status);
                return;
        }
+       if (recv_retry && NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
+               nread = 0;
+               status = NT_STATUS_OK;
+       }
        if (!NT_STATUS_IS_OK(status)) {
                return;
        }
 
-       if (nread == 0) {
+       if (nread == 0 && !recv_retry) {
                packet_eof(pc);
                return;
        }
 
        pc->num_read += nread;
 
+       if (pc->unreliable_select && nread != 0) {
+               recv_retry = true;
+               status = socket_pending(pc->sock, &npending);
+               if (!NT_STATUS_IS_OK(status)) {
+                       packet_error(pc, status);
+                       return;
+               }
+               if (npending != 0) {
+                       goto again;
+               }
+       }
+
 next_partial:
        if (pc->partial.length != pc->num_read) {
                if (!data_blob_realloc(pc, &pc->partial, pc->num_read)) {