Treat all unexpected socket errors as indicating close.

webrtc/base/physicalsocketserver.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "webrtc/base/physicalsocketserver.h"
@@ skipping 688 matching lines @@
   } else if (res == 0) {
     // EOF, so closed.
     return true;
   } else {  // error
     switch (errno) {
       // Returned if we've already closed s_.
       case EBADF:
       // Returned during ungraceful peer shutdown.
       case ECONNRESET:
         return true;
+      // This should only happen when connecting (and at most once), because
+      // in all other cases this function is only called if the file
+      // descriptor is already known to be in the readable state.
+      case EWOULDBLOCK:
+        return false;
       default:
-        // Assume that all other errors are just blocking errors, meaning the
-        // connection is still good but we just can't read from it right now.
-        // This should only happen when connecting (and at most once), because
-        // in all other cases this function is only called if the file
-        // descriptor is already known to be in the readable state. However,
-        // it's not necessary a problem if we spuriously interpret a
-        // "connection lost"-type error as a blocking error, because typically
-        // the next recv() will get EOF, so we'll still eventually notice that
-        // the socket is closed.
-        LOG_ERR(LS_WARNING) << "Assuming benign blocking error";
-        return false;
+        LOG_ERR(LS_WARNING) << "Unexpected error from recv";
+        return true;

[Taylor Brandstetter, 2017/02/09 08:59:47]

I don't think this is safe. There are errors besides EWOULDBLOCK on different
platforms that actually are benign blocking errors, in my experience. So the
default should be to assume it's a benign error.

     }
   }
 }
 
 #endif // WEBRTC_POSIX
 
 uint32_t SocketDispatcher::GetRequestedEvents() {
   return enabled_events_;
 }
 
@@ skipping 866 matching lines @@
        break;
     }
   }
 
   // Done
   return true;
 }
 #endif  // WEBRTC_WIN
 
 }  // namespace rtc