channel/transport: we now drain the outgoing send buffer when we ignore EAGAIN

When we ignore the EAGAIN from the transport layer within channel_write, we
now drain the outgoing transport layer buffer so that remainders in that
won't cause any problems in the next invoke of _libssh2_transport_write()

src/channel.c

@@ -1979,6 +1979,17 @@ _libssh2_channel_write(LIBSSH2_CHANNEL *channel, int stream_id,
 
     while (buflen > 0) {
         if (channel->write_state == libssh2_NB_state_allocated) {
+
+            /* drain the incoming flow first */
+            do
+                rc = _libssh2_transport_read(session);
+            while (rc > 0);
+
+            if(channel->local.window_size <= 0) {
+                /* there's no more room for data so we stop sending now */
+                break;
+            }
+
             channel->write_bufwrite = buflen;
             channel->write_s = channel->write_packet;
 
@@ -1992,16 +2003,6 @@ _libssh2_channel_write(LIBSSH2_CHANNEL *channel, int stream_id,
                 channel->write_s += 4;
             }
 
-            /* drain the incoming flow first */
-            do
-                rc = _libssh2_transport_read(session);
-            while (rc > 0);
-
-            if(channel->local.window_size <= 0) {
-                /* there's no more room for data so we stop sending now */
-                break;
-            }
-
             /* Don't exceed the remote end's limits */
             /* REMEMBER local means local as the SOURCE of the data */
             if (channel->write_bufwrite > channel->local.window_size) {
@@ -2038,11 +2039,13 @@ _libssh2_channel_write(LIBSSH2_CHANNEL *channel, int stream_id,
                                           channel->write_s -
                                           channel->write_packet);
             if (rc == PACKET_EAGAIN) {
-                if(wrote)
-                    /* some pieces of data was sent before the EAGAIN so
-                       we return that amount! */
+                if(wrote) {
+                    /* some pieces of data was sent before the EAGAIN so we
+                       return that amount! As we ignore EAGAIN, we must drain
+                       the outgoing transport buffer. */
+                    _libssh2_transport_drain(session);
                     goto _channel_write_done;
-
+                }
                 return libssh2_error(session, rc,
                                      "Unable to send channel data");
             }

src/transport.c

@@ -1,5 +1,5 @@
 /* Copyright (C) 2007 The Written Word, Inc.  All rights reserved.
- * Copyright (C) 2009 by Daniel Stenberg
+ * Copyright (C) 2009-2010 by Daniel Stenberg
  * Author: Daniel Stenberg <daniel@haxx.se>
  *
  * Redistribution and use in source and binary forms,
@@ -600,6 +600,20 @@ int _libssh2_transport_read(LIBSSH2_SESSION * session)
     return PACKET_FAIL;         /* we never reach this point */
 }
 
+/*
+ * _libssh2_transport_drain() empties the outgoing send buffer if there
+ * is any.
+ */
+void _libssh2_transport_drain(LIBSSH2_SESSION * session)
+{
+    struct transportpacket *p = &session->packet;
+    if(p->outbuf) {
+        LIBSSH2_FREE(session, p->outbuf);
+        p->outbuf = NULL;
+        p->ototal_num = 0;
+    }
+}
+
 static int
 send_existing(LIBSSH2_SESSION * session, unsigned char *data,
               unsigned long data_len, ssize_t * ret)

src/transport.h

@@ -2,7 +2,7 @@
 #define __LIBSSH2_TRANSPORT_H
 
 /* Copyright (C) 2007 The Written Word, Inc.  All rights reserved.
- * Copyright (C) 2009 by Daniel Stenberg
+ * Copyright (C) 2009-2010 by Daniel Stenberg
  * Author: Daniel Stenberg <daniel@haxx.se>
  *
  * Redistribution and use in source and binary forms,
@@ -77,4 +77,10 @@ int _libssh2_transport_write(LIBSSH2_SESSION * session, unsigned char *data,
  */
 int _libssh2_transport_read(LIBSSH2_SESSION * session);
 
+/*
+ * _libssh2_transport_drain() empties the outgoing send buffer if there
+ * is any.
+ */
+void _libssh2_transport_drain(LIBSSH2_SESSION *session);
+
 #endif /* __LIBSSH2_TRANSPORT_H */