=== modified file 'src/tunnel.cc'
--- src/tunnel.cc	2011-04-03 12:17:09 +0000
+++ src/tunnel.cc	2011-04-05 11:11:48 +0000
@@ -38,6 +38,7 @@
 #include "HttpRequest.h"
 #include "fde.h"
 #include "comm.h"
+#include "comm/Loops.h"
 #include "comm/Write.h"
 #include "client_side_request.h"
 #include "acl/FilledChecklist.h"
@@ -510,6 +511,27 @@
         return;
     }
 
+    // client-side appears to have scheduled a read handler. make sure we dont collide with it.
+    if (COMMIO_FD_READCB(fd)->active()) {
+        Comm::IoCallback *ccb = COMMIO_FD_READCB(fd);
+
+        // XXX: is this the right thing to do to client-side?
+        // for now it seems okay. tunnel closes the FD on completion for both success and fail.
+        //
+        // BUT in future when the tunnel traffic passes through client-side this may become broken.
+        // should we cancel the existing callback? and drop it? save for resuming later?
+
+        debugs(26, 3, HERE << "switching client FD " << fd << " with callback " << ccb->callback << " to a tunnel.");
+
+        // NP: avoid comm_read_cancel(fd, NULL, NULL) to state the CONNECT as reason for cancel
+        /* Delete the callback */
+        ccb->callback->cancel("tunnelStateData assuming control of client FD");
+        ccb->callback = NULL;
+        ccb->cancel("tunnelStateData assuming control of client FD");
+        /* And the IO event */
+        Comm::SetSelect(fd, COMM_SELECT_READ, NULL, NULL, 0);
+    }
+
     if (cbdataReferenceValid(tunnelState)) {
         tunnelState->copyRead(tunnelState->server, TunnelStateData::ReadServer);
         tunnelState->copyRead(tunnelState->client, TunnelStateData::ReadClient);