Changeset 1027 for trunk/libtorrent/src/protocol/handshake.cc

Timestamp:

01/12/08 13:39:19 (4 years ago)

Author:

rakshasa

Message:

* Fixed a race condition in the handshake read/write code. Patch by
Josef Drexler.

* Fixed the --with-xmlrpc-c autoconf check so that you can pass an
alternative path to an xmlrpc-c-config script.

Files:

• trunk/libtorrent/src/protocol/handshake.cc (modified) (5 diffs)

trunk/libtorrent/src/protocol/handshake.cc

@@ -526 +526 @@
 
   // The download is just starting so we're not sending any
-  // bitfield.
+  // bitfield. Pretend we wrote it already.
   if (m_download->file_list()->bitfield()->is_all_unset())
-    prepare_post_handshake(true);
+    m_writePos = m_download->file_list()->bitfield()->size_bytes();
   else
     prepare_bitfield();
@@ -618 +618 @@
   }
 
+  // Should've started to write post handshake data already, but we were
+  // still reading the bitfield/extension and postponed it. If we had no
+  // bitfield to send, we need to send a keep-alive now.
+  if (m_writePos == m_download->file_list()->bitfield()->size_bytes())
+    prepare_post_handshake(m_download->file_list()->bitfield()->is_all_unset());
+
   if (m_writeDone)
     throw handshake_succeeded();
@@ -1021 +1027 @@
 void
 Handshake::prepare_post_handshake(bool must_write) {
+  if (m_writePos != m_download->file_list()->bitfield()->size_bytes())
+    throw internal_error("Handshake::prepare_post_handshake called while bitfield not written completely.");
+
   m_state = POST_HANDSHAKE;
 
@@ -1042 +1051 @@
   if (!m_writeBuffer.remaining())
     write_done();
-
-  // Skip writting the bitfield.
-  m_writePos = m_download->file_list()->bitfield()->size_bytes();
 }
 
@@ -1122 +1128 @@
   }
 
-  if (m_writePos == bitfield->size_bytes())
-    prepare_post_handshake(false);
+  // We can't call prepare_post_handshake until the read code is done reading
+  // the bitfield, so if we get here before then, postpone the post handshake
+  // data until reading is done. Since we're done writing, remove us from the
+  // poll in that case.
+  if (m_writePos == bitfield->size_bytes()) {
+    if (!m_readDone)
+      manager->poll()->remove_write(this);
+    else
+      prepare_post_handshake(false);
+  }
 }